Moms, you don't need to send your second sons to remedial school just yet.

Once again, Science Magazine is a tool of publicity hounds who trumpet their incredible breakthroughs in press releases, knowing that almost nobody will read - let alone understand - the fine print and discover that their claims have all the foundation of a sand castle.

Petter Kristensen and Tor Bjerkedal (2007. Explaining the relation between birth order and intelligence. Science 316:1717) managed to squeak a one-pager in this week that gives even those of us trained to read scientific papers a run for their money. However, if one delves into the online supplements to the article, and an accompanying paper also newly available(1) it becomes clear that the results are biologically meaningless, despite the media's ever present desire to milk them for controversy. This is why:

First and foremost, this is yet another paper that uses an enormous sample size (over 250,000) to support its conclusions. Those who do not fully grasp the nature of statistics often believe that this makes results more credible, when in fact, it makes them less so. This is because in huge sample sizes, any tiny difference between groups is amplified to the point where it is likely to be statistically significant. However, statistical significance does not necessarily imply biological significance, especially when large sample sizes are required to identify a statistical effect. The authors of these papers themselves give the best demonstration of the fallacy of this technique when they cite a previous Science paper(2) that reached exactly the opposite conclusion using 400,000 Dutch men. If they repeat the study tomorrow using a different huge population, they could easily find the results reversed again.

If birth order has no correlation with IQ at all, then in randomly selected Norwegian family, there is a 50% chance that the first son has a higher score than the second son. My statistician colleague did some rough calculations based on the data in the Science paper, and concluded that it shows that in a randomly selected family, there is a 52% chance the first son scores higher than the second son. The statistical standard for biological significance in most contexts is 95%. For a first son to have a 95% chance of scoring higher than a second son, the average difference in IQ points would have to be 80. (As far as I know, there is no data showing that second sons are more likely to be retarded.)

In addition, the Norwegian soldiers did not take a standard IQ test, which has a population mean of 100. They took a test given by the Norwegian military which gives single-digit scores of 1-9, with a mean of 5. The scores are therefore much less precise than those from an IQ test, and a difference of 3 IQ points after the data transformation corresponds to a difference of 0.25 point on the Norwegian test. If two brothers both have a score of 6, which one is a quarter point smarter?

The media love these stories and will continue to broadcast them, analyze them, and give people complexes about them forever. But it is disheartening that Science, an internationally respected journal that scientists throw elbows to get published in because of the instant fame it brings, is in it purely for the publicity as well. People should no longer assume that a paper in Science must be actual science.


(1)Bjerkedal T., Kristensen P., Skjeret G.A., and Brevik J.I., 2007. Intelligence test scores and birth order among young Norwegian men (conscripts) analyzed within and between families. Intelligence doi:10.1016/j.intell.2007.01.004 (in press)

(2)Belmont, L., and Marolla, F.A., 1973. Birth order, family size and intelligence. Science 182:1096-1101.

Labels: brain, humans, statistics

Eupithecia is a large, worldwide genus of inchworms (moths in the family Geometridae). The Eupithecia in Hawaii are unique because of the particular ecological niche they fill - they are predators, while nearly all other known caterpillars are plant feeders only.

Here is the abstract of the original paper describing carnivorous Eupithecia (Montgomery, S. L., 1983. Carnivorous caterpillars: the behavior, biogeography and conservation of Eupithecia (Lepidoptera: Geometridae) in the Hawaiian Islands. GeoJournal 7:549-556.):

A completely new feeding pattern has been found among caterpillars native to Hawaii: certain geometrid larvae (commonly called inchworms) consume no leaves or other plant matter. Instead, they perch inconspicuously along leaf edges and stems to seize insects that touch their posterior body section. By bending the front of their body backwards in a very rapid strike, the caterpillars opportunistically capture their prey with elongated, spiny legs and 900 larvae and eggs of these moths have been collected from native forests of all the main islands and reared in the laboratory. All are species of Eupithecia, a worldwide group of over 1000 members that had been reported to feed only on plant matter such as flowers, leaves or seeds. At least 6 of Hawaii's described Eupithecia species are raptorially carnivorous, only 2 are known to feed predominantly on plant material, especially Metrosideros flowers. A diet including protein-rich flower pollen and a defensive behavior of snapping may have preadapted Hawaii's ancestral Eupithecia for a shift to predation. Severe barriers to dispersal of mantids and other continental insect predators into Hawaii resulted in an environment favoring behavioral and consequent morphological adaptations that produced these singular insects, which can be commonly called the grappling inchworms.

When insects colonized the remote Hawaiian Islands over millions of years, the results were remarkable because the chances of them getting there were so slim. This meant that a species that managed to be blown out over vast distances of ocean and land on one of the islands faced little competition or predation pressure. They then diversified into ecological niches that would not have been possible for their mainland relatives. Because there were fewer predators in the islands than the mainland from which the colonizing Eupithecia originated, there was wide-open opportunity in predation and Eupithecia had the right biological tools to grab it, despite its evolutionary history as an eater of plant parts. Interestingly, people collected these caterpillars for years without recognizing them as predators, because it was assumed that all caterpillars must be plant feeders. The story is that they always died in the lab until a fly inadvertantly got into a rearing cage, and the caterpillar was observed eating it. In the clarity of hindsight, it is interesting that it did not occur to people that these were predators, because they have quite distinct morphology and behavior. They have raptorial claws adapted for grabbing struggling prey, and long thin appendages on the tip of their abdomens which probably work somewhat like the trigger hairs in venus fly-traps. They are sit-and-wait predators, disguising their long bodies along the edge of a leaf -- behavior that makes no sense for an herbivore caterpillar which must move around a lot to feed on the plant. When an insect touches the Eupithecia while crawling up a leaf edge, it whips its head around and captures it.

Nearly all the 22 known Hawaiian species of Eupithecia behave as described in the paper. Interestingly, some are host plant specific, even though they do not eat the plant, because they look so much like that particular plant and it gives them a great advantage in disguise. Some are even specific to the part of the plant on which they rest. One Eupithecia is specific to the green, living fronds of the native Hawaiian fern known as uluhe, and it is the perfect green to match their color. Another dark brown species is always found on the mats of dead fronds underlying the green, living part of the plant.

One exception to the sit-and-wait behavior of most Hawaiian Eupithecia is the species E. monticolans (above), which appears to behave much more like a plant-feeding inchworm. It does not have the raptorial claws or the trigger hairs on the abdomen, and does not sit along leaf edges as its congeners do. When I first collected it, its food was not known, but assumed to be flowers on the `ohi`a tree (as mentioned in the above abstract). I suspected this was not necessarily the case because I collected many from trees that were not in flower. I was not successful in rearing E. monticolans caterpillars for over a year, until I inadvertantly provided one with leaves that were loaded with galls made by small insects related to aphids, in the family Psyllidae. Within a day the leaves looked like swiss cheese, with all the galls eaten out of the leaves. From then on, I always provided this species with leaves covered with galls and I never again had problems rearing them to adulthood. So while E. monticolans was thought to be a "missing link" from pollen-eating to predatory behavior, they are in fact predators, but without the morphology to make a quick strike, they must rely on eating sessile insects that cannot escape or defend themselves from a slow-moving caterpillar.

Almost no parasitoids have been reared from Eupithecia caterpillars. It certainly seems likely that Eupithecia may be rarely parasitized because it is difficult for a parasitic wasp to sneak up on it and lay an egg without being caught. Here is a brief video showing lightning-fast E. orichloris capturing a parasitic wasp (and releasing it - apparently they are not very tasty).



Listen to the jazz tune "Inchworm" here...

Labels: cool bugs, ecology, Hawaii, insects

Tangled Bank #82 has been posted. Rejoice in the miracles of modern biology.

Labels: carnivals

Lawyers are already circling like sharks over the recent concern about the drug rosiglitazone (brand name Avandia, produced by Glaxo-SmithKine) for treatment of type 2 diabetes was precipitated by an early press release of a paper (Nissen and Wolski, 2007. Effect of rosiglitazone on the risk of myocardial infarction and death from cardiovascular causes. New England Journal of Medicine 356:2457-2471) over three weeks before its actual publication date, which was yesterday (June 14). This means yesterday was the first day any of us except the reviewers of the paper and editors of the New England Journal of Medicine has had a chance to evaluate the actual data, rather than statements made by the authors and editors. Congressional hearings, at which a doctor said he was pressured by Glaxo-SmithKline not to reveal his concern about Avandia's safety, were underway well before this publication date.

Meta-analyses are studies that statistically analyze the results of all previous trials together to see if there is an overall trend that was not picked up in each individual trial. What the authors of this meta-analysis are saying is that based on 42 different trials that were done at various times, for different reasons, people taking Avandia are more likely to have heart attacks than people not taking it. There are several statistical problems with meta-analyses, but the authors did the best they could, using a test that should provide reasonably accurate results with the data they had, in which heart attacks were rare.

To put it that rarity in perspective, their data overall showed that for a minimum 24-week period, 86 out of 15,565 diabetes patients taking Avandia had heart attacks, versus 72 out of 12,282 not taking the drug (this was a hodge-podge pool consisting of placebo groups, and groups taking various other diabetes drugs). This translates to 0.55% (5.5 out of a thousand) of those on Avandia having heart attacks, and 0.59% of those not on Avandia having heart attacks -- a slightly higher percentage. Of course, in a proper meta-analysis one cannot simply pool all the numbers and re-analyze them together. The statistical procedure the authors used did reveal a higher risk of heart attack in the group taking Avandia, but the difference remains slight.

One fallacy people commit in statistical analyses is to believe that the larger the data set, the more meaningful the result is. But in general, the opposite tends to be true. This is because the only way the authors could find a (barely) statistical difference in the two groups was to have a sample size of nearly 28,000. If you need a sample size that big to find a real difference between the two groups, the difference is not nearly as serious as if you had found it in a sample of a few hundred people. One gets the distinct impression that this paper was a fishing expedition, an impression that is not undermined by the disclosure that the first author receives research support from the following seven drug companies that are not Glaxo-SmithKline: Pfizer, AstraZeneca, Daiichi Sankyo, Roche, Takeda, Sanofi-Aventis, and Eli Lilly.

What makes the potential hysteria surrounding this drug especially egregious is the unscrupulous press release and author interviews three weeks ago that did not reveal the unbalanced sample sizes of the two groups:

In their analysis, Nissen and Wolski pooled data from 42 studies that have been conducted on the drug. Among more than 27,843 patients in the relatively brief studies, 86 of those taking Avandia had a heart attack, compared with 72 of those not taking the drug.

The implication of course is that overall, more people taking Avandia had heart attacks when that is absolutely false.

But even assuming the results are completely valid, there is still the huge problem of the lumping of people with all sorts of medical history in these groups. The authors state themselves in the discussion:

The FDA-approved rosiglitazone product label reports a mean increase in low-density lipoprotein (LDL) cholesterol of 18.6% among patients treated for 26 weeks with an 8-mg daily dose, as compared with placebo.

This of course means that if you have a problem with high cholesterol, this drug is not for you, but your doctor knows this already. But what were the cholesterol levels and heart conditions for those having heart attacks in the meta-analysis? It is completely unknown.

Admittedly, the authors did not have access to most of the original data sets, many of which came from Glaxo-SmithKline clinical trials (though one has to wonder if they tried asking the company for the data), which means they cannot present a breakdown of heart attack victims by a priori risk. But presenting these results without that data is at best irresponsible. It has become very much clearer over time that individuals vary and a particular drug that works wonders for one person might be fatal for another. The implication of the congressional hearings and media coverage of this one paper with its weak result is that we are going to make the decision to keep that drug from those that it will benefit, rather than take the trouble to learn enough to figure out which few people will be harmed by it, and keep them off of it.

Labels: health, humans, statistics

Recently we were advised to take lots of folic acid to help prevent Alzheimer's. (Of course, that study, when scrutinized, showed itself to be highly flawed.) Now, we are supposed to avoid folic acid like the plague because it will cause cancer:

High doses of folic acid do not prevent precancerous colon polyps in people prone to them and may actually increase the risk of developing the growths, a new study finds.

This study (Cole et al., 2007. Folic acid for the prevention of colorectal adenomas: A randomized clinical trial. JAMA. 297:2351-2359) actually finds a lot of non-statistical differences between groups of about 500, one taking folic acid supplements for several years, and one not. The only probable real difference in the groups (considering the large number of comparisons they made) was in those people with 3 or more adenomas (pre-cancerous growths) found 6-8 years after the study began.

One issue muddying the water in the study, which was not the fault of the authors, was the addition of folic acid supplements to quite a lot of the American food supply by the FDA, starting in 1998, two years after the study began. This presumably helped to obscure potential differences between the treatment and control groups because all were essentially taking folic acid supplements, with the treatment groups taking more. Additionally, the supplemented amounts were more than double (1 milligram) the "recommended daily value" of 400 micrograms - and that is ignoring the folate they were getting from whatever plants they were eating, and piles of folic acid they started getting in their diet after the FDA's intervention. Six years is a long time to be pounding your body with a huge excess of any one nutrient.

The mainstream media love a more sensational representation of the latest medical news, however:

Cancer patients should discuss taking vitamins with their doctors, and anyone over 50 who takes vitamins should have a colorectal screening test, said Cornelia Ulrich of Seattle's Fred Hutchinson Cancer Research Center, who co-wrote an accompanying editorial.

Apparently, suddenly all our doctors are going to have all this knowledge about what supplements their patients should take, because of this one paper telling us that infusing our systems with one particular compound for six years is probably a bad idea. (And cancer doctors aren't exactly who I would pinpoint to be nutrition fairies - most of the cancer patients I have known would have been better off without being poisoned slowly by doctors using the euphamism "chemotherapy.") Shouldn't everyone (who can afford it) over 50 get a colorectal screening test? Colorectal cancer is one of the easiest cancers to prevent by snipping off the adenomas within the colon. Who cares about vitamins?

Our obsession with supplements has gotten entirely out of control. Instead of taking policy steps that would help people consume good foods to obtain the nutrients our bodies need at levels to which they are adapted, our government and media imply there is always an easy fix by taking some supplement or other in absurd dosages. Certainly they give lip service to eating a balanced diet, but government policies actually subsidize, and thus promote, the production of cheap processed foods that are little but empty calories. On the NIH page linked to above explaining the folic acid food supplementation, it is actually stated, after a list of the easily obtained, unprocessed plant foods that contain natural folate (as opposed to the synthetic folic acid):

The March of Dimes Birth Defects Foundation warns women not to rely on these foods for enough folic acid to prevent serious birth defects in their future babies (March of Dimes 1997).

We know the March of Dimes is focused solely on preventing every possible birth defect, but doesn't this seem a bit extreme? Certainly it is possible, and in some societies routine - to give birth to a healthy baby without taking a lot of supplements; yet we are issued a "warning" to take supplements, implying an "or else."

Fortunately, a subset of Americans is taking back control over their diet, by creating more farmer's markets, and supporting organic, and more important, local food production so more of us can eat better without resorting to cheap junk. Unfortunately, the medical community is still all about fixing us after there's something wrong. That's why even when considering prevention, they think in terms of medication, rather than the inculcation of lifestyle changes which are known to keep us healthy in the first place. Certainly in this world today the former way of thinking is much easier to promote. This has led to a plethora of studies on drugs and supplements, giving people substances our bodies are not adapted to, or abnormal amounts of substances our bodies do normally encounter, with results that have really not been very helpful in the long term. As one doctor says:

"Right now it would not be appropriate to blindly go forth and further increase the levels of folic acid without better understanding the potential risks," Mason said. "And whether we continue folic acid fortification should be an open debate over the next few years."

Amen to that. How about instead we spend some money finding a way to make it a lot easier for people to eat what they are designed to eat?

Labels: brain, health, humans, vitamins

In Lisa Belkin's recent article (subsq. req'd) on women attempting to re-enter the workplace after leaving to have kids, "while 74 percent do find work, only 40 percent find work they call satisfying."

This statement only begs the questions: What percentage of men find their work satisfying? What percentage of women who never "opted out" find their work satisfying?

What all the discussions about continuing gender inequality in the workplace fail to address is that for most people, having a job is a less attractive option in many ways than not working, whether you are male or female. White-collar women are faced with a double-edged sword, because while it is harder for them than men to achieve success in most professions, it is also socially much more acceptable for them than men to quit their jobs to raise children. I know several women who were glad to have the excuse when it came along. Men, however, live in a completely different world. Those who stay at home with kids now are in general as anomalous, and disparaged, as the first women who left their kids to go to work, when most did not.

It is a complex issue, because men are more likely to prefer work to staying home for two reasons: one, they are simply expected to so they make their reality fit expectations in order to fit in with society; and two, most professional work is easier for men than for women because it genuinely is harder for women of the same ability to be recognized for such and advance in their careers.

As explained by Ben Barres, (subsq. req'd) most working women actually ignore the signs of sexism in their quest to succeed. This makes perfect sense; if you develop a victimization complex and dwell on perceived or real obstacles that are out of your control, it will waste energy better spent on working around any obstacles that do present themselves. Many women have had the attitude that if they ignore the whole idea of sexism and just do what we do best, they will succeed. The problem with this is that we end up with the situation we have now - a whole generation of young women that don't believe in a need for feminism, because they believe the lack of officially sanctioned sexism means that women have achieved equality (even when the numbers starkly show that in most professions, increasing proportions of women at high levels have stalled, and in some there have even been recent losses, instead of gains). If women are not advancing at the same rate as men, well, it's because they have made the choice to "opt out." Young women are turned off the feminist movement because they see their current situation as having the freedom of choice. But "choice" in this context is quite often an illusion; the fact that the choice made all too often, to settle back into traditional female roles, belies the notion of true equality in the workplace.

Unfortunately the media perpetuates the myth of equality via the propagation of these terms such as "opting out" and "choice". Is it really a choice to leave a career to raise kids when women have to be twice as good as a man just to keep up? The insidious problem about sexism today is that while it is usually no longer acceptable (not to mention legal) to be blatantly discriminatory in the workplace, there is no recourse, legal or otherwise, for women dying a slow death by a thousand small cuts. From the abstract of an academic paper on the topic (Soares, 2001. Women in science and technology: Restricted success. Quimica Nova 24:281-285):

Along the way [women] come across stumbling blocks that make their progress difficult. Most of these difficulties are not gender-specific, yet women encounter them more consistently than do men. It is remarkably true for the areas of Science and Technology.

Every Ph.D. learns about rejection. All else being equal, if a woman has to apply for several more grants before one gets funded or a dozen more jobs before she gets an interview, then that many more women will drop out before they do succeed. That alone would translate into significantly fewer women in higher academic positions. We can all name plenty of women who have achieved those positions, but that is not the point. The environment is such that highly driven people will likely achieve prominent standing in science, regardless of gender. The continuing disparity lies between those who put forth a fair amount of effort, are reasonable scientists, and succeed, and those who are at least as good at what they do and work hard at their research and teaching, and yet do not have the energy to keep fighting on and on after seemingly endless job and grant rejections. The former group is dominated by men; the latter group is dominated by women. In addition, because men are much more likely to believe they must be the primary breadwinner and thus have a full-time job, which for professional women remains "optional," it is highly likely that men in the latter scenario will indeed keep fighting longer to succeed. The mistaken conclusion is that this is due to some gender disparity in tenacity, when it is only due to society's expectations forming men's and women's expectations of themselves.

So the difference has nothing to do with ability, drive, competitiveness or any of the nonsense hypothesized by sociologists and Larry Summers. It simply has to do with a still unlevel playing field in day-to-day accomplishments versus rewards. Barres, with his experience both as a female and male scientist, is in a unique position to cut right to the heart of the issue:

I think people do what they are rewarded for doing, and I think women realize, whether it's conscious or unconscious, they are not going to get the rewards. So they put the hours into their families or whatever.

Barres does bring in the child support issue, which needs to be recognized as a worker issue, not a women's issue. However, he is still probably right to mention it in tandem with the higher hurdles women face because in our society child care is still considered a women's issue, and thus the lack of it results in a double-whammy:

It is very much harder for women to be successful, to get jobs, to get grants, especially big grants. And then, and this is a huge part of the problem, they don't get the resources they need to be successful. Right now, what's fundamentally missing and absolutely vital is that women get better child care support.

Certainly no one can deny the truth of his last sentence. But until we all recognize that this is just one of many working conditions (such as long hours, short vacation times, etc.) that makes many jobs unpleasant for everyone, the gender disparity will continue. People have worked hard at societal attitudes over the years, and no one can say they haven't improved. But it would certainly help if the mainstream media weren't constantly reinforcing the myth that advancement at work is all about choice.

Labels: gender, humans, sociality

Encephalon, the brain carnival, is up now. Find out why hamsters like viagra.

Labels: brain, carnivals