Human Evolution: Are Humans Still Evolving?

[mercurial]

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.

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[Geriatrix]

I ama Hiro Nakamora, I stopa space timema

 

[FrancTheTank]

I ama Hiro Nakamora, I stopa space timema

Hahaha heroes FTW!

 

[Kompete]

Human Evolution: Are Humans Still Evolving?

The fact that humans still need prove of this and debate this, speaks to our ignorance as a species. If one considers earth's history in 24 hours:
- hominid species appeared 2 min before midnight, and
- homo sapiens appeared 2 sec before midnight

We had an entire 23hours, 59min and 58 secs of evolution of life on earth and we think that somehow evolution for humans have ended? BS! Maybe if we start looking beyond just 10 generations from now and consider human life in 1 billion years from now, that might change our perspective on how things could change.

 

[Johnsilver]

As long as anything alive, reproduce, live and die, evolution will happen.
As long as some fare better than others at living, evolution will happen.
As long as the environment is dynamic evolution will happen.
As long as there is fashion and current opinions of what is sexy (compare with 20 years ago)
Smallpox changed us
HIV is changing us
Global warming will change us
Intellectually we are changing at an alarming rate
As long as some die and some don't so soon.

Why do you choose a certain girl/dude over others? Would you knowingly choose a total loser?
Would a total loser be able to pick and choose?
Why do dudes try to impress chicks?

 

[wrathex]

Instead of having ancestral brute strength as males did then, I still would not call males today

"the sorriest cohort of masculine Homo sapiens to ever walk the planet."

Males today are working in space, using high technology to measure and observe the universe,
brought a global telecommunications network into existence,
males today are working harder than ever with their minds, to make sense of, and to use the data we harvest from our environment,
into practical tools and applications.

In other words, our bodies are becoming more energy compliant and streamlined, an excellent progression.

 

[Johnsilver]

However those loosers have 8 children, while the presy well advantaged hunk would only have 1, and that is if any.

In todays world, better genetics = less time for children. This is not evolution in the least


I say take control and respect everyone - biology is important because of sentience, not the other way round.

Go the artificial womb route. braintransplantes to cure bad genetics, ageing and all illness and children grown in artificial wombs set prefectly in a society. Now this is a beautiful world.

Agree
It may be ironic and "negative" but nevertheless the turtle moves.
How far to take engineering? A new topic perhaps?

 

[semiautomatix]

The loss of wisdom teeth, and in some rare instances, loss of eye or canine teeth is an excellent example of active evolution. We cook our meat and, as such, no longer need ripping and tearing teeth (except for biltong, of course!). Similarly the bottom half of our skulls, especially jaws, are getting smaller hence the lack of wisdom teeth.

Evolution in action, boys!

 

[semiautomatix]

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.

As humans rely more on technology we become less reliant on pure strength. This does make sence, in that respect.

 

[rurapente]

sorry, i didnt come from no Ape, fish or other one-celled organism. Not as much as throwing a deck of cards off a building results in them landing to form a smiley face in perfect sequence from 1 to Ace and in alternating colors.

 

[semiautomatix]

sorry, i didnt come from no Ape, fish or other one-celled organism. Not as much as throwing a deck of cards off a building results in them landing to form a smiley face in perfect sequence from 1 to Ace and in alternating colors.

Good now that we have your opinion: prove it!

And riddle me this: why are some humans, an ever increasing number, being born with fewer and fewer teeth?

 

[w1z4rd]

sorry, i didnt come from no Ape, fish or other one-celled organism. Not as much as throwing a deck of cards off a building results in them landing to form a smiley face in perfect sequence from 1 to Ace and in alternating colors.

Well.. Im not to sure about the ape thing.. you are closer to them than most humans.. Im surprised you have learnt to type. Want a banana?

 

[Balstrome]

Well.. Im not to sure about the ape thing.. you are closer to them than most humans.. Im surprised you have learnt to type. Want a banana?

Is eating a banana incest ?

 

[rurapente]

hahahaha . lol.

 

[Johnsilver]

sorry, i didnt come from no Ape, fish or other one-celled organism. Not as much as throwing a deck of cards off a building results in them landing to form a smiley face in perfect sequence from 1 to Ace and in alternating colors.

Your point taken. With respect, the point taken is that you don't understand the principles of evolution.
The first step I propose is to become familiar with the principle of evolution with the understanding that it doesn't mean it's actually happening. The principle works.

 

[Jabberwocky]

Interesting how in western society, being taller and skinnier is more desireable, in exact contrast with what nature has in mind. Nature's evolution is our devolution.
I also wonder what would the study reveal in a polygamous culture, where a man generally has to be successful to be able to contribute to the gene pool.

 

[Geriatrix]

Interesting how in western society, being taller and skinnier is more desireable, in exact contrast with what nature has in mind. Nature's evolution is our devolution.
I also wonder what would the study reveal in a polygamous culture, where a man generally has to be successful to be able to contribute to the gene pool.

:erm: Western society is part of nature... Its just a different environment than being in the dirt out there but its still part of nature.
Being rich is more desirable than being tall and skinny though.

 

[Jabberwocky]

:erm: Western society is part of nature... Its just a different environment than being in the dirt out there but its still part of nature.
Being rich is more desirable than being tall and skinny though.

Thats why its interesting... its like we are swimming against the tide and losing.
Wealth is not the most important factor for both sexes.

 

[Geriatrix]

Thats why its interesting... its like we are swimming against the tide and losing.
Wealth is not the most important factor for both sexes.

What do you mean we're losing? We're eating more and surviving longer.

And if you look at the general BMA of western society and the rate it is growing at I don't think being skinny is really that important.

But that being said, being tall allows you to potentially appear be assertive and imposing and being skinny means that you are more likely to still be able to be fit, nimble and healthy in this society with its abundance of food.

And yeah being rich isn't necessarily the biggest factor but it gives you the ability to get a bigger quantity of potential mates and allows you to be a lot more choosy. If that wasn't true the need to show off material wealth wouldn't nearly be as urgent in our culture as it is. Because unfortunately money equals power in our society. Being powerful makes the likelihood of your genes surviving the next generation a lot more likely.

As far as I understand evolution its not about following a set plan, its about surviving in your environment. We seem to be moving a different path to what other creatures in nature do because our environment necessitates different survival strategies.

 

[alloytoo]

sorry, i didnt come from no Ape, fish or other one-celled organism. Not as much as throwing a deck of cards off a building results in them landing to form a smiley face in perfect sequence from 1 to Ace and in alternating colors.

But you are an ape (great ape to more specific).