It's been somewhat of a commonplace, among those who worry about such things, that the increase in the power and complexity of human civilization and culture has reduced the forces of evolution on the species. After all, so one argument goes, we now enable diabetics and others afflicted with genetically-linked physical or mental illnesses to survive and reproduce, where they would have perished back before we came down from the trees. Darwin might have been right, but had become steadily less relevant to our future.
Turns out Darwin is still very much relevant. A just released paper (PDF, of highly technical nature) details a study suggesting that mutations have been accumulating in the collective human genome at a rate that has increased since the 'cultural phase' of the species began. The senior author, John Hawks, is a blogger and has a more approachable summary here.
This result is another byproduct of sequencing of the human genome. As more individual genomes are documented (usually in part), there has been a global effort to collect information on variations in sequence, called the HapMap Project. Some of these variations turn out to be genetic markers for diseases or more innocuous individual traits. Some of them are apparently benign, having little or no impact on the organism.
The variations tend to accumulate at a more or less constant rate over generations of reproduction of the organism, in more or less random locations in the sequence. The accumulation of variations can then be used as a sort of clock. Tracking which variations tend to be inherited together is also a sort of crib on which sections of the genome are actually functional units. If a longish section of such genetic material is found in a population, with few variations, than it was probably a relatively recent introduction to the genome. The more accumulated benign variations, the more likely that it's older. (Yes, I'm simplifying like crazy - follow the links.)
Applying this metric to the growing collection of human genetic variants suggests that new sequences are being introduced to the human genetic pool at a rate atypically high compared to other complex animal species, and that this increase in rate is actually concentrated in the last few tens of thousands of years. (The author has put out a list of 'rarely asked' (i.e., highly technical) questions regarding the analysis, which will be followed by a layman's FAQ on the same site.
The biggest reason for this is one of those 'right under your nose, obvious when pointed out' things - in retrospect. Quoting the paper: "Human populations have vastly increased in numbers during the past 50,000 years or more." More births, more chances for an adaptive mutation that survives. (Note that none of this implies the adaptations are present in all humans.)
Some of these adaptations fall at the far edges of human cultural history. One classic cited in this post about the study is the development of lactose tolerance, which can be dated to about 8,000 years back, and is well-known to be present in only part of the human population. Presumably this conferred an advantage on humans who had already started hanging out with (and eating) herd beasts by allowing them to also drink their milk.
One of the classic situations for evolution at a species level is the 'radiation' into newly available ecological niches of an existing species. Finds like the lactose gene suggest that human cultural variation may have the side effect of creating new kinds of niches - in this case, becoming mildly symbiotic with dairy animals. Of course, talking about all of this as 'rapid' or 'recent' is a relative matter, we are still talking about thousands of years. If we witness such adaptations during our lifetime, it's going to be because they are newly discovered through genomic analysis, not because there was a mutant born next door. However, if this result does makes into popular culture, it may erode the notion that evolution of higher animals is something that only happens on a geological time scale.
The study is also an exhibit of the spread of genomic techniques and results to other fields. Of the five authors, one is from a bioinformatics lab, two are now at commercial genomics company Affymetrix, and two are anthropologists. Digging in the genome may be more rewarding than digging into prehistoric human sites over the new few years. Likely this isn't the last field to be shaken up by the byproducts of reverse-engineering Mother Nature.
(HT: Glenn Reynolds)
Good article, as I read it though, a lot of speculation like this has been around for years. The change seems to be that they are backing it up with evidence from the genome. Or, am I misreading the article. I also think that "accelerating" is misleading "broadening" might be more descriptive.
The growth seems to be one of variations changing over a broad spectrum like geographical variance in animal species rather than a linear acceleration of the human species as a whole.
But, I may be misreading it.
I seems that it's more the reduction of selection pressure on the population that is the better explanation. It seems genetic diversity will always tend to increase as selection pressure decreases.
It is interesting that more diversity is what we'd want as a species whenever the next "pinch point" occurs. That's when you'd see what is commonly called "evolution" in action. Because, much of that built-up genetic diversity will be weeded out as only the most "fit" individuals survive and reproduce beyond the disaster, whatever it turns out to be.
Just saying that more genetic diversity proves that evolution is speeding up doesn't really explain anything, at least without some process that actually values some traits more than others with respect to long term reproductive success.
And the judgment will always be base on the number of decedents, and not how money movies or how much money someone makes. Elisabeth Taylor did have pretty eyes which helped put her in movies and make her rich, but she's definitely been out reproduced by many less monetarily successful women. In fact, a case can be made that monetary success, in the western world at least, reduces reproductive fitness for the species, e.g. the ricer you are, the fewer children you seem to have.
I think more of the speculation has historically been on the 'less evolution' side, e.g., the eugenics movement that thought we had to take a hand directly, since culture was allowing the survival of negative variations.
I agree 'acceleration' is not a precise word in this case, at least without making clear what's accelerating. The authors' thesis is largely that the accumulation of adaptive mutations in the total human gene pool is accelerating, rather than the rate of individual human's mutation is increasing.
That 'cultural niches' might be replacing some of the more traditional ecological niches, as the latter become less potent in exerting pressure on us, is more speculatively. The lactose tolerance mutation is certainly the prize exhibit in that direction. There's a rough date of origin from genomic studies, that seems to correlate with archeological evidence (see the Beeb article linked above) suggesting that it was not yet widespread in Europe at about the same time. That's no proof of a pattern, but it will be interesting to see if continuing genomic analysis comes up with others that might be linked to the shift to herding and agricultural cultures.
(We've not been living with industrial age pollutants or manufactured foods long enough to have had an observable impact, most likely. They are more likely just setting off existing (partially) genetically linked conditions, e.g., asthma.)
There's a pretty funny movie starring Luke Wilson called Idiocracy that explores the reverse evolution idea.
The premise is actually pretty disturbing- Wilson is an entirely average guy that is frozen for 500 years and wakes to a word where the intelligent and industrious have been bred out of the gene pool by the mouth breathing Springer audience who have simply reproduced their way to dominance in nerfed over world run by machines.
I think you can make an argument that short of a technological/chemical solution, intelligence has little survival value in our society and may be headed for a decline.
40 years ago, when I was in college, a professor once asked my class to what the most deleterious event in the history was. My answer was the combining of the alleles for the big brain and opposing thumb.
The "evolution" Homo Agriculturalis 10 or 12 thousand years ago might have sealed the fate of the species by domesticating it. A radical ecologist, Paul Shepard, wrote a book called the "Tender Carnivore and the Sacred Game" and "Man in the Landscape" argued that the development of Agriculture marked the beginning of the end of the species.
Bad Philosophy, cleanup in aisle 5!
I have a friend who was convinced that the move into agriculture was a bad move, and that we screwed ourselves once we left the hunter-gatherer lifestyle. He made a big deal out of his American Indian ancestry, what there was of it, and bought heavily into socio-biology, because hey, we were evolved to live as hunter-gatherers, damnit!
Papers like this tend to leave the socio-biology viewpoint looking as foolish as phrenology. If evolution is quick enough for cultural slices of a species to adapt on a historical rather than epochal time-scale, as Gregory Clark was suggesting earlier this year, then no, we didn't evolve to have our women folk sit around picking berries and our menfolk run around bareassed chasing deer. The question is, how quickly do cultural groups adapt? If you take the IQ increase of the last century at face-value, maybe it's generational? Clark seems to suggest: pretty damn fast, actually.
Milk tolerance and dry ear wax are interesting markers, not the important bits. Coding for hardwired social behavior, work patterns, and intellectual capacity are where the fireworks are going to go off, once the fuse lights.
One of the unspoken issues of Idiocracy is the role of sexual selection. Women unconstrained by other factors (economic dependency and social restrictions) WILL choose on average decisively "love em and leave em" guys as the fathers of their children.
You can see this most clearly in African women in sub-saharan Africa, but also African-American women in the US. Over 70% of births to Black American women are illegitimate. The figure rises to 90% in urban Black areas. A stunning reversal from the segregation-era figures for legitimacy (which was slightly higher than the White population but not orders of magnitude higher).
But trends in the Latino and White population are also headed in that direction: the 2006 Census reports more teen mothers, more illegitimate births, etc for those demographic sectors. We seem to be in a historic shift towards sexual selection for: aggression, high testosterone, high status among men. With only a few men (genetic bottleneck right there) reproducing. Those that do are the most hyper-macho and don't stick around, essentially "Wilt Chamberlain" types. [Chamberlain boasted of having sex with more than 10,000 women.]
Given that cultural shift, i.e. women's place in Western Society allows them unconstrained sexual selection, we are likely to see not just a decline in intelligence but also of cooperation, loyalty, etc. as women pick Wilt Chamberlain types as the fathers of their children.
[Black women often complain about Rap's misogynistic lyrics and imagery in videos. Well, considering that the average rapper sees with his own eyes sexual selection criteria among women based on hyper-aggression, violence, status etc. with a few winners and most men losers, it's not surprising. I would expect that social-evolutionary trend to accelerate and spread to other demographic slices of Western Society.]
Intelligence and an opposable thumb can only be considered a bad move if you completely ignore all energy considerations.
And considering evolution without taking into account energy concerns is like considering walking without gravity.
We've gone from tools like spears and carts which are energy multipliers, aiding (technically making more efficient) preexisting physical abilities, to tools like guns and automobiles which are additive, they inject energy into the process that wasn't present before (usually chemically based).
This ability to inject energy into processes is the entire human survival advantage in a nutshell, intelligence is simply a tool to get there. Without it were trapped in the same dilemma all other life is, trying to balance the survival advantages of nifty physical abilities with the food constraints required to power those abilities.
For example, there's no particular physical reason why a bear couldn't evolve the ability to grow and shoot it's claws at extremely high speeds, enough to kill prey at bow-shot ranges. There are some very small scale animals that do things similar to this. Yet, in spite of being an obvious aid to hunting, nothing has evolved to use self-grown ranged weapons on a larger scale. Why not? Energy. The amount of energy required to do so eclipses the additional food this might bring in.
I'd say you can make an excellent argument that, barring major climatological variation, no major new evolution is possible, all existing avenues have essentially been exhausted and we're simply looking at variations and minor rearrangements of existing themes.
The only remaining evolutionary path is to somehow work around the energy barrier and come up with some way to generate energy that's not stuck on the solar powered food cycle.
To do that you need to manipulate your environment, hence intelligence (to understand it) and thumbs (to manipulate it). Man is the animal who controls his environment. As long as we do that we're good, cease trying and we die. We waste too much energy on our brains to be competitive with other species unless we stack the deck.
On the original post topic, I'd say this means that human genetic evolution is, frankly, irrelevant. Our species advantage has never been physical, and mentally, average IQ isn't important, only the bleeding edge of the innovators is. As long as we keep coming up with the occasional Newton, Einstein and the like, that the vast majority are obsessed with the inane is irrelevant.
Taking it a step further, reliance upon natural speciation (or any natural process) is ironically contradictory to our natural advantages. We exist to stack the deck, ergo artificial physical manipulation of ourselves is the next logical step.
Actually, I'd say genetic manipulation is a substandard way of doing that, still playing by the old rules, direct replacement/augmentation (nanotech anyone?) does a much better job of shattering the old energy rules. What naturally evolved virus or bacteria could possible compete with externally powered nanites for example?
We've long since started to artificially augment our intelligence. What is writing but artificially boosted memory? Language is a tool for boosting computation power by pooling intellectual resources. Likes spears and carts, those are multiplicative tools. Now we're using computers and increasingly advanced artificial algorithms which are additive tools.
Now all we need to do is make the interface less clumsy...
I guess in order to understand that, you'd have to know what the "fate of the species" is supposed to mean.
If it means survival, the modest ambition of all self-respecting species, then it couldn't be more wrong. Agriculture guaranteed survival, which otherwise was a very chancy thing, because being a predator is one of the worst ways to survive.
If it means it ruined our romantic hunter-gatherer nature (which is some kind of "Men's Movement" bullshit) then I couldn't be more grateful to have that ruined for me. Imagine living with a woman who just carried her kids on her back for 500 miles because the stupid herd you've been living off decided to migrate to goddamn Siberia.
My best hope in a situation like that would be to encounter a sedentary agricultural tribe, who would wipe out 90% of us with their vastly superior disease immunity, then finish off the starving survivors with their iron weapons.
Well, I no longer believe what I did as a student 40 years ago and, at my age, I have no interest in becoming a Paleolithic hunter, but my post had its intended effect:
Stimulating some conversation in a thread that had been moribund for a couple of days.
Glen: Not just "Men's Movement" bullshit -- That thinking can trace its roots back to the 19th century Romantics and to Rousseau's "noble savage" before that.
I think an ingrained presupposition that "the grass is greener over there" has motivated human expansion and progress over the ages. But once life gets easy enough, and the species' past gets blurrier, it becomes easy to warp that impulse into "the grass was greener back then".
You can take the sourcing back before Rousseau. For some of those who regret their humanity, it seems Agriculture = Original Sin. Not that they'd ever admit that (subliminal?) influence.
For example, there's no particular physical reason why a bear couldn't evolve the ability to grow and shoot it's claws at extremely high speeds, enough to kill prey at bow-shot ranges.
Yes, no particular physical reason. Except for the general laws of physics. And then there's the question of how a bear would evolve such a crazy grapple? All in all, they're are many reasons why this won't happen.
TOC: worked, thanks.
Yes, no particular physical reason. Except for the general laws of physics. And then there's the question of how a bear would evolve such a crazy grapple? All in all, they're are many reasons why this won't happen.
Actually there are a number of organisms at the real small scale that do fire spikes out at extremely high speeds to catch prey.
The right kind of muscular contractions can generate the required force, and simply growing the ammunition is no different than growing any other form of cartilage, which can be done very quickly if needed.
What laws of physics are being broken, assuming sufficient input energy?
It's unlikely bears would evolve that way, but I assert that the only thing holding back similar sized predators from evolving these kinds of impressive physical capabilities is the food problem.
IQ cant increase. Its scored on a bell curb.
Its like that old saw- 80% of people believe they are better than average.
"bell curb"
Curve even.
Actually there are a number of organisms at the real small scale that do fire spikes out at extremely high speeds to catch prey.
Yes, at the small scale this is possible. As animals get larger, these feats become more and more unlikely.
Increasing variability does imply decreased selection. But it doesn't mean no selection.
Apart from lactose tolerance, we've also developed tolerance to wheat gluten, and some asians have developed tolerance to soybean toxins. We're now selecting for adaptation to excesses of simple sugars. Diabetes is not much an issue when the only sweets come from the occasional bee tree.
No telling how long we've selected for the ability to eat onions. Onions live most of the places people do.
We no longer select for resistance to corncockle, which used to contaminate wheat and mostly no longer does.
Food will always be a selective agent, but the details vary. If you're rich you can have a paleolithic diet today. Eat lean meat and organ meat, fish, shellfish, salads, fruit, and insects. Avoid wheat rice and other grains, dairy products, and many cultivated vegetables. (Onions are probably OK. Burdock? Prickly pear? Low-oxalic-acid acorns?) If you're poor you have to eat what's cheap in your area, and be selected by it.