The Scientific Fundamentalist

Why Do People Vote? I

Satoshi Kanazawa — Mon, 09 Nov 2009 02:36:55 +0000

Why millions of people turn out to vote in every national election in the United States and other large democracies is one of the persistent mysteries in the rational choice theory of politics. Why do people vote?

If you think about it, voting in a large national election – such as the US Presidential election – is a supremely irrational act, because the probability that your vote will make a difference in the outcome is infinitesimally small. The closest Presidential election in history was the 1960 contest between John F. Kennedy and Richard M. Nixon. In that election, Kennedy’s margin in the popular vote over Nixon was 118,574. Disregarding for the moment the complexity of the electoral college system, it means that the probability that any one voter will influence the outcome of the 1960 election was 1/118,574 = .00000843355. The probability is usually much, much smaller than that. In the 2000 Presidential election, if you happened to live in one of the four crucial counties in Florida, your probability of affecting the outcome was much greater (though still very small), but then you’d have to multiply that probability by a very small probability that you’d happen to find yourself voting in such a crucial county, and the end product is even smaller than .00000843355 (except that, in that particular Presidential election, the loser received more popular votes than the winner – the complexity of the electoral college system).

Any way you slice it, voting is irrational. One person’s vote is never going to make any difference in a large national election. If your favorite candidate is going to win, she’s going to win even if you don’t vote for her. If your favorite candidate is going to lose, he’s going to lose even if you vote for him. The inescapable conclusion is that, contrary to popular belief and the government propaganda, your vote does not count. So why do millions of people expend their own time, energy, and money to cast a vote that will not make any difference in the electoral outcome?

One reason that people often offer for voting is “But what if everybody thought that way?” The reasoning goes that, if everybody thought that voting was irrational and a waste of time, nobody would vote and democracy would collapse. This is known as magical thinking, and it is a very common fallacy. People often believe that what they do or how they think influences other people and others will think and behave like they do. So, in this manifestation of magical thinking, people believe that, if they bother to vote, everybody else in the country will also vote, and the American democracy will thrive, but if they don’t bother to vote, then everybody else in the country will think like them, nobody will vote, and the American democracy will collapse. Of course, this is a fallacy. Your decision to vote or not will not affect whether or not other people will vote (unless you are a highly influential person and you announce your voting intention to the world in advance of the election).

Another reason for voting, offered by political scientists and lay individuals alike, is that it is a civic duty of every citizen in a democratic country to vote in elections. It’s not about trying to affect the electoral outcome; it’s about doing your duty as a democratic citizen by voting in elections. This reasoning fails on at least two separate grounds. First, civic duty to uphold democracy has the same problem as affecting the electoral outcome as a reason to vote. One person does not make any difference in the collective outcome as it takes a large majority of the citizenry to uphold democracy. If democracy were to be upheld, it will be upheld without your voting; if it were to collapse, it will collapse even if you voted. It would take a healthy dose of magical thinking to believe that the future and health of democracy depends on your voting.

Second, the civic duty of democratic citizens simply states that one must vote in an election. It does not say whether you have to vote Democratic or Republican. So you will fulfill your civic duty as a democratic citizen simply by turning up at the polling station and casting your ballot. It does not matter who you vote for. So if the reason for voting is fulfilling a civic duty and it’s not about affecting the electoral outcome, then, once inside the voting booth, people should vote randomly. They have already fulfilled their civic duty by turning out to vote, and it doesn’t matter who they vote for. Yet virtually every single person who turns out to vote votes for their favorite candidate, never for the opponent, which means that it is about trying to affect the outcome.

So, once again, why do people vote? There is no definitive answer that everybody agrees on, but there are some ideas. I’ll talk about them in my next post.

Why Your Friends Have More Friends Than You Do

Satoshi Kanazawa — Mon, 02 Nov 2009 02:48:06 +0000

One of my all-time favorites among all the scientific papers that I have ever read in my life is “Why your friends have more friends than you do,” published in the American Journal of Sociology in 1991 by my old sociology friend Scott L. Feld, who is now Professor of Sociology at Purdue University.

The title of Feld’s paper says it all, and here’s a little demonstration you can do to confirm his conclusion. List all of your friends. Then ask each of your friends how many friends they have. No matter who you are, whether you are a man or a woman, where you live, how many (or few) friends you have, and who your friends are, you will very likely discover that your friends on average have more friends than you do.

But how can this be? Friendships are bilateral (unless you are a stalker): If X is friends with Y, then Y is friends with X. How can Y and other friends of X have more friends than X does?

Feld demonstrates (and explains) the seeming paradox with a simple example in his paper. In this example, there are eight girls, and their mutual (bilateral) friendships are denoted by solid lines in the sociogram. So, for example, Betty has only one friend (Sue), but Sue has four friends (Betty, Alice, Pam, and Dale). The table summarizes the pattern of friendships among these friends. It shows that, on average, these eight girls have 2.5 friends. But the friends of these eight girls (who are the same eight girls themselves) on average have 3 friends.

If you think about it for a moment, you’ll figure out the source of this seeming paradox (although this simple insight did not occur to anyone before Feld published his paper in 1991). You are more likely to be friends with someone who has more friends than with someone who has fewer friends. There are 12 people who have a friend who has 12 friends, but there is only one person who has a friend who has only one friend. And, of course, there is no one who has a friend who doesn’t have any friend. Yet there is actually only one person who has 12 friends. So “12” gets counted only once when you compute the average number of friends that people have, but it gets counted 12 times when you compute the average number of friends that their friends have. Hence the seeming paradox that your friends have more friends than you do.

This, incidentally, is the reason why a man often gets depressed after he has sex with a woman for the first time and then she tells him how many lovers she has had because she has had more lovers than he has. A mating version of Feld’s discovery may be termed “Why your lover has had more lovers than you have.” And the reason is the same. There are 12 men who have had a lover who has had (or will have had) 12 lovers, but there is only one man who has had a lover who has had only one lover. But you should be grateful. The reason you got to be her lover in the first place is because she has had (and will likely have) many lovers. You are 12 times as likely to have sex with a woman who has had 12 lovers as you are to have sex with a woman who has had only one lover. Quite paradoxically, if your lover only had one lover, you are probably not him. And if your lover has never had a lover, you are definitely not him.

There is also an intergenerational version of Feld’s dictum (although it is expressed less elegantly): “Why our mothers had more children than women in her generation did.” There are 12 children whose mother had 12 children, but there is only one child whose mother had one child. And, of course, there are no children whose mother had no children. Yet there is only one woman who had 12 children. So if we ask around how many children everyone’s mother had (or how many siblings we have), we get the erroneous impression that our mothers were much more fertile than they actually were. Feld’s original and highly insightful observation can explain these and many other seeming numerical paradoxes.

Why Dating Is Difficult in New York (or London)

Satoshi Kanazawa — Mon, 26 Oct 2009 00:30:42 +0000

The guest blogger and PT intern Jen Kim complains about the difficulties of dating in New York. No wonder she finds it difficult. Since 1966, it’s been mathematically proven that dating in New York is difficult....

In their 1966 paper entitled “Recognizing the Maximum of a Sequence” published in the Journal of the American Statistical Association, John P. Gilbert and Frederick Mosteller offer a solution to a problem known as the “beauty contest problem.” This is how Gilbert and Mosteller describe the problem.

Suppose a boy is to have a date with his choice of one of n unseen and unknown girls, and suppose he wishes to choose the prettiest. The girls are presented for him to see one at a time in a random order, and he must choose or reject a girl when she appears. Once he chooses, he sees the rest, and he is disappointed if his date is not the prettiest. How can he maximize his probability of choosing the prettiest of the lot?

Of course, we know by now that, for any mammalian species, including humans, it’s not the boy who does the choosing, but the girl (like Jen). But the mathematical problem remains exactly the same if you swap “boy” and “girl” in the above quote and call it the “resource contest problem” or “The (sequential) Bachelorette.”

In the paper, Gilbert and Mosteller prove (yes, this is mathematics, not science, so there can be absolute proofs) that the optimal strategy is to reject the first 37% of all the candidates, and then select the first candidate who is better than any previous candidate. Gilbert and Mosteller prove that, if you follow this strategy, you will choose the best of all possible candidates on average about 37% of the time. You may think that 37% chance is not very good, but there are no other strategies that you can consistently follow that will produce a higher average probability of choosing the best of all candidates. So this is the optimal strategy for maximizing the quality of your chosen mate.

Now the problem for Jen and millions of other single women in New York becomes clear. If you live in Ames, IA, you can expect to meet, say, 10 men – 10 potential husbands – in your life. In that case, your optimal strategy requires you to reject the first four men (no matter who and how good they are) and then marry the first man who is better than any of the ones that you have dated before. If you live in New York (or London), you can expect to meet, say, 1,000 men. Now your mathematically proven optimal strategy requires you to reject the first 369 men (as n approaches infinity, the precise number to reject becomes n/e) and marry the first man who is better than any of the hundreds of men who came before.

Remember, in order to determine who the first man is who is better than all the ones who came before, you have to evaluate each of your dates very carefully. It’s not like you can just hang up on the phone calls or delete the email messages from the first 37% of the suitors. You actually have to go on dates and talk to them and evaluate how good they are (even though you know that you will automatically reject the first 369 men). So you have to go on at least 369 separate dates in New York before you can even begin to consider each candidate seriously for marriage.

That’s why dating in New York is much more difficult, exhausting, and time-consuming than dating in Ames.

Now switching gears from mathematics to evolutionary psychology, given that this strategy is mathematically proven to be optimal, the logic of natural selection suggests that, over a long period of human evolution, all women will eventually be selected to employ this strategy, without being consciously aware of the mathematics behind it. Women who adopt the “Reject the first 37% and choose the next best” strategy are expected to achieve greater reproductive success on average than women who adopt the “Marry the first one I can find,” or “Reject the first 5% and choose the next best” or “Reject the first 90% and choose the next best” or any other potential strategy. Unconsciously, all women should have the evolved psychological mechanism to reject the first 37% of the total estimated number of lifetime potential mates, and choose the next best candidate.

While it is often difficult to estimate the precise number of lifetime potential mates that a woman will encounter in her life, it is safe to assume that she will encounter many more in a large metropolis than in a small town. This can therefore explain why women remain single longer and marry later in New York than in Ames, and, in general, why women in urban areas (with a greater number of potential mates) remain single and marry later than women in rural areas (with a smaller number of potential mates).

Predictably Irrational, Yes; Explainably Irrational, No II

Satoshi Kanazawa — Mon, 19 Oct 2009 01:31:32 +0000

In my last post, I review and highly recommend my fellow PT blogger Dan Ariely’s book Predictably Irrational. The book is full of fascinating examples of how actual human behavior – the choices and decisions people make every day – deviates from the predictions of the standard economic theory. The book is entertaining and easy to read. As great as Predictably Irrational is, however, there is one word – a very important word – missing from the book: Why.

This is my major criticism, not just of Ariely and Predictably Irrational, but of the entire field of behavioral economics. Ariely receives the brunt of the criticism because he is simply the best the field has to offer. In the past three decades, since the seminal work of Kahneman and Tversky and their Prospect Theory, behavioral economists have revealed a large number of ways that human behavior consistently and, yes, predictably deviates from rational behavior. Their major findings have been well replicated in many different studies and experiments. In this sense, Ariely and other behavioral economists have catalogued an impressive number of “whats.” Their work has revealed how humans often behave and what decisions and choices they actually make.

But science is not about whats; it’s about whys. Whats are part of science; scientists must sometimes first discover the phenomenon to study. But the ultimate purpose of science is not discovery; it’s explanation. The ultimate purpose of science is to answer the why questions. And that is where behavioral economists often fail. They know what humans do, but they don’t know why they do what they do.

To be fair, in Predictably Irrational, Ariely often does attempt to answer the why questions. In his chapter on the allure of zero cost (why people overwhelmingly prefer something if it’s free but not if it has a very small nominal cost), he speculates: “Most transactions have an upside and a downside, but when something is FREE! we forget the downside. FREE! gives us such an emotional charge that we perceive what is being offered as immensely more valuable than it really is. Why? I think it’s because humans are intrinsically afraid of loss. The real allure of FREE! is tied to this fear.” But why do we have such an irrational fear of loss? Why do we fear losing one cent, which forces us overwhelming to prefer free Hershey’s Kisses but not the same Kisses at the cost of a penny each? And, most importantly, the question that has yet to be answered after 30 years of Prospect Theory: Why do humans evaluate comparable gains and losses asymmetrically?

In another chapter on the “endowment effect” (the fact that we demand more to give up our possession than what we are initially willing to pay to acquire it in the first place), Ariely once again speculates on why we exhibit this tendency: “Why? Because of three irrational quirks in our human nature. The first quirk... is that we fall in love with what we already have.... The second quirk is that we focus on what we may lose, rather than what we may gain.... The third quirk is that we assume other people will see the transaction from the same perspective as we do.” But, to me, these explanations don’t go far enough. Why do we have these quirks in our human nature? Why do we fall in love with what we already have? Why do we focus on what we may lose rather than what we already have? Why do we assume other people will see the transaction from the same perspective as we do?

In this sense, I think Dan Ariely and other behavioral economists are like Sigmund Freud. Freud knew that conscious motives for behavior were not the real causes of behavior. He further knew that many of the true (subconscious) motives for behavior might have been sexual in origin. Of course, we now know from evolutionary psychology that he was right. So Freud was on to something; he just didn’t know what, and we didn’t find out until we had evolutionary psychology.

Similarly, Ariely notes: “We usually think of ourselves as sitting in the driver’s seat, with ultimate control over the decision we make and the direction our life takes; but, alas, this perception has more to do with our desires – with how we want to view ourselves – than with reality.” So Ariely knows, like Freud before him, that we are not in the driver’s seat. But then who is? Like Freud, Ariely (and other behavioral economists) are on to something; they just don’t know what (or why).

Perhaps it is not fair for me to criticize Ariely and other behavioral economists for not completely explaining why humans make predictably irrational choices and decisions. It was a significant enough step forward in social and behavioral sciences just to discover that human behavior indeed was irrational and predictably so. There is a clear division of labor in science, and no scientists (or scientific disciplines) can do everything. As I explain in a previous post, however, the principles of reductionism require that all human behavior ultimately be explained by biological and evolutionary factors. Perhaps it is time for evolutionary psychologists to step in to try to explain why human behavior is predictably irrational. It is to Ariely’s credit that we now know that human behavior is predictably irrational. It’s time for us to make it explainably irrational.

Predictably Irrational, Yes; Explainably Irrational, No I

Satoshi Kanazawa — Mon, 12 Oct 2009 01:19:27 +0000

My fellow PT blogger Dan Ariely is one of the most creative behavioral economists in the world today, one of the hotshots in currently the hottest academic field. Ariely is to behavioral economics what Steven Levitt (coauthor of Freakonomics) is to standard economics, simultaneously a superb and mind-bogglingly creative scientist and excellent communicator of their science to the general audience. As great as Dan Ariely is, however, he has one major flaw: He is not an evolutionary psychologist.

The field of behavioral economics began in the late 1970s and early 1980s with the pioneering work of the 2002 Nobel laureate Daniel Kahneman and the late Amos Tversky. (Tversky would most certainly have shared the Nobel prize with Kahneman, but he died in 1996 and the Nobel prize is never awarded posthumously.) Their work has demonstrated that the decisions people make routinely and predictably deviate from rationality that standard economics (otherwise known as the rational choice theory) predicts.

For example, imagine that the current swine flu epidemic is expected to kill 600 more people in the United States during this year’s winter flu season. There are two alterative vaccines available to administer. If Vaccine A is administered to everyone, it will save 200 people. If Vaccine B is administered to everyone, 400 people will die. Which vaccine is preferable?

Even though the two scenarios are mathematically identical, a large majority of people would support the administration of Vaccine A, while an equally large majority would oppose the administration of Vaccine B. This is because “saving the lives of 200 people” sounds much better than “killing 400 people,” even though, once again, they are completely equivalent. What Kahneman and Tversky discovered was that, in clear contrast to what the standard economic theory predicts, how you frame the question strongly affects people’s choices and decisions.

A long line of behavioral economists since Kahneman and Tversky has convincingly demonstrated, experiment after experiment, that people’s decision making deviates from the rational calculation posited by standard economic theory in so many predictable ways. Now Dan Ariely, the new prince of behavioral economics, has summarized his own series of experiments over the last two decades for the general audience in his book Predictably Irrational. The book is full of fascinating examples of how we make irrational decisions and how our choices do not conform to the predictions of the standard economic theory. More importantly, the book gives us a glimpse into how ingeniously Ariely demonstrates these empirical patterns (or anomalies from the perspective of standard economics) in his very creative experiments.

For example, suppose you want to subscribe to the magazine The Economist, and there are two options: 1) an electronic-only subscription (at Economist.com) for $59/year; or 2) print and electronic subscriptions for $125/year. Given these two choices, 68% of people will choose the former option, while 32% will choose the latter. In standard economic terms, it means that a majority of people considers buying an electronic-only subscription to the journal’s articles for the reduced cost of $59 to be “better value” than having to pay more than twice as much for a combination of print subscription and electronic subscription. So far so good.

But then let’s say there are three options now: 1) an electronic-only subscription for $59/year; 2) a print-only subscription for $125/year; and 3) print and electronic subscriptions for $125/year. Given these three options, 16% of people will choose the first option, 0% of people will choose the second option, and 84% of people will choose the third option. That nobody chooses the second option makes perfect sense; why would you pay $125 to get a print-only subscription when you can get both print and electronic subscriptions for the same price? But here’s the puzzle: Now a vast majority of people considers print and web subscriptions for $125/year to be “better value” than an electronic-only subscription for $59/year, in clear contrast to their expressed preference when there were only two options. If people thought that A was better value than B when there were only two options, why does throwing in a third option C, which nobody chooses, entirely reverse their preferences?

Another example: People enter an auction for several items, such as cordless computer peripheries, books, chocolates, and bottles of wine. They bid for these items by submitting their bids; they write down the maximum amount of money that they are willing to pay for each item. Whoever submits the highest bid wins the item and pays for it with the amount they wrote down. Some people enter higher bids than others because they want the items and place higher values for them. So far there’s nothing strange; that’s how auctions work everywhere.

But here’s the twist (as well as Ariely’s genius). Before they enter their bids for each item, they write down the last two digits of their Social Security number. Then they write down their bids. Remarkably, Ariely’s experiment shows that there is a significant positive correlation between the last two digits of their Social Security number and their entered bids, so that those whose last two digits of the Social Security number are lager in numerical values enter higher bids for a given item than those whose last two digits are smaller. For example, those whose last two digits of the Social Security number are between 00-19 are on average willing to pay a maximum of $8.64 for a cordless trackball. In sharp contrast, those whose last two digits of the Social Security number are between 80-99 are on average willing to pay a maximum of $26.18 for the same item, more than three times as much. In terms of standard economics, it means that those whose last two digits of Social Security number are between 80-99 value the cordless trackball more than three times as much as do those whose last two digits are between 00-19. In fact, Ariely’s experiment shows that the former group of people place greater value on (and thus are willing to pay much more for) everything than the latter group. How can the last two digits of their Social Security number possibly affect how much they are willing to pay for a whole host of items?

These are just two of the examples from the book chock full of examples of such irrational behavior that standard economics would have a hard time explaining. (And I haven’t even mentioned how many young men in their 20s would have sex with a 60-year-old woman or a 12-year-old girl or a dog if they have an erection.) I would highly recommend the book to anyone interested in human behavior and its potentially irrational manifestations. The book is very well written and highly entertaining. As an aficionado of scientific biographies, I particularly enjoyed the section in the back of the book, where Ariely introduces all of his coauthors for all of the studies discussed in the book. Ariely has nice, kind, and funny things to say about all of his collaborators.

So what’s my problem? If Predictably Irrational is full of fascinating examples of irrational human behavior, revealed by a series of highly ingenious experiments conducted by Ariely and his colleagues, and if the book is written well and highly entertaining, what’s not to like? Why do I choose to call him the worst possible name that a scientist can call another scientist – “not an evolutionary psychologist”? I’ll explain in my next post.

Do Married Women Want Their Husbands to Cheat?

Satoshi Kanazawa — Sun, 04 Oct 2009 23:08:36 +0000

Married women face a dilemma. It’s not that they want their husbands to cheat on them. But then again it’s not that they don’t want their husbands to cheat on them either.

Once married to a man, it is in the reproductive interest of the woman to monopolize access to all of his resources (material or otherwise) so that he would invest them in her joint children with him. Any sexual relationship he may have with other women might potentially jeopardize her exclusive access to his resources, so obviously it is in her interest to make sure that he does not have sexual relationships with other women.

The problem, however, is that, as I explain in a previous post, mating among all mammalian species (including humans) is a female choice; it happens whenever and with whomever the female wants, not whenever and with whomever the male wants. The more desirable a man is (the more resourceful, the higher his social status, the physically more attractive), the larger the number of other women who would want to have sex with him regardless of whether he is married, either in an attempt to steal him away from his current mate (mate poaching) or in an attempt to be impregnated by him so that their child will have his superior genes but then to turn around and pass off the child as their current long-term mates’ genetic offspring (cuckoldry).

All women have a vested reproductive interest to marry a man who is as desirable and attractive (physically and otherwise) as possible, but the more desirable and attractive the husband is, the greater the chances that other women would want him as well and thus the greater the chances that he would be unfaithful. There is a surefire way to guarantee that their husband will never cheat on them, and that is to marry the biggest loser that they can find so that nobody else would want him. But obviously no woman would want to do that.

There is an additional complication in the matter. Humans are naturally polygynous; humans have been mildly polygynous throughout evolutionary history. So it is natural for resourceful men of high status to mate with multiple women simultaneously. (But recall the dangers of naturalistic fallacy. Natural means neither good nor desirable. It just means is; it does not mean ought.) So polygyny – marriage of one man to more than one woman – is a deeply embedded part of male and female human nature. Men have always had multiple wives, and women have always been married to men who have had other wives.

It is true that, even under polygyny, many men still only have one wife while other men remain completely mateless. But we are disproportionately descended from polygynous men, because polygynous men invariably have more children than monogamous men. So most of us are descended from polygynous men (and, disproportionately, from highly successful polygynous men with a large number of wives), only a few of us are descended from monogamous men, and none of us are descended from mateless men. So polygyny remains a significant part of human nature.

Such is the dilemma faced by women, especially highly desirable women who are more likely to marry highly desirable men. The more desirable the woman is, the more desirable her husband is likely to be, and the more likely he is to cheat on her. The more likely her husband is to remain sexually faithful to her, the less desirable he is (and the greater the probability that perhaps she could have done much better than him).

Social sciences are branches of biology II

Satoshi Kanazawa — Mon, 28 Sep 2009 00:13:50 +0000

Contrary to popular belief (and what most social scientists think), all good science is reductionist. The particle physicist and Nobel laureate (and one of my intellectual heroes) Steven Weinberg expresses it best, when he says “The reductionist worldview is chilling and impersonal. It has to be accepted as it is, not because we like it, but because this is the way the world works.”

But why is it? Why is the reductionist worldview the way the world works? It’s very simple. In nature, bigger things are made up of smaller things. Smaller things are not made up of bigger things. So phenomena at a higher level of aggregation (“bigger things”) must be explained by causal mechanisms operative at a lower level of aggregation (“smaller things”). Humans are made up of genes and cells and proteins. Genes and cells and proteins are not made up of humans. So human behavior (phenomena at the level of humans) must be explained by mechanisms operative at the levels of genes, cells, and proteins. Of course, the behavior of genes, cells, and proteins must be explained at the levels of molecules, elements and, ultimately, elementary particles and, possibly, vibrating strings. Just like turtles, reductionism goes all the way down (but, unlike turtles, it stops at the fundamental constituent in nature, formerly believed to be the atom and currently thought to be the vibrating string).

It is important to point out, however, that reductionism does not mean that physics, the most fundamental of all sciences, can explain everything in nature all by itself. Higher-level, emergent phenomena require separate laws, in addition to more fundamental laws, for their explanation. In other words, reductionism does not mean that we can do away with higher-level, less fundamental, sciences, such as social sciences. Once again, Weinberg explains it perfectly in his 1992 book Dreams of a Final Theory:

I do believe there is a sense in which everything is explained by the laws of nature and the laws of nature are what physicists are trying to discover. But the explanation is an explanation in principle of a sort that doesn't in any way threaten the autonomy of the other sciences. We see this even within physics itself. The study of statistical mechanics, the behavior of large numbers of particles, and its applications in studying matter in general, like condensed matter, crystals, and liquids, is a separate science because when you deal with very large numbers of particles, new phenomena emerge. To take an example I have used elsewhere, even if you tried the reductionist approach and plotted out the motion of each molecule in a glass of water using equations of molecular physics to follow how each molecule went, nowhere in the mountain of computer tape you produced would you find the things that interested you about the water, things like turbulence, or temperature, or entropy. Each science deals with nature on its own terms because each science finds something else in nature that is interesting. Nevertheless, there is a sense that the principles of statistical mechanics are what they are because of the properties of the particles out of which bodies are composed. Statistical mechanics does not have principles that stand alone and cannot be deduced from a deeper level.

Similarly, laws of evolutionary biology alone cannot explain why some men become career criminals while others become law-abiding citizens, or why some marriages last forever while others end in divorce, let alone why wars and revolutions and economic recessions occur. In order to explain these macrolevel, emergent phenomena, one needs laws of sociology, political science, and economics. However, these additional laws of social sciences cannot be inconsistent with more fundamental laws of evolutionary biology; for example, a complete macrosociological theory of revolutions cannot contain an assumption which states that human actors equally value the welfare of their own genetic offspring and that of someone else’s offspring, or that men and women are equally predisposed to engage in physical violence. In other words, social sciences are to evolutionary biology what statistical mechanics are to elementary particle physics in the Weinberg quote above. To paraphrase Weinberg, social sciences do not have principles that stand alone and cannot be deduced from a deeper level.

Leda Cosmides and John Tooby, cofounders of evolutionary psychology, remind us that, before Galileo and Newton, the celestial science (about the motions of heavenly bodies) and terrestrial science (about the movements of objects on earth) were considered to be separate sciences, governed by separate sets of laws and principles. It was a huge step forward in the history of science to break down the wall of separation between them, as Galileo and Newton did, and to recognize that the same set of laws and principles applies to both celestial and terrestrial bodies.

That, unfortunately, is the sorry state of social sciences today. Social sciences in the 21st century are where physical sciences were in the 17th century. Social scientists believe in the firm separation between human sciences (social sciences) about the behavior of human species, and nonhuman sciences (biology) about the behavior of all other species in nature, governed by entirely different sets of laws and principles. It would be a huge step forward in the history of science to break down this wall as well, and subsume social sciences under biology.

I will conclude this post with another favorite quote of mine from Weinberg.

The reason we give the impression that we think that elementary particle physics is more fundamental than other branches of physics is because it is.

The reason we give the impression that we think that evolutionary psychology is more fundamental than other branches of social and behavioral sciences is because it is.

Social sciences are branches of biology I

Satoshi Kanazawa — Mon, 21 Sep 2009 06:03:49 +0000

Biology is the study of all living organisms, their behavior and social systems. Humans are living organisms. Thus, social sciences (the study of human behavior and their social systems) are within the purview of biology. Social sciences are branches of biology, and all social scientific theories about human behavior must be consistent with established principles and laws of biology.

Yet most social scientists would object to such subsumption of social sciences under biology, and claim that the uniqueness of the human species would require a separate science. Some would even claim that such uniqueness makes humans independent of and immune to laws and principles of biology; biology is not important for human behavior. According to a 1996 study, 168 sociologists surveyed on average attribute only 4.7% of sex differences in occupational interests, and 15.3% of sex differences in aggressive criminality, to biological (genetic, prenatal, and postnatal nonsocial) factors. A typical sociologist therefore believes that nearly 85% of the variance in sex differences in violence and aggression is explained by purely social and cultural factors like gender socialization. Many years ago, I was once such a sociologist.

There is no question that humans are unique. As the great sociobiologist Pierre van den Berghe points out, however, humans are not unique in being unique. For every species is unique. If it is not, it would not be a separate species. If uniqueness of a species requires a separate scientific discipline, then there would have to be as many scientific disciplines as there are species (dog science, cat science, giraffe science, etc.). In reality, biology covers all species in nature, except for humans, or so goes the conventional wisdom in social sciences.

To claim that social sciences are not part of biology and to establish a separate and incompatible science just for humans is as peculiar and unnecessary as the establishment of hydrogenology, the study of hydrogen apart from, and incompatible with, physics. Yet the idea of hydrogenology separate from physics makes as much sense as the idea of social sciences separate from biology. Hydrogen is a very unique element: It is by far the most abundant element in the universe; it is the lightest and simplest element; it is the only element whose nucleus does not contain a neutron; it has the fewest number of isotopes in nature; it has extremely low boiling and melting points; the hydrogen molecule is the simplest molecule; it has a velocity higher than any other gas at any given temperature and it therefore diffuses faster than any other gas.... The list goes on.

Yet it is completely unnecessary to establish hydrogenology devoted only to the study of hydrogen because physics constructs general laws and principles applicable to all elements, including hydrogen. Boyle's Law and Avogadro's Law hold for hydrogen as they do for all other gases despite its uniqueness. Physics as a science has advanced as it has because it does not make exceptions; it formulates general laws and principles that apply to all elements, not specific ones for each element.

Of course, physicists, like other scientists, specialize in certain types of matter; some are elementary particle physicists, others are condensed matter physicists. So there is nothing wrong with some scientists specializing in human behavior. In chemistry, some specialize in the study of carbon compounds, but nothing in "carbonology" (organic chemistry) is inconsistent with the general principles of chemistry. I am not calling for the elimination of social sciences, only its subsumption as "human biology." In his 1998 book Consilience, the Harvard entomologist Edward O. Wilson most comprehensively and emphatically calls for the unity, or consilience, of all sciences and humanities (such as arts, literature, music, and ethics), guided by the principles of evolutionary biology. Consilience is what we need in order to subsume social sciences under biology.

Most social scientists do not see how the same laws of biology hold for humans as they do for all other species. For instance, most social scientists claim that, even though all other species in nature have innate, species-typical nature, which determines how members of the species behave, humans are an exception to this rule and have no innate nature. They claim that humans are born blank slates and all of their behavior is determined by socialization and other environmental factors. Most social scientists do not see how such human exceptionalism - their tendency to formulate theories specific only to humans - has hindered the development of social sciences. It would take tremendous faith in the Biblical creation to believe that humans are somehow the only species that is exempt from the laws of biology that permeate the rest of nature.

Hydrogenology apart from physics is not necessary, because hydrogen, while unique, is only quantitatively, not qualitatively, different from other elements. Hydrogen is a distinct element from helium, but helium is nothing but hydrogen with an extra pair of proton and electron. Lithium, while distinct from hydrogen and helium, is nothing but helium with an extra pair of proton and electron. All elements are the same, except in the number of protons and electrons they contain; all unique properties of different elements derive from it. That is why the same laws and principles of physics apply to all elements, regardless of their unique natures.

The same is true of biological organisms. Humans are a distinct species from chimpanzees, but chimpanzees are nothing but humans with a few percentage points of their genome altered, and gorillas are a few more percentage points away. All animal species are the same, except for the genes contained in their genomes. All laws and principles of biology apply to humans as they do to all other animal species. Biology's reductionism (classifying all biological organisms in terms of their genetic makeups, and explaining their behavior and social systems by the same set of principles of evolutionary biology) and generality (not making exceptions for any species) allow it to be applicable to all species. Reductionism and generality are two important principles of science.

In my next post, I will explain why, contrary to what most social scientists believe, all good science is reductionist, and all human behavior must be explained at the level of the genes (and molecules, and atoms, and particles).

Why Hollywood marriages don’t last

Satoshi Kanazawa — Mon, 14 Sep 2009 01:28:21 +0000

Douglas T. Kenrick of the Arizona State University is one of the leading evolutionary psychologists in the world. He's also widely regarded as the funniest evolutionary psychologist alive. Among Kenrick's numerous scientific achievements are a series of experiments he conducted with his ASU colleagues in the late 1980s and early 1990s, which indirectly launched my career in evolutionary psychology, and led to their discovery of a significant phenomenon known as the contrast effect.

In one of these experiments, Kenrick and colleagues showed men either 16 Playboy centerfolds or 16 abstract art slides. Those who viewed the Playboy centerfolds subsequently rated their girlfriends as less sexually attractive and expressed less love for them than those who viewed the abstract art. In another experiment, Kenrick and colleagues showed men either seven photographs of physically attractive women or seven photographs of average-looking women. Those who viewed pictures of physically attractive women rated their girlfriends less physically attractive and expressed less commitment to their relationships with them than those who viewed pictures of average-looking women.

What Kenrick and colleagues discovered in these experiments is now known as the contrast effect. Because their current girlfriends tend to pale in comparison to the Playboy centerfold models or physically attractive women, men come to view their girlfriends as less attractive and become less satisfied with them when they are faced with much more attractive potential alternatives. Never mind the fact that none of these men will ever get to date the Playboy centerfolds. Their brains cannot comprehend that, because there were no photographs in the ancestral environment. Any woman that our male ancestors "saw" was a potential mate.

In 2000, Kenrick's remarkable findings led Mary C. Still and me to pose two questions. First, if men can become more dissatisfied with their current girlfriends after viewing only 7 or 16 photographs of more attractive women in one brief experimental session, what would be the cumulative effect for men of being constantly exposed to young, attractive women? Second, are there any behavioral consequences of their dissatisfaction with their girlfriends as a result of their exposure to physically attractive women? In other words, do these men do anything about their dissatisfaction?

Because women's reproductive value (the number of children they are likely to have in the remainder of their reproductive careers) peaks at menarche (onset of menstruation), and their fertility (the actual number of children that women have) is highest in their early 20s, men's evolved psychological mechanisms incline them to find women who are in their teenage years and early 20s more physically and sexually attractive than older women, despite laws of civilized society concerning the age of consent and the minimum age of marriage. Compared to most adult women, teenage girls also have lower waist-to-hip ratios that men prefer, as I explain in an earlier post.

Few occupations and professions afford men with greater opportunities to come in contact with women in their teenage years than teachers in secondary and postsecondary schools. These teachers experience the cumulative effect of exposure, day after day, year after year, to young, attractive women who are at the peak of their reproductive value and fertility more acutely than men in most other occupations. If the findings of Kenrick et al. generalize beyond their experimental stimuli (exposure to a few photographs of attractive women during an experimental session) and if the contrast effect is cumulative, then male teachers in secondary and postsecondary schools should be more dissatisfied with their mates than other men. If there are behavioral consequences to their dissatisfaction, then these male teachers should be more likely to be divorced or separated than other men.

Our analysis of the General Social Survey data showed that male secondary and postsecondary school teachers were significantly more likely to be currently divorced and significantly less likely to remarry than men in other occupations. This effect is not observable among male kindergarten and elementary school teachers. Nor are female teachers in secondary and postsecondary schools more likely to be currently divorced or less likely to remarry. So it's not about being a teacher per se. The significantly higher likelihood of being currently divorced and lower likelihood of remarriage are observed only among male teachers in secondary schools and universities, those who are surrounded by young nubile women all the time.

This study was widely covered by the media back in 2000. The question that I was most frequently asked by journalists back then was "What other occupations, besides teachers in secondary and postsecondary schools, would lead men to experience a greater risk of divorce due to the contrast effect? In what other occupations are men surrounded by young nubile women?"

I think the most obvious answer is Hollywood actors. There is always a new generation of younger and younger starlets in Hollywood, while their actress/model wives can only get older. The mating career of Tom Cruise illustrates this perfectly. Mimi Rogers (his first wife) was six years older than him (illustrating another finding by Doug Kenrick that, while men generally prefer younger women, teenage boys prefer older women because, for them, younger women would be subfecund or infertile, although Tom Cruise was 24 when he married Rogers). Nicole Kidman, his next wife, was five years younger than him. Penelope Cruz, his next long-term girlfriend, was 12 years younger than him. And Katie Holmes, his current wife, is 16 years younger than him. I'm guessing his next wife will be one of the Olsen twins (who are 24 years younger than him).

The contrast effect, which Kenrick and his colleagues discovered in their ingenious experiments, can explain why Hollywood actors are notorious for their short, unstable marriages and relationships. Just like male high school teachers and university professors, Hollywood actors are constantly surrounded by young attractive women.

Who took the picture of Joe Wilson? And how?

Satoshi Kanazawa — Fri, 11 Sep 2009 02:40:31 +0000

So here's what I don't understand. If Joe Wilson's outburst during Obama's speech Wednesday night was truly "spontaneous," as Wilson claims, and no one (including Wilson himself) could have anticipated it, how come there is a sharply focused and neatly centered picture of Wilson right at the moment he shouted "You lie!" when the outburst lasted less than a second? In the picture, Wilson's mouth is still open, apparently in the middle of his shouting "lie."

There are 535 members of Congress in attendance during the joint session, plus a few extras like Michelle Obama and Vicki Kennedy. Until last night, Wilson was just about the least well known member of Congress. Why did someone have a camera fixed and focused on him during Obama's speech? The picture in question has been variously credited to "Getty Images," "AFP" (Agence France-Presse) or "Chip Somodevilla." None of them are local press in South Carolina, which might have had a reason to pay particular attention to their local Congressman during the speech. I doubt local press photographers are allowed in the joint session of Congress during a Presidential speech anyway.

Think about it. If you were one of the (probably) dozen press photographers in the chamber last night, generally taking pictures of the Congressmen and Senators during the speech, and if you suddenly heard a two-word, one-second outburst coming from somewhere in the chamber, uttered by one of the 535 members of Congress (okay, one of the Republicans), there is no way you could take a (well focused and neatly centered) picture of the culprit during the second word of the outburst. Whoever took the picture must have anticipated the outburst.

This is the question that Albert Brooks asked about William Hurt in Broadcast News, which eventually ended the relationship between Hurt and Holly Hunter. I just don't see how the picture could be possible. How can you capture someone's "spontaneous" moment, when there are more than 535 other people around to pay attention to?