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zaphirplane

What I don’t get about evolution is why humans haven’t evolved in the last 5000 years probably 10,000 years

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But they have. Here are some mutations from the last 10K years:

- white skincolor

- lactose tolerance

http://www.sciencemag.org/news/2015/04/how-europeans-evolved...

- high-altitude adaptations of Andean populations (independent Ethiopian and Tibetan adaptations are older than your 10KY limit)

- possibly HgbS? Couldn't find much numbers related to its evolutionary history. And it's just one of the independent evolutions for malaria resistance: Thalassemias, Duffy blood groups and a few others seem to provide some level of malaria resistance to malaria

- CCR5-Δ32, while it provides resistance to HIV it's too old to have been selected for it but it's too young to have not been selected for as well (95% confidence that it's 900 to 5000 years old, likely circa 2250, a non-selected random survival would be ~100kY given how widespread it is)

And narrowing jaws make us ever more likely to miss some wisdom teeth. They part always struggle to emerge from the gums from narrow jaws due to our large brains, and are also less necessary today with softer foods. Softer foods also weaken our jaw muscles a bit, so they are more likely to remain under the gums and cause infections.

All in all, they are probably more or less going away in the long run.

The timespan of a generation in humans is about 20 years. So in 5000-10000 years that's 250-500 generations, a tiny amount.

For evolution to happen, a genetic mutation has to endow an advantage that makes its carrier more likely to survive and reproduce. Given that the reproductive selection process (which characteristics are attractive to a mate) is largely driven by cultural norms now, it's hard to see what advantages are going to raise a person's chances of reproducing. Fashion tastes change several times in a single generation.

Women are often said to like taller men. Well we are getting taller as a species [1]. If men prefer a woman with a certain 'look', maybe women are evolving towards that look (it seems like a much harder thing to quantify). Manipulative, cheating males have more sexual partners - maybe we're evolving towards more of that kind of behaviour.

If you're expecting humans to grow extra arms or become super-strong or something, I don't think it's going to happen. Extra limbs is too 'abnormal' and culture doesn't like that. Being physically strong doesn't affect chances of survival in humans any more. Same applies to better vision, hearing... any super-senses. They don't affect our survival. I've heard people posit that maybe we'll lose our little fingers as they don't do anything. Same again though - even if it's true that we don't use them, it doesn't mean that someone born without little fingers is going to have a higher chance of reproducing.

Our development happens at a rate much faster than biological evolution now because of culture (meme vs gene). A lot of what constitutes a modern human is external (as a thought experiment just imagine what a human would be like if he'd never spoken to another human, read anything, or absorbed any culture in any other way). From this point of view, cultural evolution could be seen as evolution v2.0 as it happens and spreads much more quickly that genetic evolution.

[1] https://www.scientificamerican.com/article/why-are-we-gettin...

The interesting question is if human changes are liable to speciate or not. It is possible that just a few changes would result in biological incompatibilities. Combine it with differentiating sexual selection and things might become interesting.

Interesting indeed.

If humanity in its current state somehow manages not to destroy itself (and much of everything else) the probability of speciation of our survivors is close to a certainty. Not so much as a consequence of natural selection or sexual selection but of human selection.

If we survive another 100 thousand years, we will inevitably see another emergent species genetically superior but incompatible with current homo sapiens. I think that will be an incredible day for humans to acknowledge (the death/extinction of homo sapiens). We had better sort our differences out before that day arrives.

I think it's unlikely these days because we all intermingle too much. If anything it'll go the other way with races fading out as our descendents become mixed.

Yes I am assuming a large and notable mutation. Humans fought for thousands of years with implements so where is the human with Star Trek armor skeleton. I guess in the books the diversity caused evolution is strong and notable

Ps choosing your mate is a recent thing for humanity

> For evolution to happen, a genetic mutation has to endow an advantage that makes its carrier more likely to survive and reproduce.

Or sometimes a mutation can survive just by being benign enough not to make much difference to reproductive chances.

Well humans have evolved and are still evolving, there are differences between humans that emerged in the last few thousand years, or what do you call the differences between the human races.

"There are only a few groups who diverged at a set time and remained discrete until now. The KhoiSan split off from the rest of us 100,000 years ago, and the Australian Aborigines about 40,000 years ago. Native Americans, who are a sub-set of the East Asian population, became isolated from population-exchange with Eurasia and Africa 12,000+ years ago." [1]

The thing is humans in the modern age intermingle much more so the differences are subtle and much harder to pick out since they don't remain as discrete.

[1] https://www.quora.com/When-did-the-human-races-diverge

It’s not like obvious evolutionary change typically happens in the course of just a few generations.

But a quick web search turns up various discussions of recent evolution, e.g. https://www.nytimes.com/2010/07/20/science/20adapt.html

A couple of points here.

- Humans have evolved. Look at our huge array of characteristic physical appearances. These differences have emerged in spite of the fact that we all share an extremely common same-species common ancestor. And that's just what's on the outside. Our primary divergence from our evolutionary (different species) ancestors has not been what's on the outside, as we've become worse in nearly every way, but what's on the inside. Intelligence > all. Discussing this topic as it relates to humans today is very sensitive.

- Evolution is driven by natural selection and ultimately by who's most successful at breeding. Humanity has socially evolved in a bizarre way in that today those who are least successful tend to breed far more successfully than those are more successful. Lower income, lower education, and higher religiosity are strongly correlated with higher fertility.

The Flynn Effect [1] was the observation that 'real' IQ scores were constantly increasing in developed nations. This was a major issue since IQ is normalized such that for any given population that mean is always 100 with a standard deviation of around 15. That means that somebody in 1960 with an IQ of 100 was probably more intelligent than somebody from 1920 with an IQ of 100. This was convenient for the environmental view of intelligence as improvement in environmental factors correlated with the increases in IQ. However, the Flynn effect in many developed nations has actually reversed, in spite of the continuing improvement in environmental factors. It continues to remain in effect in less developed nations. There are many ways to interpret this, but it's certainly interesting to consider it from an evolutionary perspective.

[1] - https://en.wikipedia.org/wiki/Flynn_effect

By evolution, we assume you mean "turn into another species". If so ...

But then neither has the mosquito "evolved", or the shark. At a genetic level changes are continuous in every organism and genetic changes can even happen as rapidly as from one generation to next. We may not see the molecular changes translate to the phenotype level but the changes are there. (See topic of epigenetics)

Actually, you can see changes at phenotype level too (e.g body morphology of offspring affected by the diet of parents).

Evolution is a slow process. Plus humans are complex, so the small changes might be relatively invisible

Well, first of all, we have, a little. But 10k years really isn't a very long time.

our brains shrank, we have that going for us

https://phys.org/news/2011-06-farming-blame-size-brains.html

Humans have evolved more myopic eyes in only the past few 100 years, perhaps because of more time spent indoors looking at closer objects.

You haven’t noticed people with gills behind their ears?

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