Humans are evolving into... Grey!

[Umbran]

Going from quadrupedal to bipedal had a direct influence on the skeleton

Well, more the reverse - changes in the skeleton had a direct influence on our posture. Some poor monkey had a "deformed" pelvis, and could stand more straight and for some reason he survived better

It that trend continues, the jaws will become smaller and the skull bigger. Hence my comment that we would eventually ressemble (the so-called) Grey. As a last note, two scientists, who had been invited to debate the documentary, said that the environment had a direct influence on homo-sapiens evolution. If that's so, I guess that living in an urban civilization like our own is certainly a big change of environment for homo-sapiens!

There's the rub - you're looking at a trend over 3 million years. In the last 400 or so there's been a masssive change in environment. Who is in a position to then say that the trend will continue?

So maybe the changes do not affect directly the genes, but first the sturcture of bones, etc., and with time the body is "molded into a new expression".

It isn't that the environment alters the genes directly. Nor is it that the environment effects the structure of the bones, and thence to the genes. It is a sort of feedback loop: Genes->Bones->survival in environment->genes.

I find it difficult to believe that there's any particular selective pressure on us for bigger skulls and smaller jaws. The former especially - as it is, human skulls are a bit large to pass through the mother's birth canal. And, much to the dismay of many - there is little to no correllation between larger brain/skull size and intelligence or success among humans. Having a big head doesn't make you smarter, and it makes it harder for you to be born.

It is possible for us to just "drift" into having larger skulls. However it is much less plausible for that to be happening "worldwide" - drift happens less in larger, open populations.

 

[Desdichado]

The theory was convincing enough, but I am unable to explain it in English. I think that if I tried to explain it in French, my explanations would look like gibberish too.

I imagine that's so if you're not really very familiar with the theory of evolution and how it is proposed that evolution works.

Granted, keep in mind that it is still a theory, without firm confirmation, and therefore the details of the model may change as more information is discovered, etc. But this is how the model works currently.

Evolution has no "plan" it cannot, as a matter of fact, proceed according to a plan. Nor is it a broad, trend-like change that affects and entire population. Evolution--according to the theory--occurs when a random mutation in a single individual is passed on to it's heirs. This random mutation is generally supposed to give those who have it an "evolutionary advantage", so it therefore becomes dominent either because those who have it monopolize breeding populations and therefore pass on the change, or they literally replace those who don't have it because they "outcompete" those without it, and the more primitive, unmutated form goes extinct.

That's the highest level snapshot of the model, but keep in mind that such developed traits may or may not actually be an "evoluationary advantage"--they could be "evolutionarily neutral" yet still dominant so that they end up spreading. There may not be any direct head-to-head competition either, other circumstances can lead to extinction, and subsequent repopulation by more derived (or even entirely new) forms.

But, since the model is predicated on evolutionary change starting with a single individual and thus spreading through the population by either diffusion or replacement of genes, the entire premise of the show you watched is flawed from our understanding of evolution.

 

[Thornir Alekeg]

But, since the model is predicated on evolutionary change starting with a single individual and thus spreading through the population by either diffusion or replacement of genes, the entire premise of the show you watched is flawed from our understanding of evolution.

400 years is somewhere in the range of 15 or so generations. If the trait were perfectly dominant you are still only talking hundreds of thousands, perhaps a few million progeny. In a world of 6+ billion (what is the current number?) its pretty hard to say that some evolutionary change is happening across the species based upon those numbers.

 

[Aust Diamondew]

I highly doubt humans are evolving into much of anything. Natural selection with the advent of modern medicine and civilization I would think that human it would have come to a stop. The only selection at all that is currently occuring might be in the different levels/classes of society (which would be SES or socio-economic status). People in these classes will pick mates that society tells them are good to pick.
I think the only evolution we're going to see anytime soon is going to be counciously initiated by us using genetic engineering.

More importantly why would we need to evolve anyway? We seem to be doing pretty well as is. If there is no need to change and nothing to react against to cause a change (disease, enviroment, predators) why should we change?

To sum it all up natural selection is at an all time low.

 

[Turanil]

I just regret that you cannot comment after having actually seen the documentary, but rather my short post and dubious explanations. Not that the theory did satisfy the two scientists who were invited anyway. In any case we must not forget that scientific truths regularly evolve themselves... As a last note, it is me, but I find hard to believe that a single set of superior genes could spread over a whole population, hence promote evolution into a specie. I clearly believe that the bigger animals get the females first, so in the end the trend is to have bigger animals : this is not as if a single one, gifted with an advantage, is eventually (with his heirs at several generations) taking over a whole population. But well.

 

[Thornir Alekeg]

I highly doubt humans are evolving into much of anything. Natural selection with the advent of modern medicine and civilization I would think that human it would have come to a stop. The only selection at all that is currently occuring might be in the different levels/classes of society (which would be SES or socio-economic status). People in these classes will pick mates that society tells them are good to pick.
I think the only evolution we're going to see anytime soon is going to be counciously initiated by us using genetic engineering.

More importantly why would we need to evolve anyway? We seem to be doing pretty well as is. If there is no need to change and nothing to react against to cause a change (disease, enviroment, predators) why should we change?

To sum it all up natural selection is at an all time low.

True, we just don't adapt to change now so much as we either change the environmental pressure or find a way to circumvent it. Of course evolutionary changes happen so slowly that its not like we would be aware of them occuring anyway.

 

[Turanil]

Of course evolutionary changes happen so slowly that its not like we would be aware of them occuring anyway.

There is in fact an ongoing debate, within the scientific community, as to whether evolution happens suddenly "by jumps" (a jump taking 10,000 years anyway), or slowly and steadily. This debate has yet to be resolved.

 

[frankthedm]

Actually. I'm curious about the evolution of man. Umbran you seem to knowledgable about such things. I often argue the use of helmets and knee pads while on bikes and skateboards, along with the Antibacterial soaps could hurt the evolution of humans by making us more weaker. Am I wrong?

Yes it does hurt the human race by making us weaker overall by letting the dumb, unhealty and thin boned live to breeding age.