Humans evolving 100 times faster than historical levels.

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

by danteembermage • 17 years ago

64 69 17 years ago

latimes.com

darkxanthos• 17 years ago

"evolving 100 faster"

100 what?! You're making my brain frustrated.

EDIT: Ahh FTA: 100 times historical levels.

danteembermage• 17 years ago

FTFY, thanks.

BRadmin2• 17 years ago

"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."

Now that's interesting. Any theories?

slackerIII2• 17 years ago

The theory I've heard is that a blue iris makes it easier to see pupil dilation, which is an indication of attraction. People are more likely to hook up when they can tell the other person is attracted to them, so...

prat2• 17 years ago

That is possible, but the gene for blue eyes may also be linked with some other characteristic (biologically more relevant than attraction - like resistance to cancer) that might provide selective advantage. Linkage (close enough genes travel together) among genes plays a huge role in selection but often, and understandably, we regard the the feature that is easily visible to us as essential.

anigbrowl• 17 years ago

Novelty? I have red hair, which I'm not sure is adaptive (eg it puts me at greater risk for skin cancer) but which partners have rated highly as an attractive feature specifically because it's unusual. Then again I have a compulsive draw towards partners from outside my own ethnic group, so there's some selection bias going on with that interpretation.

Tichy2• 17 years ago

I think being attracted to different ethnic groups might have an advantage, too - keeping diversity in the gene pool up is probably beneficial.

breck2• 17 years ago

"Nobody 10,000 years ago had blue eyes,"

My reaction is that he misspoke here or he overstated his claim to make a point.

I know nothing about the proportion of people with blue eyes back then or right now for that matter. But I think at the very least, you could only make that claim with a tiny, tiny, tiny amount of confidence.

Maybe the proportion of humans with blue eyes was smaller back then, maybe it was larger, or maybe it was the same. I don't know. But to claim nobody 10,000 years ago had blue eyes is an impossible point to prove unless you have DNA samples from every human alive 10,000 years ago. We might be able to say that all the people alive today with blue eyes descended from one ancestor, but we can't claim to know about the population of people with blue eyes back then. For all I know, half the population 10,000 years ago could have had blue eyes but then got wiped out by swine blue.

That's like saying no one 100 years ago was over 7'6" tall. I know a bit more about height and think that this statement may be true. But it would be real hard to prove. Now shift the timespan back by 2 orders of magnitude, and I think it'd be harder to prove.

I'm not saying that the general idea is wrong, but I'm just it would be a good idea to question that claim a lot before thinking about reasons why that might be the case.

aaronblohowiak3• 17 years ago

" We might be able to say that all the people alive today with blue eyes descended from one ancestor"

-- exactly.

And, if you follow the science of using mitochondrial DNA to date genetic changes..

http://en.wikipedia.org/wiki/Molecular_clock

http://www.livescience.com/health/080131-blue-eyes.html

BRadmin2• 17 years ago

All blue eyed people traced to 10000 year old ancestor:

http://www.dailymail.co.uk/sciencetech/article-511473/All-bl...

tyn• 17 years ago

You could just attribute it to the attractiveness of blue eyes. Most people consider blue (and green) eyes more beautiful than eyes with a different color. But this will get you only as far as the next inevitable question: why are blue eyes attractive?

baltoo2• 17 years ago

Status will always be defined by scarcity. Perhaps blue eyes where novel and scares, which could be enough?

rsheridan6• 17 years ago

Children are have lighter eyes (and everything else) than adults. It's a sign of youth.

baltoo2• 17 years ago

As I've heard it, the development of both blue eyes and blond hair is thought of as mainly being driven by sexual preferences, i.e. status of novelty.

Sexual preferences are pretty strong drivers and combined with periods of harsh environments (e.g. where either of the sexes die off early in life) can create really fast evolution.

gojomo• 17 years ago

Speculation in no particular order:

(1) Perhaps less pigment in the eyes improves vision in certain conditions (especially those in colder latitudes).

(2) As a recessive trait, blue-eyed mating limited a woman's ability to pass off offspring from other (dark-eyed) fathers as that of a blue-eyed father. This greater confidence in paternity won greater fatherly support, and in some eras/places (inheritable property?) this dominates the advantages of promiscuity. (This effect may fade or even reverse depending on proportion of eye colors.)

(3) Handicap principle -- even if blue-eyes are a disadvantage in some dimensions (sun-robustness, alien look), sometimes a conspicuous disadvantage is effective as a signal that fitness in other harder-to-measure dimensions is better. ( http://en.wikipedia.org/wiki/Handicap_principle )

(4) I suspect just about any unique visible characteristic, advantageous or mildly disadvantageous, can find some reinforcement as a quick signal of genetic kinship against outside competitive groups that look different. So just, "different enough to tell closer-cousins from distant-cousins" could be a sufficient explanation.

tokenadult4• 17 years ago

Beats me. I married someone with brown eyes (and black hair). On the other hand, she married a man with blue eyes (and blond hair), and my genes have been replicated into four children. My dad's genes for red hair have passed on to be expressed in two of my children.

tamas• 17 years ago

Blue eyes and blonde/red hair are recessive traits, while brown eyes and hair are dominant. You having blue eyes means both of the gene pairs that control eye color have the recessive blue, while your wifes brown eyes can be caused by having a set of blue and a set of brown genes, and as brown is the dominant one, it is what was actually expressed in here eye color. The fact that your children have blue eyes means she does have genes for blue eyes, and they are inherited into your children as well as your blue genes, hence their blue eyes. The same goes for blonde/red vs brown hair.

Either that, or consult with your milkman/gardener.

jordyhoyt• 17 years ago

How do we know that nobody 10,000 years ago had blue eyes? Er, well, of course it's impossible to _know_, but what leads us to conclude that nobody 10,000 years ago had blue eyes? Anyone know?

Edit: posted this before I saw the other thread and the excellent answer here - http://news.ycombinator.com/item?id=824543 My mistake.

asdlfj2sd333• 17 years ago

Don't only Caucasians have blue eyes? And aren't they (full disclosure "we" in my case) also the only ones with the mutated version of the gene which controls how much melanin is deposited in skill, hair and... I think also irises? Asians and Africans both have the normal version of the same gene.

And melanin has many roles, sun protection being just one, the other is as a structural protein. Just compare how black skin ages vs. how a redhead of the same (advanced) age looks.

And why would Caucasians have a mutation which deposits less of such a useful protein? Vitamin D.

It is produced when UV light hits the skin. In northern climates with less sun, and skin being covered or you die of exposure, often even when the sun is up, people get a lot less vitamin D.

Inuit get more due to their diet, and modern man also gets much more again because of diet. And yet most people living in the north even today lack vitamin D.

Also, I thought all of the above is common knowledge which makes me question the whole article.

aaronblohowiak3• 17 years ago

"Don't only Caucasians have blue eyes?" No.

More than you ever wanted to know about eyes: http://en.wikipedia.org/wiki/Eye_color

Also, this is neat: A 2002 study found the prevalence of blue eye color among Caucasians in the United States to be 33.8 percent for those born from 1936 through 1951 compared with 57.4 percent for those born from 1899 through 1905.[10] Blue eyes have become increasingly rare among American children with only 1 out of every 6 – 16.6 percent which is 49.8 million out of 300 million (22.4% of white Americans) of the total United States population having blue eyes.[33][34] The plunge in the past few decades has taken place at a remarkable rate. A century ago, 80 percent of people married within their ethnic group. Blue eyes, a genetically recessive trait, were routinely passed down, especially among people of Scottish, English, Irish, Welsh, Western and Northern Slavic, and Northern European ancestry.[33][34][35] In the 1930s, eugenicists[citation needed] used the disappearance of blue eyes as a rallying cry to support immigration restrictions. They went so far as to map the parts of the country with the highest and lowest percentage of blue-eyed people.[citation needed]

kqr2• 17 years ago

Does anyone know if blue-eyed people continue to have a 5% advantage?

tome• 17 years ago

It seems to me that amongst (white) people who play badminton, a larger proportion have blue eyes than amongst the general population.

A friend told me that in baseball, batters have a higher tendency towards blue eyes, and pitchers to brown, but I couldn't find any references.

Does anyone know if this has any scientific basis?

ryne• 17 years ago

Is there any credit to the rumour that blue-eyed individuals have better sight, indicating why there are so many blue-eyed fighter pilots etc?

pmichaud• 17 years ago

I was confused by the part that said white skin allows more sun light to be absorbed. I'm quite sure this is wrong:

Dark skin means more light is absorbed, and therefore doesn't bounce back at the viewer's eyes.

the only explanation I can think of is that the rules are somehow different for light outside the visible range?

slackerIII2• 17 years ago

I'm guessing the absorption they are talking about happens below the pigment level.

nopassrecover3• 17 years ago

Well the advantage of increased melanin in the skin is protection from UV damage. Perhaps this is what they are referring to.

pedermoeller• 17 years ago

As I remember the explanation: Dark skin means more melanin in the skin. Melanin blocks the UV light that the body uses to synthesize D vitamin. So white people in north are better suited for utilizing the scarce sunlight for D vitamin production and black people in the south are better protected against the skin cancer risk caused by the UV radiation.

igrekel2• 17 years ago

I wouldn't dismiss this so quickly. It is widely accepted and is also part of what is evaluated when the doctor recommends or not that you give extra vitamin D to your child, having white skin means you need to spend less time in the sun to have sufficient vitamin D and not require supplements.

Perhaps the question is more complex because sunlight is not all in the visible wavelengths and skin is actually translucent and light reaches different level through the skin, melanin prevents parts of the light to reach deeper levels in the skin and also converts parts of light.

giardini• 17 years ago

UV-B sunlight strikes a substance on the skin called 7-dehydrocholesterol converting it into vitamin D3. The vitamin D created by this reaction is then reabsorbed by the skin and enters the bloodstream. Apparently some new research indicates reabsorption may take up to 48 hours!

Melanin inhibits the above reaction, so blacks need more sun to get the same amount of vitamin D.

More details: http://www.cholesterol-and-health.com/Vitamin-D.html

chasingsparks• 17 years ago

I find this odd because I have "been around the world and found, that only stupid people are breeding."

(Pure joke)

igrekel2• 17 years ago

Anyone has real details on how they actually date the origin of the presence of DNA sequences? I sure have my own uneducated guesses but I'd be curious to know. Or even better find a reference to the explanation.

req22• 17 years ago

http://findarticles.com/p/articles/mi_m1200/is_n4_v148/ai_17...

skushch• 17 years ago

The actual article http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pub...

Greater population = greater opportunity for mutation. Sounds right...

tokenadult4• 17 years ago

Thanks for posting the link to the published study, as I was about to. I see both the study and the submitted news article about it are more than two years old.

After edit: Here is a link to a more recent article on a closely related subject:

http://pritch.bsd.uchicago.edu/publications/pdfs/CoopEtAl09....

daniel-cussen2• 17 years ago

Evolution works in spurts. We are spurt of evolution as long as our environment is changing, which it has constantly been for the last 40,000 years.

joubert6• 17 years ago

According to Gould (a paleontologist).

Dawkins, with his gene-centered view of Darwinian evolution, refutes this, explaining that evolution by natural selection is gradual.

daniel-cussen2• 17 years ago

>Dawkins, with his gene-centered view of Darwinian evolution, refutes this, explaining that evolution by natural selection is gradual.

People say he refutes this. According to him, he never said anything to refute this. In either case, you have to be specific about what "gradual" means. Dawkin's evolution is more gradual than intelligent design, but not so gradual that it is inconsistent with Stephen Gould's claim.

thras• 17 years ago

Hawks has a great blog at http://johnhawks.net/

And Cochran and Harpending, the "Utah colleagues" mentioned in the article, have already written a book about this accelerated human evolution: http://www.amazon.com/000-Year-Explosion-Civilization-Accele...

timwiseman• 17 years ago

Interesting article.

One thing to remember is that evolution != progress

joubert6• 17 years ago

But survival is good.

dkarl• 17 years ago

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.

1) This blows my mind -- am I reading it right that there was virtually no variation in skin color 20,000 years ago? I assumed there was always variation in skin pigmentation, with darker skin colors predominating until we expanded into northern latitudes where lighter colors made sense.

2) What about Neandertals? I always imagined them being light-skinned, since they were adapted to northern climates. I wonder if they evolved genes for light skin tens of thousands of years before modern humans did. If so, that must have made them look even more freakish to modern human eyes, and vice-versa.

tokenadult4• 17 years ago

am I reading it right that there was virtually no variation in skin color 20,000 years ago?

I think the correct statement is as you say in another part of your post: there has always been variation in skin color in the human population. It was geographically segregated (forming "races" in the biological sense) only very recently. And even today there is a lot of variation among individuals in skin color within each continental subpopulation of human beings.

The usual view of evolution of skin color is that the ancestral condition was white skin under dark hair (as we still see in chimpanzees). Then at some unknown time, human ancestors became less hairy, and darker skin pigmentation became necessary. Then as human beings (Homo sapiens) migrated to latitudes with less sunlight (VERY recently) gene frequencies changed again in favor of lighter skin in some areas. (Inuit people are quite dark skinned for people who live near the North Pole and usually wear heavy clothing.)

Humans evolving 100 times faster than historical levels.

Related Stories