Basically: Everyone outside of Africa has some Neanderthal DNA. It looks like the ancestors of the Melanesians interbred once with Neanderthals; the ancestors of Europeans interbred twice; the ancestors of Asians interbred three times.
Small amounts of Neanderthal DNA also show up in Africa, probably due to back-migration of people from Eurasia.
Denisovan DNA shows up mainly in Melanesians, but I think there is also a very small amount that shows up in south east Asia, some (or something similar) in Tibetans, and possibly a small amount in the Brazilian rainforest.
Now some kind of other archaic DNA has been detected in the Hazda, Sandawe, and Pygmies of Africa.
In the beautiful things file, we have A New Thermodynamics Theory of the Origin of Life. If you read the comments, you’ll see that it’s not really “new” and that other people have been working on it for a while, but the article is still a nice explanation of the concept.
ETA: And finally, I just discovered Still a Pygmy, by Isaac Bacirongo and Michael Nest. From the blurb:
How did a Pygmy from Congo end up living in Sydney, Australia? Growing up as a hunter-gatherer in the forests of Congo, where Pygmies were considered inferior to all other Africans and fit only for slave labor and witchcraft rituals*, Isaac Bacirongo never dreamed he would end up living in Australia. He also never imagined that he would get a high school education, fall in love with a “town girl,” start a prosperous business, and even own his own car—unheard of for a Pygmy. … When the tensions of Rwanda’s civil war spilled over into Congo, Isaac’s family fled the invading army, but a brutal occupation force eventually took control of the east and threw Isaac into prison for his human rights activism. After bribing his way out of jail, Isaac escaped Congo to reunite with his wife and 10 children in Kenya. He got work as an interpreter on an investigation into corruption in the UN, only to be threatened again by his involvement in the case and by spies working for Congolese rebel forces. With no future in Kenya and unable to return home, Isaac applied for and eventually received a humanitarian visa to Australia. … This is the inspiring and true story of one man’s transformation from hunter-gatherer to prosperous businessman to Australian resident, and advocate for the rights of his people’s identity. It is the first memoir by a Pygmy author ever published.
*Note: “witchcraft rituals” means “human sacrifice.” Also, cannibalism.
Anyone read it? I’m going to see if the library has it.
Anyway, thanks for reading, everyone. Here’s to the next 330 posts!
Biologically speaking, you are a member of the species Homo sapiens, (subspecies Homo sapiens sapiens.) Your genus is Homo–this includes all of our near cousins, like Homo neanderthalensis (with whom H. sapiens interbred,) Homo erectus, and the 2+million year old Homo habilis. Your family is hominidae, aka the great apes–chimps, gibbons, orangutans, gorillas, and us. We cannot interbreed with these groups. Your order is primates. The first primates probably evolved 65 million years (or more) ago; their modern members include apes, monkeys, lemurs, and lemur-like creatures like bushbabies.
Your class is mammalia–all animals with hair,[a] three middle ear bones, mammary glands, and a neocortex, at least according to Wikipedia. Most mammals have placentas and don’t lay eggs, but platypuses and echidnas have to be different. The first mammals appeared 225 million years ago.
From there, we head up to the sub-phylum Vertebrata, or all animals with backbones, then to the phylum Chordates, all animals with a nerve cord running down their back (but not necessarily any bones.) Chordates includes all birds, amphibians, reptiles, fish, and obscure creatures like salps, squishy, tubular creatures that look like jelly fish, and sea squirts, basically brainless tubes. Chordates appear to be over 500 million years old.
Next we have the kingdom Animalia, which includes all of the squishy things like sponges, jellyfish, octopuses, earthworms, and starfish, and crunchy things like insects, crabs, and spiders, in addition to us. The first fossil animals are 665 million years old, though older animals may simply not have been fossilized, due to being too soft. All animals are multi-cellular.
Above that, we have the domain Eukaryotes. All Eukaryotes have a nucleus and other organelles enclosed within membranes. Eukaryotes are divided into plants, animals, fungi, and protists, which are generally single-cells and include algae and the malaria parasite.
This is an animal cell, but all Eukaryotes are similar, due to their nucleus (1) enclosed within a membrane (2) and other organelles.
There are two other major domains of life, bacteria and archaea, collectively known as prokaryotes. They have neither nuclei nor any other membrane-bound organelles. As distant cousins go, these guys are pretty distant–the common ancestors of eukaryotes, bacteria, and archaea lived over 1.6 billion years ago, possibly over 2.7 billion years ago (it’s really hard to find fossilized algae and bacteria.)
Humming away inside your H. sapiens cells, making energy for you, are mitochondria. You might have heard that your mitochondria can be used to trace your maternal family line, because they 1. Are only passed down from mother to child (eggs have mitochondria but sperm don’t;) 2. Possess their own DNA, referred to as mtDNA or mDNA.
Why do mitochondria have their own DNA?
Because they aren’t human. They aren’t animals; they aren’t even eukaryotes. They’re prokaryotes, like bacteria.
Approximately one or two billion years ago, our ancestor–probably a primitive eukaryote cell–ate a prokaryote. But this prokaryote, by a great stroke of luck, didn’t get digested. Instead it got comfy, settled in, and stuck around. Here’s a helpful graphic to explain the process in more detail:
Yes, chloroplasts are prokaryotic invaders, too.
Mitochondias’ closest living relatives are the other Rickettsiales, an order of proteobacteria, which cause a variety of diseases including Typhus and Q fever. Luckily for us, our mitochondria help keep us alive, rather than kill us.
