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Sunday, November 18, 2012

The Most Spectacular Mutation in Recent Human History

Benjamin Phelan is a writer. He has an article in Slate on The Most Spectacular Mutation in Recent Human History.

I'm not going to tell you what it is. You'll have to read his article. But here are a few hints.
  1. The mutation is only common in Europeans. Asians and Africans get along just fine without it.
  2. It's not clear whether the mutation confers selective advantage. There's some evidence that it does but it's difficult to understand why.
  3. There are several different mutations that produce the same phenotype and it's not clear which one of them is the "most spectacular."
  4. The article claims that the mutation appeared 10,000 years ago but that's probably not true.
  5. The mutation has nothing to do with walking upright, opposable thumbs, big brains, or the ability to talk. Apparently those mutations are either much less spectacular or they don't qualify as "recent."

[Photo Credit: How to Milk a Cow]
[Hat Tip: Mike the Mad Biologist]


Steve Watson said...

That photo is waaaay too big a hint.

Mark Sturtevant said...

Meh. How about duplications of the amylase enzyme in Asians?

Piotr Gąsiorowski said...

This one was quite spectacular too, and still more recent:

Anonymous said...

The picture reminds me of a story told by a small-time dairy farmer many years ago. A man from a neighboring farm, not a dairy farm, wanted to buy from him a cow, to provide milk for his own family. The dairy farmer was quite willing to sell his friend a cow, and tried to guide him to a cow which he believed would suit the mans purpose, but which happened to have a smaller 'bag' than one of the others. The purchaser was having none of that - insisted on buying the cow with a noticeably larger 'bag'. Later he came back to the dairy farmer, angry because he had been sold a cow which gave very little milk.

Allen MacNeill said...

W0rked on dairy farms most of my teenage years. Got to know the different breeds: their temperament, their production, the kinds and "flavors" of milk they produce, what they're like in the barn, in the field, etc. All-time favorite: Jerseys, with Guernseys a close second. Would never voluntarily work with again: Brown Swiss (mean). Although the Scots are more famous for raising sheep, that's only been since the Clearances. Our real love is cattle, especially our neighbors'...

Gary S. Hurd said...


Ed said...

I would argue that lactose intolerance, for cow milk not goat or sheep, only really became an issue when the general idea about food production was that it had to be done sterile.
This meant milk couldn't ferment into it's lesser harmful yoghurt variant, because the bacteria got killed by the method of Pasteurisation.
Secondly cow milk is being mass produced by forcing cows to lactate the whole year round. There's millions liters of milk being produced daily, a lot of which get freeze dried and is used as a baby milk powder substitute instead of mothers breast milk.

I would thus argue, the genetic flaw was there already, the effect has been enchanced by the uber clean way milk is being made ready for mass consumption, the amount of milk produced and the fact babies get fed with powder milk alternatives earlier in life.

And if you look at the spread of the mutation, and European military history it might also explain why the mutation has spread at such high rates. You had Rome controlling large bits of Europe, Alexander the Great, the Turkish invasions to name a few. Combine this fact with the diabolic habit of mass rape of females when cities and countries where conquered by victoriuous armies and this might be another reason why the lactose intolerance fenotype spread as fast as it did.

Robert Byers said...

I gtot it.
Evolutionists go on and on about this.
Yet I say it helps creationism.
It was not 10, 000 years ago. The flood was only 4500 years ago.
It has been a quick adaption because , I think, the greater wealth of Europe and so use of the cow, over use perhaps, brought a reaction in some of are bodies and lineage.
I t was wealth in these creatures that brought the problems unlike the rest of the world.
There is no reason to need long periods of time.
I don't like the idea of mutations but rather think genetic failings are the cause.
It wasn't a roving mutation but a logical reaction to copious use of the cow.

Nigel Thomas said...

I am not really sure what you are trying to say. Your points 1 and 2 are covered in the article. Your point 4 does not seem very significant: the precise dating is not very relevant to the article's point (that lactose tolerance is a very significant adaptation that has, in relatively recent times, spread very quickly). As for point 5, recency is a relative thing, but do you really mean to suggest that the wide spread of lactose tolerance in the human population is not a much more recent development than the evolution of opposable thumbs, big brains or speech? Really?

On point three, yes well I guess he should have said adaptation or phenotype rather than mutation, no matter that most of his readers would not have understood him, and would not understand or care about the distinction.

Who or what is helped by this sort of sneering at science journalists for doing their job of trying to make science interesting and understandable to the public? Maybe Phelan says some things that are badly wrong or misleading, I do not know, but you , sir, have in no wise shown that he is in any significant way wrong. You are just picking nits, mostly ones that are tiny, or even imaginary.

Anonymous said...

Concerning selective advantage: Years ago I read that for a mutation to spread as fast as that leading to lactose tolerance (amongst northern Europeans and some African populations), the selective advantage would be in the range of 10%. This would assume that there was no selection before the begin of dairying (since milk would not have been part of the adult diet before that), so to assume that the selection started some 7,000 years ago doesn't seem so unreasonable. Note that despite the name suggesting a pathological condition, adult lactose intolerance is the "wild type" also seen in other mammals.
Regarding point 2, the existence of multiple mutations: The two that are widespread are only a few nucleotides apart, both within a putative enhancer element some 13 kb upstream of the coding region. One is that widely found in northern Europeans, the other in certain African populations that--not an accident--also practice dairying.
So while I agree that "most spectacular mutations" would not have been in my choice of article title, the development of lactose tolerance is certainly of interest to population geneticists.
Finally, when you go to an Asian restaurant you will notice that there is nothing on the menu containing fresh milk. There is a reason for that.

Why does all this interest me? Because, among other things, the first sequence of a chromosomal human lactase gene was derived from a gene bank constructed using my own DNA.

Ned (lactose tolerant)

Chas Peterson said...

The mutation has nothing to do with walking upright, opposable thumbs, big brains, or the ability to talk. Apparently those mutations are either much less spectacular or they don't qualify as "recent."

How about the fact that none of these phenotypes is the result of a single mutation?

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