Humans and men: there are differences

The tendency to equate men with humankind is an old one, evidenced by little things like the age-old icon of evolution seen here:

Bob McDonald, on his CBC show Quirks and Quarks, did a masterful job of talking about humankind without ever mentioning or speaking to a woman on his August 22nd “best of” show, which was a re-broadcast of his show from April 25th, 2009 (available in full here). In attempting to answer the question “Are we inherently violent, or are we a naturally peaceful creature trapped in a violent culture?” Mr. McDonald, not surprisingly, seeks out academic sources who support the former option.

The first person he talks to is Dr. Richard Wrangham, professor of “biological anthropology” at Harvard University and coauthor of the book Demonic Males: Apes and the Origins of Human Violence. Dr. Wrangham describes to Mr. McDonald the incident in chimpanzee research that led to the idea that chimpanzees may be inherently violent; prior to 1974, the bulk of chimpanzee observation, primarily constituted by Jane Goodall’s work with the Gombe chimpanzees in Tanzania, had revealed that chimpanzees are only mildly violent, with most altercations being only minor (with the exception of one incident in which they stole and killed a human baby). In 1974, a group of chimpanzees was observed to silently approach a male member of a neighbouring chimpanzee community and then ambush and brutally kill him.  Since then, the same behaviour has been observed a number of times, and is in fact featured prominently in the popular BBC series Planet Earth. Prof. Wrangham explains that this behaviour is evolved as a way for groups of chimpanzees to expand their territory so as to have more resources to support more children.

The second person Mr. McDonald speaks with is Dr. David Carrier, a comparative physiologist at the University of Utah. Dr. Carrier points out that there is an energy cost to bipedalism, which suggests that there must be some evolutionary advantage to standing upright. This advantage is the ability of bipeds to use their forelimbs as weapons. Dr. Carrier rejects the notion that there might be other uses for one’s forelimbs that might offset the mechanical disadvantage of being two-legged, based on the two facts that a) Australopithecines had short legs, which would have given them a stabler base for hand-to-hand combat, and b) human hands are better-proportioned for forming fists than those of any other primates. [He really said this! I recommend to Dr. Carrier that he punch someone, and see how well-evolved his  metacarpals are.]

The third person invited on the show is Dr. Aaron Sell, an evolutionary psychologist from UC Santa Barbara. Dr. Sell did an experiement where he took male participants to the gym and had them lift weights to determine their level of strength, then they photographed the participants’ faces and had other participants look at the photos to see how well they could judge the strength of these people by their looks. As it turns out, “at least with men,” people were generally able to determine the strength of a person by looking at their face. Dr. Sell suggests that facial structures such as the brow and the jawbone are determined by testosterone, which is the same hormone that makes men big and strong; thus, men with low brows and big jawbones are more likely to be strong. That’s why, when someone makes an angry face, the muscles they use tend to accentuate the brow and the jawbone.

The fourth and final guest on the show is Dr. Craig Kennedy, a neuroscientist at Vanderbilt University in Nashville. He noticed that trained male mice are able to learn a complex task (in this case, pushing a button) in order to get the chance at fighting with another male mouse. The same mice, with their dopamine receptors disabled, do not exhibit the same behaviour; this suggests that the mice’s brains release dopamine – the “pleasure chemical” – when they experience aggression. Dr. Kennedy wanted to see if humans were the same way, so he designed an experiment that involved young men watching things such as hockey fights and scantily clad young women. He found that watching a hockey fight and ogling a scantily clad woman had similar effects on the dopamine receptors in these men’s brains, thus supporting the hypothesis that watching violence is pleasurable. [He conventiently declined to remark on the effects of partaking in violence.]

Although they all have their flaws and quirks, these particular experiments and hypotheses are not what I have a problem with. I have a problem with the fact that Bob McDonald had four men on his show and used their observations about male behaviour as grounds for the conclusion that “humans are inherently violent.” It shouldn’t take a university degree to notice that the guests on Quirks and Quarks were only talking about half of humankind. Using evidence from a small and non-representative sample to make conclusions about a whole population is known in philosophy as a hasty generalization, the bane of inductive reasoning. It’s a scientists job to avoid making generalizations by using as representative a sample as  possible; with the exception of Dr. Carrier, who appears to have his own set of problems, all of these scientists do their job very poorly in this regard, as does Mr. McDonald.

Correlation does not equal causation

One of the central talking points in the recent hullabaloo over evolutionary psychology has been the difference between correlation and causation.  Thanks to Echidne, I came across this remarkable example of correlation being confused with causation in USA Today (not exactly a bastion of good science):

Breast-feeding has well-documented benefits. Studies have shown it nourishes babies while fighting off infections and even boosting IQ. Now a study in Monday’s Pediatrics suggests nursing also may protect infants from neglect.

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In a study of 6,621 Australian children over 15 years, researchers found that those who were breast-fed were far less likely to be neglected or abused by their mothers. Babies who weren’t breast-fed were more than 2½ times as likely to be maltreated by their mothers as those who were nursed for four months or more, the study shows. There was no link between breast-feeding and the risk of maltreatment by fathers or others.

Apparently a hormone released during breastfeeding that strengthens the bond between mother and child is responsible for this correlation. Although this dubious claim is discredited by a disinterested psychologist later in the article, the wording of the claim contains an interesting linguistic twist. Compare the sentence in the article

those who were breast-fed were far less likely to be neglected or abused by their mothers

with a revised version that switches the components around:

those who were neglected or abused by their mothers were far less likely to [have been] breast-fed.

What exactly is the difference between these two sentences? Well, among other obvious things, I had to change the aspect of the second sentence because the abuse usually comes after the breastfeeding, and the present perfect aspect indicates a completed action (i.e. the breastfeeding was completed before the abuse started). The order of events are important in this case because the two sentences have no overt semantic indication of causation other than the order in which the events occurred.

If we took a sample population that was made up of 20 cows and 20 dalmatians, and out of the 20 cows only 5 were Holsteins, we might say that those animals that are spotted are much more likely to be dalmatians. This claim has no inherent or implied indication that the cause of the animals being dalmatians is their spots; rather, the relationship between being spotted and being a dalmatian is simply one of strong correlation. (Note that the inverse, “those animals that are dalmatians are much more likely to be spotted,” is also true without need for the present perfect.)

However, if we take the same sample, and out of the 15 brown cows 13 of them were born in May, we might say that those cows that are born in May are much more likely to be brown. In this example, although their are still no overt or deliberate signs of causation, the sentence is more easily interpreted as depicting a relationship of causation because of the time element. Unlike in the case of the last example, the inverse of this sentence has to be “those cows that are brown are much more likely to have been born in May.”

I don’t want to give the impression that the cow examples are meant to be parallel to the breastfeeding example; I just want to show that the time element is encoded in the first type of sentence, and that time element implies causation rather than simply correlation. The use of the progression of time to indicate a relation of causation is known, in the parlance of our times, as the post hoc fallacy – post hoc, ergo propter hoc is Latin for “after this, therefore because of this,” and it is the name for the classic tendency to confuse correlation with causation that has been around since the dawn of argumentation.

Like the post hoc fallacy, the tendency for researchers to notice relationships of correlation and then make up reasons why the correlation might be causal is one of those things that just won’t go away.

Do potatoes need drugs? No.

As a follow-up to this post and this post, I wanted to link to a recent SciAm article about antibiotics in vegetables. According to the article, 70% of all the antibiotics used in the United States are fed to livestock pre-emptively to prevent disease. Since 90% of the drugs then come out as excrement or urine, which is then used to fertilize vegetable crops, antibiotics are showing up in vegetables at alarming concentrations, including in organically grown vegetables.

[Steve] Roach [public health program director for the non-profit Food Animal Concerns Trust] said “the clearest public health implication” from treating livestock with antibiotics is the development of resistant bacteria that reduces the effectiveness of human medicine. Past studies have shown overuse of antibiotics reduces their ability to cure infections. Over time, certain antibiotics are rendered ineffective.

The Do Bugs Need Drugs campaign gives no indication that the drugs used by prescribed-antibiotic users constitute the minority of antibiotics produced, nor does it give any indication of what impact the rest of these drugs has on drug-resistant bacteria due to their gratuitous use in the farm industries.

Study: Why Science Writers Stink

Pink has been a girl’s colour for about seventy or eighty years. Since the blue-for-boys/pink-for-girls thing has been taken up with such aplomb and vigour by marketers of gendered products, primarily toys and clothes, and since people tend to be painfully ignorant of times other than those they live in, there is a contemporary debate about whether the pink-for-girls/blue-for-boys dichotomy is learned or innate. The very existence of this debate is an embarrassment for anyone who knows anything about anything, but it does provide a good example of how science writers in the popular media tend to skew the results of scientific studies so that they appear to provide support for culturally produced norms or biases. So here it is.

The paper “Biological components of sex differences in color preference” appeared in the August 2007 issue of Current Biology, and is thankfully available in full here. The two researchers involved with this study did a cross-cultural comparison of colour preferences among 208 participants, 171 of which were British caucasian, and 27 of which were mainland Han Chinese. The two groups were roughly split in half by gender. The study involved a simple forced-choice rapid paired-comparison task, where participants were shown two colours on a screen and were asked to select the one they preferred as quickly as possible using a mouse cursor. These were the results:

The two graphs on the bottom, B and C, represent the two sets of tests they did that targeted different contrast-pairs based on the cones in the retina–test B represents the S vs. L and M cones, or blue-yellow contrast, and C represents the L vs. M cones, or red-green contrast. As the graphs show, all participants preferred blue on the blue-yellow test, although men preferred it more, and women preferred red on the red-green test, whereas men preferred green. Keep in mind that these weren’t solid primary colours that were used in the tests, but were rather ranges of hues that were weighted according to the contrast pairs – in other words, women preferred reddish blues overall, whereas men preferred greenish blues.

Note that these results reflect the well-researched phenomenon of male colourblindness, which is something like 10 times greater in the male population than in the female population. The researchers cite two possible causes for these results, based on the possibility that this sex difference is an adaptation: first, women may have evolved the ability to distinguish reds from greens because they were the gatherers and they needed the ability to distinguish fruits from foliage, whereas making subtle colour distinctions was not as necessary for men, who were the hunters. Second, women may have evolved the ability to distinguish subtle shades of red in order to recognize flushed faces, which was necessary to fulfill their role as nurturing caregivers.

The second explanation seems like bunk, to use the parlance of our times. A study that showed a group of men and women flushed faces and demonstrated that men were less able to distinguish them from regular faces might give this theory more credence, but until then it seems like pure speculation. The second explanation makes sense, assuming that we have reliable data somewhere that indicates women were the gatherers while men were out hunting (I am by no means an anthropologist). Trichromacy would be a very useful adaptation if reddish fruits and vegetables were a big part of our diet, and females would evolve better colour vision if finding those fruits and veggies was their job. However well paleoanthropology explains trichromacy, though, I am not clear from reading the paper how preference for reddish colours is based on the ability to distinguish reddish colours. If I conceded that women are more likely to be trichromatic because of the evolutionary explanation, it would not follow that they like reddish colours more just because they can distinguish them. If they indicated a preference because “red” indicates “food,” then why wouldn’t men with normal colour vision register the same preference? Indeed, even in the case of the bunk explanation, reddish colours may well be associated with distress, which would make them less preferable. The point I’m trying to make is not that either theory is more or less correct, but that neither theory does even a half-assed job of explaining the results, so it’s tempting to look at the proffered explanations as being heavily biased.

Compared to the article in Time, though, the research paper is a work of extreme sensitivity. The Time article overlooks the dubious link between the article’s data and its explanation, and frames the whole thing as if the study were proof that women inherently like pink more than blue. Nevermind that the study had very little to do with pink, or that the study said more about preferences for red and green than about pink and blue; the Times saw an opportunity to reinforce their previously held assumptions under the guise of science, and they went for it. It’s unfortunate, then, that although they did a surprisingly good job of summarizing the article, the message that they ended up getting across had less to do with the study itself than it did with Time’s biases. Their caveat near the beginning,

women may be biologically programmed to prefer the color pink — or, at least, redder shades of blue — more than men

(emphasis added) ends up drowned under the headline just above it that proclaims definitively that the study explains “Why Girls Like Pink.” As Kapitano once said with regard to Neuroskeptic, “To be well informed about science, ignore everything you read about it in newspapers. Then read some science books if you like, but ignoring journalists is the important thing.”

Sci Am dislikes evolutionary psych, too

David Buller at Scientific American weighed in on the burgeoning field of evolutionary psychology, claiming it “misguided”:

It may be a cold, hard fact that there are many things about the evolution of the human mind that we will never know and about which we can only idly speculate. Of course, some speculations are worse than others. Those of Pop EP [evolutionary psychology] are deeply flawed. We are unlikely ever to learn much about our evolutionary past by slicing our Pleistocene history into discrete adaptive problems, supposing the mind to be partitioned into discrete solutions to those problems, and then supporting those suppositions with pencil-and-paper data. The field of evolutionary psychology will have to do better.

I don’t have anything original to say about the article that Feministe, Pandagon, and 3 Quarks Daily haven’t already said, other than to point out that this comes at an opportune time, considering that the only outspoken opposition to evolutionary psychology that I’m aware of comes from the aforementioned radical liberal extremists writing to their picayune blogs. Hopefully Scientific American carries more cachet than we do.

Buller outlines four fallacies often committed by evolutionary psychologists:

1) Believing that an “analysis of Pleistocene adaptive problems yields clues to the mind’s design.” We have little to no evidence of the psychological behaviour of Pleistocene hominids, and we have no basis for inferring how those behaviours were adaptive to environmental or social problems in the lives of these hominids; as a result, all inferences made about their psychological adaptations are purely speculative, hardly better than guesses.

2) The belief that “we know, or can discover, why distinctively human traits evolved.” Comparing different species that share a common ancestor is a common and useful way of determining how the adaptations of those species is contingent on unique environmental factors. Unfortunately, humans have no living counterparts that can be used in such a comparison, since our nearest relatives apparently have none of the higher cognitive functions that EP hopes to explain (language, etc.).

3) The belief that “our modern skulls house a Stone Age mind.” This belief depends on a narrow view of the influences on human psychology; Buller suggests that not only may many of our adaptive psychological traits be held over from pre-human evolution, but it has also been shown that the interaction of genes with rapidly changing modern environments produces behaviours that would be drastically divergent from those of Stone Age hominids.

4) The belief that “the psychological data provide clear evidence for pop EP.” “Pencil-and-paper” data provides weak evidence for drawing conclusions about universal human nature or behaviour. This is the fallacy that gets to the heart of the liberal extremist radical bloggers’ complaints; Buller states that “the appearance that the evidence is compelling is created less by the data themselves than by the failure to consider and adequately test viable alternative explanations.” Coupled with the speculative inferences made by way of fallacy number one, evolutionary psychology serves as a ripe breeding ground for justifying preconceptions about human nature under the guise of scientific “proof”; since much of evolutionary psychology is inexplicably obsessed with competition for “mates,” a great deal of conclusions are drawn about gender differences that reinforce researchers’ preconceptions about normative gender roles. Holly at Feministe, referring to Echidne, characterizes EP methodology thusly: “a small amount of data is used to confabulate a hypothesis that just happens to provide moral support for traditional gender roles.”

I would add to Buller’s list a reliance on sketchy statistical methods, including, famously, tiny sample sizes and forced-choice questionnaires that are old hat in the pollster’s quiver of data-skewing tools. I hope that this article is the start of a trend that gives evolutionary psychology a reputation for bad science, which will either drive it out of existence or force it to adopt some more rigorous standards. And then, hopefully, the science journalists will lay off making things even worse for everybody by exaggerating and misrepresenting the already shoddy research.

Read and Listen

The Neuroskeptic has a great post tucked away in the archives about the Galileo Gambit, which is, in his words, “when people with unpopular ideas compare themselves to Galileo with the implication that, like him, they’re being persecuted for their unorthodox views but that they will eventually be proved right.”

Arguing for the unpopular view that “if most scientists believe something you probably should believe it, just because scientists say so,” he invokes some common instances of people thinking and acting like they know stuff when they clearly don’t, and in fact clearly couldn’t. Deniers of climate change are a great example of people who choose to scoff at the vast majority of climate scientists, apparently without acknowledging that climate scientists are the only people who are actually qualified to come to a conclusion about climate change. The psychological processes that would lead someone to deny climate change despite the fact that they have no basis for coming to a conclusion about it are complex and puzzling, especially since this tendency is so ubiquitous. (Cornell psychologists Kruger and Dunning have a theory – incompetent individuals lack what cognitive psychologists call metacognition, the ability to evaluate one’s own performance.) “Unless you are a professional climate scientist (or whatever), or an amateur with an unhealthy amount of spare time,” Neuroskeptic points out, “the chances are that you just don’t know enough to come to an informed conclusion.”

In a recent episode of CSI, Grissom explains to his gullible disciples why a string of cases were linked together, apparently coincidentally:

String theory is the theory of everything. Quantum mechanics tells us about the very small. The theory of relativity explains the immense. String theory ties it all together. It proposes that atomic particles are made up of infinitesimal vibrating loops of energy, or strings. Each string vibrates at its own frequency, like on a violin, producing notes, and these notes make up everything in the universe. These strings have been combining and recombining ever since the Big Bang. So the connections between our victims, or any of us, are not that extraordinary.

The problem with this passage isn’t necessarily his characterization of string theory, which could probably be, on some vastly simplified level, defensible as a pop characterization of the theory. The problem is his use of the theory to explain the coincidence of his cases, where as a matter of fact the coincidence of his cases has nothing whatsoever to do with string theory. Theoretical physics isn’t philosophy. Gerard ‘t Hooft, a physicist at the University of Ultrecht, put together a list of subjects you need to master in order to know what you’re talking about when you talk about string theory:

# Languages
# Primary Mathematics
# Classical Mechanics
# Optics
# Statistical Mechanics and Thermodynamics
# Electronics
# Electromagnetism
# Quantum Mechanics
# Atoms and Molecules
# Solid State Physics
# Nuclear Physics
# Plasma Physics
# Advanced Mathematics
# Special Relativity
# Advanced Quantum Mechanics
# Phenomenology
# General Relativity
# Quantum Field Theory
# Superstring Theory

The point being, if you don’t have a PhD in theoretical physics, you can’t really talk about string theory with any remote degree of accuracy. The same holds true for a lot of other disciplines that laypeople talk about all the time, notably psychology, economics, and statistics.

The increasing breadth and complexity of modern science has made it largely inaccessible to amateurs and laypeople. For that reason, we rely on other people’s word every day, when we read the newspaper or watch the news or, at another level, when we read journal articles and attend lectures. Its unavoidable. What we can do, though, to a reasonable degree, is evaluate the word that we’re taking from these people based on how qualified they are to come to the conclusions they come to. (Journalists, for instance, rarely have any expertise about anything they write about.) As NS says, if we’re going to take someone’s word, we might as well take the word of an expert, or better, a huge group of experts who agree with one another.

I bring this up now because my recent post about Mindful Education raised this issue in my mind. Both Ken Kavenagh and Ryan, who responded at length to my post agreeing with Kavenagh, have taken an unpopular view that goes against the empirical, verifiable knowledge of hundreds of psychologists and educators. It’s not clear why Kavenagh and Ryan consider themselves to be more knowledgeable about the subject of mindful meditation than these hundreds of experts are, considering that the experts are the ones who have actually researched mindful meditation and are qualified to come to a conclusion about it. What I was trying to get at in the last paragraph of my reply to Ryan is that, as NS says, “if thousands of intelligent people freely discuss something and reach a certain conclusion, that in itself is evidence (although not proof) that what they conclude is true.” While obviously skepticism is a desirable intellectual trait, assuming your own expertise on the basis of a few articles you’ve read here and there is a weird and counterproductive tendency that people enact all the time. (Including me! I can’t pretend to be innocent of this phenomenon.)