The out-of-Africa theory basically says that humans evolved in Africa, then spread in several pulses across the rest of the planet. The first hominin to leave Africa–as far as we know–was Erectus, followed by the Neanderthals/Denisovans, and finally Sapiens. Where exactly smaller, less well-known hominins like Homo Floresiensis fit into the picture we don’t know, yet.)
One of the incredible things about human evolution is just how many other human species we used to co-exist with. We shared this earth with at least 8 other species of human, met and mated with at least 4 of them. Before us came a proliferation of australopithecines.
Today, there is only us. This stunning diversity of upright apes has been winnowed to a single line. Species that had survived for thousands if not millions of years disappeared, either because they died out or were wiped out. We, sapiens, are the last ones standing.
Humans met Neanderthals. We interbred, briefly. Then the Neanderthals died out. Humans met Denisovans. We interbred, briefly. Then the Denisovans disappeared. Humans met so-called “Ghost populations” in west and southern Africa and interbred. The ghosts then disappeared. It’s all very mysterious how every other species of hominin and australopithecine seems to have died out immediately after we sapiens arrived in the area.
This implies, then, that sapiens didn’t live in these areas during the thousands or so years before we wiped out the locals (though some small exceptions may exist.)
So where did we live?
The West African Ghost Population contributed a big chunk of DNA to modern humans a mere 50,000 years ago–around the same time as sapiens were mating with Neanderthals. This seems to have been a much more significant encounter than the one with Neanderthals–perhaps many of these “ghosts” joined the sapiens who moved into their area.
So west Africa was likely not inhabited by modern humans before 50,000 years ago.
Homo naledi is too small to have co-existed with us, effectively ruling out their part of South Africa during that period, and the Pygmies probably interbred with their mystery hominin around 35,000 years ago, so that rules out the Congolese forest area.
The Neanderthal ancestry is in pretty much everyone not in Africa, (and a little in Africa due to recent back-migration) which is pretty strong support for the out-of-Africa theory. The most parsimonious explanation is that a single population split, and half of that population, as it entered Eurasia, encountered Neanderthals, while the other half traveled deeper into Africa and encountered African hominins.
East Africa/the horn of Africa region remains, therefore, the most logical spot to locate Homo sapiens immediately before this splitting phase, but I wouldn’t rule out the Middle East.
On the other hand, Homo sapiens’s ancestor, Homo heidelbergensis, lived in Africa, Europe, and the Middle East for thousands, possibly a million years (depending on how we classify the similar bones of Homo antecessor, who lived near Norfolk, England, about 950,000 years ago. Homo heidelbergensis’s (probable) ancestor, Homo erectus, lived in Africa, Europe, and Asia for over a million years.
Here’s where it gets complicated, because while species like the little hobbits from Flores are clearly different from other varieties of Homo, there are no clear dividing lines between folks like erectus, heidelbergensis, and ergastor. We have a bunch of bones, a few nice skulls, scattered across continents and centuries, from which we try to derive a vague sense of whether this population and that population were similar enough to consider them a single species. Quoting Wikipedia:
Although “Homo ergaster” has gained some acceptance as a valid taxon since its proposal in 1975, ergaster and erectus since the 1980s have increasingly come to be seen as separate (that is, African or Asian) populations of the larger species H. erectus. … The question was described as “famously unresolved” as of 2003. Sura et al (2007) concluded that Homo erectus “was a likely source of multiple events of gene flow to the Eurasian continent”.
The discoveries of the Dmanisi skulls in the South Caucasus since 2005 have re-opened this question. Their great morphological diversity suggests that the variability of Eurasian H. erectus already includes the African fossils dubbed H. ergaster. The discovery of Dmanisi skull 5 in 2013, dated to 1.8 million years ago, now dates evidence of H. erectus in Eurasia as of virtually the same age as evidence for H. ergaster in Africa, so that it is unclear if the speciation of H. erectus/ergaster from H. habilis took place in Africa or Asia. This has reinforced the trend of considering H. ergaster as synonymous with H. erectus, a species which would have evolved just after 2 million years ago, either in Africa or West Asia, and later dispersed throughout Africa and Eurasia.
Homo habilis, by contrast, is (so far) only found in east Africa.
What does it mean to evolve in a place? Habilis, as far as we know, actually did evolve in Africa. It didn’t leave Africa; neither did the australopithecines (unless one of those little hobbity folks out in the Philippines turn out to be australopiths, but that would be very remarkable). But after that, “humans” spread from Africa to Europe and Asia with remarkable speed. They lived in England almost a million years ago. And within this range, we seem to have become repeatedly isolated, speciated, and then met back up again when the weather improved.
Personally, I wouldn’t say that the out of Africa theory is wrong. It is still the most parsimonious explanation of human evolutionary history. However, I would say that it simplifies a huge chunk of our history, since for most of our time on this earth, our range has been quite a bit larger than Africa.
Homo Sapiens–that is, us, modern humans, are about 200-300,000 years old. Our ancestor, Homo heidelbergensis, lived in Africa around 700,000-300,000 years ago.
Around 700,000 years ago, another group of humans split off from the main group. By 400,000 years ago, their descendants, Homo neanderthalensis–Neanderthals–had arrived in Europe, and another band of their descendants, the enigmatic Denisovans, arrived in Asia.
While we have found quite a few Neanderthal remains and archaeological sites with tools, hearths, and other artifacts, we’ve uncovered very few Denisovan remains–a couple of teeth, a finger bone, and part of an arm in Denisova Cave, Russia. (Perhaps a few other remains I am unaware of.)
Yet from these paltry remains scientists have extracted enough DNA to ascertain that no only were Denisovans a distinct species, but also that Melanesians, Papuans, and Aborigines derive about 3-6% of their DNA from a Denisovan ancestors. (All non-African populations also have a small amount of Neanderthal DNA, derived from a Neanderthal ancestors.)
If Neanderthals and Homo sapiens interbred, and Denisovans and Homo sapiens interbred, did Neanderthals and Denisovans ever mate?
The girl, affectionately nicknamed Denny, lived and died about 90,000 years ago in Siberia. The remains of an arm, found in Denisova Cave, reveal that her mother was a Neanderthal, her father a Denisovan.
We don’t yet know what Denisovans looked like, because we don’t have any complete skeletons of them, much less good skulls to examine, so we don’t know what a Neanderthal-Denisovan hybrid like Denny looked like.
But the fact that we can extract so much information from a single bone–or fragment of bone–preserved in a Siberian cave for 90,000 years–is amazing.
We are still far from truly understanding what sorts of people our evolutionary cousins were, but we are gaining new insights all the time.
Greetings! Grab a cup of coffee and pull up a chair. Tea is also good. Today we’re diving into chapter one of Philip Auerswald’s The Code Economy, “Jobs: Divide and Coordinate.”
I wish this chapter had been much longer; we speed through almost 2.5 million years of cognitive evolution in a couple of pages.
The earliest hominins had about the same short-term memory as a modern-day chimpanzee, which is to say they could keep track of only two operations at a time. … Our methods for creating tools gradually became more sophisticated, until we were using the tools we created to produce other tools in a repetitive and predictable manner. These processes for creating stone tools were among humanity’s first production algorithms-that is, the earliest code. They appeared almost simultaneously in human communities in most part of the world around 40,000 BC.
…[E.O.] Wilson refers to this phenomenon more broadly as the discovery of eusocial behavior… Wilson situates the date far earlier in human history than I do here. I chose 50,000 years [ago] because my focus is on the economy. it is clear that an epochal change in society occurred roughly 10,000 years BCE, when humans invented agriculture in six parts of the world simultaneously. The fact of this simultaneity directly suggests the advance of code represented by the invention of agriculture was part of a forward movement of code that started much earlier.
What do you think? Does the simultaneous advent of behavioral modernity–or eusociality–in far-flung human groups roughly 50,000 years ago, followed by the simultaneous advent of agriculture in several far-flung groups about 10,000 years ago speak to the existence of some universal, underlying process? Why did so many different groups of people develop similar patterns of life and technology around the same time, despite some of them being highly isolated? Was society simply inevitable?
The caption on the photo is similarly interesting:
Demand on Short-Term Working Memory in the Production of an Obsidian Axe [from Read and van der Leeuw, 2015] … We can relate the concepts invoked in the prodcution of stone tools to the number of dimensions involved and thereby to the size of short-term workign memory (STWM) required for the prodction of the kind of stone tools that exemplify each stage in hominin evolution. …
Just hitting the end of a pebble once to create one edge, as in the simplest tools, they calculate requires holding three items in the working memory. Removing several flakes to create a longer edge (a line), takes STWM 4; working an entire side takes STWM 5; and working both sides of the stone in preparation for knapping flakes from the third requires both an ability to think about the pebble’s shape in three dimensions and STWM 7.
(The Wikipedia article on Lithic Reduction has a lovely animation of the technique.)
It took about 2 million years to proceed from the simplest tools (working memory: 3) to the most complex (working memory: 7.) Since the Neolithic, our working memory hasn’t improved–most of us are still limited to a mere 7 items in our working memory, just enough to remember a phone number if you already know the area code.
All of our advances since the Neolithic, Auerswald argues, haven’t been due to an increase in STWM, but our ability to build complexity externally: through code. And it was this invention of code that really made society take off.
By about 10,000 BCE, humans had formed the first villages… Villages were the precursors of modern-day business firms in that they were durable association built around routines. … the advance of code at the village level through the creation of new technological combinations set into motion the evolution from simplicity to complexity that has resulted in the modern economy.
It was in the village, then, that code began to evolve.
What do you think? Are Read and van der Leeuw just retroactively fitting numbers 3-7 to the tools, or do they really show an advance in working memory? Is the village really the source of most code evolution? And who do you think is more correct, Herbert Spencer or Thomas Malthus?
Auerswald then forward to 1557, with the first use of the word “job” (spelled “jobbe,” most likely from “gobbe,” or lump.)
The advent of the “jobbe” a a lump of work was to the evolution of modern society something like what the first single-celled organism was to the evolution of life.
The “jobbe” contrasted with the obligation to perform labor continuously and without clearly defined roles–slavery, serfdom, indentured servitude, or even apprenticeship–as had been the norm throughout human history.
Did the Black Death help create the modern “job market” by inspiring Parliament to pass the Statute of Laborers?
I am reminded here of a passage from Gulick’s Evolution of the Japanese, Social and Psychic, (published in 1903):
The idea of making a bargain when two persons entered upon some particular piece of work, the one as employer, the other as employed, was entirely repugnant to the older generation, since it was assumed that their relations as inferior and superior should determine their financial relations; the superior would do what was right, and the inferior should accept what the superior might give without a question or a murmur. Among the samurai, where the arrangement is between equals, bargaining or making fixed and fast terms which will hold to the end, and which may be carried to the courts in case of differences, was a thing practically unknown in the older civilization. Everything of a business nature was left to honor, and was carried on in mutual confidence.
“A few illustrations of this spirit of confidence from my own experience may not be without interest. On first coming to Japan, I found it usual for a Japanese who wished to take a jinrikisha to call the runner and take the ride without making any bargain, giving him at the end what seemed right. And the men generally accepted the payment without question. I have found that recently, unless there is some definite understanding arrived at before the ride, there is apt to be some disagreement, the runner presuming on the hold he has, by virtue of work done, to get more than is customary. This is especially true in case the rider is a foreigner. Another set of examples in which astonishing simplicity and confidence were manifested was in the employment of evangelists. I have known several instances in which a full correspondence with an evangelist with regard to his employment was carried on, and the settlement finally concluded, and the man set to work without a word said about money matters. It need hardly be said that no foreigner took part in that correspondence. …
“This confidence and trustfulness were the product of a civilization resting on communalistic feudalism; the people were kept as children in dependence on their feudal lord; they had to accept what he said and did; they were accustomed to that order of things from the beginning and had no other thought; on the whole too, without doubt, they received regular and kindly treatment. Furthermore, there was no redress for the peasant in case of harshness; it was always the wise policy, therefore, for him to accept whatever was given without even the appearance of dissatisfaction. This spirit was connected with the dominance of the military class. Simple trustfulness was, therefore, chiefly that of the non-military classes. …
“Since the overthrow of communal feudalism and the establishment of an individualistic social order, necessitating personal ownership of property, and the universal use of money, trustful confidence is rapidly passing away.
We still identify ourselves with our profession–“I am a doctor” or “I am a paleontologist”–but much less so than in the days when “Smith” wasn’t a name.
Auerswald progresses to the modern day:
In the past two hundred years, the complexity of human economic organization has increased by orders of magnitude. Death rates began to fall rapidly in the middle of the nineteenth century, due to a combination of increased agricultural output, improved hygiene, and the beginning of better medical practices–all different dimensions of the advance of code…. Greater numbers of people living in greater density than ever before accelerated the advance of code.
Sounds great, but:
By the twentieth century, the continued advance of code necessitated the creation of government bureaucracies and large corporations that employed vast numbers of people. These organizations executed code of sufficient complexity that it was beyond the capacity of any single individual to master.
I’ve often wondered if the explosion of communist disasters at the beginning of the 20th century occurred because we could imagine a kind of nation-wide code for production and consumption and we had the power to implement it, but we didn’t actually have the capabilities and tools necessary to make it work.
We can imagine Utopia, but we cannot reach it.
Auerswald delineates two broad categories of “epochal change” as a result of the code-explosion of the past two centuries: First, our capabilities grew. Second:
“we have, to an increasing degree, ceded to other people–and to code itself–authority and autonomy, which for millennia we had kept unto ourselves and our immediate tribal groups as uncodified cultural norms.”
Before the “job”, before even the “trade,” people lived and worked far more at their own discretion. Hoeing fields or gathering yams might be long and tedious work, but at least you didn’t have to pee in a bottle because Amazon didn’t give you time for bathroom breaks.
Every time voters demand that politicians “bring back the jobs” or politicians promise to create them, we are implicitly stating that the vast majority of people are no longer capable of making their own jobs. (At least, not jobs that afford a modern lifestyle.) The Appalachians lived in utter poverty (the vast majority of people before 1900 lived in what we would now call utter poverty), but they did not depend on anyone else to create “jobs” for them; they cleared their own land, planted their own corn, hunted their own hogs, and provided for their own needs.
Today’s humans are (probably not less intelligent nor innately capable than the average Appalachian of 1900, but the economy (and our standards of living) are much more complex. The average person no longer has the capacity to drive job growth in such a complicated system, but the solution isn’t necessarily for everyone to become smarter. After all, large, complicated organizations need hundreds of employees who are not out founding their own companies.
But this, in turn, means all of those employees–and even the companies themselves–are dependent on forces far outside their control, like Chinese monetary policy or the American electoral cycle. And this, in turn, raises demand for some kind of centralized, planned system to protect the workers from economic hardship and ensure that everyone enjoys a minimum standard of living.
Microstates suggest themselves as a way to speed the evolution of economic code by increasing the total number of organisms in the ecosystem.
With eusociality, man already became a political (that is, polis) animal around 10,000 or 40,000 or perhaps 100,000 years ago, largely unable to subsist on his own, absent the tribe. We do not seem to regret this ill-remembered transition very much, but what about the current one? Is the job-man somehow less human, less complete than the tradesman? Do we feel that something essential to the human spirit has been lost in defining and routinizing our daily tasks down to the minute, forcing men to bend to the timetables of factories and international corporations? Or have we, through the benefits of civilization (mostly health improvements) gained something far richer?
The smartest non-human primates, like Kanzi the bonobo and Koko the gorilla, understand about 2,000 to 4,000 words. Koko can make about 1,000 signs in sign language and Kanzi can use about 450 lexigrams (pictures that stand for words.) Koko can also make some onomatopoetic words–that is, she can make and use imitative sounds in conversation.
A four year human knows about 4,000 words, similar to an exceptional gorilla. An adult knows about 20,000-35,000 words. (Another study puts the upper bound at 42,000.)
Somewhere along our journey from ape-like hominins to homo sapiens sapiens, our ancestors began talking, but exactly when remains a mystery. The origins of writing have been amusingly easy to discover, because early writers were fond of very durable surfaces, like clay, stone, and bone. Speech, by contrast, evaporates as soon as it is heard–leaving no trace for archaeologists to uncover.
But we can find the things necessary for speech and the things for which speech, in turn, is necessary.
The main reason why chimps and gorillas, even those taught human language, must rely on lexigrams or gestures to communicate is that their voiceboxes, lungs, and throats work differently than ours. Their semi-arborial lifestyle requires using the ribs as a rigid base for the arm and shoulder muscles while climbing, which in turn requires closing the lungs while climbing to provide support for the ribs.
Full bipedalism released our early ancestors from the constraints on airway design imposed by climbing, freeing us to make a wider variety of vocalizations.
Now is the perfect time to break out my file of relevant human evolution illustrations:
We humans split from our nearest living ape relatives about 7-8 million years ago, but true bipedalism may not have evolved for a few more million years. Since there are many different named hominins, here is a quick guide:
Australopithecines (light blue in the graph,) such as the famous Lucy, are believed to have been the first fully bipedal hominins, although, based on the shape of their toes, they may have still occasionally retreated into the trees. They lived between 4 and 2 million years ago.
Without delving into the myriad classification debates along the lines of “should we count this set of skulls as a separate species or are they all part of the natural variation within one species,” by the time the homo genus arises with H Habilis or H. Rudolfensis around 2.8 million years ag, humans were much worse at climbing trees.
Interestingly, one direction humans have continued evolving in is up.
The reliable production of stone tools represents an enormous leap forward in human cognition. The first known stone tools–Oldowan–are about 2.5-2.6 million years old and were probably made by homo Habilis. These simple tools are typically shaped only one one side.
By the Acheulean–1.75 million-100,000 years ago–tool making had become much more sophisticated. Not only did knappers shape both sides of both the tops and bottoms of stones, but they also made tools by first shaping a core stone and then flaking derivative pieces from it.
The first Acheulean tools were fashioned by h Erectus; by 100,000 years ago, h Sapiens had presumably taken over the technology.
Flint knapping is surprisingly difficult, as many an archaeology student has discovered.
These technological advances were accompanied by steadily increasing brain sizes.
I propose that the complexities of the Acheulean tool complex required some form of language to facilitate learning and teaching; this gives us a potential lower bound on language around 1.75 million years ago. Bipedalism gives us an upper bound around 4 million years ago, before which our voice boxes were likely more restricted in the sounds they could make.
A Different View
Even though “homo Sapiens” has been around for about 300,000 years (or so we have defined the point where we chose to differentiate between our species and the previous one,) “behavioral modernity” only emerged around 50,000 years ago (very awkward timing if you know anything about human dispersal.)
Everything about behavioral modernity is heavily contested (including when it began,) but no matter how and when you date it, compared to the million years or so it took humans to figure out how to knap the back side of a rock, human technologic advance has accelerated significantly over the past 100,000 and even moreso over the past 50,000 and even 10,000.
Fire was another of humanity’s early technologies:
Claims for the earliest definitive evidence of control of fire by a member of Homo range from 1.7 to 0.2 million years ago (Mya). Evidence for the controlled use of fire by Homo erectus, beginning some 600,000 years ago, has wide scholarly support. Flint blades burned in fires roughly 300,000 years ago were found near fossils of early but not entirely modern Homo sapiens in Morocco. Evidence of widespread control of fire by anatomically modern humans dates to approximately 125,000 years ago.
What prompted this sudden acceleration? Noam Chomsky suggests that it was triggered by the evolution of our ability to use and understand language:
Noam Chomsky, a prominent proponent of discontinuity theory, argues that a single chance mutation occurred in one individual in the order of 100,000 years ago, installing the language faculty (a component of the mind–brain) in “perfect” or “near-perfect” form.
More specifically, we might say that this single chance mutation created the capacity for figurative or symbolic language, as clearly apes already have the capacity for very simple language. It was this ability to convey abstract ideas, then, that allowed humans to begin expressing themselves in other abstract ways, like cave painting.
I disagree with this view on the grounds that human groups were already pretty widely dispersed by 100,000 years ago. For example, Pygmies and Bushmen are descended from groups of humans who had already split off from the rest of us by then, but they still have symbolic language, art, and everything else contained in the behavioral modernity toolkit. Of course, if a trait is particularly useful or otherwise successful, it can spread extremely quickly (think lactose tolerance,) and neither Bushmen nor Pygmies were 100% genetically isolated for the past 250,000 years, but I simply think the math here doesn’t work out.
However, that doesn’t mean Chomsky isn’t on to something. For example, Johanna Nichols (another linguist,) used statistical models of language differentiation to argue that modern languages split around 100,000 years ago. This coincides neatly with the upper bound on the Out of Africa theory, suggesting that Nichols may actually have found the point when language began differentiating because humans left Africa, or perhaps she found the origin of the linguistic skills necessary to accomplish humanity’s cross-continental trek.
In normal adults these two portions of the SVT form a right angle to one another and are approximately equal in length—in a 1:1 proportion. Movements of the tongue within this space, at its midpoint, are capable of producing tenfold changes in the diameter of the SVT. These tongue maneuvers produce the abrupt diameter changes needed to produce the formant frequencies of the vowels found most frequently among the world’s languages—the “quantal” vowels [i], [u], and [a] of the words “see,” “do,” and “ma.” In contrast, the vocal tracts of other living primates are physiologically incapable of producing such vowels.
(Since juvenile humans are shaped differently than adults, they pronounce sounds slightly differently until their voiceboxes fully develop.)
…Neanderthal necks were too short and their faces too long to have accommodated equally proportioned SVTs. Although we could not reconstruct the shape of the SVT in the Homo erectus fossil because it does not preserve any cervical vertebrae, it is clear that its face (and underlying horizontal SVT) would have been too long for a 1:1 SVT to fit into its head and neck. Likewise, in order to fit a 1:1 SVT into the reconstructed Neanderthal anatomy, the larynx would have had to be positioned in the Neanderthal’s thorax, behind the sternum and clavicles, much too low for effective swallowing. …
Surprisingly, our reconstruction of the 100,000-year-old specimen from Israel, which is anatomically modern in most respects, also would not have been able to accommodate a SVT with a 1:1 ratio, albeit for a different reason. … Again, like its Neanderthal relatives, this early modern human probably had an SVT with a horizontal dimension longer than its vertical one, translating into an inability to reproduce the full range of today’s human speech.
It was only in our reconstruction of the most recent fossil specimens—the modern humans postdating 50,000 years— that we identified an anatomy that could have accommodated a fully modern, equally proportioned vocal tract.
Just as small children who can’t yet pronounce the letter “r” can nevertheless make and understand language, I don’t think early humans needed to have all of the same sounds as we have in order to communicate with each other. They would have just used fewer sounds.
The change in our voiceboxes may not have triggered the evolution of language, but been triggered by language itself. As humans began transmitting more knowledge via language, humans who could make more sounds could utter a greater range of words perhaps had an edge over their peers–maybe they were seen as particularly clever, or perhaps they had an easier time organizing bands of hunters and warriors.
One of the interesting things about human language is that it is clearly simultaneously cultural–which language you speak is entirely determined by culture–and genetic–only humans can produce language in the way we do. Even the smartest chimps and dolphins cannot match our vocabularies, nor imitate our sounds. Human infants–unless they have some form of brain damage–learn language instinctually, without conscious teaching. (Insert reference to Steven Pinker.)
Some kind of genetic changes were obviously necessary to get from apes to human language use, but exactly what remains unclear.
A variety of genes are associated with language use, eg FOXP2. H Sapiens and chimps have different versions of the FOXP2 gene, (and Neanderthals have a third, but more similar to the H Sapiens version than the chimp,) but to my knowledge we have yet to discover exactly when the necessary mutations arose.
Despite their impressive skulls and survival in a harsh, novel climate, Neanderthals seem not to have engaged in much symbolic activity, (though to be fair, they were wiped out right about the time Sapiens really got going with its symbolic activity.) Homo Sapiens and Homo Nanderthalis split around 800-400,000 years ago–perhaps the difference in our language genes ultimately gave Sapiens the upper hand.
Just as farming appears to have emerged relatively independently in several different locations around the world at about the same time, so behavioral modernity seems to have taken off in several different groups around the same time. Of course we can’t rule out the possibility that these groups had some form of contact with each other–peaceful or otherwise–but it seems more likely to me that similar behaviors emerged in disparate groups around the same time because the cognitive precursors necessary for those behaviors had already begun before they split.
Based on genetics, the shape of their larynges, and their cultural toolkits, Neanderthals probably did not have modern speech, but they may have had something similar to it. This suggests that at the time of the Sapiens-Neanderthal split, our common ancestor possessed some primitive speech capacity.
By the time Sapiens and Neanderthals encountered each other again, nearly half a million years later, Sapiens’ language ability had advanced, possibly due to further modification of FOXP2 and other genes like it, plus our newly modified voiceboxes, while Neanderthals’ had lagged. Sapiens achieved behavioral modernity and took over the planet, while Neanderthals disappeared.
The Pirahã are a small tribe (about 420) of Amazonian hunter-gatherers whose language is nearly unique: it has no numbers, and you can whistle it. Everett spent much of his childhood among the Piraha because his parents were missionaries, which probably makes him one of the world’s foremost non-Piraha experts on the Piraha.
Occasionally as a child I would wake up in the jungle to the cacophony of people sharing their dreams with one another–impromptu monologues followed by spurts of intense feedback. The people in question, a fascinating (to me anyhow) group known as the Piraha, are known to wake up and speak to their immediate neighbors at all hours of the night. … the voices suggested the people in the village were relaxed and completely unconcerned with my own preoccupations. …
The Piraha village my family lived in was reachable via a one-week sinuous trip along a series of Amazonian tributaries, or alternatively by a one-or flight in a Cessna single-engine airplane.
Piraha culture is, to say the least, very different from ours. Everett cites studies of Piraha counting ability in support of his idea that our ability to count past 3 is a culturally acquired process–that is, we can only count because we grew up in a numeric society where people taught us numbers, and the Piraha can’t count because they grew up in an anumeric society that not only lacks numbers, but lacks various other abstractions necessary for helping make sense of numbers. Our innate, genetic numerical abilities, (the ability to count to three and distinguish between small and large amounts,) he insists, are the same.
You see, the Piraha really can’t count. Line up 3 spools of thread and ask them to make an identical line, and they can do it. Line up 4 spools of thread, and they start getting the wrong number of spools. Line up 10 spools of thread, and it’s obvious that they’re just guessing and you’re wasting your time. Put five nuts in a can, then take two out and ask how many nuts are left: you get a response on the order of “some.”*
And this is not for lack of trying. The Piraha know other people have these things called “numbers.” They once asked Everett’s parents, the missionaries, to teach them numbers so they wouldn’t get cheated in trade deals. The missionaries tried for 8 months to teach them to count to ten and add small sums like 1 + 1. It didn’t work and the Piraha gave up.
Despite these difficulties, Everett insists that the Piraha are not dumb. After all, they survive in a very complex and demanding environment. He grew up with them; many of the are his personal friends and he regards them as mentally normal people with the exact same genetic abilities as everyone else who just lack the culturally-acquired skill of counting.
After all, on a standard IQ scale, someone who cannot even count to 4 would be severely if not profoundly retarded, institutionalized and cared for by others. The Piraha obviously live independently, hunt, raise, and gather their own food, navigate through the rainforest, raise their own children, build houses, etc. They aren’t building aqueducts, but they are surviving perfectly well outside of an institution.
Everett neglects the possibility that the Piraha are otherwise normal people who are innately bad at math.
Normally, yes, different mental abilities correlate because they depend highly on things like “how fast is your brain overall” or “were you neglected as a child?” But people also vary in their mental abilities. I have a friend who is above average in reading and writing abilities, but is almost completely unable to do math. This is despite being raised in a completely numerate culture, going to school, etc.
This is a really obvious and life-impairing problem in a society like ours, where you have to use math to function; my friend has been marked since childhood as “not cognitively normal.” It would be a completely invisible non-problem in a society like the Piraha, who use no math at all; in Piraha society, my friend would be “a totally normal guy” (or at least close.)
Everett states, explicitly, that not only are the Piraha only constrained by culture, but other people’s abilities are also directly determined by their cultures:
What is probably more remarkable about the relevant studies, though, is that they suggest that climbing any rungs of the arithmetic ladder requires numbers. How high we climb the ladder is not the result of our own inherent intelligence, but a result of the language we speak and of the culture we are born into. (page 136)
This is an absurd claim. Even my own children, raised in identically numerate environments and possessing, on the global scale, nearly identical genetics, vary in math abilities. You are probably not identical in abilities to your relatives, childhood classmates, next door neighbors, spouse, or office mates. We observe variations in mathematical abilities within cultures, families, cities, towns, schools, and virtually any group you chose that isn’t selected for math abilities. We can’t all do calculus just because we happen to live in a culture with calculus textbooks.
Various studies have found the heritability of IQ to be between 0.7 and 0.8 in adults and 0.45 in childhood in the United States. It may seem reasonable to expect that genetic influences on traits like IQ should become less important as one gains experiences with age. However, that the opposite occurs is well documented. Heritability measures in infancy are as low as 0.2, around 0.4 in middle childhood, and as high as 0.8 in adulthood. One proposed explanation is that people with different genes tend to seek out different environments that reinforce the effects of those genes. The brain undergoes morphological changes in development which suggests that age-related physical changes could also contribute to this effect.
A 1994 article in Behavior Genetics based on a study of Swedish monozygotic and dizygotic twins found the heritability of the sample to be as high as 0.80 in general cognitive ability; however, it also varies by trait, with 0.60 for verbal tests, 0.50 for spatial and speed-of-processing tests, and 0.40 for memory tests. In contrast, studies of other populations estimate an average heritability of 0.50 for general cognitive ability.
In plain speak, this means that intelligence in healthy adults is about 70-80% genetic and the rest seems to be random chance (like whether you were dropped on your head as a child or had enough iodine). So far, no one has proven that things like whole language vs. phonics instruction or two parents vs. one in the household have any effect on IQ, though they might effect how happy you are.
(Childhood IQ is much more amenable to environmental changes like “good teachers,” but these effects wear off as soon as children aren’t being forced to go to school every day.)
A full discussion of the scientific literature is beyond our current scope, but if you aren’t convinced about the heritability of IQ–including math abilities–I urge you to go explore the literature yourself–you might want to start with some of Jayman’s relevant FAQs on the subject.
Everett uses experiments done with the Piraha to support his claim that mathematical ability is culturally dependent, but this is dependent on is claim that the Piraha are cognitively identical to the rest of us in innate mathematical ability. Given that normal people are not cognitively identical in innate mathematical abilities, and mathematical abilities vary, on average, between groups (this is why people buy “Singapore Math” books and not “Congolese Math,”) there is no particular reason to assume Piraha and non-Piraha are cognitively identical. Further, there’s no reason to assume that any two groups are cognitively identical.
Mathematics only really got started when people invented agriculture, as they needed to keep track of things like “How many goats do I have?” or “Have the peasants paid their taxes?” A world in which mathematical ability is useful will select for mathematical ability; a world where it is useless cannot select for it.
Everett may still be correct that you wouldn’t be able to count if you hadn’t been taught how, but the Piraha can’t prove that one way or another. He would first have to show that Piraha who are raised in numerate cultures (say, by adoption,) are just as good at calculus as people from Singapore or Japan, but he cites no adoption studies nor anything else to this end. (And adoption studies don’t even show that for the groups we have studied, like whites, blacks, or Asians.)
Let me offer a cognitive contrast:
The Piraha are an anumeric, illiterate culture. They have encountered both letters and numbers, but not adopted them.
The Cherokee were once illiterate: they had no written language. Around 1809, an illiterate Cherokee man, Sequoyah, observed whites reading and writing letters. In a flash of insight, Sequoyah understand the concept of “use a symbol to encode a sound” even without being taught to read English. He developed his own alphabet (really a syllabary) for writing Cherokee sounds and began teaching it to others. Within 5 years of the syllabary’s completion, a majority of the Cherokee were literate; they soon had their own publishing industry producing Cherokee-language books and newspapers.
The Cherokee, though illiterate, possessed the innate ability to be literate, if only exposed to the cultural idea of letters. Once exposed, literacy spread rapidly–instantly, in human cultural evolution terms.
By contrast, the Piraha, despite their desire to adopt numbers, have not been able to do so.
(Yet. With enough effort, the Piraha probably can learn to count–after all, there are trained parrots who can count to 8. It would be strange if they permanently underperformed parrots. But it’s a difficult journey.)
That all said, I would like to make an anthropological defense of anumeracy: numeracy, as in ascribing exact values to specific items, is more productive in some contexts than others.
Do you keep track of the exact values of things you give your spouse, children, or close friends? If you invite a neighbor over for a meal, do you mark down what it cost to feed them and then expect them to feed you the same amount in return? Do you count the exact value of gifts and give the same value in return?
In Kabloona, de Poncin discusses the quasi-communist nature of the Eskimo economic system. For the Eskimo, hunter-gatherers living in the world’s harshest environment, the unit of exchange isn’t the item, but survival. A man whom you keep alive by giving him fish today is a man who can keep you alive by giving you fish tomorrow. Declaring that you will only give a starving man five fish because he previously gave you five fish will do you no good at all if he starves from not enough fish and can no longer give you some of his fish when he has an excess. The fish have, in this context, no innate, immutable value–they are as valuable as the life they preserve. To think otherwise would kill them.
It’s only when people have goods to trade, regularly, with strangers, that they begin thinking of objects as having defined values that hold steady over different transactions. A chicken is more valuable if I am starving than if I am not, but it has an identical value whether I am trading it for nuts or cows.
So it is not surprising that most agricultural societies have more complicated number systems than most hunter-gatherer societies. As Everett explains:
Led by Patience Epps of the University of Texas, a team of linguists recently documented the complexity of the number systems in many of the world’s languages. In particular, the researchers were concerned with the languages’ upper numerical limit–the highest quantity with a specific name. …
We are fond of coining new names for numbers in English, but the largest commonly used number name is googol (googolplex I define as an operation,) though there are bigger one’s like Graham’s.
The linguistic team in question found the upper numerical limits in 193 languages of hunter-gatherer cultures in Australia, Amazonia, Africa, and North America. Additionally, they examined the upper limits of 204 languages spoken by agriculturalists and pastoralists in these regions. They discovered that the languages of hunter-gatherer groups generally have low upper limits. This is particularly true in Australia and Amazonia, the regions with so-called pure hunter-gatherer subsistence strategies.
In the case of the Australian languages, the study in question observed that more than 80 percent are limited numerically, with the highest quantity represetned in such cases being only 3 or 4. Only one Australian language, Gamilaraay, was found to have an upper limit above 10, an dits highest number is for 20. … The association [between hunter-gathering and limited numbers] is also robust in South America and Amazonia more specifically. The languages of hunter-gatherer cultures in this region generally have upper limits below ten. Only one surveyed language … Huaorani, has numbers for quantities greater than 20. Approximately two-thirds of the languages of such groups in the region have upper limits of five or less, while one-third have an upper limit of 10. Similarly, about two-thirds of African hunter-gatherer languages have upper limits of 10 or less.
There are a few exceptions–agricultural societies with very few numbers, and hunter-gatherers with relatively large numbers of numbers, but:
…there are no large agricultural states without elaborate number systems, now or in recorded history.
So how did the first people develop numbers? Of course we don’t know, but Everett suggests that at some point we began associating collections of things, like shells, with the cluster of fingers found on our hands. One finger, one shell; five fingers, five shells–easy correspondences. Once we mastered five, we skipped forward to 10 and 20 rather quickly.
Everett proposes that some numeracy was a necessary prerequisite for agriculture, as agricultural people would need to keep track of things like seasons and equinoxes in order to know when to plant and harvest. I question this on the grounds that I myself don’t look at the calendar and say, “Oh look, it’s the equinox, I’d better plant my garden!” but instead look outside and say, “Oh, it’s getting warm and the grass is growing again, I’d better get busy.” The harvest is even more obvious: I harvest when the plants are ripe.
Of course, I live in a society with calendars, so I can’t claim that I don’t look at the calendar. I look at the calendar almost every day to make sure I have the date correct. So perhaps I am using my calendrical knowledge to plan my planting schedule without even realizing it because I am just so used to looking at the calendar.
Rather than develop numbers and then start planting barley and millet, I propose that humans first domesticated animals, like pigs and goats. At first people were content to have “a few,” “some,” or “many” animals, but soon they were inspired to keep better track of their flocks.
By the time we started planting millet and wheat (a couple thousand years later,) we were probably already pretty good at counting sheep.
Our fondness for tracking astronomical cycles, I suspect, began for less utilitarian reasons: they were there. The cycles of the sun, moon, and other planets were obvious and easy to track, and we wanted to figure out what they meant. We put a ton of work into tracking equinoxes and eclipses and the epicycles of Jupiter and Mars (before we figured out heliocentrism.) People ascribed all sorts of import to these cycles (“Communicator Mercury is retrograde in outspoken Sagittarius from December 3-22, mixing up messages and disrupting pre-holiday plans.”) that turned out to be completely wrong. Unless you’re a fisherman or sailor, the moon’s phases don’t make any difference in your life; the other planets’ cycles turned out to be completely useless unless you’re trying to send a space probe to visit them. Eclipses are interesting, but don’t have any real effects. For all of the effort we’ve put into astronomy, the most important results have been good calendars to keep track of dates and allow us to plan multiple years into the future.
Speaking of dates, let’s continue this discussion in a week–on the next Anthropology Friday.
*Footnote: Even though I don’t think the Piraha prove as much as Everett thinks they do, that doesn’t mean Everett is completely wrong. Maybe already having number words is (in the vast majority of cases) a necessary precondition for learning to count.
One potentially illuminating case Everett didn’t explore is how young children in numerate culture acquire numbers. Obviously they grow up in an environment with numbers, but below a certain age can’t really use them. Can children at these ages duplicate lines of objects or patterns? Or do they master that behavior only after learning to count?
Back in October I commented on Schiller and Peterson’s claim in Count on Math (a book of math curriculum ideas for toddlers and preschoolers) that young children must learn mathematical “foundation” concepts in a particular order, ie:
Developmental sequence is fundamental to children’s ability to build conceptual understanding. … The chapters in this book present math in a developmental sequence that provides children a natural transition from one concept to the next, preventing gaps in their understanding. …
When children are allowed to explore many objects, they begin to recognize similarities and differences of objects.
When children can determine similarities and differences, they can classify objects.
When children can classify objects, they can see similarities and difference well enough to recognize patterns.
When children can recognize, copy, extend and create patterns, they can arrange sets in a one-to-one relationship.
When children can match objects one to one, they can compare sets to determine which have more and which have less.
When children can compare sets, they can begin to look at the “manyness” of one set and develop number concepts.
This developmental sequence provides a conceptual framework that serves as a springboard to developing higher level math skills.
The Count on Math curriculum doesn’t even introduce the numbers 1-5 until week 39 for 4 year olds (3 year olds are never introduced to numbers) and numbers 6-10 aren’t introduced until week 37 for the 5 year olds!
Note that Schiller and Everett are arguing diametrical opposites–Everett says the ability to count to three and distinguish the “manyness” of sets is instinctual, present even in infants, but that the ability to copy patterns and match items one-to-one only comes after long acquaintance and practice with counting, specifically number words.
Schiller claims that children only develop the ability to distinguish manyness and count to three after learning to copy patterns and match items one-to-one.
As I said back in October, I think Count on Math’s claim is pure bollocks. If you miss the “comparing sets” day at preschool, you aren’t going to end up unable to multiply. The Piraha may not prove as much as Everett wants them to, but the neuroscience and animal studies he cites aren’t worthless. In general, I distrust anyone who claims that you must introduce this long a set of concepts in this strict an order just to develop a basic competency that the vast majority of people seem to acquire without difficulty.
Of course, Lynne Peterson is a real teacher with a real teacher’s certificate and a BA in … it doesn’t say, and Pam Schiller was Vice President of Professional Development for the Early childhood Division at McGraw Hill publishers and president of the Southern Early Childhood Association. She has a PhD in… it doesn’t say. Here’s some more on Dr. Schiller’s many awards. So maybe they know better than Everett, who’s just an anthropologist. But Everett has some actual evidence on his side.
But I’m a parent who has watched several children learn to count… and Schiller and Peterson are wrong.
The Negritos are a fascinating group of short-statured, dark-skinned, frizzy-haired peoples from southeast Asia–chiefly the Andaman Islands, Malaysia, Philippines, and Thailand. (Spelling note: “Negritoes” is also an acceptable plural, and some sources use the Spanish Negrillos.)
Because of their appearance, they have long been associated with African peoples, especially the Pygmies. Pygmies are formally defined as any group where adult men are, on average 4’11” or less and is almost always used specifically to refer to African Pygmies; the term pygmoid is sometimes used for groups whose men average 5’1″ or below, including the Negritos. (Some of the Bushmen tribes, Bolivians, Amazonians, the remote Taron, and a variety of others may also be pygmoid, by this definition.)
However, genetic testing has long indicated that they, along with other Melanesians and Australian Aborigines, are more closely related to other east Asian peoples than any African groups. In other words, they’re part of the greater Asian race, albeit a distant branch of it.
But how distant? And are the various Negrito groups closely related to each other, or do there just happen to be a variety of short groups of people in the area, perhaps due to convergent evolution triggered by insular dwarfism?
They found that the Negrito groups they studied “are basal to other East and Southeast Asians,” (basal: forming the bottom layer or base. In this case, it means they split off first,) “and that they diverged from West Eurasians at least 38,000 years ago.” (West Eurasians: Caucasians, consisting of Europeans, Middle Easterners, North Africans, and people from India.) “We also found relatively high traces of Denisovan admixture in the Philippine Negritos, but not in the Malaysian and Andamanese groups.” (Denisovans are a group of extinct humans similar to Neanderthals, but we’ve yet to find many of their bones. Just as Neanderthal DNA shows up in non-Sub-Saharan-Africans, so Denisvoan shows up in Melanesians.)
Figure 1 (A) shows PC analysis of Andamanese, Malaysian, and Philippine Negritos, revealing three distinct clusters:
In the upper right-hand corner, the Aeta, Agta, Batak, and Mamanwa are Philippine Negritos. The Manobo are non-Negrito Filipinos.
In the lower right-hand corner are the Jehai, Kintak and Batek are Malaysian Negritos.
And in the upper left, we have the extremely isolated Andamanese Onge and Jarawa Negritos.
(Phil-NN and Mly-NN I believe are Filipino and Malaysian Non-Negritos.)
You can find the same chart, but flipped upside down, with Papuan and Melanesian DNA in the supplemental materials. Of the three groups, they cluster closest to the Philippine Negritos, along the same line with the Malaysians.
By excluding the Andamanese (and Kintak) Negritos, Figure 1 (B) allows a closer look at the structure of the Philippine Negritos.
The Agta, Aeta, and Batak form a horizontal “comet-like pattern,” which likely indicates admixture with non-Negrito Philipine groups like the Manobo. The Mamanawa, who hail from a different part of the Philippines, also show this comet-like patterns, but along a different axis–likely because they intermixed with the different Filipinos who lived in their area. As you can see, there’s a fair amount of overlap–several of the Manobo individuals clustered with the Mamanwa Negritos, and the Batak cluster near several non-Negrito groups (see supplemental chart S4 B)–suggesting high amounts of mixing between these groups.
ADMIXTURE analysis reveals a similar picture. The non-Negrito Filipino groups show up primarily as Orange. The Aeta, Agta, and Batak form a clear genetic cluster with each other and cline with the Orange Filipinos, with the Aeta the least admixed and Batak the most.
The white are on the chart isn’t a data error, but the unique signature of the geographically separated Mananwa, who are highly mixed with the Manobo–and the Manobo, in turn, are mixed with them.
But this alone doesn’t tell us how ancient these populations are, nor if they’re descended from one ancestral pop. For this, the authors constructed several phylogenetic trees, based on all of the data at hand and assuming from 0 – 5 admixture events. The one on the left assumes 5 events, but for clarity only shows three of them. The Denisovan DNA is fascinating and well-documented elsewhere in Melanesian populatons; that Malaysian and Philippine Negritos mixed with their neighbors is also known, supporting the choice of this tree as the most likely to be accurate.
Regardless of which you pick, all of the trees show very similar results, with the biggest difference being whether the Melanesians/Papuans split before or after the Andamanese/Malaysian Negritos.
In case you are unfamiliar with these trees, I’ll run down a quick explanation: This is a human family tree, with each split showing where one group of humans split off from the others and became an isolated group with its own unique genetic patterns. The orange and red lines mark places where formerly isolated groups met and interbred, producing children that are a mix of both. The first split in the tree, going back million of years, is between all Homo sapiens (our species) and the Denisovans, a sister species related to the Neanderthals.
All humans outside of sub-Saharan Africans have some Neanderthal DNA because their ancestors met and interbred with Neanderthals on their way Out of Africa. Melanesians, Papuans, and some Negritos also have some Denisovan DNA, because their ancestors met and made children with members of this obscure human species, but Denisovan DNA is quite rare outside these groups.
Here is a map of Denisovan DNA levels the authors found, with 4% of Papuan DNA hailing from Denisivan ancestors, and Aeta nearly as high. By contrast, the Andamanese Negritos appear to have zero Denisovan. Either the Andamanese split off before the ancestors of the Philippine Negritos and Papuans met the Denisovans, or all Denisovan DNA has been purged from their bloodlines, perhaps because it just wasn’t helpful for surviving on their islands.
Back to the Tree: The second node is where the Biaka, a group of Pygmies from the Congo Rainforest in central Africa. Pygmy lineages are among the most ancient on earth, potentially going back over 200,000 years, well before any Homo sapiens had left Africa.
The next group that splits off from the rest of humanity are the Yoruba, a single ethnic group chosen to stand in for the entirety of the Bantus. Bantus are the group that you most likely think of when you think of black Africans, because over the past three millennia they have expanded greatly and conquered most of sub-Saharan Africa.
Next we have the Out of Africa event and the split between Caucasians (here represented by the French) and the greater Asian clade, which includes Australian Aborigines, Melanesians, Polynesians, Chinese, Japanese, Siberians, Inuit, and Native Americans.
The first groups to split off from the greater Asian clade (aka race) were the Andamanese and Malaysian Negritos, followed by the Papuans/Melanesians Australian Aborigines are closely related to Papuans, as Australia and Papua New Guinea were connected in a single continent (called Sahul) back during the last Ice Age. Most of Indonesia and parts of the Philippines were also connected into a single landmass, called Sunda. Sensibly, people reached Sunda before Sahul, though (Perhaps at that time the Andaman islands, to the northwest of Sumatra, were also connected or at least closer to the mainland.)
Irrespective of the exact order in which Melanesians and individual Negrito groups split off, they all split well before all of the other Asian groups in the area.
This is supported by legends told by the Filipinos themselves:
Legends, such as those involving the Ten Bornean Datus and the Binirayan Festival, tell tales about how, at the beginning of the 12th century when Indonesia and Philippines were under the rule of Indianized native kingdoms, the ancestors of the Bisaya escaped from Borneo from the persecution of Rajah Makatunaw. Led by Datu Puti and Datu Sumakwel and sailing with boats called balangays, they landed near a river called Suaragan, on the southwest coast of Panay, (the place then known as Aninipay), and bartered the land from an Ati [Negrito] headman named Polpolan and his son Marikudo for the price of a necklace and one golden salakot. The hills were left to the Atis while the plains and rivers to the Malays. This meeting is commemorated through the Ati-atihan festival.
The study’s authors estimate that the Negritos split from Europeans (Caucasians) around 30-38,000 years ago, and that the Malaysian and Philippine Negritos split around
13-15,000 years ago. (This all seems a bit tentative, IMO, especially since we have physical evidence of people in the area going back much further than that, and the authors themselves admit in the discussion that their time estimate may be too short.)
The authors also note:
Both our NJ (fig. 3A) and UPGMA (supplementary fig. S10) trees show that after divergence from Europeans, the ancestral Asians subsequently split into Papuans, Negritos and East Asians, implying a one-wave colonization of Asia. … This is in contrast to the study based on whole genome sequences that suggested Australian Aboriginal/Papuan first split from European/East Asians 60 kya, and later Europeans and East Asians diverged 40 kya (Malaspinas et al. 2016). This implies a two-wave migration into Asia…
The matter is still up for debate/more study.
In conclusion: All of the Negrito groups are likely descended from a common ancestor, (rather than having evolved from separate groups that happened to develop similar body types due to exposure to similar environments,) and were among the very first inhabitants of their regions. Despite their short stature, they are more closely related to other Asian groups (like the Chinese) than to African Pygmies. Significant mixing with their neighbors, however, is quickly obscuring their ancient lineages.
I wonder if all ancient human groups were originally short, and height a recently evolved trait in some groups?
In closing, I’d like to thank Jinam et al for their hard work in writing this article and making it available to the public, their sponsors, and the unique Negrito peoples themselves for surviving so long.
Welcome back to our discussion of recent exciting advances in our knowledge of human evolution:
Ancient hominins in the US?
Humans evolved in Europe?
In two days, first H Sap was pushed back to 260,000 years,
then to 300,000 years!
Bell beaker paper
As we’ve been discussing for the past couple of weeks, the exact dividing line between “human” and “non-human” isn’t always hard and fast. The very first Homo species, such as Homo habilis, undoubtedly had more in common with its immediate Australopithecine ancestors than with today’s modern humans, 3 million years later, but that doesn’t mean these dividing lines are meaningless. Homo sapiens and Homo neandethalensis, while considered different species, interbred and produced fertile offspring (most non-Africans have 3-5% Neanderthal DNA as a result of these pairings;) by contrast, humans and chimps cannot produce fertile offspring, because humans and chimps have a different number of chromosomes. The genetic distance between the two groups is just too far.
The grouping of ancient individuals into Homo or not-Homo, Erectus or Habilis, Sapiens or not, is partly based on physical morphology–what they looked like, how they moved–and partly based on culture, such as the ability to make tools or control fire. While australopithecines made some stone tools (and chimps can make tools out of twigs to retrieve tasty termites from nests,) Homo habilis (“handy man”) was the first to master the art and produce large numbers of more sophisticated tools for different purposes, such as this Oldowan chopper.
But we also group species based on moral or political beliefs–scientists generally believe it would be immoral to say that different modern human groups belong to different species, and so the date when Homo ergaster transforms into Homo sapiens is dependent on the date when the most divergent human groups alive today split apart–no one wants to come up with a finding that will get trumpeted in media as “Scientists Prove Pygmies aren’t Human!” (Pygmies already have enough problems, what with their immediate neighbors actually thinking they aren’t human and using their organs for magic rituals.)
(Of course they would still be Human even if they part of an ancient lineage.)
But if an ecologically-minded space alien arrived on earth back in 1490 and was charged with documenting terrestrial species, it might easily decide–based on morphology, culture, and physical distribution–that there were several different Homo “species” which all deserve to be preserved.
But we are not space aliens, and we have the concerns of our own day.
So when a paper was published last year on archaic admixture in Pygmies and the Pygmy/Bushmen/everyone else split, West Hunter noted the authors used a fast–but discredited–estimate of mutation rate to avoid the claim that Pygmies split off 300,000 years ago, 100,000 years before the emergence of Homo sapiens:
There are a couple of recent papers on introgression from some quite divergent archaic population into Pygmies ( this also looks to be the case with Bushmen). Among other things, one of those papers discussed the time of the split between African farmers (Bantu) and Pygmies, as determined from whole-genome analysis and the mutation rate. They preferred to use the once-fashionable rate of 2.5 x 10-8 per-site per-generation (based on nothing), instead of the new pedigree-based estimate of about 1.2 x 10-8 (based on sequencing parents and child: new stuff in the kid is mutation). The old fast rate indicates that the split between Neanderthals and modern humans is much more recent than the age of early Neanderthal-looking skeletons, while the new slow rate fits the fossil record – so what’s to like about the fast rate? Thing is, using the slow rate, the split time between Pygmies and Bantu is ~300k years ago – long before any archaeological sign of behavioral modernity (however you define it) and well before the first known fossils of AMH (although that shouldn’t bother anyone, considering the raggedness of the fossil record).
Southern Africa is consistently placed as one of the potential regions for the evolution of Homo sapiens. To examine the region’s human prehistory prior to the arrival of migrants from East and West Africa or Eurasia in the last 1,700 years, we generated and analyzed genome sequence data from seven ancient individuals from KwaZulu-Natal, South Africa. Three Stone Age hunter-gatherers date to ~2,000 years ago, and we show that they were related to current-day southern San groups such as the Karretjie People. Four Iron Age farmers (300-500 years old) have genetic signatures similar to present day Bantu-speakers. The genome sequence (13x coverage) of a juvenile boy from Ballito Bay, who lived ~2,000 years ago, demonstrates that southern African Stone Age hunter-gatherers were not impacted by recent admixture; however, we estimate that all modern-day Khoekhoe and San groups have been influenced by 9-22% genetic admixture from East African/Eurasian pastoralist groups arriving >1,000 years ago, including the Ju|’hoansi San, previously thought to have very low levels of admixture. Using traditional and new approaches, we estimate the population divergence time between the Ballito Bay boy and other groups to beyond 260,000 years ago.
260,000 years! Looks like West Hunter was correct, and we should be looking at the earlier Pygmy divergence date, too.
Fossil evidence points to an African origin of Homo sapiens from a group called either H. heidelbergensis or H. rhodesiensis. However, the exact place and time of emergence of H. sapiens remain obscure … In particular, it is unclear whether the present day ‘modern’ morphology rapidly emerged approximately 200 thousand years ago (ka) among earlier representatives of H. sapiens1 or evolved gradually over the last 400 thousand years2. Here we report newly discovered human fossils from Jebel Irhoud, Morocco, and interpret the affinities of the hominins from this site with other archaic and recent human groups. We identified a mosaic of features including facial, mandibular and dental morphology that aligns the Jebel Irhoud material with early or recent anatomically modern humans and more primitive neurocranial and endocranial morphology. In combination with an age of 315 ± 34 thousand years (as determined by thermoluminescence dating)3, this evidence makes Jebel Irhoud the oldest and richest African Middle Stone Age hominin site that documents early stages of the H. sapiens clade in which key features of modern morphology were established.
Hublin–one of the study’s coauthors–notes that between 330,000 and 300,000 years ago, the Sahara was green and animals could range freely across it.
While the Moroccan fossils do look like modern H sapiens, they also still look a lot like pre-sapiens, and the matter is still up for debate. Paleoanthropologist Chris Stringer suggests that we should consider all of our ancestors after the Neanderthals split off to be Homo sapiens, which would make our species 500,000 years old. Others would undoubtedly prefer to use a more recent date, arguing that the physical and cultural differences between 500,000 year old humans and today’s people are too large to consider them one species.
According to the Atlantic:
[The Jebel Irhoud] people had very similar faces to today’s humans, albeit with slightly more prominent brows. But the backs of their heads were very different. Our skulls are rounded globes, but theirs were lower on the top and longer at the back. If you saw them face on, they could pass for a modern human. But they turned around, you’d be looking at a skull that’s closer to extinct hominids like Homo erectus. “Today, you wouldn’t be able to find anyone with a braincase that shape,” says Gunz.
Their brains, though already as large as ours, must also have been shaped differently. It seems that the size of the human brain had already been finalized 300,000 years ago, but its structure—and perhaps its abilities—were fine-tuned over the subsequent millennia of evolution.
No matter how we split it, these are exciting days in the field!
This all occasioned some very annoying conversations along the lines of “White skin tone couldn’t possibly have evolved within the past 20,000 years because humans evolved in Europe! Don’t you know anything about science?”
Ohkay. Let’s step back a moment and take a look at what Graecopithecus is and what it isn’t.
This is Graecopithecus:
I think there is a second jawbone, but that’s basically it–and that’s not six teeth, that’s three teeth, shown from two different perspectives. There’s no skull, no shoulder blades, no pelvis, no legs.
By contrast, here are Lucy, the famous Australopithecus from Ethiopia, and a sample of the over 1,500 bones and pieces of Homo naledi recently recovered from a cave in South Africa.
Now, given what little scientists had to work with, the fact that they managed to figure out anything about Graecopithecus is quite impressive. The study, reasonably titled “Potential hominin affinities of Graecopithecus from the Late Miocene of Europe,” by
Jochen Fuss, Nikolai Spassov, David R. Begun, and Madelaine Böhm, used μCT and 3D reconstructions of the jawbones and teeth to compare Graecopithecus’s teeth to those of other apes. They decided the teeth were different enough to distinguish Graecopithecus from the nearby but older Ouranopithecus, while looking more like hominin teeth:
G. freybergi uniquely shares p4 partial root fusion and a possible canine root reduction with this tribe and therefore, provides intriguing evidence of what could be the oldest known hominin.
My hat’s off to the authors, but not to all of the reporters who dressed up “teeth look kind of like hominin teeth” as “Humans evolved in Europe!”
First of all, you cannot make that kind of jump based off of two jawbones and a handfull of teeth. Many of the hominin species we have recovered–such as Homo naledi and Homo floresiensis, as you know if you already read the previous post–possessed a mosaic of “ape like” and “human like” traits, ie:
The physical characteristics of H. naledi are described as having traits similar to the genus Australopithecus, mixed with traits more characteristic of the genus Homo, and traits not known in other hominin species. The skeletal anatomy displays plesiomorphic (“ancestral”) features found in the australopithecines and more apomorphic (“derived,” or traits arising separately from the ancestral state) features known from later hominins.
If we only had six Homo naledi bones instead of 1,500 of them, we might be looking only at the part that looks like an Australopithecus instead of the parts that look like H. erectus or totally novel. You simply cannot make that kind of claim off a couple of jawbones. You’re far too likely to be wrong, and then not only will you end up with egg on your face, but you’ll only be giving more fuel to folks who like to proclaim that “Nebraska Man turned out to be a pig!”:
In February 1922, Harold Cook wrote to Dr. Henry Osborn to inform him of the tooth that he had had in his possession for some time. The tooth had been found years prior in the Upper Snake Creek beds of Nebraska along with other fossils typical of North America. … Osborn, along with Dr. William D. Matthew soon came to the conclusion that the tooth had belonged to an anthropoid ape. They then passed the tooth along to William K. Gregory and Dr. Milo Hellman who agreed that the tooth belonged to an anthropoid ape more closely related to humans than to other apes. Only a few months later, an article was published in Science announcing the discovery of a manlike ape in North America. An illustration of H. haroldcookii was done by artist Amédée Forestier, who modeled the drawing on the proportions of “Pithecanthropus” (now Homo erectus), the “Java ape-man,” for the Illustrated London News. …
Examinations of the specimen continued, and the original describers continued to draw comparisons between Hesperopithecus and apes. Further field work on the site in the summers of 1925 and 1926 uncovered other parts of the skeleton. These discoveries revealed that the tooth was incorrectly identified. According to these discovered pieces, the tooth belonged neither to a man nor an ape, but to a fossil of an extinct species of peccary called Prosthennops serus.
That basically sums up everything I learned about human evolution in highschool.
Second, “HUMANS” DID NOT EVOLVE 7 MILLION YEARS AGO.
Scientists define “humans” as members of the genus Homo, which emerged around 3 million years ago. These are the guys with funny names like Homo habilis, Homo neanderthalensis, and the embarrassingly named Homo erectus. The genus also includes ourselves, Homo sapiens, who emerged around 200-300,000 years ago.
Homo habilis descended from an Australopithecus, perhaps Lucy herself. Australopithecines are not in the Homo genus; they are not “human,” though they are more like us than modern chimps and bonobos are. They evolved around 4 million years ago.
Regardless, humans didn’t evolve 7 million years ago. Sahelanthropus and even Lucy do not look like anyone you would call “human.” Humans have only been around for about 3 million years, and our own specific species is only about 300,000 years old. Even if Graecopithecus turns out to be the missing link–the true ancestor of both modern chimps and modern humans–that still does not change where humans evolved, because Graecopithecus narrowly missed being a human by 4 million years.
If you want to challenge the Out of Africa narrative, I think you’d do far better arguing for a multi-regional model of human evolution that includes back-migration of H. erectus into Africa and interbreeding with hominins there as spurring the emergence of H. sapiens than arguing about a 7 million year old jawbone. (I just made that up, by the way. It has no basis in anything I have read. But it at least has the right characters, in the right time frame, in a reasonable situation.)
Sorry this was a bit of a rant; I am just rather passionate about the subject. Next time we’ll examine very exciting news about Bushmen and Pygmy DNA!
Continuing with our series on recent exciting discoveries in human genetics/paleo anthropology:
Ancient hominins in the US?
Humans evolved in Europe?
In two days, first H Sap was pushed back to 260,000 years,
then to 300,000 years!
Bell beaker paper
One of the most interesting things about our human family tree (the Homo genus and our near primate relatives, chimps, gorillas, orangs, gibbons, etc.) is that for most of our existence, “we” weren’t the only humans in town. We probably coexisted, mated with, killed, were killed by, and at times perhaps completely ignored 7 other human species–Homo erectus, floresiensis, Neanderthals, Denisovans, heidelbergensis, rhodesiensis, and now Naledi.
That said, these “species” are a bit controversial. Some scientists like to declare practically every jawbone and skull fragment they find a new species (“splitters”,) and some claim that lots of different bones actually just represent natural variation within a species (“lumpers.”)
Take the canine family: dogs and wolves can interbreed, but I doubt great danes and chihuahuas can. For practical purposes, though, the behavior of great danes and chihuahuas is similar enough to each other–and different enough from wolves’–that we class them as one species and wolves as another. Additionally, when we take a look at the complete variety of dogs in existence, it is obvious that there is actually a genetic gradient in size between the largest and smallest breeds, with few sharp breaks (maybe the basenji.) If we had a complete fossil record, and could reliably reconstruct ancient hominin behaviors and cultural patterns, then we could say with far more confidence whether we are looking at something like dogs vs. wolves or great danes vs. chihuahuas. For now, though, paleoanthropology and genetics remain exciting fields with constant new discoveries!
Homo naledi and homo Floresiensis may ultimately be small branches on the human tree, but each provides us with a little more insight into the whole.
Naledi’s story is particularly entertaining. Back in 2013, some spelunkers crawled through a tiny opening in a South African cave and found a chamber full of bones–hominin bones.
Anthropologists often have to content themselves with a handful of bones, sometimes just a fragment of a cranium or part of a jaw. (The recent claim that humans evolved in Europe is based entirely on a jaw fragment plus a few teeth.) But in the Rising Star Cave system, they found an incredible 1,500+ bones or bone fragments, the remains of at least 15 people, and they haven’t even finished excavating.
According to Wikipedia:
The physical characteristics of H. naledi are described as having traits similar to the genus Australopithecus, mixed with traits more characteristic of the genus Homo, and traits not known in other hominin species. The skeletal anatomy displays plesiomorphic (“ancestral”) features found in the australopithecines and more apomorphic (“derived,” or traits arising separately from the ancestral state) features known from later hominins.
Adult males are estimated to have stood around 150 cm (5 ft) tall and weighed around 45 kg (100 lb), while females would likely have been a little shorter and weighed a little less. An analysis of H. naledi‘s skeleton suggests it stood upright and was bipedal. Its hip mechanics, the flared shape of the pelvis are similar to australopithecines, but its legs, feet and ankles are more similar to the genus Homo.
I note that the modern humans in South Africa are also kind of short–According to Time, the Bushmen average about 5 feet tall, (that’s probably supposed to be Bushmen men, not the group average,) and the men of nearby Pygmy peoples of central Africa average 4’11” or less.
The hands of H. naledi appear to have been better suited for object manipulation than those of australopithecines. Some of the bones resemble modern human bones, but other bones are more primitive than Australopithecus, an early ancestor of humans. The thumb, wrist, and palm bones are modern-like while the fingers are curved, more australopithecine, and useful for climbing. The shoulders are configured largely like those of australopithecines. The vertebrae are most similar to Pleistocene members of the genus Homo, whereas the ribcage is wide distally as is A. afarensis. The arm has an Australopithecus-similar shoulder and fingers and a Homo-similar wrist and palm. The structure of the upper body seems to have been more primitive than that of other members of the genus Homo, even apelike. In evolutionary biology, such a mixture of features is known as an anatomical mosaic.
Four skulls were discovered in the Dinaledi chamber, thought to be two females and two males, with a cranial volume of 560 cm3 (34 cu in) for the males and 465 cm3 (28.4 cu in) for females, about 40% to 45% the volume of modern human skulls; average Homo erectus skulls are 900 cm3 (55 cu in). A fifth, male skull found in the Lesedi chamber has a larger estimated cranial volume of 610 cm3 (37 cu in) . The H. naledi skulls are closer in cranial volume to australopithecine skulls. Nonetheless, the cranial structure is described as more similar to those found in the genus Homo than to australopithecines, particularly in its slender features, and the presence of temporal and occipitalbossing, and the fact that the skulls do not narrow in behind the eye-sockets. The brains of the species were markedly smaller than modern Homo sapiens, measuring between 450 and 610 cm3 (27–37 cu in). The teeth and mandiblemusculature are much smaller than those of most australopithecines, which suggests a diet that did not require heavy mastication. The teeth are small, similar to modern humans, but the third molar is larger than the other molars, similar to australopithecines. The teeth have both primitive and derived dental development.
The overall anatomical structure of the species has prompted the investigating scientists to classify the species within the genus Homo, rather than within the genus Australopithecus. The H. naledi skeletons indicate that the origins of the genus Homo were complex and may be polyphyletic (hybrid), and that the species may have evolved separately in different parts of Africa.
Because caves don’t have regular sediment layers like riverbeds or floodplains, scientists initially had trouble dating the bones. Because of their relative “primitiveness,” that is, their similarity to our older, more ape-like ancestors, they initially thought Homo naledi must have lived a long time ago–around 2 million years ago. But when they finally got the bones dated, they found they were much younger–only around 335,000 and 236,000 years old, which means H naledi and Homo sapiens–whose age was also recently adjusted–actually lived at the same time, though not necessarily in the same place.
(On the techniques used for dating the bones:
Francis Thackeray, of the University of the Witwatersrand, suggested that H. naledi lived 2 ± 0.5 million years ago, based on the skulls’ similarities to H. rudolfensis, H. erectus, and H. habilis, species that existed around 1.5, 2.5, and 1.8 million years ago, respectively. Early estimates derived from statistical analysis of cranial traits yielded a range of 2 million years to 912,000 years before present.
H naledi is unlikely to be a major branch on the human family tree–much too recent to be one of our ancestors–but it still offers important information on the development of “human” traits and how human and ape-like traits can exist side-by-side in the same individual (a theme we will return to later.) (Perhaps, just as we modern Homo sapiens contain traits derived from ancestors who mated with Neanderthals, Denisovans, and others, H naledi owes some of its traits to hybridization between two very different hominins.) It’s also important because it is one more data point in favor of the recent existence of a great many different human varieties, not just a single group.
The Flores hominin, (aka the Hobbit,) tells a similar tale, but much further afield from humanity’s evolutionary cradle.
The island of Flores is part of the Indonesian archipelago, a surprisingly rich source of early hominin fossils. Homo erectus, the famous Java Man, arrived in the area around 1.7 million years ago, but to date no erectus remains have been discovered on the actual island of Flores. During the last Glacial Maximum, ocean levels were lower and most of Indonesia was connected in a single continent, called Sundaland. During one of these glacial periods, H erectus could have easily walked from China to Java, but Flores remained an island, cut off from the mainland by several miles of open ocean.
The diminutive Hobbits show up later, around 50,000 to 100,000 years ago, though stone tools recovered alongside their remains have been dated from 50,000 to 190,000 years ago. Homo erectus is generally believed to have lived between 2 million and 140,000 years ago, and Homo sapiens arrived in Indonesia around 50,000 years ago. This places Floresiensis neatly between the two–it could have interacted with either species–perhaps descended from erectus and wiped out, in turn, by sapiens. (Or perhaps floresiensis represents an altogether novel line of hominins who left Africa on a completely separate trek from erectus.)
Unlike H naledi, whose diminutive stature is still within the current human range (especially of humans in the area,) floresiensis is exceptionally small for a hominin. According to Wikipedia:
The first set of remains to have been found, LB1, was chosen as the type specimen for the proposed species. LB1 is a fairly complete skeleton, including a nearly complete cranium (skull), determined to be that of a 30-year-old female. LB1 has been nicknamed the Little Lady of Flores or “Flo”.
LB1’s height has been estimated at about 1.06 m (3 ft 6 in). The height of a second skeleton, LB8, has been estimated at 1.09 m (3 ft 7 in) based on measurements of its tibia. These estimates are outside the range of normal modern human height and considerably shorter than the average adult height of even the smallest modern humans, such as the Mbenga and Mbuti (< 1.5 m (4 ft 11 in)),Twa, Semang (1.37 m (4 ft 6 in) for adult women) of the Malay Peninsula, or the Andamanese (1.37 m (4 ft 6 in) for adult women).
By body mass, differences between modern pygmies and Homo floresiensis are even greater. LB1’s body mass has been estimated at 25 kg (55 lb). This is smaller than that of not only modern H. sapiens, but also H. erectus, which Brown and colleagues have suggested is the immediate ancestor of H. floresiensis. LB1 and LB8 are also somewhat smaller than the australopithecines from three million years ago, not previously thought to have expanded beyond Africa. Thus, LB1 and LB8 may be the shortest and smallest members of the extended human family discovered thus far.
Aside from smaller body size, the specimens seem otherwise to resemble H. erectus, a species known to have been living in Southeast Asia at times coincident with earlier finds purported to be of H. floresiensis.
There’s a lot of debate about whether floresiensis is a real species–perhaps affected by insular dwarfism–or just a hominin that had some severe problems. Interestingly, we have a find from about 700,000 years ago on Flores of another hominin, which we think was also a Hobbit, but is even smaller than Flo and her relatives.
Floresiensis, like Naledi, didn’t contribute to modern humans. Rather, it is interesting because it shows the breadth of our genus. We tend to assume that, ever since we split off from the rest of the great apes, some 7 or 8 million years ago, our path has been ever upward, more complex and successful. But these Hobbits, most likely descendants of one of the most successful human species, (Homo erectus, who mastered fire, was the first to leave Africa, spread across Asia and Indonesia, and lasted for over a million and half years, far longer than our puny 300,000 years,) went in the opposite direction from its ancestors. It became much smaller than even the smallest living human groups. Its brain shrank:
In addition to a small body size, H. floresiensis had a remarkably small brain size. The brain of the holotype LB1 is estimated to have had a volume of 380 cm3 (23 cu in), placing it at the range of chimpanzees or the extinct australopithecines. LB1’s brain size is half that of its presumed immediate ancestor, H. erectus (980 cm3 (60 cu in)). The brain-to-body mass ratio of LB1 lies between that of H. erectus and the great apes.
Nevertheless, it still made tools, probably controlled fire, and hunted cooperatively.
Whatever it was, it was like us–and very much not like us.
There has been SO MUCH EXCITING NEWS out of paleoanthropology/genetics lately, it’s been a little tricky keeping up with it all. I’ve been holding off on commenting on some of the recent developments to give myself time to think them over, but here goes:
Ancient hominins in the US?
Humans evolved in Europe?
In two days, first H Sap was pushed back to 260,000 years,
Here we describe the Cerutti Mastodon (CM) site, an archaeological site from the early late Pleistocene epoch, where in situ hammerstones and stone anvils occur in spatio-temporal association with fragmentary remains of a single mastodon (Mammut americanum). The CM site contains spiral-fractured bone and molar fragments, indicating that breakage occured while fresh. Several of these fragments also preserve evidence of percussion. The occurrence and distribution of bone, molar and stone refits suggest that breakage occurred at the site of burial. Five large cobbles (hammerstones and anvils) in the CM bone bed display use-wear and impact marks, and are hydraulically anomalous relative to the low-energy context of the enclosing sandy silt stratum. 230Th/U radiometric analysis of multiple bone specimens using diffusion–adsorption–decay dating models indicates a burial date of 130.7 ± 9.4 thousand years ago. These findings confirm the presence of an unidentified species of Homo at the CM site during the last interglacial period (MIS 5e; early late Pleistocene), indicating that humans with manual dexterity and the experiential knowledge to use hammerstones and anvils processed mastodon limb bones for marrow extraction and/or raw material for tool production.
Note that “Homo” here is probably not H. sapiens, but a related or ancestral species, like Denisovans or Homo erectus, because as far as we know, H. sapiens was still living in Africa at the time.
This is obviously a highly controversial claim. Heck, “earliest human presence in the Americas” was already controversial, with some folks firmly camped at 15,000 years ago and others camped around 40,000 yeas ago. 130,000 years ago wasn’t even on the table.
Unfortunately, the article is paywalled, so I can’t read the whole thing and answer simple questions like, “Did they test the thickness of mineral accumulation on the bones to see if the breaks/scratches are the same age as the bones themselves?” That is, minerals build up on the surfaces of old bones over time. If the breaks and scratches were made before the bones were buried, they’ll have the same amount of buildup as the rest of the bone surfaces. If the breaks are more recent–say, the result of a bulldozer accidentally backing over the bones–they won’t.
They did get an actual elephant skeleton and smacked it with rocks to see if it would break in the same ways as the mammoth skeleton. A truck rolling over a rib and a rock striking it at an angle are bound to produce different kinds and patterns of breakage (the truck is likely to do more crushing, the rock to leave percussive impacts.) I’d also like to know if they compared the overall butchering pattern to known stone-tool-butchered elephants or mammoths, although I don’t know how easy it would be to find one.
They also looked at the pattern of impacts and shapes of the “hammerstones.” A rock which has been modified by humans hitting it with another rock will typically have certain shapes and patterns on its surface that can tell you things like which angle the rock was struck from during crafting. I’ve found a few arrowheads, and they are pretty distinct from other rocks.
Here’s a picture of an Oldowan stone chopper, about 2 million years old, which is therefore far older than these potential 130,000 year old tools. Homo sapiens didn’t exist 2 million years ago; this pointy rock was probably wielded by species such as Australopithecus garhi,H. habilis, orH. ergaster. Note that one side of this chopper is rounded, intended for holding comfortably in your hand, while the other side has had several chunks of rock smacked off, resulting in convex surfaces. Often you can tel exactly where the stone tool was struck to remove a flake, based on the shape and angle of the surface and the pattern of concentric, circular lines radiating out from the impact spot.
Homo erectus, who lived after the Oldowan tool makers and had a fancier, more complicated lithic technology, did make it out of Africa and spread across southeast Asia, up into China. This is, as far as I know, the first case of a hominin species using tools to significantly expand its range, but we have no evidence of erectus ever expanding into places that get significantly cold in the winter, and boat-building is a pretty advanced skill. We don’t even think erectus made it to Madagascar, which makes it sailing to the Americans rather doubtful.
I dislike passing judgment on the paper without reading it, but my basic instinct is skepticism. While I think the peopling of the Americas will ultimately turn out to be a longer, more complex, and interesting process than the 15,000 years camp, 130,000 years is just too interesting a claim to believe without further evidence (like the bones of said hominins.)
Still, I keep an open mind and await new findings.