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August 24, 2003

Humans evolving....

Nick Wade surveys the theory that humans are evolving now, contrary to the conventional assertion that culture, not biology, is driving the transformation of our species....

Here something that I am surprised that Wade included in the article:

Not everything is roses in evolution's garden. Ronald Fisher, the British biologist, pointed out in 1930 that the genes for mental ability tend to move upward through the social classes but that fertility is higher in the lower social classes. He concluded that selection constantly opposes genes that favor creativity and intelligence.

Fisher's idea has not been proven wrong in theory, although many biologists, besides detesting it for the support it gave to eugenic policies, believe it has proven false in practice. "It hasn't been formally refuted in the sense that we could never test it," Dr. Pagel said. Though people with fewer resources tend to have more children, that may be for lack of education, not intelligence. "Education is the best contraceptive. If you brought these people up in the middle class they would have fewer children," Dr. Pagel said. "Fisher's empirical observation is correct, that the lower orders have more babies, but that doesn't mean their genotypes are inferior."

Does anyone really buy this? Yes, the Flynn Effect is undeniable, but assuming the premises, that intelligence is heritable to some extent, that socioeconomic status (SES) has some relationship to innate intellectual capacities and low SES status has a positive correlation with fecundity-it doesn't take a rocket scientist to connect the dots. Oh, and by the way, I have heard several liberal friends who are in graduate studies in the biological sciences who express concern with the the dysgenic trends of our species, so it isn't only people "on the street" that wonder about this, when you get biologists off the record I suspect you hear a different tune.... (The collected papers of eminent evolutionary biologist W.D. Hamilton for instance is a case in point-there is quite a bit of embarrassing material for potentional pangyrists & friends)

Posted by razib at 12:19 PM

The biologist seems to suggest that Fisher's theories are dubious but never shows any serious evidence to the contrary. All he does is demonstrate alternative possibilities that might be plausible.

Posted by: R at August 24, 2003 02:59 PM

The discussion in the quoted text is ill-informed and out of date. Fears of a dysgenic trend were common in the early part of the C20, but studies in the 50s and 60s (notably by Carl Bajema) showed that things were not so bad. Low IQ people with children tended to have large families, but this was offset by the fact that low IQ people were less likely than average to have children at all. The overall effect was roughly neutral. (Some studies also showed a bimodal distribution, with both low IQ and high IQ people having more kids than average.)

There hasn't been much research on this recently, and some people (e.g. Richard Lynn) think there is a dysgenic trend after all. But the evidence is very thin.

Posted by: David B at August 25, 2003 03:44 AM

As I've stated before in these comments, I don't buy into the Flynn Effect being real. His tests that show intelligence increasing must actually be measuring something else besides intelligence.

Posted by: Gordon Gekko at August 25, 2003 07:34 AM

While I agree with David B, I'm not so sure if those studies are apposite now. In the 50's and 60's you didn't see obesity as the number 1 health concern of poor people in the US...

In the past century many different regions have developed welfare policies (either internally or, by poor countries, due to external aid) that enable those who don't produce to feed themselves, as well as receive housing, medicine. Thus, for example, you see African population more than doubling since 1960 in spite of little economic development on that continent. I think there's good reason to suspect a regime shift in the evolutionary success of different groups; it is, after all, an endogenous variable.

Posted by: eric f at August 25, 2003 09:39 AM

Strictly speaking, welfare or welfare-like subsidization shouldn't be a prerequisite to buoying the fecundity of the poor. Technologically induced drops in the absolute cost of food could be sufficient for boosting prole babies. No?

Posted by: temporary_account at August 25, 2003 12:57 PM

eric, the real reasons for the allegedly increasing obesity deserve more serious scientific speculation than they get.

First of all, blacks and hispanics both tend to be more portly than whites, so perhaps their increasing share of the population partly explains why obesity is allegedly rising.

Maybe big people have more children than small people, all other factors being the same? This has never been looked into.

Maybe some of the extra weight we carry around is muscle not fat? This could be because of (1) the increasing popularity of bodybuilding and weight lifting; and (2) maybe men with more muscles have more children (because they have sex with more women because women find their buff bods more attractive).

Maybe there are biological correlates between having childen and being heavier. Maybe testosterone makes men weigh more and also increases their sex drive?

Maybe the definition of "obesity" changed, because they (whomever "they" are) modified the height/weight charts?

Posted by: Gordon Gekko at August 25, 2003 02:30 PM

the greatest decrease in mortality rates comes from nutrition, then sanitation (clean water), then medicinal treatment of infectious diseases like Tuberculosis, pneumonia, and influenza (see The Role of Medicine by Thomas Mckeown). Fertility decreased in developed countries later (for most developed countries around 1900, accelerating after 1950), usually after some initial developement to say $USD 2000/capita or so, and so in Africa it hasn't changed.

Technologically induced drops in the absolute cost of food could be sufficient for boosting prole babies. No?

This is probably the dominant effect (food productivity growth, after all, in the US it used to take 95% of us to feed us all, now just 3%). But for the severe underclass, a minority of say 5%, this implies subsidies.

Maybe the definition of "obesity" changed, because they (whomever "they" are) modified the height/weight charts?

I havenít the reference, but I would say definitely not. There simply isnít any material amount of malnutrition due to lack of access in the US, just perverse cases where care is neglected due to very poor parenting (usually involving drug use by a parent).

Posted by: eric f at August 25, 2003 07:24 PM

Noting that people live longer now than ever before in human history, it also doesn't make scientific sense to conclude that our modern diet is somehow unhealthy.

Posted by: Gordon Gekko at August 26, 2003 06:12 AM

to David B: quite wrong. The evidence is strong for a dysgenic trend.
This has probably happened before, in Classical times. Sylphium contributed.

Posted by: gcochran at August 26, 2003 08:24 PM

"I don't buy into the Flynn Effect being real."

I don't know what to make of the Flynn Effect, but it is real - the data supports it's existence and Crystallized G is not increasing as much as Fluid G (as shown on the general knowlege sections and Crystallized portions of the tests as well as the period of SAT decline which is a good measure of Crystallized G).

A good analogy presented by Jensen that mirrors the Flynn Effect phenomenon is the increase in height that has paralleled the increase in intelligence. Nobody questions that height is increasing, even though the gene pool of humans hasn't changed much in the last hundred years.

I believe Jensen states that a combination of better nutrition, heterosis, the inability of the extreme bottom end of the Intelligence bell curve to reproduce, a reduction (on average) worldwide of inbreeding have had positive effects on both intelligence and height.

These effects would be enough to mask the general dysgenic trend as it relates to individuals that lie to the left of the bell curve in intelligence reproducing at a greater rate than those who lie to the right hand side of the curve.

Posted by: the_alpha_male at August 27, 2003 12:42 PM

I suppose no one will read this, but I have two points to make nonetheless: I have read that the size of human craniums has decreased significantly over the last 2000 years; also, many of the founding fathers came from huge families and I would assume many of their parents were rather intelligent people, although then again almost all the found fathers were the first in their families to attend a university.

Posted by: Inventor at August 31, 2003 04:30 AM