Pleistocene nostalgia for evolution's end times?

One of the memes frequently tossed about -- especially by promoters of the various "caveman" diets -- is how "we" (meaning all human beings) have not evolved since Upper Paleolithic times, and that illness results from our failure to limit our diet to what our Cro Magnon ancestors ate. The premise is that thousands of years of daily consumption of dairy products by ethnicities in some regions, or lots of rice in others, or lots of fish in others -- had no effect whatsoever on the evolution of these populations. Not to knock the possible health benefits of the Caveman Diet, but I've always been a bit skeptical of that particular premise, because if you think about it, modern medicine has only been around for a century or so, and as there was no one to diagnose or treat health problems caused by food, the people who couldn't hack their prevailing regional diets were unlikely to live long enough to contribute to the gene pool. But what the hell do I know? I have not studied human genetics in sufficient detail to know for sure. Not that a little thing like that would stop people who are not geneticists from saying they know we have not evolved, and that we should return to eating raw meat (preferably from wild animals killed with our bare hands....)

Anyway, this piece about dog genetics is a reminder that evolution might occur a lot more rapidly than most of us realize:

Like humans, dogs are more than 99 percent genetically identical to one another - despite a lot more diversity in shapes and sizes.

When scientists examined the head shapes of different breeds, they found as much diversity in dogs as existed across the much wider group of animals called carnivora - which includes walruses, cats, skunks, and weasels as well as dogs.

That was surprising, considering how fast this diversity came about in dogs, said biologist Abby Drake, lead author of the study. Most of the 400 known breeds emerged in just the last several centuries.

And yet they haven't branched off into different species: Technically, most breeds can produce fertile offspring with any other breed (though size differences might make it tough for some).

Humans have allowed some of this variety to come about by interfering with the normal workings of natural selection - thus allowing all kinds of things that might not last long in the wild. Imagine Chihuahuas or miniature poodles competing against wolves. "It's a massive evolutionary experiment we've conducted," Drake said.

I've noticed that some dogs handle different foods differently, and that dog A might do well on a diet which would give diarrhea to dog B. These tendencies can be expected to be passed on to their pups, and can become breed characteristics. I noticed that Coco (a notoriously picky eater) loves and has no problems eating "NUTRISH" -- a dog food which Rachel Ray designed for her pit bull Isaboo, but which some dog owners have condemned as not agreeing with their dogs. Over the years I have seen that many dogs differ over what they like, and what they can and cannot tolerate. I'm no expert, but I have been around dogs long enough to learn that there is no "one size fits all" rule where it comes to diet in dogs.

Asians tend to be allergic to milk and milk products. This is because of lactose intolerance:

Lactose intolerance is the inability to metabolize lactose, because of a lack of the required enzyme lactase in the digestive system. It is estimated that 75% of adults worldwide show some decrease in lactase activity during adulthood.[1] The frequency of decreased lactase activity ranges from as little as 5% in northern Europe, up to 71% for Sicily, to more than 90% in some African and Asian countries.[2]
Not only is this genetic, but there is evidence that the genetic differences are attributable to recent evolution:
....certain human populations have a mutation on chromosome 2 which eliminates the shutdown in lactase production, making it possible for members of these populations to continue consumption of fresh milk and other dairy products throughout their lives without difficulty. This appears to be an evolutionarily recent adaptation to dairy consumption, and has occurred independently in both northern Europe and east Africa in populations with a historically pastoral lifestyle.[10] Lactase persistence, allowing lactose digestion to continue into adulthood, is a dominant allele, making lactose intolerance a recessive genetic trait. A noncoding variation in the MCM6 gene has been strongly associated with adult type hypolactasia (lactose intolerance)[4].
Sounds like massive unintentional experimentation has been going on for some time. Whether such evolution is "good" is a moral question. (And in my view a silly question.)

But I try to keep an open mind about these things. Perhaps I should sample some fresh road kill and see whether I feel better.

ADDITIONAL NOTE: I realize that what we call "processed foods" (especially milled flour, sugar, and the various preservative-laden fast foods) are of recent origin, and that "we" have not had time to adapt to them genetically. But this does not mean that they would affect all people the same way. Nor does it necessarily follow that because they are new and we have not sorted out the evolutionary implications, that they are bad.

UPDATE: Oregon Guy links a fascinating post about the European bison, which makes me wish I'd titled this post "Traditional Pleistocene Values."

MORE: Alan Kellogg links Razib Khan "for a good introduction to the subject of human evolution"; I found this post about rice, alcohol and genes especially fascinating:

....in many pre-modern societies alcohol consumption was very widespread. In societies where nutritional stress was common it was a major source of calories, and as I note above its advantage in terms of low pathogen load vis-a-vis water was probably a major factor in its healthful effects (many ancient societies mixed water and wine freely). Not only does alcohol provide energy, but its psychological boost is obvious when it comes to the grinding life of a farmer. Rum rations was one of the major factors which allowed Caribbean slavery to be as economically profitable as it was, its existence made the short and brutal lives of human chattel more tolerable. The attraction of people who had little experience with alcohol, in particular its more potent varieties, to the substance seems a clear signal that once discovered it would inevitably exhibit a magnetic appeal. In this case the bias in favor of those who were more metabolically suited toward processing the new source of calories with the least deleterious consequences would have a great fitness consequence.
I think these genetic issues make hard to come up with hard and fast rules about what we should and should not eat or drink.

"We" are not all the same.

If you are one of those mean-spirited people who hates "good" veggies like Brussel Sprouts or broccoli, did you ever wonder why?

That, too, might be evolutionary -- natural selection favoring the survival of humans who avoided bitter tastes:

MADRID - Spanish researchers say they're a step closer to resolving a "mystery of evolution" -- why some people like Brussels sprouts but others hate them.

They have found that a gene in modern humans that makes some people dislike a bitter chemical called phenylthiocarbamide, or PTC, was also present in Neanderthals hundreds of thousands of years ago.

The scientists made the discovery after recovering and sequencing a fragment of the TAS2R38 gene taken from 48,000-year-old Neanderthal bones found at a site in El Sidron, in northern Spain, they said in a report released Wednesday by the Spanish National Research Council (CSIC).

"This indicates that variation in bitter taste perception predates the divergence of the lineages leading to Neanderthals and modern humans," they said.

Substances similar to PTC give a bitter taste to green vegetables such as Brussels sprouts, broccoli and cabbage as well as some fruits.

But they are also present in some poisonous plants, so having a distaste for it makes evolutionary sense.

"The sense of bitter taste protects us from ingesting toxic substances," the report said.

Whether there's an evolutionary advantage to loving sweet-tasting things is certainly open to debate. In the case of dogs (and children), it can prove fatal:
Antifreeze has a sweet taste, which appeals to animals and children. A dog can walk through antifreeze spilled on the driveway and ingest a fatal amount just from licking its paws clean.
Maybe the solution is to put Brussels sprouts in the antifreeze!

AND MORE: "Human evolution speeding up."

Why it would have stopped 20,000 years ago, no one has explained.

posted by Eric on 01.25.10 at 12:20 PM





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I don't even know if this is appropriate--as in "off topic"--but you be the judge.

http://roguepundit.typepad.com/roguepundit/2010/01/random-nature-247.html
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OregonGuy   ·  January 25, 2010 02:56 PM

Try Razib Khan for a good introduction to the subject of human evolution.

Alan Kellogg   ·  January 25, 2010 05:16 PM

Try http://www.paleonu.com for a good, straight-forward explanation of eating paleo/primal. It does not involve eating raw meat or living in caves. I've fed my Goldens a raw, natural diet for 14 years. I try to do the equivalent for myself (but cooked!). However, I do get sucked back by the evil sugar at times! ;) I'm better at avoiding the grains.

For a more "in your face" exposure to paleo/primal, see Richard's blog: http://www.freetheanimal.com.

There is also a paleo-libertarian email list! Seems that lots of paleo eaters are libertarian in mindset. In other words, they think for themselves and take responsibility for their own bodies.

Karen   ·  January 25, 2010 06:20 PM

Modern medicine has not allowed natural selection to weed out the weak and sick as it did before 1940. We will spend massive amounts of medicare on these people as they age.

Hugh   ·  January 25, 2010 08:27 PM

Perhaps Obama care will get us back to caveman medicine??

Hugh   ·  January 25, 2010 08:29 PM

Too bad we aren't getting any smarter.

Veeshir   ·  January 25, 2010 09:38 PM

One argument in favor of "paleo": most people prefer aged meats, especially from ungulants (cows, deer, etc.)

This, it is argued, a holdover from the days when we didn't have the strength and/or speed to kill our own large animals, and had to depend on the carnivores to do it for us... then wait until the dire wolves (or whatever) had their fill before harvesting the kill.

Seems plausible, though of course there's no way to prove any such thing. I can testify that I definitely participate in the preference, though.

Regards,
Ric

Ric Locke   ·  January 26, 2010 05:31 PM

I'm a meat-eater too, and I admit my bias.

But what also should not be forgotten is very important -- the vital role of the dog. In the dog (which crossed the animal aisle and self-domesticated to become what is colloquially known as "man's best friend"), we had not only a weapon to kill game, but a hunting -- and above all, tracking -- system superior to our own, as well as a defense system against other predators and hostile humans. Plus, they let us eat what they killed! The dog may thus have ensured human survival during touch-and-go periods in our early existence. I think that not only did we affect their evolution, but they affected ours.

And obviously, to a great extent we ate what they ate....

BTW dogs will eat carbs, and fats, as well as meats!

Eric Scheie   ·  January 26, 2010 06:47 PM

How do we know dogs "self-domsesticated"? I've been hearing that my whole life and it's always sounded a little stupid.
Wolves don't like people, except occasionally as a meal, why would they like us any better 50,000 years ago?

Maybe some humans just picked up some wolf puppies and raised them as their own?
I mean, maybe somebody said, "Man, those wolves are a lot like people, they hunt together and they recognize a heirarcy in their pack but they're much better at seeing and smelling than we are.
I wonder what would happen if we raised some from puppies and made them part of our pack?"(Probably with a lot of "ughs" and hoots, but you get the idea).

What seems most likely is that one or more tribes killed some wolves and some woman in each one said, "Awwww, look at the cute puppies. Let's keep them." Naturally, the mans said, "No way, we'll kill them and eat them".
So they took the puppies home and the rest is history.

Veeshir   ·  January 27, 2010 10:28 AM

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