Humans are still evolving

[pscot]

http://www.latimes.com/news/science/la-sci-evolution11dec11,0,5882337.story

The pace of human evolution has been increasing at a stunning rate since our ancestors began spreading through Europe, Asia and Africa 40,000 years ago, quickening to 100 times historical levels after agriculture became widespread, according to a study published today.
By examining more than 3 million variants of DNA in 269 people, researchers identified about 1,800 genes that have been widely adopted in relatively recent times because they offer some evolutionary benefit.Until recently, anthropologists believed that evolutionary pressure on humans eased after the transition to a more stable agrarian lifestyle. But in the last few years, they realized the opposite was true -- diseases swept through societies in which large groups lived in close quarters for a long time.


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One of the most famous examples is the spread of a gene that allows adults to digest milk.Though children were able to drink milk, they typically developed lactose intolerance as they grew up. But after cattle and goats were domesticated in Europe and yaks and mares were domesticated in Asia, adults with a mutation that allowed them to digest milk had a nutritional advantage over those without.As a result, they were more likely to have healthy offspring, prompting the mutation to spread, Hawks said.

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Most of the genetic changes the researchers identified were found in only one geographic group or another. Races as we know them today didn't exist until fewer than 20,000 years ago, when genes involved in skin pigmentation emerged, Hawks said. Paler skin allowed people in northern latitudes to absorb more sunlight to make vitamin D.



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In the last 5,000 to 10,000 years, as agriculture was able to support increasingly large societies, the rate of evolutionary change rose to more than 100 times historical levels, the study concluded.

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"Nobody 10,000 years ago had blue eyes," Hawks said. "Why is it that blue-eyed people had a 5% advantage in reproducing compared to non-blue-eyed people? I have no idea."

[redwitch]

1. Some days it's hard to believe. nt

[unpossibles]

15. What was the Bill Hicks line?

Ever notice the people who don't believe in evolution look like they have not evolved?

Something along those lines.

[redqueen]

2. Every species continues to evolve as generations pass.

So... duh.

[HamdenRice]

10. I think what he's saying, and it's interesting and unprecedented, is that it's happening faster

It's as though we are selectively breeding ourselves. So wolves evolve, yes. But we "evolved" dogs in fantastical ways and at break neck speed.

Because we apply the same pressures to ourselves that we apply to domestic animals, we are evolving ourselves tens or hundreds of times faster than our closest relatives, say the chimps, are evolving.

[redqueen]

12. Yes, I see that...

and you're right it is very interesting.

But that screamingly stupid headline distracts from the material... it's almost as bad as 'de-evoltion'.

[Johonny]

26. I think it depends how you talk about evolution

There is a fairly constant mutation rate in DNA. However the spread of certain genes over the whole population may only occur when the conditions are favorable. The genes for extremely delay weaning from milk or for blue eyes or light skin may have existed in the species for a long time. But only changes in habitat lead to them becoming more common. Hence rapid change is not that surprising.

The fossil record is a record of species appearing, staying relatively unchanged for millions of years and then going extinct. However that does not mean at the Gene/DNA level they were not evolving.

So evolution is generally talked about on the morphological scale and on the molecular scale. Morphologically people pretty much look like they did some 200,000 years ago. On the molecular level new genes have constantly been coming along. I think how scientists use the word evolved is a constant source of fun geek fights. See Gould-Dawkins and punctuated equilibrium.

[JohnnyLib2]

3. I'm holding on to that hope.....

[Laelth]

4. Very interesting. k&r n/t

:dem:

-Laelth

[dugaresa]

5. i have a bit of a problem with skin pigmentation remark, it was an evolutionary change

that had advantages (vitamin D absorbtion) but it didn't occur because those folks needed it. It probably occurred due in part to the fact that one perhaps two people had their genes change and for some reason lived longer, were healthier (due to the vitamin D absorbtion) and perhaps it made them unique and therefore prized for breeding with other humans.

The blue eyes is another aspect, not really necessary but perhaps the first person to have those blue eyes became prized for beauty (male or female) and it made it easier to mate. I suspect the first was a male because 20,000 years ago there probably was more serial monogamy and his blue eyes made him the Paul Newman of the caveman set.

edit: evolutionary changes that are not prized or that were bad typically get "bred out", makes the person carrying the defect less likely to have offspring.

[shireen]

16. yup! good ol natural selection ...

i wonder how that's going to play out over the next 5k to 10k years. Will we have teabaggers living in caves? Progress is evil. :evilgrin:

[TxRider]

20. If history is any indication...

We will likely be quite a bit larger, and likely be riddled with harmful genetic mutations (diseases) that we have learned to compensate for with science that nature would have ruled out and gotten rid of because we have virtually eliminated natural selection..

[AngryAmish]

22. Isn't the scientific method an adaptive behavior?

[shireen]

17. dupe

duplicate post. sorry.

[kenfrequed]

24. Hmm

Well the blue eyes end up being sort of related pigmentation genes. Of course sexual selection for blue eyes may have been a factor. But if you absorb more vitamin D from the sun through your less melanin shielded skin then you maintain decently strong bones even in northern climes.

Stronger bones means you survive better in any competition for sex that could occur and/or that you would live longer to produce more offspring.

Much more importantly among women, who lose calcium with each child produced, the ability to absorb vitamin D through the skin allows them to restrengthen their bones and produce more offspring in a direct fashion.

I think again blue eyes are sort of just a related gene cluster or a side effect or mutation that came out because of a favoring of a gradual advantaging of paler complexions.

[dugaresa]

25. skin pigmentation was a benefit in northern climates but the defect

itself did not occur because of that, it happened and perhaps made those with that defect stronger and therefore more likely to survive.

[David Zephyr]

6. Read the book "Before the Dawn". It deals with all of this. Wonderful book.

We are all the same family.

[AngryAmish]

19. fantastic book

[kenfrequed]

27. Sounds interesting.

I have read Diamonds "Third Chimpanzee" It was pretty good overview.

[Lucy Goosey]

7. Pfft. Everyone knows that the planet is only 8,000 years old.

And god made the races so that we could tell which Presidents are Fascist-Communist-Nazi-Muslins, obviously.

KIDDING!

I'm kidding of course. Very interesting article

[The River]

8. Evolution Is More Than

just biological. The evolution of organisms is only 25% of the equation.
I and It. Both interior and exterior qualities/behaviors must be factored in.

[NRaleighLiberal]

9. physically evolving, intellectually devolving, I'm afraid.

[The River]

11. Just The Republicans

They are going the way of the Neanderthal thankfully.
They can keep looking like evolved humans but mentally
they do not have what it takes to survive in a more complex
and inclusive social environment.

[Xithras]

13. We know why blue eyes evolved in Northern Europe.

When the first Europeans moved into northern Eurasia, they were confronted with a thickly forested landscape that experienced much longer, much darker nights than their southern cousins had to deal with. Even when the sun was up, the thick and nearly universal forest cover kept the ground very dark from fall to spring, when the sun was lower on the horizon.

The iris of a blue eye has fewer pigmented cells than are present in a brown eye, which gives the iris more flexibility. That greater flexibility allows the pupil to dilate further, permitting better night vision (the difference isn't huge, but it is measurable). This adaptation to a darker environment gave the advantage of allowing prehistoric Europeans to better hunt prey in low-light conditions that their brown-eyed cousins would find impenetrable. The more food you catch, the better the odds are that your kids will survive to adulthood. Evolution in action. It's not a feature that's strictly limited to humans either...researchers recently found that reindeer eyes in Norway turn blue during the winter for the same reason...it permits them to see better in the dark.

BTW, this is also largely why Europeans turned white. Those same dark conditions led to vitamin D deficiency, and paler skin evolved to counter it.

For discussion sake, here's a shot of the Białowieża Primaeval Forest in Poland, the last major stretch of forest anywhere in Europe that has never been cut by man. At one time, this type of forest extended from the southern Scottish border to the Alps and Pyrenees, and southwest across Russia and Ukraine to the Urals and to the Black Sea, unbroken by anything but water. Today only tiny fragments are left. Look at how dark the forest was, and keep in mind that the photo was taken midday during the summer. Imagine this same forest in the evening, or during winter. This is what the ancestors of modern Europeans lived in, every single day of their lives.

[FarCenter]

14. Part of the speedup has been enabled by rapid population replacements

The hunter-gatherers of Europe were largely replaced by agriculturalist moving northwest from the Balkans and lower Danube valley.

The inhabitants of Southeast Asia, who would have been more like the people of New Guinea, were replaced by the current Malaysians and Indonesians.

The Bantu speakers in Africa expanded and replaced earlier populations.

[rug]

18. I'm dubious.

[LeftHander]

21. A former roommate was a missing link for sure....

I'm just saying...

[pscot]

23. I look at my sons-in law

and the premise seems highly dubious. On the other hand, if we ever screw things up to the point where we revert to a new, new stone age they will be well ahead of the curve.