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October 08, 2006

Women in Science; DDT and Overpopulation--Posner's Response to Comments

I want to reply to some of the comments on both my last posting, which was on the NAS report on women in science, and also the previous one, on DDT.

Women in Science . I notice that the comments in defense of the NAS report tend to be--defensive; and also emotional. One comment suggests that if a committee 17/18 female is likely to be biased, any male who comments on the report is likely to be biased too. But I did not suggest that the committee should have been composed primarily of men, only that it should have been more balanced, and that the fact that the only man on the committee could not, because of his position, dissent from the report, made his inclusion, as the lone man on the committee, entirely unprofessional. Another commenter vigorously denies that there is any difference between men and women, then states that he prefers female doctors because they are more caring!

A number of comments point to the range of differences between men and women, encompassing behaviors (crime, sports), preferences, test results, psychology, and much else besides, including the tendency of women in science to prefer the less mathematical fields (I gave the example of primatology). These differences could I suppose all be the product of discrimination, but that seems highly unlikely.

One comment states that the underrepresentation of women in science may be a result of path dependency (where you start may determine where you end up)--the fewness of women in science in past times. This is not persuasive, because there were virtually no women in academic law when I was a law student in the 1950s, but now about half of all law professors are women.

One last point: a good test for whether there is discrimination against or in favor of a group is its average performance in the profession alleged to be a site of discrimination relative to that of the majority. If women were discriminated against in science, one would expect the average woman in science to outperform the average man in publications, awards, etc., simply because only women who were better than men could overleap the discrimination hurdle. But if there is discrimination in favor of women in science, then the average man should outperform the average woman, because then it is the men who have to overcome the discrimination barrier. (If there is no difference in average performance of men and women in a given field, the inference is that there is no sex discrimination in that field--employers and other performance evaluators regard sex as irrelevant.) Since men outperform women in science rather than vice versa, the inference is that there is discrimination in favor of women.

DDT and Overpopulation I repeat my abject apology for calling DDT a herbicide rather than a pesticide. Some comments suggest that the mistake reveals my complete incompetence to discuss environmental issues. That seems a bit harsh. The reason for the mistake was simply that herbicides play a particularly important role in diminution of genetic diversity--thanks in part to the ban on DDT--so I was thinking about herbicides when I was considering the effects of DDT.

Some comments point out correctly that interior spraying won't eliminate mosquitoes and therefore malaria; and that is true. But complete eradication may not be cost justified. Costs and benefits must be compared at the margin. If 99 percent of deaths from malaria can be eliminated by interior spraying, it may not be worthwhile to spend billions of dollars developing and producing a vaccine. That is why I find the Gates Foundation's campaign to eradicate malaria puzzling. (Actually, I don't think it's very puzzling. There is often a strong political and public-relations dimension to foundation giving, even foundation giving for activities thought nonpolitical, such as saving lives. Somehow giving money to spray the interior of houses with DDT lacks pizzazz and could even be thought politically incorrect.)

Most of the comments fasten on the following paragraph in my posting: "Not that eliminating childhood deaths from malaria (I have seen an estimate that 80 percent of malaria deaths are of children) would be a completely unalloyed boon for Africa, which suffers from overpopulation. But on balance the case for eradicating malaria in Africa, as for eradicating AIDS (an even bigger killer) in Africa, is compelling. Malaria is a chronic, debilitating disease afflicting many more people than die of it, and the consequence is a significant reduction in economic productivity." Many commenters regard "unalloyed boon" as a particularly callous chardacterization. I think some of the commenters don't understand the meaning of the word "unalloyed." I did not say it was a good thing that children die of malaria; I just said that it was not just a good thing, if the deaths reduce population. Now, they may not, as one comment explains, because a family that loses a child to malaria may decide to have another child in its place, and indeed if the family is risk averse it may end up having more children because of the high risk of losing one or more of them to malaria than if there were no such risk. That is an interesting empirical question. I suspect that on balance there will be fewer children surviving to adulthood, simply because of the cost of additional children.

I continue to insist that overpopulation, including in subsaharan Africa, is a real problem. It is true but absurdly irrelevant that New York City has a greater population density than Africa. Overpopulation is not a simple matter of dividing people by square miles. In an agricultural society, population density tends to be negatively correlated with wealth, simply because the land must be worked harder to obtain food. Good land is not the only resource that is in limited supply--so is fresh water, forest products, game, and mineral resources. Scarcities in these resources can be overcome, but only at a cost. It is true as several comments point out that as a society grows wealthier, the birthrate tends to drop (the "demographic transition"), but Africa seems to be trapped by extreme poverty exacerbated by overpopulation.

Is it foolish for China to try to limit its population? If not, the case for limiting the African population is much stronger, because Africa has a far less productive population.

And so far I have been speaking only of the effects of population on the populous country. There are external effects as well. The effects of population on the destruction of forests and on the demand for electricity and cars are major contributors to global warming.

Posted by Richard Posner at 09:02 AM | Comments (14) | TrackBack (0)

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What is puzzling is your refusal to consider the possibility that the Gates foundation might know what they are doing. If you done some research into the history of the fight against malaria you would know that India has been using DDT against malaria for six decades without managing to eradicate it. They do use it less than they used to, but that is because DDT resistance by mosquitoes is widespread. And India is a much more favourable place for DDT since it has much better infrastructure than Africa.

To even hold the line against malaria will require the development of new insecicides and drugs because the mosquitoes and malaria parasites keep developing resistance agaisnt the ones we have. The Gates Foundation is quite properly working on these as well.

Your ill-informed criticism is most unfair.

Posted by Tim Lambert at October 8, 2006 10:52 AM | direct link

I originally suggested that the absence of women could be path dependent, in the sense that we have few women in science now because we had few women in science in the past. Judge Posner, and many others, correctly pointed out that even though no women were present in law and medicine, for example, they are there now. I realize this myself; what I was getting at is that no one adequately explains why women are so successful in other fields but not in science or engineering.

Posted by Haris at October 8, 2006 05:32 PM | direct link

I find it interesting, in the women in science debate, that no-one seems to regard medicine as a science.

Posted by Brian Ferguson at October 8, 2006 05:41 PM | direct link

I think we are all using "science" in this debate to refer to the research portion of science, rather than the application. So pharmacology, vaccine research, etc are the parts of medicine that most of us consider "science" in this discussion, rather than the actual practice of medicine.

Posted by Haris at October 8, 2006 07:30 PM | direct link

"simply because only women who were better than men could overleap the discrimination hurdle."

You answered your own question by thinking of discrimination as a "hurdle.' That is, something that operates only as a barrier to entry.

In fact, discrimination is better modeled as a weight attached to the leg of its subject. It does not go away once she gains access to a field, but merely relocates and changes form.

Women must do better than their male peers to get the same credentials, and they have to be better than their male peers to get the same assignments, mentoring, and responsibility once they start work.

Because discrimination affects both the proces of getting credentials and the process of doing the job, you cannot isolate discrimination by comparing performance in school to job performance.

Posted by Corey at October 9, 2006 01:01 PM | direct link

POSNER: "Since men outperform women in science rather than vice versa, the inference is that there is discrimination in favor of women."

Exactly so! Of course this is no secret, since the desirability of appointing a woman to a post or promotion is frequently and openly asserted.

LAMBERT: "... no one adequately explains why women are so successful in other fields but not in science or engineering."

I have seen it explained fairly often - for example by ex-Harvard President Larry Summers, but also by evolutionary psychologists.

1. There is a specifically mathemetical aptitude difference between men and women which explains why there have been no female mathematicians of genius (or classical music composers, for that matter). The differential ability gets larger with increasing aptitude - rather like the way that the height differential between men and women gets greater with increasing height (there are just a few-fold more men than women at the average height for a man; but thousands-fold more men than women at - say - two standard deviations above male average height).

2. There is another difference in terms of single-minded status-seeking (due to sexual selection, probably) being on average stronger in men - which leads to men being found more frequently in _any_ job which requires single-minded status-seeking and sacrifice of other goods (such as family, leisure, comfort etc). This has been very well studied by Kingsley R Browne of Wayne State University law school.

Posted by Bruce G Charlton at October 9, 2006 01:02 PM | direct link

The Shalala committee of female academics is riddled with obvious financial conflicts of interest that make their report useless as science. Indeed, monetary corruption is a rampant theme among powerful academic feminists, as the Denton-Greenwood scandal in the University of California shows:

http://www.vdare.com/sailer/061001_diversity.htm

Posted by Steve Sailer at October 10, 2006 01:14 AM | direct link

Sailer's comment reminds me of the quote from Steven Pinker (of MIT) in a debate posted on Edge.org "...the harder the science, the greater the participation of women! ... it's the most subjective fields within academia — the social sciences, the humanities, the helping professions — that have the greatest representation of women."

In other words, the pattern of male-female representation by academic subject confirms the statistical evidence of academic discrimination in favour of women mentioned by Posner (ie. higher perfomance in men at equivalent positions).

The particular domination of men in mathematical subjects (physics, engineering, hard-economics etc.) is then potentially explicable by the fact that since these are the most objective sciences, they are the subjects in which it is most difficult to implement the prevailing pattern of discrimination in favour of women.

Posted by Bruce G Charlton at October 10, 2006 12:06 PM | direct link

It’s not surprising to find men dominate in academic fields that are cognitively demanding such as mathematics. While it’s commonly believed that men and women have the same average IQ, recent research shows that’s only true until age 16. After that men gain an average advantage of about 5.5 points over women (Colom and Lynn 2004). The most plausible explanation is a difference in brain size. Modern measurements using MRI scans (Vernon 2000) show a correlation between IQ and brain size of 0.44 (after making a correction for IQ test reliability). Men have brains that average 100 grams more mass (Ankney 1992) than women (after correcting for body size). Using this correlation and a brain size difference (0.78 in standard deviation units) gives a differential IQ of 5.1 points well within sampling variation of the observed difference of 5.5. This difference will not show up on IQ tests that have a high verbal component as this creates a sex bias in the measurement of general g.

This small shift in mean implies a large ratio of the upper tail area of the IQ distributions for men and women. For example, if we assume IQ is normally distributed, and set a threshold level 4 standard deviations above the male mean, we get a ratio of about 5. This means we have 5 times more men than women with really high IQs. Male IQs also show greater dispersion. A single point increase in the standard deviation for men bumps the ratio up to almost 18 when combined with the shift in mean. Thus it’s not at all surprising that we would find far more men than women in the hard sciences.

Charlton says, “… there have been no female mathematicians of genius….” This is not correct from a historical perspective. Emily Noether was a female mathematician of the genius level. In 1918 she proved Noether’s theorem, which shows the connection between the fundamental laws of physics and symmetry. General relativity falls out as a special case. The famous mathematician David Hilbert recognized her genius and got her admitted to the mathematical institute at Göttingen.

Colom and Lynn: Personal and Individual Differences, 36,75-82

Vernon: Handbook of Intelligence, Cambridge Press, R. J. Sternberg Ed.

Ankley: Intellegence 16, 329-336

Posted by A. Zarkov at October 13, 2006 03:43 AM | direct link

"Since men outperform women in science"

How do you know that. Since performance in science is rated by peer review this result may be the result of bias by male peers. Even small biases matter. Studies have show that having a last name starting with A, B, C improves your "performance" in science because you are first author on joint papers. You distrust a committee composed primarily of women, but you trust peer review in science when the peers are primarily men. You might question your own biases also.

Posted by joan at October 13, 2006 06:49 AM | direct link

"One comment states that the underrepresentation of women in science may be a result of path dependency (where you start may determine where you end up)--the fewness of women in science in past times. This is not persuasive, because there were virtually no women in academic law when I was a law student in the 1950s, but now about half of all law professors are women.

I guess it is the responce to my comment. Looks like my point is not clear enough. I said that the lack of female physicists in the past makes it hard for "scientific advertisiment" to target young females. While the "advertising" of science in popular culture is often focused on the image of famous great scientist, not necessuary rich. The advertisment of law as profession is focused on nameless rich lawyer. Also not that the most popular heroes of crime fiction books are both males and females. Take Miss Marple for example.

I say, that the targeting of "advertisement" of different professions to children in families and popular culture is uneven.

Posted by muxec at October 13, 2006 09:33 AM | direct link

Thanks to Zarkov for the suggestion (above) of Emily Noether as a possible female mathematical genius.

From what - very little - I could find about Noether on a Google Search (she has no page in Wikipedia, and about 400 Google hits - fewer than I do myself - compared with hundreds of thousands for Gauss, Hilbert and the like) she certainly sounds like she did very important work.

But she is certainly _not_ one of the major recognized first-rate mathematicians.

Posted by Bruce G Charlton at October 15, 2006 03:57 PM | direct link

there is an obvious mechanism that we know happens that calls into question posner's inference about discrimination against women in science:

while many women in science do indeed face discrimination, a few (particularly in highly-visible positions) nonetheless benefit from some preferential treatment as an ad-hoc solution to the inequity, or as a false committment to equity for public consumption.

Posted by shiva at October 15, 2006 06:41 PM | direct link

She does have a page in Wikipedia, look under “Emmy Noether.” When I google “emmy noether,” I get 344,000 hits. I’m sorry I initially gave the less common spelling of her first name. If you read Wikipedia and the other hits you will see she did significant work in mathematics. Moreover she did face career barriers on account of her sex. Of course it didn’t help to be Jewish and a socialist in Germany in the early 20th Century. Tragically her brother (also a socialist and a mathematician) went to the Soviet Union where he ended up getting shot. She also had her career cut short by an untimely death from natural causes or botched surgery. While Noether does not have the stature of a Hilbert, Poincare, Von Neumann, Hardy, or Kolmogorov, she certainly was a genius, and I personally would put her in the top 100 mathematicians of the 20th Century. Of course some people go a little to far in Noether worship. The mathematics library at UC Berkeley (Evans Hall) used to have a pantheon of posters of great mathematicians posted across the wall. A few years ago I saw that the library saw fit to rip all of them down except Noether’s.

Posted by A. Zarkov at October 16, 2006 04:30 PM | direct link

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