Humans & Evolution

[sen_no_ongaku]

Thought: in the past few thousand years, genetic evolution in humans has been largely -- though not wholly -- supplanted by technological innovation.

What sets humans apart from other animals is the ability to adapt to selection pressure on an individual rather than generational level. For example, in response to colder temperatures, rather than grow a warmer coat of fur over a thousand years of breeding, we could simply kill a creature that already has a lot of hair and wear its skin. Another example might be the invention of spectacles for people with poor vision, a trait which would otherwise be crippling in.

This is not to say that such innovation can completely replace biological adaptation. Our technology has limits -- and we can see those limits; but we can also move them. Nevertheless, we can't guarantee we can move those limits in time.

Anyway, in the absence of the environment as a driver of evolution, are there other, perhaps societal sources of selection pressure?

Comments

[archaica.livejournal.com]

Completely pulling this out of my ass, but I think body shape and weight are one of those things which could fall under that rubric.

[2h2o.livejournal.com]

Three thousand years is a blip on the evolutionary scale of an organism with a reproductive cycle as long as humans'. Also, we don't really have any idea of how our environment and genes interact. Which is all to say that it's impossible to look back and judge what the effect of civilization has been on genetic selection.

The idea of social selection seems extremely plausible. That's part of The Bell Curve that made a lot of sense to me. I don't think anyone would question the idea that smart, motivated, attractive people seek each other out and intermarry. But societies tend to be fragile and short-lived; the idea that one could last long enough, essentially unchanged, to matter on the evolutionary scale seems absurd.

Overlapping societies (Etruscans-Romans-Gauls-French, e.g.) could conceivably have similar social pressures, and so be treated as a single society for evolutionary purposes, but even short periods of chaos might interrupt that dynamic. It's sometimes said that the reason the French are ugly (not saying I agree, but it's an interesting idea) is that the aristocracy was killed off during the French Revolution. The idea that the aristocracy was attractive fits with societally driven evolution, but if only a decade of violence can undo generations of "progress," it's hard to believe that any succession of societies would be stable enough to replace natural selection.

There may be other mechanisms that shape us (e.g., technology, or something akin to "domesticating ourselves"), but they aren't precisely evolution, and I'm not sure anyone has even begun to understand how they might work.

Good topic!

[sylvantechie.livejournal.com]

Speciation is relatively slow, but phenotype selection can be relatively fast, and it still counts as evolution.

Has genetic evolution been supplanted by memetic evolution? With modern tech there's a very broad range of neutral (neither contributiong to nor hampering reproduction) traits. With in that range what people think and learn probably has more evolutionary weight their their physical attributes. As technology improves the physical capabilities of the individual matter less and less.

Societal pressures act as a darwinian evolutionary landscape for anything that cycles faster much than the society changes (no idea what the relative change rates would need to be, other than the landscape needs to be relatively still). Long term societies drive genetic changes to favor given phenotypes, but probably aren't stable enough and/or isolated enough to drive speciation. The isolation aspect is probably more of a factor than the time.

In a larmarckian situation adaption can take place in a single generation, or less - instead of generational changes it's a continuum of change that's independent of the carrier. Society is based on individual ideas, attitudes, knowledge, etc., all of which continuously change. Serious feedback cycles result. The stability of the societal landscape ties to how quickly and easily ideas can propogate - global networking certainly makes things interesting.

I think one of the big things that sets modern humans apart is the storage and transfer of knowledge independent of individuals.

Is being human about biology and physics or about beliefs and actions? It depends on the context of the discussion. Outside the strict realms of biology, I tend to equate 'human' with more general terms like sapient, sophont, etc.


Bruce Sterling explors this general topic in his novel Schismatrix. I highly recommend it, and can loan you a copy if you like. The Culture novels by Iain Banks are also a good exploration of this. I'd also recommend Kaleidoscope Century by John Barnes as a good (though disturbing) novel with this theme.

[osirusbrisbane.livejournal.com]

For example, in response to colder temperatures, rather than grow a warmer coat of fur over a thousand years of breeding, we could simply kill a creature that already has a lot of hair and wear its skin.

Oddly, this made me think of Heroes.


Anyway, I think we have our own bizarre society as a driver of evolution, both in terms of what we consume and in terms of our physical existence -- surely the advent of chairs and keyboards must shape us.

[ellinor.livejournal.com]

I wonder if, in time, we will observe that the we have bred for the ability to develop and use tools. That would be consistent with your observations, but perhaps not not your postulate. Our tools have become more and more sophisticated, and we have become better and better at using them, as the species has progressed over the last several thousand years. Those who use tools better become safer and more attractive for breeding partners. Tools have always had danger involved with them too, from the physical danger of using a sharp tool to skin an animal, to the health dangers of the sedentary lifestyle inherent in using many of today's more sophisticated tools. Those who use the tools best while staying safe and healthy become the bellwethers for the next generation. Over thousands of years, we find that as a species we use better and more sophisticated tools (the question is whether we are inherently physically and mentally better suited to using them; I don't know the answer to that, but I suspect we are). Evolution, or coincidence? Dunno.


:)

[balsamicdragon.livejournal.com]

I think that nurture is so strong a force, versus nature, that evolution in human beings who provide intense and varied forms of nurture to their children is somewhat obselete. Combine this with the sharp class divide that encourages the rich to marry each other and pass the wealth on to their children, producing stale gene pools which nonetheless prosper, and evolution is too simple a theory to explain how the human race is changing over time.