Recent (lack of) human evolution

A short while ago I was reading an archaeological article which was discussing early humans, namely the Cro-Magnons of western Europe. These were a group of people who lived around the time of the ending of the last ice age circa 35.000 - 10,000 years ago.

Reading the article
archaeology.about.com...
it became obvious that there had been a recent and substantial shift in our scientific perspective regarding these early people and that physically, there apparently was very little difference between their appearance and that of modern humans.

Recent research over the past 20 years or so, however, has led scholars to believe that the physical dimensions of so-called 'Cro-Magnon' are not sufficiently different enough from modern humans to warrant a separate designation. Scientists today use 'Anatomically Modern Human' (AMH) or 'Early Modern Human' (EMH) to designate the Upper Paleolithic human beings who looked a lot like us, but did not have the complete suite of modern human behaviors.

My interpretation of the above quote is that except for the differing social and cultural values between the two groups, anatomically these early humans were for all intents and purposes identical to ourselves ... even though there was a gap of up to 30 millenia seperating us from them.

That got me to thinking about the role of evolution, especially human evolution and the theory that evolution is a continuously ongoing and relentless mechanism that operates on generation after generation after generation ... the following summarizes this process well ...

Over many generations, adaptations occur through a combination of successive, small, random changes in traits, and natural selection of the variants best-suited for their environment.[4] The other major mechanism driving evolution is genetic drift, an independent process that produces random changes in the frequency of traits in a population. Genetic drift results from the role that chance plays in whether a given trait will be passed on as individuals survive and reproduce.

Now over a span of say 30,000 years and if we take a generation to consist of approximately 25 years, then approximately 1,200 generations seperate us from those people once labeled Cro-magnon.

So, my question is as follows:

If evolution is a continuous and inexorable process, then surely those 1200 generations should have been enough time for many mutations to have taken place and become part of modern man's physiology and biology.
And yet, science has conceded that there is virtually minimal genetic/physiological differences between these 2 groups of humans over that span of approximately 1200 generations.
So, how long WOULD it take for significant changes to arise if 30,000 years seems to be an insufficient amount of time ... 40,000 perhaps ? maybe 100,000 ? perhaps 200,000 ?
What about the 3 main human sundivisions of Caucasian, Negroid and Mongoloid ... these are obviously major genetic/physiological changes ... so how long did it take for them to arise ? Obviously far longer than 30,000 years.

[edit on 27/10/09 by tauristercus]

[edit on 27/10/09 by tauristercus]

Well, all valid I think. But look at today, we have medicine and stuff that keep the "weak" alive. Nature is "survival of the fittest"

Originally posted by qwiksilva
Well, all valid I think. But look at today, we have medicine and stuff that keep the "weak" alive. Nature is "survival of the fittest"

Spot on mate, I even think our genes are degenerating... But I don't really have any proof of this. Except for the 100's of weird people I come across each and every day...

Evolution can take place in as little as 10 generations (the recent goldfish study - will try and find a link) or over the course of 100,000 years. The speed is generally determined by circumstances (as far as genetics will allow).

However, it's all a moot point now. We've effectively killed human evolution in the last generation or 2. Any future evolution is likely to be environmental (and given the environment, not good). I wonder what pollution-mutated humans would look like?

Originally posted by qwiksilva
Well, all valid I think. But look at today, we have medicine and stuff that keep the "weak" alive. Nature is "survival of the fittest"

Sure, I agree with you that modern medicine is keeping many people alive and able to breed that would have just a few short years ago, died, which would simply have been natural selection at work.

But this makes it even harder to understand why over the course of 1200 generations, with NO medical knowledge to speak and allowing natural selection to operate at peak efficiency, that there appears to have been NO obvious evolutionary changes taking place.
If no apparent evolutionary changes in the last 30,000 years, then why should there be any apparent changes in the NEXT 30,000 years ... or the 30,000 years after that ?

Is evolution in fact, much, much slower than we have been taught to believe it is ?

[edit on 27/10/09 by tauristercus]

Evolution is not a continuous nor inexorable process. Evolution is a species' adaptation to change. If the environment remains stable, then no adaptation is necessary or even beneficial, once a species has adapted to it. In other words, when a species is in harmony with the environment, then any mutations are likely to have less chance of surviving, than the main species.

Evolution theory once did assume that the changes were continuous and gradual. However, the fossil record doesn't support this. The fossils show that species tended to remain more or less stable for millions of years, with sudden extinctions and major changes in species within a relatively short time. The thinking now is that evolution occurs in jumps, when there are major changes in climate or other environmental factors. These upheavals wipe out many species, while offering others a chance to thrive in the new conditions.

Humans apparently haven't changed much in a few tens of thousands of years. That's not much time for evolution. We probably *have* changed in many subtle ways that don't show up in fossils. For example, as population increases and forces people together more, those with serious anti-social tendencies probably don't thrive. They might have done fine in an earlier time, maybe even survived better because they didn't have to rely on others. But now we're all stuck in a small world, and being able to get along is much more likely to help you survive and reproduce. This wouldn't show up in the fossils, so we wouldn't necessarily see any changes of this nature.

Another consideration is that for the first time, an animal has had the ability to modify its environment, instead of having to adapt to it. So we learned to make clothes and build houses, instead of having to develop thicker fur or other physical features.

We have been at the top of our planets hierarchy for many years, so there has been no need to change or evolve.

We have been at the top of our planets hierarchy for many years, so there has been no need to change or evolve.

Evolution is about adapting to your environment, but now Man has advanced to such a point he no longer feels the need to evolve, instead of adapting to his environment he simply adapts the environment to HIS wants not his NEEDS thus halting evolution or at least pausing it.

Maybe in the far future when Man has gotten past the greed for material goods that satisfy his wants will he achieve a more beneficical evolutionary path. Maybe when the goods have run out and there are no more 'resources' then maybe he can adapt to his new environment allowing evolution to start again.

But one good thing has started with the stagnation of man , is that in a few thousand years we'll all be of mixed race due to modern transport so racism will die out.

Originally posted by GW8UK
We have been at the top of our planets hierarchy for many years, so there has been no need to change or evolve.

What if, we have always been at the top of our planets hierarchy, so there has never been a need to change or evolve...

We can't look into the past, we can only look at the now.

Science = Believe in Observable
Religion = Believe in Nonobservable

we are still evolving but not so much on the physical side. Our evolution now is making better tools. I'm not a genetics guru so I may be wrong, but the development of tools changed us from darwinian evolution to technological.

It may seem funny or insane but the phase we are beginning now is becoming suerhuman through gene manipulation and bionics. Its an evolution of man and machine together. It's only a matter of time before cyborg like humanity emerges.

Just my .02

I would bet that there have been thousands if not millions of genetic / proteomic changes on average since EMH. EMH was physically similar enough to us to not be regarded as a different species taxonomically.

Likely improvements are; immune system, dexterity, intelligence, height and food tolerances such as lactose.

Likey losses are; strength (possibly lots) and hair coverage

As others have mentioned, our current physical design is not poor enough to affect our survival in our environment for evolution to make changes. You can see some minor adaptations in the difference between races though.

We have now entered the murky waters of the next stage of evolution, where we can direcly alter our genome to achieve purposeful improvements.