[ExI] The Yamnaya question

spike at rainier66.com spike at rainier66.com
Sat Jun 1 05:43:54 UTC 2019




Cool, great stuff Rafal!  I left it all in there below intentionally in order to refer to concepts therein.


A dentist friend and I were pondering this and speculating idly.  Evolutionary pressure can be thought of as operating most quickly when advantage gradient is highest.  In human forms, I have long thought of two areas which would vary the most with respect to a particular environment: the body-fat content and the configuration of the jaw.  In both cases, those two things would carry a lot of survival advantage gradient.  If you think about it, that makes sense: if a lot of meat is available, it requires a different optimal dentition configuration than if the human populations subsists on grass seed such as rice or wheat.


OK then, we get the whole body-fat thing: in cold climates the advantage goes to the Inuit, a typically short round guy, but in the tropics, the tall slender guy has the advantage.


Regarding your notion of optimal breeding distance…


>… in some situations is called heterosis…


Ah yes, heterosis.  Our society has gay pride parades, so one might be tempted to think there should be the counterpart: straight shame parades.  We shamble along, heads hung in ignominy, silent, sullen, colorless we are, sick with this dreaded disease known as…heterosis.


OK that part was just for fun.  You know me.  {8-]


If we go with this notion of optimal breeding distance, we can imagine how it would work with body-fat ratios, but even easier is to think about dentition.  My dentist friend was also an orthodontist.  I asked him once why it is that so many of us Euro-mutts seem to need braces.  His notion was a bit similar to yours: we are genetically made of so many disparate parts, populations which evolved under so many varying conditions and climates, we just have too much stuff in our genes, too many incompatible instructions.  So we have cases of gapped teeth up top and crowding on the bottom for instance in the same person.  We have jaws too large or too small for the teeth they have in them.  


In our times, we Euro-mutts, the Yamnaya descendants, are now drifting towards breeding distance that is too great.


Rafal you really have my wheels spinning.  More ideas tomorrow perhaps.







From: extropy-chat <extropy-chat-bounces at lists.extropy.org> On Behalf Of Rafal Smigrodzki
Sent: Friday, May 31, 2019 8:39 PM
To: ExI chat list <extropy-chat at lists.extropy.org>
Subject: [ExI] The Yamnaya question


About 5000 years ago the male ancestors of most of our list members burst forth from their Yamnaya Russian steppe domain and started merrily slaughtering their way across the world. Nowadays known as Proto-Indo-Europeans, over a period of a few thousand years they spread their language and their genes from Norway to Sri Lanka and the Gibraltar, ruthlessly exterminating local men and taking their women. With the invention of guns and ships they continued their expansion to the Americas, the tip of Africa and to Australia, before finally running out of steam sometime in the 1960's. 


This was the most successful single demographic expansion in the history of our species, at least as measured by the acreage settled or conquered, and there are many hypotheses as to why the Yamnaya succeeded to this extent. Nazis, who called the Yamnaya Aryans, believed they were simply superior to other people. Some researchers say that the Yamnaya won because they had carts and horses. Nobody knows for sure.


It occurred to me that the answer might not lie in the intrinsic genetic endowments of the Yamnaya and is not explained merely by technological superiority but rather it is related to a quirk of genetics, the optimum mating distance.


It is well established that mating with close relatives dramatically reduces evolutionary fitness - this is why the children of incest are so often sickly, deformed and mentally slow. On the other end of the spectrum, mating among organisms that are so far from each other genetically that they are just barely able to have offspring also leads to diminished or zero fitness, as in mules and tigons. In between these extremes there is an optimum mating distance, where the parents are not so close as to share large numbers of deleterious rare mutations but not so far as to have incompatible adaptations. Their babies are stronger, faster, resistant to infections and smarter, an effect that in some situations is called heterosis, or hybrid vigor.


One of the typical features of prehistoric life in established communities was a very restricted ability to travel due to presence of hostile neighbors. Thus, after an initial settlement of an area, for example when the Anatolians swamped the local hunter-gatherers throughout Europe, each small location would become reproductively isolated from even relatively close neighbors (we are talking 100 miles distance or less) and thus increasingly inbred. This splintering into tiny tribes and inbreeding has been observed in many locations, from Europe, to Africa to Papua. The effect persists even as neighboring tribes, such as modern Yanomamo, raid each other to steal women and slaughter competing men - since they are in effect stealing from their extended families, they still remain inbred.


The Yamnaya developed their culture around horses, carts and a nomadic lifestyle. By themselves these technologies may not have dramatic genetic implications except for one thing - they allow long distance kidnapping of women. Long-distance raiders can not only increase the number of mates available to them but also can increase the genetic distance between themselves and their mates. Geographic distance translates into genetic distance, and a technology for fast movement on the Earth's surface translates into an exploration of new genetic possibilities.


The spread of Yamnaya thus resulted in the generation of less inbred offspring, which in turn used their mobility technology to extend their reach with each generation, consuming the inbred, sessile populations in the process. The Yamnaya genes were not intrinsically "better" than the genes of e.g. the Anatolians or Dravidians but the offspring of far-away invaders and their local slaves was more genetically diverse, and thus fitter.


This mechanism may be responsible for the demographic transformation of the ancient world and it does have implications for prospective parents today - a bit of genetic adventurousness and out-of-the-shtetl thinking may go a long way towards having beautiful and smart babies.

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