Human Evolution: Are Humans Still Evolving?

[Phantom]

Hey all, been awhile since I made a thread worth posting in I.D. Anyway, a question to all us human beings: Are Humans "still evolving"?

http://news.yahoo.com/s/time/2009102...08599193175700

Human Evolution: Are Humans Still Evolving?

Modern Homo sapiens is still evolving. Despite the long-held view that natural selection has ceased to affect humans because almost everybody now lives long enough to have children, a new study of a contemporary Massachusetts population offers evidence of evolution still in action.


A team of scientists led by Yale University evolutionary biologist Stephen Stearns suggests that if the natural selection of fitter traits is no longer driven by survival, perhaps it owes to differences in women's fertility. "Variations in reproductive success still exist among humans, and therefore some traits related to fertility continue to be shaped by natural selection," Stearns says. That is, women who have more children are more likely to pass on certain traits to their progeny. (See the top 10 scientific discoveries of 2008.)


Stearns' team examined the vital statistics of 2,238 postmenopausal women participating in the Framingham Heart Study, which has tracked the medical histories of some 14,000 residents of Framingham, Mass., since 1948. Investigators searched for correlations between women's physical characteristics - including height, weight, blood pressure and cholesterol levels - and the number of offspring they produced. According to their findings, it was stout, slightly plump (but not obese) women who tended to have more children - "Women with very low body fat don't ovulate," Stearns explains - as did women with lower blood pressure and cholesterol levels. Using a sophisticated statistical analysis that controlled for any social or cultural factors that could impact childbearing, researchers determined that these characteristics were passed on genetically from mothers to daughters and granddaughters.


If these trends were to continue with no cultural changes in the town for the next 10 generations, by 2409 the average Framingham woman would be 2 cm (0.8 in) shorter, 1 kg (2.2 lb.) heavier, have a healthier heart, have her first child five months earlier and enter menopause 10 months later than a woman today, the study found. "That rate of evolution is slow but pretty similar to what we see in other plants and animals. Humans don't seem to be any exception," Stearns says. (See TIME's photo-essay "Happy 200th Darwin Day.")


Douglas Ewbank, a demographer at the University of Pennsylvania who undertook the statistical analysis for the study, which was published Oct. 21 in the Proceedings of the National Academy of Sciences (PNAS), says that because cultural factors tend to have a much more prominent impact than natural selection in the shaping of future generations, people tend to write off the effect of evolution. "Those changes we predict for 2409 could be wiped out by something as simple as a new school-lunch program. But whatever happens, it's likely that in 2409, Framingham women will be 2 cm shorter and 1 kg heavier than they would have been without natural selection. Evolution is a very slow process. We don't see it if we look at our grandparents, but it's there."


Other recent genetic research has backed up that notion. One study, published in PNAS in 2007 and led by John Hawks, an anthropologist at the University of Wisconsin at Madison, found that some 1,800 human gene variations had become widespread in recent generations because of their modern-day evolutionary benefits. Among those genetic changes, discovered by examining more than 3 million DNA variants in 269 individuals: mutations that allow people to digest milk or resist malaria and others that govern brain development. (Watch TIME's video "Darwin and Lincoln: Birthdays and Evolution.")


But not all evolutionary changes make inherent sense. Since the Industrial Revolution, modern humans have grown taller and stronger, so it's easy to assume that evolution is making humans fitter. But according to anthropologist Peter McAllister, author of Manthropology: the Science of Inadequate Modern Man, the contemporary male has evolved, at least physically, into "the sorriest cohort of masculine Homo sapiens to ever walk the planet." Thanks to genetic differences, an average Neanderthal woman, McAllister notes, could have whupped Arnold Schwarzenegger at his muscular peak in an arm-wrestling match. And prehistoric Australian Aborigines, who typically built up great strength in their joints and muscles through childhood and adolescence, could have easily beat Usain Bolt in a 100-m dash.


Steve Jones, an evolutionary biologist at University College London who has previously held that human evolution was nearing its end, says the Framingham study is indeed an important example of how natural selection still operates through inherited differences in reproductive ability. But Jones argues that variation in female fertility - as measured in the Framingham study - is a much less important factor in human evolution than differences in male fertility. Sperm hold a much higher chance of carrying an error or mutation than an egg, especially among older men. "While it used to be that men had many children in older age to many different women, now men tend to have only a few children at a younger age with one wife. The drop in the number of older fathers has had a major effect on the rate of mutation and has at least reduced the amount of new diversity - the raw material of evolution. Darwin's machine has not stopped, but it surely has slowed greatly," Jones says. (See TIME's special report on the environment.)


Despite evidence that human evolution still functions, biologists concede that it's anyone's guess where it will take us from here. Artificial selection in the form of genetic medicine could push natural selection into obsolescence, but a lethal pandemic or other cataclysm could suddenly make natural selection central to the future of the species. Whatever happens, Jones says, it is worth remembering that Darwin's beautiful theory has suffered a long history of abuse. The bastard science of eugenics, he says, will haunt humanity as long as people are tempted to confuse evolution with improvement. "Uniquely in the living world, what makes humans what we are is in our minds, in our society, and not in our evolution," he says.
================================================== ========
Personally, all humans are still in an evolving process, in our minds, in our hearts, and in our souls, but yes I believe we are a race in progress.

Your Throughts?

[Alpha]

It seems as though other factors, such as diet and societal (I'm picturing things such as pollution, car use, sports) could have a greater effect. I've heard that pre-Industrial Revolution people were shorter, but in many respects healthier, and pre-Agricultural Revolution they were taller and faster. A lot of it simply isn't genetic, and I wonder what impact the Green Revolution (GM crops and synthsised fertilisers) will have in the medium- to long-term.

Sigh. I can see this developing into a 'is evolution even real' thread. Which would sadden me.

[RagnaToad]

An interesting take on evolution.

The answer to me is rather obvious: Of course we are.

Evolution is not a process that starts or ends somewhere. There will always be a type of individual that has more success of creating an offspring than other types.

Whereas physical health used to be the reigning factor in terms of surviving, I believe that beautiful women and rich men are now the most attractive types, which would make it easy for them to have children. Obviously, it's not because you cán that you wíll. Many-many poor families are huge, and a lot of poor countries have so many people starving, partially due to lack of birth control etc.

I did read that humans are becoming more attractive, which is only natural, seeing how physical beauty is a major trait when looking for a sex partner or even a spouse.

[Locke4God]

Well Evolution always has the potential to continue in any species. It's never finished, however there are creatures which have reached such a perfect balance with their environment that they haven't had a need to evolve for a long time. Crocodiles and Roaches come to mind. Those things have been the same for millions of years, and yet humans have changed quite a lot in that time.

It may well be, that we've gotten so good and manipulating our environment that we either stop evolving by virtue of the fact that we have everything controlled, or that we devolve.

It might be possible that we pollute our own genepool by keeping those suseptible to things like cancer alive long enough to have children. We no longer abide in large part by the survival of the fittest principle, and that could come back to haunt us much later on.

Population is another factor. It's a fact that men are far less prone to want to get married. Why? Because there's literally no need. The human race has grown in population by 12x in the past 150 years. And so men will get married, as Ragna Toad just mentioned, if there's a hot chick to marry. I for one was perfectly happy single, but I did find a nice girl, who was quite attractive to marry. I wouldn't have married her if she was a bitch, and I wouldn't have married her if she was ugly, no matter how nice she was. That goes for billions of men too.

[Zerobanshee]

For once, in this entire forum, I agree--somewhat, with Locke4God.

Evolution implies that a species either physically or enviornmentally adapts to their surroundings. The finches, for example. They each have a distinct beak, used for different uses. One has a beak made for cacti, others have a wider beak used to break open nuts.

Humanity, as a species, has had little time to actually enviornmentally adapt to any specific region. Where almost everyone has the opportunity to travel almost anywhere, we have no need to develop physically based on our surroundings. We have eliminated that aspect of evolution.

So, you ask. How do we evolve, then? I say genetics.

Disregarding the many illnesses our bodies adapt to, and overcome, we genetically adapt to the wants and needs of our current modern society. Men want beautiful women, and women want handsome men. These standards may change every twenty years, but the neutral base stays the same. Both want successful partners, and both want to be happy.

We have adapted for means of individual pleasures, instead of a collective pleasure. Two thousand years ago, we mated to keep our people alive, to keep the race surviving. Now, we mate for completely different reasonings.

[RagnaToad]

For once, in this entire thread, I agree--somewhat, with Locke4God.

I was thinking the exact same thing. I'd replace the word 'thread' with forum' though.

Also, I never really thought about how man could be devolving in certain aspects of life.

But I think the survival of the fittest should be interpret in the widest sense of the expression. It's not necessarily the most physically capable beings that are represented more and more, I think it's fair to say that pretty women and rich men are the fit ones today.

Also, I read that man is actually getting dumber, in a relative sense. There are more dumb people.

Because intelligent people know how tough raising children is, and stupid people often are, well, stupid, the stupid ones create a larger offspring, making it so that the percentage of stupid people is going up.

Which, honestly, makes me sad.

[Alpha]

Douglas Ewbank, a demographer at the University of Pennsylvania who undertook the statistical analysis for the study, which was published Oct. 21 in the Proceedings of the National Academy of Sciences (PNAS), says that because cultural factors tend to have a much more prominent impact than natural selection in the shaping of future generations, people tend to write off the effect of evolution. "Those changes we predict for 2409 could be wiped out by something as simple as a new school-lunch program.

I still want to emphasise this. Personally, I'm not the tallest. Both of my older brothers are taller than me, and by a margin that I doubt I will make up in the next few years, as I've pretty much done all my growing. The reason I'm shorter, I feel, is because I was a really fussy eater when I was a small child. I had a very particular diet, though not unhealthy, just not diverse.

We can sit all day and talk about how we select partners and that are genes are changing on average, but the pace that modern human's environment is in flux means that our physical attributes are much more heavily influence by our surroundings and diet.

[ViveLaVive]

Well, i believe that evolution will never truly stop, but as we enter the Scientific/Technological age, no doubt that will have some effect, no? As the line between Human and Machine(I'm speaking metaphorically, of course, although its is completely possible.) becomes blurred, such as human/technology hybrids,to some extent, will eventually effect us. I'm not sure to what degree, though.

And on a slightly random note, i would like to say that i(and many other religious activists) do believe in evolution. if anyone of any religion denounces evolution, please, take it to another forum. that goes vise-versa!