Something changed

Jared Diamond notes (p 161) that the wild ancestors of domesticated animals are spread unevenly – only two are in South America, while none come from North America, sub-Saharan Africa, or Australia. He then argues that only a few special species are good candidates for domestication, and there just weren’t any in these regions.

The world’s climate was similar to today’s, back the Eemian, the last interglacial (before this one). Every animal species that humans have ever domesticated existed back then, along with many other now extinct. Yet none were domesticated. As far as we know, no plants were domesticated, either. Why not? I’d guess it was because people were different back then. So that’s a possible reason. We could push this argument further, back to earlier interglacial periods, or even back before the Pleistocene: people must have been different.

I could believe this for Australia. Marsupials are significantly different from placental animals – dumber, for one thing – and most of the large ones in Australia had been wiped out a long time ago. Do I believe Diamond’s ” no good candidates” line for North America or Africa? No, I don’t. Zebras might have a lousy disposition, but then so did aurochsen. While eland are easy to domesticate. Tarpans, the wild ancestor of horses, only died out in the 19th century. We have descriptions: they were “absolutely untameable”. Yet here we are.

Lots of domestic animals started out with difficult behavior (aurochsen, tarpans, wild boars): domestication is always first and foremost for tameness. Selection can change behavior just as it changes size and speed and milk production. That’s selection on animal behavior, of course. There’s a special principle that keeps selection from changing behavior in humans.

mtDNA capers

There’s an interesting pattern in the mtDNA of archaic humans. Neanderthals have mtDNA that’s a lot closer to that of anatomically modern humans than to Denisovans, although Neanderthals and Denisovans are close if you look at nuclear DNA. While really ancient mtDNA from Atapuerca is like Denisovan DNA.

People now suspect that there was a bit of contact between Neanderthals and AMH a long time, maybe two interglacials ago, contact that led to a mtDNA lineage from AMH humans being introduced into Neanderthals – one that spread until all (or almost all) Neanderthals had it.

This kind of thing is especially likely to happen with mtDNA, because there is reason to suspect that Neanderthals had crummy mtDNA.

The first problem is that there may not have been enough Neanderthals. Selection is not very effective in removing deleterious alleles when their selective disadvantage is < 1/N. For Neanderthals, some analyses indicate the effective population size was around 1000 (others think it was a large but deeply subdivided population), but the effective pop for mtDNA (haploid and only transmitted by females ) was 1/4th that – so, N ~250. Not very big.

The other, general, problem with mtDNA is lack of recombination. In an asexual lineage, mutations accumulate. Muller's ratchet. The only fix is back-mutation, which is very rare, unless the species population size is huge. Sex, on the other hand, reshuffles: a kid can have fewer deleterious mutations than either parent.

So you don’t expect hominid mtDNA to be in great shape, nearly perfectly optimized. That’s closer to true for nuclear genes. Since hominid mtDNA is not too close to optimal, it’s not a huge surprise if population A has noticeably more effective mitochondria than population B.

Since mtDNA also does something very important, Neanderthal mtDNA being replaced by AMH mtDNA isn’t particularly surprising. Along the same line of thought, zero success of Neanderthal mtDNA in modern humans is also not terribly surprising. Neanderthal and AMH mtdna being so functionally close as to be effectively neutral – now that would be surprising.

Persistence

Jared Diamond notices that early development of complex civilizations had ongoing consequences: peoples that developed such things way later or not at all continue to do poorly today, even if they encountered Western technology and technologists several hundred years ago. “We see in our daily lives that some of the conquered peoples continue to form an underclass, centuries after the conquests or slave imports took place.” p 25 ” Yes, the transistor, invented at Bell Labs in the eastern United States in 1947, leapt 8,000 miles to launch an electronics industry in Japan – but it did not make the shorter leap to found new industries in Zaire or Paraguay. The nations rising to new power are still ones that were incorporated thousands of years ago into the old centers of dominance based on food production, or that have been repopulated by peoples from those centers. Unlike Zaire or Paraguay, Japan and the other new powers were able to exploit the transistor quickly because their populations already had a long history of literacy, metal machinery, and centralized government. The world’s two earliest centers of food production, the Fertile Crescent and China, still dominate the modern world, either through their immediate successor states (modern China) or through states situated in neighboring regions influenced early by those two centers (Japan, Korea, Malaysia, and Europe), or through states repopulated or ruled by their overseas emigrants (the United States, Australia, Brazil). Prospects for world dominance of sub-Saharan Africans, Aboriginal Australians, and Native Americans remain dim. The hand of history’s course at 8000 B.C. lies heavily on us.” p 417.

Some economists have noticed this same pattern: Was the Wealth of Nations determined in 1000 BC?

This is not what his overall theory would lead us to expect. If people in New Guinea or the Mato Grosso are smarter than Europeans or east Asians, or even just the same, why can’t they adopt (and then go on to advance) new technologies? Yet they haven’t. Why aren’t people in the Democratic Republic of the Congo building particle accelerators? Even if they’re too broke right now, they could be sending theorists, mathematicians and physicists, off to CERN. All they need is chalk. Yet they don’t. Neither does the African diaspora.

Diamond says ” peoples who until recently were technologically primitive – such as Australian Aborigines and New Guineans – routinely master industrial technologies when given opportunities to do so. ” p 19. That’s just false. There’s a world of difference between using a smartphone and designing & manufacturing one. Toddlers can use smartphones, but it’s the rare two-year old that know enough about computers and electrical engineering to build one. sub-Saharan Africans, Aboriginal Australians, and Native Americans play almost no part in modern technological development.

Why should a certain level of development in the Bronze Age predict modern economic success? To be exact, most (but not all) populations that had high civilization levels back then are capable of playing the game ( on average) today. Populations that reached that level of development much later, or not at all, are not very good at it.

Could it be an effect of institutions? Well, it’s a bit hard to see how. There are very few institutions that have existed continuously for the past three thousand years. And if it’s a question of gradual accumulation of organizational knowledge – why hasn’t anyone written it down? Couldn’t people trying to catch up read a book? Japan did, although I think they forgot to read Chapter 9.

Even if institutions were an important factor, in some mysterious way, couldn’t individuals from those peoples with late development of agriculture and states simply immigrate to better-organized countries and swiftly catch up? They do immigrate: but they don’t swiftly catch up. That’s the long-lived underclass thing Diamond mentions.

Norse trace

Jennifer Raff has an article in the Guardian, discussing why there’s no genetic sign of black African ancestry ( from Roman times) in contemporary British DNA. Well, the simple explanation is very few such people ever came to Britain. She mentions the case of the Norse Colony on Newfoundland at L’Anse aux Meadows in Newfoundland, which also doesn’t seem to have left any genetic trace.

In the Newfie case, I’m fairly sure why there’s no genetic trace, having read the Greenland Saga. The Norse colony ( which was small) only lasted for a couple of years: the Skraelings turned hostile & the Norse apparently fought among themselves [Freydis]. Moreover, even if the Norse did manage to get it on with the local Amerindians [the Beothuk], the Beothuks’ extinction around 1830 makes genetic transmission to the present day most unlikely.

PNG Über Alles

One of the more interesting points in Guns, Germs, and Steel is Diamond’s claim that people in Papua New Guinea (PNG) “are probably genetically superior to Westerners”: p21. More quotes: “Natural selection for intelligence has probably been far more ruthless in New Guinea than in more densely populated, politically complex societies”. p21. ‘ Modern “Stone Age” peoples are on the average probably more intelligent, not less intelligent, than industrialized peoples. Certainly is no hint at all of any intellectual disadvantage of New Guineans that might serve to answer Yali’s question. p21’

Now this crap is not really essential to Diamond’s overall thesis – that biogeographical factors are completely responsible for different levels of cultural development, rather than (even in part) average differences in population characteristics like personality or cognition. In fact he’s getting in his own way here, stepping on his own dick: if local selective pressures could make hunter-gatherers smarter than Chinese or Jews – then they might also make Chinese or Jews smarter than hunter-gatherers. Arguing for one people’s innate intellectual advantage over others is generally frowned upon – for political/social reasons, not scientific ones – but it’s ok if A. it’s not pro-European-specialness ( pro-Korean would simply leave people confused) or B. nobody takes it seriously.

I’d say that the reaction is some A, but more B. A goodly fraction of people reading GGS simply expel these claims from their memory as confusing and indigestible, and if asked say that Diamond said no such thing. I’ve seen this, repeatedly. Some came away with the impression that he was saying that Stone-Age people are better at what they do, better adapted to their particular life-style – but that’s not what he said. It’s irrelevant anyway – what matters are abilities useful in the modern industrial world, not ones that no longer pay off. Fracking, not tracking.

Even Diamond doesn’t take it seriously: or, at minimum, doesn’t understand the implications of his claim. He’s saying that Papuans are noticeably smarter than industrialized populations, obviously so. (although apparently not obvious to anyone else on earth – I’ve never seen anyone else make this claim.) I say that you couldn’t possibly notice a 1 or 2 pt average advantage in average IQ from personal observation. 5 pts, maybe: but really, to be so striking, something more like a 10 pt difference, minimum. A moderate difference in average trait value causes a huge change in the fraction that exceeds a high cutoff: if the PNG edge were 10 pts, then the fraction of people with IQs > 148 (3 standard deviations above average) would be much, much higher in PNG than in Britain or the US – something like 7 times higher. if this were the case, PNG, population 7 million, would have as approximately as many potential Nobel-level intellects as Great Britain. If anyone believed this, they’d be searching PNG (inch by inch) for those diamonds in the rough. That hasn’t happened. Nobody takes the implications seriously, or maybe they don’t see them. Or, maybe, they think that Diamond is sucking up to his hosts – the Fore are the kindest, bravest, warmest, most wonderful humans beings he’s ever known in his life.

Diamond’s argument is general, not just about PNG. He says that peoples who were hunter-gatherers until recently are probably smarter. Yet in no case does reality actually conform to his hypothesis. In every case, people with such backgrounds do poorly in in conventional schooling, often very poorly.

Genetic evidence for self-domestication in humans

There’s an interesting recent paper on the genetic basis of the changes we see in domestication – and the extent to which humans exhibit similar genetic changes. domesticated species end to have depigmentation, floppy ears, shorter muzzles, curly tails, smaller teeth, smaller cranial capacity, neotenous behavior, reduced sexual dimorphism, docility, and more frequent estrous cycles: the ‘domestication syndrome’. There is reason to think that this syndrome arises from a mild deficit of neural crest cells.

They talk about a number of loci that look to be involved in such changes in in anatomically modern humans, and show evidence of selection (when compared to archaic humans like Neanderthals and Denisovans). They discuss a number of such genes and gene pathways.

I noticed something interesting about one of the genes mentioned [ ERBB4] & the other genes it interacts with. ERBB4 (the neuregulin receptor) negatively regulates ERK, which plays a critical role in neural crest development and regulates neuronal gene expression in both the neocortex and hippocampus. Closely related is BRAF, upstream of ERK. BRAF interacts with YWHAH (selected in dogs), PPP2CA (selected in horses), while ERBB4 shows selection in anatomically modern humans and cattle. Upstream of BRAF, SOSI has been selected in domesticated foxes.

ERBB4 binds with NRG1, NRG2, NRG3, NRG4, and ADAM17. NRG2 was selected in cats, cattle, and dogs. NRG4 was selected in cattle, NRG3 in AMH.

But there’s more: there is evidence for recent regional selection of variants in the ERBB4 pathway [ work from Joe Pickrell] . ERBB4 shows strong signals of selection in all non-African populations, NRG3 shows strong signs of selection in West Eurasian populations, while NRG1, NRG2, and ADAM17 show signs of selection in East Asians.

It is not necessarily the case that all humans are equally domesticated, or became domesticated in exactly the same way. We know that some populations split off as long as a quarter of a million years ago. Although the earliest known AMH skeletons already show signs of the domestication syndrome ( the childlike flat face), their skulls were a good deal more robust than those of any people today. Probably the process has continued over time, quite possibly it even accelerated in dense agriculture agricultural populations in the Holocene. But that wouldn’t have taken the same course everywhere.

Members of populations that have gone further down the path of self-domestication should be easier to enslave.

For all I know, some populations moved into new environments that effectively reversed these selection pressures (feral humans] .

And with rapidly improving genetic technology, we could probably create truly feral humans.

Self-domestication

I wonder if there are neural crest changes in modern humans. Perhaps in all of them, or maybe in just some ( not in Nicholas van Rijn ).