Burning Seed Corn

According to Sylvia Ann Hewlett, writing in the Harvard Business Review, 33% of successful career women (business executives, doctors, lawyers, academics,  etc) in the 41-55 age bracket are childless. In corporate America, 42%.  I figure that the TFR of this class is under 1.0  .

The numbers are worse for the best-paid, most exalted positions, so TFR for women emerging from Harvard Business School or Harvard Law must be lower yet.

On the whole these Harvard women are a good deal smarter than average, albeit crazy as a bedbug.  Since intelligence is highly heritable, this trend (along with others, of course) is fueling that hell-bound train.

Now if these women were part of a short-term maximum effort aimed at stopping an asteroid impact, this would make sense, but I’m pretty sure they’re not.

Posted in dysgenics | 91 Comments

Assortive mating and income inequality

More than in the past, we have doctors marrying other doctors,  rather than nurses, basically because of an increase in assortative mating for education. Ceteris paribus, this would tend to cause greater income equality among families. Is it the main driver of increasing income inequality?

Not at all.  Most of the increase over the last 30 years has been among business executives and people working in finance.  Since 1979, 58% of the expansion of income of the top 1% of households has this origin.  For the top 0.1% of households, it’s been 67%.

Business executives are making more relative to the average worker than they used to. The average compensation of a Fortune 500 CEO was 20 times that of his average employee in 1950, 42 times larger in 1980, 350 times larger today.

Now if hedge funds and Fortune 500 companies were being managed by married teams, dynamic duos like Justinian & Theodora or Burns & Allen, you could attribute this change to increased assortative mating.  In fact, I should probably write a best-selling book on this counter-intuitive idea, even though (especially though!) it never, ever happens.

Now I’m about to say something a little dangerous – so get your nitroglycerin pills ready.

Maybe those finance guys and CEOs are delivering enormously more value than they did in the 1950s!

For those remaining readers that haven’t died laughing, increased assortative mating probably has contributed to income inequality.  Just not very much.  Changes in the tax code, outsourcing, automation,  smothering the board of directors in cream, and inattentive stockholders all matter more.

Posted in assortative mating | Tagged | 53 Comments

Sperm competition

Mostly, people are talking about competition between sperm produced by different  males. In humans, this means women that are into speed dating.

The non-paternity rate is an upper limit to the rate of sperm competition:  in many, probably most cases of non-paternity, the woman has not had sex with two different men in a short period of time.  But the non-paternity rate is low!

So classical sperm competition is insignificant in humans, at least in every population we have any data for.  There are those that argue that back in the  stone age, things were far more crazy [hunter gatherers were highly promiscuous, they say], but they’re utterly full of shit.

Now if you go far back enough, a few million years, things were different.  Chimps are highly promiscuous, and have specific adaptations for sperm competition, for example a protein that causes ejaculate to form a plug.  Humans have a non-working version of that protein, which shows that sperm competition used to matter in our ancient ancestors, but hasn’t for a long time.

Still, a number of genes involved with spermatogenesis evolve quite rapidly.  We know several ways in which selection might favor a lot of change.  One is that sperm cells from a given male compete with each other. The other is sexual conflict: the sperm and the egg have conflicting interests.   An allele that increased a sperm’s chance of being first to the egg would be favored.  On the other hand, it is absolutely vital that egg not be fertilized by more than one sperm, so barriers to over-fertilization must exist. Sperm adapt to vault those  barriers more effectively, eggs evolve better barriers, etc.  It’s a Red Queen situation.

A lot of ink has been spilled about all the special physical and psychological adaptations in humans driven by sperm competition of the first kind.  They don’t exist.

Baker and Bellis wrote a lot of nonsense along these lines back in the 90s, sprinkled with fascinating false facts like 20% rates of non-paternity in Britain.  Loons, both of them.

Posted in Genetics | 143 Comments

Stolen generations

Someone was quoted as saying that if you adopted an Australian Aborigine kid and raised him in England, he’d do just fine.  This is a standard prediction, or maybe really an assumption, of most social scientists: people are the same everywhere. Let me put it more precisely: If you adopted a random draw of such kids just after birth, and then treated them in the same way that local native kids were treated,  they’d end up with the same adult IQ, on average. And the same rate of alcoholism, and so forth.   Same with any other racial group, the prediction says.

But is this actually true?  The same people would say that one-day-old babies from different groups ought to act the same, and that’s certainly not true.

I would think that there was a lot of adoption of Australian Aborigines going on in Australia, back in the day.  What were the results?



Posted in Australian Aboriginals | 94 Comments

Genetic Architectures

Dairy cattle eventually graduate to McDonalds, so there is some interest in the genetics of beef production in dairy breeds.  There is course more interest in the genetics of beef production in beef breeds of cattle.

Usually you don’t find a single allele that makes a lot of difference, but in some beef breeds, there are myostatin mutations that result in a ridiculous-looking, ‘double-muscled’ beast. Homozygosity for myostatin mutations causes difficulties in birth, so it takes really strong selection for  beef production to make a myostatin null common.  I  don’t think you ever see this in dairy breeds.

But, as it turns out, there is a deletion that is pretty common in some dairy breeds that significantly increases milk production while killing homozygotes before birth.

Breeds under weaker selection for single traits, your typical cow of the past, probably have neither.

The point is that the genetic architecture of a  quantitative trait does not have to be the same in different populations of the same species.  For example, I have the impression that height is not as highly polygenic in Pygmies as it is most other human populations. There’s a particular region on chromosome 3 that seems to influence height- you don’t see such a concentration in Europeans.

Posted in Genetics | 15 Comments

It made their brown eyes blue..

A recent report in PNAS shows the inhabitants of the Ukraine and its environs had much darker hair, skin, and eyes back in the Bronze Age and earlier.

Assuming population continuity, the selective advantage of the alleles they examined must have been very high. In order to see if there had been population continuity, they looked at the mtDNA frequencies of the ancient populations and compared them with mtDNA frequencies of modern populations in the same areas.  Since they’re different, but not wildly different, they conclude that there has been population continuity, which was their null assumption.

That null assumption might have been reasonable, if someone had burned every history book ever written, while at the same time suppressing all the ancient DNA evidence.

Since that has not yet happened,  I think their assumption is downright embarrassing. People have been moving in and out of this area for all of recorded history (as Razib Khan has also pointed out) : Cimmerians, Scythians, Goths, Khazars, Kievian Rus, the Golden Horde, eventually Russians.

There is no logical reason for geneticists to ignore information outside their field. Ignorance is no excuse. I could say the same for every other discipline.  Cross the streams – it would be good.

Back on the original issue: there really has been a lot of change in the European frequencies of alleles that influence skin, hair, and eye color over the past few thousand years.  Two population turnovers are a big part of the story, but surely selection is as well.  I don’t think we can be sure of the underlying reasons – Vitamin D may not be all of the story. Maybe not even most of the story.


Posted in Uncategorized | 40 Comments

The Great IQ Depression

We hear that poverty can sap brainpower,  reduce frontal lobe function,  induce the  fantods, etc.  But exactly what do we mean by ‘poverty’?  If we’re talking about an absolute, rather than relative, standard of living,  most of the world today must be in poverty, as well as almost everyone who lived much before the present.  Most Chinese are poorer than the official US poverty level, right?  The US had fairly rapid economic growth until the last generation or so, so if you go very far back in time, almost everyone was poor, by modern standards. Even those who were considered rich at the time suffered from zero prenatal care, largely useless medicine, tabletless high schools,  and slow Internet connections.  They had to ride horses that had lousy acceleration and pooped all over the place.

In particular, if all this poverty-gives-you-emerods stuff is true, scholastic achievement should have collapsed in the Great Depression – and with the miracle of epigenetics, most of us should still be suffering those bad effects.

But somehow none of this seems to have gone through the formality of actually happening.

Posted in Uncategorized | 143 Comments