Southpaw Genetics

Warning: Totally speculative

This is an attempt at a coherent explanation for why left-handedness (and right-handedness) exist in the distributions that they do.

Handedness is a rather exceptional human trait. Most animals don’t have a dominant hand (or foot.) Horses have no dominant hooves; anteaters dig equally well with both paws; dolphins don’t favor one flipper over the other; monkeys don’t fall out of trees if they try to grab a branch with their left hands. Only humans have a really distinct tendency to use one side of their bodies over the other.

And about 90% of us use our right hands, and about 10% of us use our left hands, (Wikipedia claims 10%, but The Lopsided Ape reports 12%.) an observation that appears to hold pretty consistently throughout both time and culture, so long as we aren’t dealing with a culture where lefties are forced to write with their right hands.

A simple Mendel-square two-gene explanation for handedness–a dominant allele for right-handedness and a recessive one for left-handedness, with equal proportions of alleles in society, would result in a 75% righties to 25% lefties. Even if the proportions weren’t equal, the offspring of two lefties ought to be 100% left-handed. This is not, however, what we see. The children of two lefties have only a 25% chance or so of being left-handed themselves.

So let’s try a more complicated model.

Let’s assume that there are two alleles that code for right-handedness. (Hereafter “R”) You get one from your mom and one from your dad.

Each of these alleles is accompanied by a second allele that codes for either nothing (hereafter “O”) or potentially switches the expression of your handedness (hereafter “S”)

Everybody in the world gets two identical R alleles, one from mom and one from dad.

Everyone also gets two S or O alleles, one from mom and one from dad. One of these S or O alleles affects one of your Rs, and the other affects the other R.

Your potential pairs, then, are:

RO/RO, RO/RS, RS/RO, or RS/RS

RO=right handed allele.

RS=50% chance of expressing for right or left dominance; RS/RS thus => 25% chance of both alleles coming out lefty.

So RO/RO, RO/RS, and RS/RO = righties, (but the RO/ROs may have especially dominant right hands; half of the RO/RS guys may have weakly dominant right hands.)

Only RS/RS produces lefties, and of those, only 25% defeat the dominance odds.

This gets us our observed correlation of only 25% of children of left-handed couples being left-handed themselves.

(Please note that this is still a very simplified model; Wikipedia claims that there may be more than 40 alleles involved.)

What of the general population as a whole?

Assuming random mating in a population with equal quantities of RO/RO, RO/RS, RS/RO and RS/RS, we’d end up with 25% of children RS/RS. But if only 25% of RS/RS turn out lefties, only 6.25% of children would be lefties. We’re still missing 4-6% of the population.

This implies that either: A. Wikipedia has the wrong #s for % of children of lefties who are left-handed; B. about half of lefties are RO/RS (about 1/8th of the RO/RS population); C. RS is found in twice the proportion as RO in the population; or D. my model is wrong.

According to Anything Left-Handed:

Dr Chris McManus reported in his book Right Hand, Left Hand on a study he had done based on a review of scientific literature which showed parent handedness for 70,000 children. On average, the chances of two right-handed parents having a left-handed child were around 9% left-handed children, two left-handed parents around 26% and one left and one right-handed parent around 19%. …
More than 50% of left-handers do not know of any other left-hander anywhere in their living family.

This implies B, that about half of lefties are RO/RS. Having one RS combination gives you a 12.5% chance of being left-handed; having two RS combinations gives you a 25% chance.

And that… I think that works. And it means we can refine our theory–we don’t need two R alleles; we only need one. (Obviously it is more likely a whole bunch of alleles that code for a whole system, but since they act together, we can model them as one.) The R allele is then modified by a pair of alleles that comes in either O (do nothing,) or S (switch.)

One S allele gives you a 12.5% chance of being a lefty; two doubles your chances to 25%.

Interestingly, this model suggests that not only does no gene for “left handedness” exist, but that “left handedness” might not even be the allele’s goal. Despite the rarity of lefties, the S allele is found in 75% of the population (an equal % as the O allele.) My suspicion is that the S allele is doing something else valuable, like making sure we don’t become too lopsided in our abilities or try to shunt all of our mental functions to one side of our brain.

I’m probably wrong!

When trying to learn and understand approximately everything, one is forced to periodically admit that there are a great many things one does not yet know.

I made a diagram of my thoughts from yesterday:

humantreebasedonHaakMy intuition tells me this is wrong.

Abbreviations: SSA =  Sub-Saharan Africa; ANE = Ancient North Eurasian, even though they’re found all over the place; WHG = European hunter-gatherers; I-Es = Indo-Europeans.

I tried my best to make it neat and clear, focusing on the big separations and leaving out the frequent cross-mixing. Where several groups had similar DNA, I used one group to represent the group (eg, Yoruba,) and left out groups whose histories were just too complicated to express clearly at this size. A big chunk of the Middle East/middle of Eurasia is a mixing zone where lots of groups seem to have merged. (Likewise, I obviously left out groups that weren’t in Haak’s dataset, like Polynesians.)

I tried to arrange the groups sensibly, so that ones that are geographically near each other and/or have intermixed are near each other on the graph, but this didn’t always work out–eg, the Inuit share some DNA with other Native American groups, but ended up sandwiched between India and Siberia.

Things get complicated around the emergence of the Indo-Europeans (I-Es), who emerged from the combination of a known population (WHG) and an unknown population that I’m super-speculating might have come from India, after which some of the I-Es might have returned to India. But then there is the mystery of why the color on the graph changes from light green to teal–did another group related to the original IEs emerge, or is this just change over time?

The IEs are also, IMO, at the wrong spot in time (so are the Pygmies.) Maybe this is just a really bad proxy for time? Maybe getting conquered makes groups combine in ways that look like they differentiated at times other than when they did?

Either way, I am, well, frustrated.

EDIT: Oh, I just realized something I did wrong.

*Fiddles*

Still speculative, but hopefully better
Still speculative, but hopefully better

Among other things, I realized I’d messed up counting off where some of the groups split, so while I fixing that, I went ahead and switched the Siberians and Melanesians so I could get the Inuit near the other Americans.

I also realized that I was trying to smush together the emergence of the WHG and the Yamnaya, even though those events happened at different times. The new version shows the WHG and Yamnaya (proto-Indo-Europeans) at two very different times.

Third, I have fixed it so that the ANE don’t feed directly into modern Europeans. The downside of the current model is that it makes it look like the ANE disappeaed, when really they just dispersed into so many groups which mixed in turn with other groups that they ceased existing in “pure” form, though the Bedouins, I suspect, come closest.

The “light green” and “teal” colors on Haak’s graph are still problematic–light green doesn’t exist in “pure” form anywhere on the graph, but it appears to be highest in India. My interpretation is that the light green derived early on from an ANE population somewhere around India (though Iran, Pakistan, the Caucuses, or the Steppes are also possibilities,) and somewhat later mixed with an “East” population in India. A bit of that light green population also made it into the Onge, and later, I think a branch of it combined with the WHG to create the Yamnaya. (Who, in turn, conquered some ANE groups, creating the modern Europeans.)

I should also note that I might have the Khoi and San groups backwards, because I’m not all that familiar with them.

I could edit this post and just eliminate my embarrassing mistakes, but I think I’ll let them stay in order to show the importance of paying attention to the nagging sense of being wrong. It turns out I was! I might still be wrong, but hopefully I’m less wrong.

Tesla, Edison, Genius, and Loneliness (part 2/2)

Part 1 is here.

“If I am walking with two other men, each of them will serve as my teacher. I will pick out the good points of the one and imitate them, and the bad points of the other and correct them in myself.” — Confucius

This quote is one of my personal mottoes, but I have added a corollary: “If I am walking with only one man, I still have two teachers, for I may learn to achieve goodness from a man’s good side, and to avoid evil from a man’s bad side.”

At any rate, Edison is a man whose goodness instructs us on how to take brilliant ideas and build the structures necessary for them to benefit humanity. Edison is a man who literally built civilization and deserves credit for both seeing how the structures needed to fit together to work, and for having the skills necessary to actually bring people together and build those structures.

Tesla is a lesson on how society should not manage its creative geniuses, (and I don’t mean the dumb pay dispute with Edison.)

Tesla is an interesting character. He appears to have been one of the world’s exceedingly rare true short sleepers, which appears to be a genetic condition:

“Ying-Hui Fu … studies the genetics and other characteristics of short sleepers at her neurogenetics lab.

“Currently, Fu knows of three types of genetic mutations that are related to the ability to function well on minimal amounts of sleep, which often runs in the family. In a 2009 paper published in the journal Science, she described a mother and a daughter who shared the same genetic mutation of the gene DEC2 that allowed them to thrive on six hours of sleep per night. So far Fu has identified about 50 families of short sleepers.

“This group of short sleepers is unique,” Fu said, describing them as optimistic and energetic, often holding more than one job. …

“Interestingly, these high energy levels typical of short sleepers can sometimes reach behavioral extremes. For instance, a 2001 study published in the Journal of Sleep Research that examined the sleep patterns and personality of 12 short sleepers, researchers found some evidence of subclinical hypomania — a milder form of manic behavior, characterized by euphoria, disinhibition and, in fact, a decreased need for sleep.”

Please note that drinking 10 5-hour-energy drinks in a row is not the same as having a genetic mutation that lets you get by on less sleep. Chances are extremely likely that you, my friend, are already not getting as much sleep as you need for optimum health. Also, since very few short sleepers have actually been studied, what we think we know about them may not be entirely accurate; they may suffer long-term consequences that have not yet been documented, for example. I do wonder if chronic lack of sleep eventually got to Tesla, reducing him to a state of waking-dreaming toward the end of his life, when he began going obviously loopy.

 

Tesla’s rigidity of personality, behavior, and dress are reminiscent of the compulsive, repetitive, and restrictive behaviors associated with autism/Asperger’s Syndrome (now just another part of “autism” in the DSM,) eg,

“People with Asperger syndrome display behavior, interests, and activities that are restricted and repetitive and are sometimes abnormally intense or focused. They may stick to inflexible routines, move in stereotyped and repetitive ways, or preoccupy themselves with parts of objects.

“Pursuit of specific and narrow areas of interest is one of the most striking features of AS.[1] Individuals with AS may collect volumes of detailed information on a relatively narrow topic such as weather data or star names, without necessarily having a genuine understanding of the broader topic.” (Wikipedia.)

I’ve long thought it a problem that these definitions/descriptions make no effort to distinguish between “Aspies” and genuinely intelligent people, who simply have more ability to memorize facts of any sort and will learn about any subject in more depth than someone of ordinary intelligence. If we want to define high IQ as a mental disorder, then, well, I guess we can, but it seems like a bad idea to me.

Autistic children apparently also have difficulty sleeping, which is why many of them are being prescribed melatonin as a sleep aid (as I discussed back in Melanin, Sexuality, and Aggression.) However, these autistic kids appear to actually need more sleep than they’re getting; they just seem to have trouble turning off their brains and keeping them off long enough for a proper sleep.

Anyway, to get extremely speculative: Much like Fu’s short sleepers, the autistic people I have worked with personally (N=small) seemed like they had brains on overdrive. Imagine that a normal brain is an Amish buggy, going along at a nice, reasonable clip, and their brains are Formula One race cars. Brain speed in this case may have nothing to do with IQ, per say, or may in fact be detrimental to it–autistics are far more likely than the general population to test as mentally retarded–but I favor a theory that having a small quantity of autistic-like traits may be useful for people in fields or occupations that require high IQ, but large quantities of autistic-like traits cause too many negative side effects, resulting in full-blown autism. In Tesla’s case, he got the benefits of the massively high-powered, sped-up brain, with a side effect that he couldn’t turn it off long enough to get more than a few hours of sleep and lacked the normal social instincts that lead people to marry, have children, and generally form stable relationships with other people.

There’s a certain irony to Tesla advocating for sterilization of the unfit and hanging out with Nazi propagandist George Sylvester Viereck at the same time as the Nazis were ignoring Hans Asperger’s plea that his subjects be employed as codebreakers and executing them as mental defectives instead. But then, the Nazis are kind of a great big case of how not to treat your smart people.

To be fair, this is not evidence that Tesla actually supported the Nazis or their policies.

Back in Is Genius Fragile?, I discussed a recent paper in Molecular Psychology that claimed to have studied 1,400 students with IQs of 170 or above, and found no rare genetic alleles that were more common in them than people of normal or low IQ, but did find rare, deleterious alleles in regular/dumb people.

Edit: I just realized that for scheduling reasons, “Is Genius Fragile” actually got moved to mid-November. The Molecular Psychology paper is here.

But are such alleles actually deleterious? Tesla never married and had no children; neither did Isaac Newton. Einstein had three children, but one of them seems to have died in infancy and one was institutionalized for schizophrenia.

In other words, perhaps some of these alleles they’ve noticed aren’t deleterious, but actually helpful in some way. Perhaps, for example, there is an allele that codes for processes that help you turn off your brain at night and transition to certain sleep states. Without that allele, your brain is more “on” all the time, you feel more alert and can think more clearly than others without getting tired, but ultimately there are some bad side effects to not sleeping. Or perhaps the brain’s ability to see patterns is normally regulated by another mechanism that helps you distinguish between real patterns and false matches, which might malfunction in people like John Nash, resulting both in increased pattern-matching ability and in schizophrenia. By the way, I am totally speculating and might be completely wrong.

Please note that from the evolutionary POV, traits–like IQ–are not inherently valuable. A trait is adaptive if it leads to the continuation of your DNA into future generations, and is deleterious or maladaptive if it hinders the continuation of your DNA. If high IQ people do not have children, the high IQ is maladaptive and being selected out of the population. (Please note, also, that different environments, both physical and cultural, select for different traits. Had Tesla remained near his family back in Croatia, they might have helped arrange a marriage for him, leading eventually to children and romantic entanglements with someone who wasn’t a pigeon.)

However, even if high-IQ people never reproduced under any circumstances, their existence in a population might still be advantageous to the population as a whole–you probably enjoy having lightbulbs, electricity, cell phones, and other such things, for example. The development of vaccines, industrial agriculture, and modern theories about nutrition and hygiene have vastly expanded the Earth’s human population over the past hundred years, and would have done so even if the people involved had not had any children at all.

This is a somewhat complicated issue that depends on the interaction of a lot of variables, like whether society can consistently produce high-IQ people even if the high-IQ people themselves do not have many children, and whether the innovations of modernity will actually help us survive (the Amish, after all, have more children than your average person with a cell phone.) See: “How–and why–genius is group selected–massive cultural amplification” for some more discussion on the subject.

Regardless, I am operating under the assumption that society benefits from the existence of people like Tesla (and, of course, Edison.)

Anyway, back to Tesla and his job difficulties.

In “The Improperly Excluded,” Micheal Ferguson theorizes that there exists a maximum IQ difference between two people beyond which they cannot effectively communicate, which he places around 20 IQ points. (I think I discussed it here and here.) So a person with an average IQ of 100 can understand and communicate with someone with a 120 IQ, and someone with a 120 can understand a 140, but the 100 and 140 are essentially speaking Greek to each other; the 100 IQ person cannot make heads or tails of the 140’s thoughts, nor distinguish their claims from those of a crazy person or charlatan. If the 100 trusts the 120, the 120 can take advice from the 140 and recommend it to the 100, but beyond that, people of, say, 160 IQ are just too far removed from the average population to even get their ideas effectively communicated. Extremely high IQ people, therefore, may be improperly excluded from positions where they could actually do important work just because average people have no way to understand what they’re saying. Additionally, since extremely high IQ people are very rare, they may have to cope with a world in which almost no one they meet is within their comfortable conversation zone.

Note: see Hollingworth Fan’s comment below for some very interesting quotes on this subject.

Tesla, a guy who could do integer calculus in his head, was undoubtedly brilliant far beyond the common walks of man, and so seems to have faced the constant frustration of being surrounded by idiots like Edison. Upon Edison’s death, Tesla opined in the NY Times about his former boss:

“He had no hobby, cared for no sort of amusement of any kind and lived in utter disregard of the most elementary rules of hygiene … His method was inefficient in the extreme, for an immense ground had to be covered to get anything at all unless blind chance intervened and, at first, I was almost a sorry witness of his doings, knowing that just a little theory and calculation would have saved him 90 percent of the labor. But he had a veritable contempt for book learning and mathematical knowledge, trusting himself entirely to his inventor’s instinct and practical American sense.”

That idiot Edison, by the way, had six children, none of whom seem to have died in infancy or gone crazy. Three went into science/inventing, two were women, and I don’t know what happened to the fourth boy. Edison was undoubtedly helped in life by living in the same country as his family, but he also seems to have just been a more stable person who successfully managed to balance his work and social life. Edison: better adapted to his environment than Tesla.

Tesla’s genius was undoubtedly under-utilized. Tesla could not manage his own affairs, and so needed, at the very least, the strong structural support of a family that would prevent him from doing stupid things like gambling away his tuition money and dropping out of college, as well as a sound employer or university that would manage the business end of Tesla’s laboratory expenses and design implementation. Immigration to the US left Tesla without the support of his family, and his own stubbornness lead him to quit what would otherwise have been a productive career.

Additionally, Tesla’s ideas may truly have been too far ahead of their time for even other smart people to appreciate and understand. There were few people in the world at his level, and he must have spent much of his life completely isolated from anyone who could understand him. Even an employer willing to finance his schemes might not have been able to understand (and thus implement) some of them.

Isolation, I suspect, leads eventually to madness. Not because (or just because) isolation makes people lonely, which makes them depressed. But because the human animal is not designed to work in isolation.

In the extreme example, we know from observing people in solitary confinement that it breaks their brains and drives them insane.

In everyday life, our brains require regular feedback from others to make sure our ideas and impulses are correct. To give a trivial example, suppose I mention to my husband that a friend of mine did something today that really annoyed me, and he responds that I am misinterpreting things, that he heard from my friend’s husband that morning about some extenuating circumstances that explain her behavior and that I should not be annoyed with her. Likewise, he might come to me with a story about a co-worker who seems to be stealing his ideas, and I could help figure out if the guy really is.

Isolation removes this feedback, leading to more and more incorrect ideas.

In his recent post, “Mysticism and Pattern-Matching,” Scott Alexander writes:

“Think of top-down processing as taking noise and organizing it to fit a pattern. Normally, you’ll only fit it to the patterns that are actually there. But if your pattern-matching system is broken, you’ll fit it to patterns that aren’t in the data at all. …

“So hallucinations are when your top-down processing/pattern-matching ability becomes so dysfunctional that it can generate people and objects out of random visual noise. Why it chooses some people and objects over others I don’t know, but it’s hardly surprising – it does the same thing every night in your dreams.

“Many of the same people who have hallucinations also have paranoia. Paranoia seems to me to be overfunctioning of social pattern-matching. … When a paranoiac hears a stray word here, or sees a sideways glance there, they turn it into this vast social edifice of connected plots.”

Tesla’s claims to have been working on a “Death Ray” that turned out to be an old battery, his romantic entanglement with a pigeon, claims that “thieves” had broken into his hotel room in search of his “Death Ray” but not been able to find, and the Mythbusters’ thorough busting of his claims to have built an oscillator that nearly brought down the building and had to be destroyed with a sledgehammer all sound a lot like what Scott’s describing. As a guy who could do calculus in his head, Tesla had an extreme talent for pattern matching–perhaps too extreme. Scott continues:

“So to skip to the point: I think all of this is about strengthening the pattern-matching faculty. You’re exercising it uselessly but impressively, the same way as the body-builder who lifts the same weight a thousand times until their arms are the size of tree trunks. Once the pattern-matching faculty is way way way overactive, it (spuriously) hallucinates a top-down abstract pattern in the whole universe. This is the experience that mystics describe as “everything is connected” or “all is one”, or “everything makes sense” or “everything in the universe is good and there for a purpose”. The discovery of a beautiful all-encompassing pattern in the universe is understandably associated with “seeing God”.”

Recovered schizophrenics I’ve talked to report the exact same thing: both a mystical sense of the union of all things, and joy at the experience (though they also report that schizophrenia can be absolutely terrifying, because sometimes the voices are evil.)

And finally (at least for the quoting):

“I think other methods of inducing weird states of consciousness, like drugs and meditation, probably do the same thing by some roundabout route. Meditation seems like reducing stimuli, which is known to lead to hallucinations in eg sensory deprivation tanks or solitary confinement cells in jail. I think the general principle is that a low level of external stimuli makes your brain adjust its threshold for stimulus detection up until anything including random noise satisfies the threshold.”

Isolation/ lack of stimulus has a direct effect of lowering the brain’s threshold for identifying patterns until random background noise gets interpreted as conversation. (The general correlation between schizophrenia and low IQ could be partially an effect of smarter people being better at avoiding severe isolation, and dumber people being more likely to end up in situations where literally no one has a real conversation with them for years at a time.

Tesla seems to have been isolated in his own way, both by being far more intelligent than the vast majority of people, and so unable to converse properly with them, and also by having none of his family, kin, or fellow countrymen around. He even had to communicate primarily in a language that was hardly his first.

Long term, I suspect such isolation had a negative effect on Tesla’s sanity and ability to wisely conduct his own affairs.

 

Tesla is a difficult case, because he willingly walked away from what were probably excellent career opportunities, and there’s hardly anything anyone could do about his family being back in Croatia. However, since most people do live in the same country as their families, we can still draw some general conclusions:

Some really smart people may require significant support from society and/or their families/employers in order to properly function and fully realize their potential. Their families should probably step in and help them get married if they can’t do it themselves, at the very least to help keep them happy and stable.

The Wikipedia quotes physicist Y. S. Kim on the subject of P. A. M. Dirac (one of my favorite scientists)’s marriage to Margit Wigner, sister of Nobel Prize winning theoretical physicist Eugene Wigner:

“It is quite fortunate for the physics community that Manci took good care of our respected Paul A. M. Dirac. Dirac published eleven papers during the period 1939–46…. Dirac was able to maintain his normal research productivity only because Manci was in charge of everything else.”

Dirac and Manci in Kopenhagen
Dirac and Manci in Kopenhagen

Alas, the Wikipedia does not give the details of how an autist like Dirac managed to marry Manci.

Really smart people may have some ideas that are astounding brilliant, and also have a lot of ideas that don’t work at all, because that is just the nature of creativity, but the average person probably can’t tell the difference. They need other people like themselves to bounce ideas off of and generally converse with. Their eccentricities are generally harmless, and the community is better off tolerating them.

Above all, try not to abandon them. Humans are not built to be alone.