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Comment by JoelMcCracken | Hacker News Reader

That isn't evolution, it is a diversification of our genetics. There are lots of things that many humans are intolerant to which would have probably been a really big weakness in the past.

Humans are no longer subject to natural selection. There needs to be significant culling pressure for real evolution to happen.

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It is evolution, and it speeds up with higher populations. As for natural selection, consider that only small changes in allele frequencies add up quickly through the generations. Also, sexual selection is very much a force.

http://www.scribd.com/doc/33322719/Cochran-Gregory-10-000-ye... http://www.nytimes.com/2007/12/11/science/11gene.html http://www.wired.com/wiredscience/2007/12/humans-evolving/

"Humans are no longer subject to natural selection."

What? Are you sure? Because we most certainly are subject to natural selection.

Yes. But not to any significant degree that will cause a change as a species.

I'm sorry, but anyone who says this has failed to understand evolution.

Evolution is a slow process. But there is no reason to believe that it is going any slower today than it ever did in the past - we're just being selected for different things than in the past. (For instance carelessness about birth control.)

No, he's right. The most powerful force shaping the future is intelligence. Natural selection on biological genes is orders of magnitude slower.

The fact that intelligence is shaping our future faster than evolution does not affect the fact that evolution is still proceeding at the current moment in our species.

No, he's wrong. Natural selection doesn't speed up or slow down, it just is. Each passing generation there are pressures put on the spreading of human genes, and those pressures are the manifestation of natural selection. Whether those pressures are different now than before, or whether they shape "the future" is irrelevant to the biological impact of natural selection.

Sure it does, in the sense that there are fewer selective pressures on us, and those pressures are weaker. Our intelligence is able to overcome many of the pressures our environment exerts on us.

I'm highly skeptical that there are fewer selective pressures. One example, aren't industrial countries having fewer and fewer kids?

Just to clarify, When I say "us" I mean the western world. True, industrial countries are having fewer kids, and thats an example of a new selective pressure. It's a result of a new environment we've created for ourselves. I'm sure there are many to go along with that. But the sheer number of (potential) selective pressures we've removed through technology doesn't compare: many diseases, muscle size, brain size, vitamin D synthesis (its put in everything now), body hair, skeletal structure, the list goes on. Our interaction with our environment is on such a fundamentally different level that there are many classes of environmental pressures that simply don't affect us anymore.

Think of it this way: we used to be directly reliant our the environment for survival, like animals are. But now, we process our environment to such an extent that small variations in it are overcome by our intellect. Those variations in the past would constantly be exerting selective pressure on us in many different directions. Those pressures are processed out now.

we most certainly change as a species. Something as simple as choosing who to reproduce with affects the distribution of genes that are passed on to the next generation.

A more obvious example of the sorts of changes we can still go through is sickle cell.

Natural selection is just one component of evolution. Genetic drift and, especially, artificial selection are certainly in full swing.

And anyway, I completely disagree that we're no longer subject to natural selection. We're always subject to natural selection. We're not immune to everything.

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