Category: Science

Why do parents adopt so many girls?

The evidence suggests that fathers prefer boys over girls. For instance a couple is more likely to stay married when they have a boy rather than a girl. Here is my earlier summary of the research.

At the same time couples are far more likely to adopt girls rather than boys? How can this be?

A recent Slate article offers some figures:

Numbers vary, but it’s pretty safe to say that somewhere between 70 percent and 90 percent of parents looking to adopt register some preference for a girl with an agency. It doesn’t matter if they’re adopting from China, where girls far outnumber boys; from Russia, where the numbers are about even; or from Cambodia, where there is typically a glut of orphan boys and a paucity of girls. Everywhere, demand tends to favor the feminine.

Steven Landsburg had suggested an adverse selection argument. Yes boys are favored but if a boy is put up for adoption, you can figure there is something wrong with the boy, for precisely that reason.

Or perhaps it is easier to nurture girls, and the nurturing motive may be central to the adoption decision. It also may be the case that mothers prefer girls and mothers also drive adoptions:

“The extent to which women are the driving force in most adoptions is probably a factor,” he says. “It’s usually true that the women are filling out the paperwork, going to the conferences, the support groups.” He adds, “If I speak at a conference–whether it’s on adoption or family issues–at least 80 to 90 percent of any of these audiences are women.”

My take: Having a boy is a riskier investment than having a girl. The risk rises dramatically with adoptions, given the associated genetic uncertainty. Males are more likely to have genetic roots for criminality and mental illness. So if you don’t know much about the parents, better to play it safe and opt for a girl.

Hubble to die

At first, I was merely uninspired by President Bush’s plan to resend men to the moon and then on to Mars (Here are better ideas from MR readers). Now I am upset and saddened. The Hubble telescope is one of the great achievements of the recent space program, especially after the amazing in-space eyeglass repair job. Data from the Hubble have helped us to understand the universe in all its awesomeness and yet the Hubble will now die an early death because of the budget shift.

Here is Hubble’s picture of the eye of Sauron:


Just kidding about the last one, it’s MyCn18, a young planetary nebula, the glowing relic of a dying, Sun-like star.

This is the Cartwheel Galaxy, located 500 million light-years from Earth in the constellation Sculptor.


Here are two galaxies, NGC 2207, is on the left and IC 2163 on the right that are slowly colliding.


Here are more Hubble pictures.

Marriage Mathematics and Political Change

John Gottman has spent decades studying how married couples interact. His most striking finding is the tendency of couples at risk of divorce to have markedly different interaction styles. His recent book, The Mathematics of Marriage, summarizes his observations of married couples and presents a parsimonious model of marriage (see here for Slate’s review). The highlight of the research is that couples where the dominant mode of interaction includes criticism, contempt, defensiveness and stonewalling are very, very likely to divorce. Successful marriages involve a great deal of mending and reworking of the relationship. The mathematics links some theories about emotions and interaction to this observed pattern.

What I find interesting is the implication for thinking about politics. Let’s assume that political order is a sort of “marriage” between state and citizen. At least from the perspective of the citizen, it’s a relationship that can be broken, if warranted. This is a premise of many normative theories of revolution – the citizens have a right to a new government if they feel the written and unwritten rules have been violated. Unfortunately, what we know about exactly how this happens – moving to abandon the social contract – is sketchy at best, although political scientists and sociologists have a hunch that it involves some combination of repression of the population and a de-legitimizing of the government, which itself might have multiple causes.

Gottman’s approach to studying relationships offers a useful way to think about these issues. Gottman’s point is that there may be varying sources of the emotions that destroy marriages, but the road to divorce usually starts in the same place – once spouses have learned certain interaction strategies, they create hard to change feedback loops. Similarly, governments and populations that learn certain strategies for interacting with each other probably set up hard to break cycles leading to long term stability or perpetual crisis. The nice thing about Gottman’s analysis of marriage is that the math predicts stability or decline, and not much in between – a non-trivial prediction. The same prediction for states is that states tend to be on a tough to change road to constant crisis (like in Africa and the Middle East) or stability (like in the US). Switches from one path to the other should be infrequent and difficult, which seems to describe the world pretty well.

Researchers find a key gene for human intelligence

Read the ever-impressive Randall Parker over at Here is a quotation from one of his links:

Lahn and his colleagues found that the ASPM gene showed clear evidence of changes accelerated by evolutionary pressure in the lineage leading to humans, and the acceleration is most prominent in recent human evolution after humans parted way from chimpanzees.

“In our work, we have looked at evolution of a large number of genes, and in the vast number of cases, we see only weak signatures of adaptive changes,” said Lahn. “So, I was quite surprised to see that this one gene shows such strong and unambiguous signatures of adaptive evolution – more so than most other genes we’ve studied.”

By contrast, the researchers’ analyses of the ASPM gene in the more primitive monkeys and in cows, sheep, cats, dogs, mice and rats, showed no accelerated evolutionary change. “The fact that we see this accelerated evolution of ASPM specifically in the primate lineage leading to humans, and not in these other mammals, makes a good case that the human lineage is special,” said Lahn.

The bottom line: The plausibility of the view that human beings are special has just gone up.

Parker is one of the most rigorous and versatile writers in the blogosphere, here is his recent account of our greater ability to predict earthquakes.

Addendum: Read this article on exactly why monkeys have trouble with human language.

Why do you share?

Sometimes you share just to shut people up:

Stevens [the researcher] placed chimpanzees (Pan troglodytes) or squirrel monkeys (Saimiri boliviensis) in a cage and provided them with a meal of fruit. In an adjoining cage was a hungry member of the same species.

The primates rarely passed food through the cage to their hungry mate next door. But if the partition was opened – giving the hungry animal the chance to beg, steal or fight for food – sharing was common.

It is analogous to a parent buying a child a toy just to shut them up, says Stevens. “It’s a selfish way to stop the constant pestering,” he says.

Intriguingly, hungry chimps harassed their neighbour more when the food was cut into small chunks. This could reflect the fact that a beggar is more likely to get a handout if it doesn’t seriously deplete the donor’s stash.

This form of ‘strategic begging’ could help scroungers find success by setting their sights low, Stevens speculates. “It’s like a kid saying: ‘Can I have four cookies? Ok, how about one?’,” he says. Likewise, most street-corner beggars ask passers-by for nothing more than their small change.

Here is the full story. Right now the link to the original paper is not working.

Is risk-aversion bad for you?

It is bad for rats, or so it seems:

…new research published in the Proceedings of the National Academy of Science shows that caution can actually kill you. Sonia Cavigelli and Martha McClintock of the Department of Psychology and Institute for Mind and Biology at the University of Chicago found in a recent experiment that individuals who fear novelty–a condition scientists have named “neophobia”–are likelier to die at an earlier age than those who are unafraid of change. It is the first time, says Cavigelli, that a study has demonstrated that an emotional trait that shows up in infancy can shorten life span.

For this research, Cavigelli and McClintock followed the lives and fortunes of pairs of rat brothers for several years. The scientists chose their subjects by first establishing which of the rats were neophobic. To do this, they placed the young rats inside a bowl in a small room. Objects the rats hadn’t seen before–a rock, a metal box, and a plastic tunnel–were placed in each corner of the room. The rats the scientists deemed neophobic either stayed hunkered down in the bowl or left it only hesitantly, with hunched backs, stilted walks, and bristling fur. The rats who left the bowl quickly to explore the room and the various unfamiliar objects were dubbed neophilic.

And the results? These risk-averse rats showed a consistent pattern of stress throughout their lives and died at earlier ages. What does this mean for people?

A number of parallels exist between humans and their rat surrogates. Neophobia shows up in human infants as early as 14 months of age, and like the rats, fearful children have a faster and stronger hormonal response than children who are not afraid of new situations. It’s also been shown that if you are neophobic at a young age, you tend to remain that way throughout childhood. Cavigelli suggests, however, that individuals may develop strategies to avoid the negative effects of neophobia. “If you are a neophobic-type person, you might avoid any novel situations thereby minimizing that stress,” she says. Staying away from stressful situations could be a form of “self-medication.”…The wear and tear of stress hormones can cause neophobes to get sick more quickly, suggests Cavigelli. So if you know you’re a neophobe–and therefore more vulnerable to any bug going around–you might want to be seek medical intervention promptly in the case of illness.

Although it looks like the neophiles have an unfair advantage, they may not have it as good as it seems. In the experiment, Cavigelli and McClintock played God by controlling the environment of their subjects and essentially creating a safe universe where being brave didn’t get you into trouble. But real life, with its car accidents, plane crashes, and human predators does not always reward the fearless. Human neophiles might also have longer lives if we were all just rats in a cage.

The researchers suggest that it makes evolutionary sense for mothers to have emotionally diverse litters. In other words, there is an evolutionary reason why some but not all teenagers can act like such foolish idiots. See for the full story.

How many species is global warming destroying?

Gregg Easterbrook debunks some recent doomsaying on this topic. You might have noticed a recent study claiming that more than one million species are being endangered by global warming. Easterbrook points out a calmer yet still environmentalist estimate of 12,259 endangered species, and that is from all causes, not just global warming. Easterbrook writes:

…the study in question is dubious because extinctions don’t seem to be happening at anywhere near the rate called for by other assumptions, mainly concerning habitat loss. Species-extinction theories say habitat loss, development, and logging should lead to rapid declines in species. All these factors are at play in the Pacific Northwest of the United States–and no animal species is known to have fallen extinct there in the last couple decades. (Several salmon species and other species of the area are imperiled.) This is significant because the Pacific Northwest is an elaborately studied area; far more is known about it than the tropical regions about which the Thomas study makes vague computer projections. Graduate students comb over the Pacific Northwest, knowing that tenure and academic renown will go to anyone who documents an animal species loss. And average temperatures are rising in the Pacific Northwest. For anything even remotely close to Thomas’s 1.25 million extinctions to be a hard number, we should already be seeing the bow wave in the form of dozens if not hundreds of extinctions in well-studied areas like the Pacific Northwest. Instead we see, um, zero.

Habitat loss and species extinctions are real problems, but let us not politicize science to scare up support for our favorite proposals.

Addendum: See also this trenchant critique from Carl Zimmer defends the study, thanks to Chris Mooney for the link.

The Poincare conjecture

Has the Poincare Conjecture been solved? Possibly. Read this recent news report about a new proof by an obscure Russian loner, Grisha Perelman. The Conjecture is one of the famous Millennium Problems in mathematics.

“This is arguably the most famous unsolved problem in math and has been for some time,” said Bruce Kleiner, a University of Michigan math professor reviewing Perelman’s work.

Here is the clearest statement I can find of what the whole thing means:

To solve it, one would have to prove something that no one seriously doubts: that, just as there is only one way to bend a two-dimensional plane into a shape without holes — the sphere — there is likewise only one way to bend three-dimensional space into a shape that has no holes. Though abstract, the conjecture has powerful practical implications: Solve it and you may be able to describe the shape of the universe.

Or try this:

[the] work has huge implications for our understanding of partial differential equations. PDEs (as they are known in the trade) are the mainstay of physics and engineering. Mazur notes that physicists and engineers use PDEs to model everything from the flow of water to the buildup of heat in aircraft engines. “I would expect this work to have enormous applications in many fields of science,” he says.

There may also be applications for scientists studying DNA…Some kinds of DNA wrap themselves into knot formations that can be insanely difficult to decipher. But Mazur says Thurston’s classification [referring to related work] may provide a way to calculate the exact nature of any knot – so in theory it could be used to work out the structure of knotty DNA molecules.

The upper reaches of mathematics can often seem absurdly detached from life down here on planet earth, but Mazur points out that you can never know where things might lead. He cites the case of James Clerk Maxwell. In the late 19th century Maxwell worked out the equations of electromagnetism. “At the time it would have been easy to write off Maxwell’s ideas about invisible forces as a mystical abstraction,” Mazur says. But Maxwell’s work laid the foundations for the development of radio, and hence the communications revolution. Every time we turn on the TV or pick up a cellphone or log onto a WiFi system we are reaping the rewards of Maxwell’s equations.

Another bottom line: Perelman will receive a million dollars if his result stands up. Alex says this is another win for bounty hunters!

Cads vs Dads II

Social psychologists have found that women prefer to have sex with a “Cad” when considering a brief affair but for longer term relationships they prefer “Dads.” Leading Tyler to ask in an earlier post, Why do women like cads?

Patrick Vlaskovits, a reader, hypothesizes that Cads have better genes than Dads. Patrick writes:

Why is a Cad a Cad? I think it is because: He can be. His genes are so good, so much in demand, that women are willing to mate with him knowing that he might not stick around. Same reason why a Dad is a Dad. He knows if based solely on looks (proxy for gene competition), he will lose to the Cad every time. So, he must compensate for his lower quality genes by investing more resources in the female and offspring.

Symmetry is an important aspect of beauty and has been shown to be a signal of good genes so the theory can be tested by looking at how mating strategies vary with symmetrical features. Psychologists Steven Gangestad and Jeffrey Simpson report that this has been done with birds:

In a recent review of 18 bird species, Møller and Thornhill (1997a) have documented an association between extra-pair paternity and the extent to which attractive males engage in direct parental care. Specifically, when the rate of extra-pair paternity is high (and, thus, when males can benefit more from trying to attract extra-pair mates), attractive males perform a smaller proportion of offspring feedings than do less attractive males. Exerting greater extra-pair mating effort should yield larger payoffs for more attractive males, and this is evident in the time they fail to spend engaging in a competing activity: providing direct parental care.

Gangestad and Simpson suggest that the theory also applies to humans:

Over evolutionary history, men who had indicators of genotypic quality should have experienced larger gains in fitness payoffs than men who lacked these indicators. Moreover, men should have evolved to conditionally “decide” to allocate more versus less effort to mating or parenting, depending on the degree to which they possess these features.

Note, however, that the context in which men play the Cad v. Dad strategy, human society, is much more variable than that faced by birds. The Cad strategy will not work well in times and places where extra-marital sex is uncommon. Ever heard of an Amish Cad?

French revenge on Hollywood?

Henri Crohas’s company, Archos SA, makes a small hand-held device, like a bulky Palm Pilot, that can record and then play back scores of movies, TV shows and digital photos on its color screen or a TV set. The gadget — which in effect does to movies what Apple Computer Inc.’s iPod does to music — already has sold 100,000 units world-wide during the past six months, beating the big consumer electronics makers to the U.S. market.

Archos’s device, which costs about $500 to $900 depending on the model, ignores an anticopying code found on a majority of prerecorded DVDs. That means consumers can plug the Archos device into a DVD player and transfer a movie to it. Users also can transfer recorded TV programs and digital music files to the Archos device.

Yes this item is from a small company in France, here is the full story. Stay tuned for further developments. The bottom line is that the Internet is not the only means of pirating music and movies.

You are a better bargainer than you think

Negotiators tend to think they are more transparent than they truly are. They believe that their negotiating partners can discern their thoughts, and negotiating positions, when in fact the partners are clueless. See the experimental evidence from this recent paper by Leaf van Boven, Thomas Gilovich, and Victoria Medvec. There is good evidence that we send involuntary signals of our own trustworthiness. Still, we do not always have a good sense of how those signals are interpreted by others.

The basic result may stem from a kind of excess sympathy. The negotiator tries to put herself in the position of the “other mind,” but cannot eradicate the knowledge of her own bargaining position. So the model of the other mind contains more self-knowledge than is rationally justifiable. Related results have been found in other areas. Individuals overestimate how much others pick up on the cues from their facial expressions. Similarly, individuals who are laughing think they appear more expressive than they do to others. As for bloggers, well, they probably think that readers pick up more of the nuances of their writing than is the case.

Do we overvalue the difficult?

Experimental subjects consistently value a poem or artwork more highly when they are told it took a long time to produce. See this study by four psychologists. The increase in perceived value is strongest when quality is difficult to judge by other means. Furthermore other research suggests that we value artworks more highly, the more time and trouble it took us to understand them.

What does this mean for the arts? We will tend to overvalue difficult works of high culture, most likely. We also will undervalue that which is accessible. In other words, Seinfeld is better than you think.

The authors note that Jackson Pollock, in his lifetime, was attacked for producing paintings that “anyone could have done.” In reality Pollock’s paintings were the result of a painstaking process, difficult for anyone else to mimic. He often was defended on these grounds. A single painting could require months of hard work. So if you don’t like Pollock, perhaps now you will think more of it.

And this blog, well, this blog just takes forever to write…