Are there any evolutionary pressures at work on Homo Sapiens today? How?

Factual Questions
21

Do I get extra points for being a sort-of for real scientist? I’m working on a PhD in biology, and spent a few years in an evolutionary biology lab, for what it’s worth.

I think the interesting, and tricky, thing about future human evolution is that we are, ourselves, changing our own selective pressures, and we’re doing so far faster than evolution can keep up with. Medicine is removing all sorts of things that used to kill us - but not all of them. At least not yet. Suddenly, economic factors come into play in various ways that affect how likely we each are to have kids. There’s the environment, which is shifting very rapidly (in evolutionary time). Although there are exceptions, evolutionary biologists generally speak in terms of dozens or hundreds of generations. The bigger the population, the longer it takes for any adaptation to spread, and humans have a very large population. There’s no way that the selective pressures that exist right now will be the same in even a single generation, let alone a hundred.

As a semi-trivial example, I saw a question on another website asking if humans were all going to evolve extra fingers to type faster and improved eyesight adapted to staring at glowing screens. Putting aside the obvious silliness, you could argue that the ability to type could be a selective advantage - it might help you get a better job that involves less physical danger, pay more, and let you afford more kids. Or a disadvantage, because you sit on your ass all day typing instead of getting exercise. It doesn’t really matter, because either way, natural selection is not going to have enough time to adapt us to it. How many more years do you think we’ll all be using keyboards? Or staring at physical, glowing screens? 10? 50? 100? There’s simply no way that natural selection can keep up with how fast we’re changing our own environments.

This has never happened before, as far as we know, so any speculation on how that’s going to effect our evolution is just that - speculation. It seems likely that sooner or later we’ll develop the technology to make whatever changes to ourselves that we deem necessary, but that’s just one possibility. Maybe we’ll destroy ourselves. Maybe we’ll nearly all be wiped out by a disease. Maybe we’ll send small groups out into space, where reproductive isolation will eventually cause speciation. Or maybe we’ll all just keep on basically muddling on more or less the way we are right now. We don’t really know.

So back to the original question. Do we have evolutionary pressures? Certainly. No organism will ever stop evolving as long as the basic fundamentals are in place: genetic variation and insufficient resources for all offspring to survive equally well. Evolution is an automatic, inevitable consequence of those conditions. But the pressures are changing very rapidly, in ways we don’t really understand. We’ll just have to wait and see what the consequences are.

22

Of course they will. For one thing, not all humans live in the same environment. For another, all the fancy technology we’ve created only serves to change our environment - it does not change the fact that selection is still occurs. And for a third, what is considered ‘harmful’ is dependent on either the viability of a living organism in general, or on the environment in which the organism finds itself.

23

Well, then, I disagree with you too, Mijin.

Now it seems like you’re saying that because of all our stuff, we have more of a buffer against some of the stresses that other species face. That’s not true for the whole species, as DF points out, *and *natural selection still works. Just because our natural selection favors guys who are good at math, and squirrels’ realities favor the individuals who can outrun dogs, I don’t see the pressures as qualitatively different.

<tangent> I *think *humans are the only social species that lives in societies larger than extended families, too, which is interesting, and favors humans as an adaptive behavior, but perfectly falls in the category of a trait. Individuals that aren’t good at living among and interacting with strangers get fewer mating opportunities. It doesn’t lift us out of the evolution game.</tangent>

It only gets different, in my view, when you realize the game, and selectively breed, or genetically engineer. Even then, I agree with DF that we still experience the consequences of the game, and we’re still in the game, but I think we’re qualitatively differently prepared because we *understand *the game.

24

Your response is not relevant to what you’ve quoted. I have responses but I don’t want to second-guess the relevancy.

25

That’s just it: it doesn’t.

You’ve just made exactly the mistake that I was trying to warn people against making.

26

But this is the point. Just because you are good at math, do you tend to have more children? Do they survive to have more children?

Or are we selecting for smooth-talking deadbeat dads, and then you the math major will hook up with the jilted woman and raise the cuckoo-child as your own?

(How many families do you know where the first child is NOT the child of both the couple…?)

27

Viruses kill a lot of people, depends what you mean by predators and they are changing all the time…

28

Do you have any evidence or logical argument that brings you to this conclusion. I note that you have repeated it a couple of times, but i see no actual evidence for the claim.

As do all mammal, probably all vertebrate, species. Wolves living in the deserts of India don;t have the same habits as wolves living in the arctic tundra. In no possible sense is this unique to humans.

29

I think Smeghead is spot on in describing how natural evolution cannot keep up with our pace of development. While we may not be sure where this is leading to, we are heading towards it at breakneck speed.

That alone should be enough to justify ample consideration, but in (my) reality it’s a total none issue.

30

Since the invention of repeating firearms beginning about 1860, reckless bravery in the face of threat has become an increasingly unsuccessful survival strategy.

31

I meant to write “Of course it will”, rather than “Of course they will” - the ‘it’ being the rule of thumb which you were stating would not apply to humans. The sentences which followed explain why I think your rule of thumb does, indeed, apply to humans.

32

Your summary has actually confused me somewhat. Genetic variation is in place sure, but in the developed world, there are sufficient resources, provided by society, for all offspring to survive equally well (in evolutionary terms - i.e there is little/no reason why someone won’t be able to grow up and reproduce successfully, because no matter how deadbeat they are, society will again take care of their kids). So is that the necessary and sufficient condition?

33

Do you have any counter-examples?
I’m trying to think of some, but it seems to me most activities we spend a lot of effort on are prestige activities of some sort that enhance our social status and hence the ability to score with chicks and pad the nest for our offspring. Bigger, fancier, noisier cars or motorcycles - attract chicks. Smoking - looks cool (or used to) attracts chicks, and you don’t die until well after you reproduced. Getting rich - really attracts chicks. Music - is for dancing and sounding cool - attracts chicks. Just ask Jagger or the guy from Kiss or any other victim of groupie swarming.

On the chick side, a lot of money is spent on clothes, makeup, and cosmetic surgery - to snare a guy.

Heck, the internet was invented mainly to dish up porn, to encourage one’s libido and fool nerds into thinking they have a chance with chicks, so they’ll keep trying to reproduce.

Not sure how this relates to…

Basically, humans, especially homo technologis, have used things like clothing, central heating, air conditioning, agriculture, refrigerators and freezers, vitamin D and tanning oil, etc. to bypass the environmental pressures - climate, finding food, etc. - that other species would live. Some grow fur coats, others hibernate, some (like the polar bear) fast for months at a time, some (camels) have fancy adaptions to hot dry climates to preserve body fluids, etc.

Humans are pretty much one size fits all because we change the immediate environment to fit ourselves. Agriculture and food preservation have made us less dependent on the daily or seasonal food opportunities of our environment. Similarly, arabs covered from head to toe and living in tents are less subject to the selection pressures that produced melanin-rich southern African or original Australian inhabitants.

34

So you ask for counter examples, then list a dozen counter examples. :dubious:

As does almost every pother mammal species. Once again, humans aren’t in any way unique in this regard.

Apparently Indians in Ecuador also cover themselves form head to toe, since they are also paler than equatorial Africans or Australians. Spaniards and Japanese also apparently covered themselves form head to toe, since they are less dark than Tasmanian Aborigines.

35

Indeed. If we were to discover that, say, certain people in Africa had a genetic ability to fight off AIDS, it would be huge. AIDS can’t compare to a lot of other diseases in sheer body count, but the fact that it can be spread in utero makes it a biggest evolutionary concern than, say, Cancer, which typically strikes people after breeding age.

But the OP was asking about the modern world. While a resistance to heart disease and cancer would be nice, neither are big concerns when it comes to spreading of genes. The vast majority of Western world problems when it comes to survival are behavioral, both on the individual and group levels. How genes affect behavior is… controversial, to say the least.

36

My point follows, frankly, from a basic appreciation of what natural selection is.
If a common behaviour has a cost, then it is very likely to aid that species/individual’s survival or reproduction. Otherwise it is a behaviour which was useful, and will now probably be selected out.
What part of this would you dispute? Can you think of any examples that refute the claim?

First of all, there are of course physiological differences between those subspecies (and there’s some dispute that they are merely different subspecies). For one thing the indian wolf has shorter fur and no “underfur”. They also lose most of their longer hair in the summer.

So your example confirms exactly what I was saying.

37

The response still makes no sense in that context. Read your post #22; I think perhaps you’ve quoted the wrong part of what I said.

38

Um, let’s see: well for starters how about any leisure activity?

Of course, we can then go into human psychology: there are reasons, in our evolutionary past, why we find playing call of duty enjoyable, say.

But this doesn’t go against my point, which was simply that you can observe animal behaviours and conclude that those behaviours are very likely to aid their survival or reproduction. This would be a bad extrapolation to make about a human playing CoD.

39

So you can’t provide any evidence, it just stands to reason. Except in the case of humans, where it doesn’t stand to reason. And that proves the point you are trying to make. Which is that it doesn’t apply to humans.

Gotcha. :dubious:

No, it doesn’t confirm what you are saying. What you are saying is that humans are unique in adapting their behaviour and technology to the environment. The fact that other species also have physiological adaptations in addition to behavioural and technological adaptations doesn’t refute the fact that they *have * behavioural and technological adaptations.

There are of course physiological differences between human populations. If we were to follow your logic this confirms that humans do not have behavioural and technological adaptations to their environment.

You can’t have it both ways. You can’t argue that you can prove that humans are unique in exhibiting behavioural and technologal adapation to environment because other species have physiological adaptations and thus don’t have behavioural and technological adaptations, and then argue that human physiological adpatations don’t discount humans having behavioural and technological adaptations.

Either a plurality of species, including humans and wolves, exhibit behavioural and technological adaptations in addition to physiological adaptations, or else physiological adaptations preclude behavioural and technological adaptations, and therefore humans, exhibiting physiological adaptations, do not exhibit behavioural and technological adaptations.

Of course what you are actually trying to do is engage in special pleading, absent any evidence at all beyond “it stands to reason that only humans exhibit these traits.”

That won’t cut it.

40

So you acknowledge that there are sound reasons why playing COD aids in our survival, but you can’t extrapolate form that that humans playing CoD aids in our survival.

Does this make any sense at all to you? You are demolishing your own position.