Cognitive Fingerprinting

Doreen Kimura has found a relationship between body asymmetries and cognitive functioning.

Evidently fingerprint ridges are like tree rings, they measure the amount of development during an early stage of embryonic development (in the forth fetal month, specifically). Males, on average, show more ridges. Most people show more ridges on the thumb and little finger of their right hand than on the thumb and little finger of their left hand; this is holds true for both left and right handed people. About a fifth show the reverse pattern, with more ridges on the left than right. Most of the people with the reverse pattern of greater left ridge prevalence are female. (Like women, gay males show greater left ridge prevalence than non-gay males). People who had a larger amount of ridges on their left thumb and little finger, both male and female, were better at cognitive tasks that females tend to dominate when compared to matched right ridge prevalent controls. Females with greater left ridge prevalence were better at the female predominate tasks than females that had greater right ridge prevalence. The overall pattern is that left lateral asymmetry favors female dominate cognitive functioning.

Since most parents and educators are unaware of the details of dermal ridges, it is hard to argue that this is a result of upbringing. A more likely explanation is that the cognitive test and dermal ridge results are covariantly determined by fetal brain development

The Bend Sinister

Suggestions that left-handedness might be associated with learning difficulties probably started with the observation that left handedness is more common in groups of retarded individuals, a fact we mentioned earlier. This observation eventually led researchers to ask if there was a relationship between left-handedness and some of the other milder forms of learning problems. In some respects this sort of a question comes right out of the issue of how quickly and completely individuals mature. It has been suggested that people with learning difficulties are people whose development has been delayed, so that they never achieve the level of maturity of their nervous system that would allow the most efficient processing of information. You now only have to go one step further in terms of speculation. As left-handedness is associated with slow development and learning disabilities are associated with slow development then it should be possible to suggest that left handedness should be more common on groups of individuals with learning problems.

A variety of learning disabilities have been measured. One of the most common is dyslexia, which usually shows up as a reading difficulty in which the dyslexic individual has trouble interpreting the strings of symbols that make up a word or a sentence. Thus a dyslexic might read the word “saw” for the printed word “was.” Writing difficulties often appear in the form of letter reversals, and dyslexic individuals may write b for d, p for q, and so forth. Such problems can greatly impair a child’s performance in school.

A good deal of evidence shows that the number of left-handers is greater in groups of learning disabled and dyslexic people. For instance, one study compared 500 consistent left-handers to 900 consistent right-handers. Approximately 12 percent of the left-handers reported learning difficulties such as dyslexia while only 1 percent of the right-handers did. In other words, left-handers were 12 times more likely to have this learning disability.

Even in groups of individuals in whom there is no evidence of a learning disability, left- and right-handers perform differently, with most researchers finding a slight difference in favor of right-handers in certain in certain intellectual abilities or academic skills. For example, in our laboratory we have tested university students. This means that we can be sure that we are not dealing with any severely learning disabled individuals, but even in this group we found that the left-handers didn’t do quite as well as the right-handers in vocabulary tests, in tests of arithmetic ability and in certain types of problem solving tasks. The differences were quite reliable, but not very large, which is consistent with our notion that left-handers are alinormal rather than abnormal. Similar results were found in a study of records of academic achievement in high school in Somerset, England. There is was found that right-handers did better in virtually every school subject tested. Again, the differences were reliable but small, with an average difference between left- and right-handers of only about three percentage points in their grades.

Difference in learning and thinking ability between left- and right-handers, however, are not always consistent. Some researchers have found no differences at all in some areas of ability. Others have found that the pattern depends upon the sex of the individual, with left-handed males often showing the poorest overall performance. Part of the reasons for the inconsistency has to do with the fact that systematic differences in the abilities of left- and right-handers don’t seen to show up until after puberty. In young school children, handedness is seldom found to be related to learning or to problem-solving ability. In adults the results are much clearer. The differences don’t really make themselves visible until high school or, at the earliest, junior high school, when the children are around thirteen or older.

The picture is not all gloom and intellectual dullness for left-handers however. In our laboratory we did find certain tests, involving the ability to visualize objects and mentally manipulate their images that produced the reverse pattern. A typical example is the Mental Rotation Test. A sample item from this test is shown in figure 10.1 Notice that we start with a “test” item, which looks like an object made up of ten blocks glued together. The person’s task is to look at the three items next to the example that are marked “target items.” One of these figures is exactly the same object as the test object. In this task, which requires the ability to create an image of an object in your mind and to maneuver it around, twisting and turning the image mentally, we find that left-handers are better than right-handers.

A test like the mental rotation test is useful because this kind of mental imaging skill is an important part of certain scientific applications of mathematics. It is particularly useful in subjects such as in physics, chemistry, and engineering, which require a certain degree of geometrical imaging and reasoning. A study conducted at Oxford University looked at the handedness of university faculty members and found that left-handers were more common in these applied mathematical subject areas than in theoretical mathematics, which does not require these visualization skills.

This same set of skills probably explains why these are so many left-handed chess players, since the game of chess requires the ability to visualize geometric patters and how they would change for each given move. Similarly these visualization skills may also explain the over-abundance of left-handed architect and artists that we discussed in chapter 7.

There is also some evidence that suggests that left-handers tend to be more extreme in their overall abilities. By extreme we mean that the intellectual abilities of southpaws are often a case of feast for famine. To illustrate the famine part, we have already seen that there are more left-handers in the learning disables groups and in the more extremely intellectually disadvantaged groups such as mental retardates. There is, however, a feast part as well. This is shown by the fact that there is an unexpectedly high number of left-handers in certain groups of extremely bright individuals. For example, the psychologist Camilla Benbow and her research associates from Iowa State University have been studying exceptionally bright and intellectually precocious young (high school age) individuals. To give you some idea of the degree of talent that she is dealing with she has singled out students whose Scholastic Aptitude Tests scores (a college admissions test) are extremely high. The cut-off scores that Benbow used would place a student as being the top one in 10,000 students. When Benbow looked at the handedness of this extremely bright group of students, she found that they were more than twice as likely to be left-handed than are the general run of students taking this exam. The implication if that the left-handers are apt to be extremely dull or extremely bright.

Stanley Coren The Left-Hander Syndrome (Vintage: 1993) pp 174-177

On the Other Kind of Color-Blindness About Race

In America, color blindness effects males more often than females at a ratio over 8 to 1. Color blindness is not distributed equally among the large outlier races.

Inherited color vision deficiency usually is gender-based, with the majority of sufferers being male. Some women may carry the gene defect andpass it on to their children. The overall incidence of color vision deficiency for whites of European origin is 8 percent for males and 1 percent for women. The incidence is lower for Asians and Native Americans and lowest of all for blacks.

Embryologically, eyes are a pair of peninsular outgrowths of the brain. Given that the condition is inherited, the asysmetical distribution of color blindness suggests that the brains of the various races as well as the brains of the sexes are different in structure and function.

Dominican Switch Hitters

The case of the Dominican male pseudohermaphrodites who were raised and socialized as females in childhood until they matured into men in adulthood is additional subversive evidence that transgresses against the hegemonic social-construstivist meta-narrative.

In an isolated village of the southwestern Dominican Republic, 2% of the live births were in the 1970's, guevedoces (actually male pseudohermaphrodites). These children appeared to be girls at birth, but at puberty these 'girls' sprout muscles, testes, and a penis. For the rest of their lives they are men in nearly all respects (see photograph 6 below). Their underlying pathology was found to be a deficiency of the enzyme, 5-alpha Reductase.

Save the Males

Are males an endangered subspecies?

Scientific American has an article on David Page's work on the Y chomosome.

But perhaps the most interesting result attests to the survival prospects for the Y. The myth of the Y as weak and irrelevant has led to ponderings about what will happen in the event that males become extinct. Musings by some biologists have projected the Y's demise anywhere from 125,000 to 10 million years from now. But Page's work shows that the Y may have staying power. The male chromosome contains stretches of DNA that are virtually identical mirror copies of each other, creating huge genetic palindromes (the equivalent of the sentence "MADAM I'M ADAM"). If one of these sections makes a hairpin bend in the middle, it appears capable of donating an intact gene to fix a defective copy on the neighboring section. In essence, the Y seems to have its own self-repair mechanism, a process called gene conversion, making reports of its impending demise highly premature. Because it is the male chromosome, the seat of human recklessness to some observers, controversy may never fully abate. Biologist Jennifer A. Marshall Graves of the Australian National University in Canberra argues that gene conversion in the palindromes represents a form of "genetic masturbation" that may not only fail to inhibit deleterious mutations but may even speed the process of the chromosome's decline. Page's terse response: "Ah, rhetoric and theory unburdened by experimental data."

Keep in mind, civilization has been with us (and we with civilization) for a mere 10,000 years (give or take). The low end of the range for projected male extinction is 125,000. I would be willing to bet good money that we (males?) will find a patch (or at least a half-way decent work-around) before then.

Dmitri's "Dogs": 40 Years Later.

Lyudmila Trut now oversees the fox breeding inaugurated by Belyaev. The March-April 1999 edition of American Scientist ran an article on the 40 year long experiment.

Early Canid Domestication: The Farm-Fox Experiment

Foxes bred for tamability in a 40-year experiment exhibit remarkable transformations that suggest an interplay between behavioral genetics and development

Lyudmila N. Trut

At an experimental farm in Novosibirsk, Siberia, geneticists have been working for four decades to turn foxes into dogs. They are not trying to create the next pet craze. Instead, author Trut and her predecessors hope to explain why domesticated animals such as pigs, cattle and dogs are so different from their wild ancestors. Selective breeding alone cannot explain all the differences. Trut's mentor, the eminent Russian geneticist Dmitri Belyaev, thought that the answers lay in the process of domestication itself, which might have dramatically changed wolves' appearance and behavior even in the absence of selective breeding. To test his hypothesis, Belyaev and his successors at the Institute have been breeding another canine species, silver foxes, for a single trait: friendliness toward people. Although no one would mistake them for dogs, the Siberian foxes appear to be on the same overall evolutionary path—a route that other domesticated animals also may have followed while coming in from the wild.

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Dmitri's "Dogs"

NARRATOR: Traits like coat color, or the way a dog carries its ears or tail, are determined by its genes. Genes are pieces of DNA, and they often come in subtly different versions. Every dog gets one copy of every gene from mom and one from dad. These genes can be mixed and matched in countless ways, but if the parents don't have it, the pup can't get it.

And that's what makes curly tails and patchy coats in dogs so mysterious. Wolves don't have them. It took a remarkable experiment in a most unlikely place, to solve this mystery. The place was the middle of nowhere, Siberia. And the experimenter was an out-of-favor Russian geneticist named Dmitri Belyaev.

Local fox farmers had asked Belyaev for help in breeding a less vicious animal. Belyaev began with the tamest foxes he could find. From their offspring, and for many generations thereafter, he chose only the tamest for breeding. He'd expected that each new generation would be a little less vicious, a little more tame. But by the tenth generation, he was seeing things he'd never expected.

RAY COPPINGER: All of a sudden his fox ears started down, his fox tails started up, they started to bark, which is not characteristic of foxes. They started to have different coats, all these little features that you can't imagine being in the wild type. I mean it's not a matter of selecting for, because they're not there to be selected for—that variation isn't there.

NARRATOR: What does tameness have to do with ears, and barking and coat color? Belyaev and his colleagues immediately went looking for an explanation. They checked the foxes' adrenaline levels—that's the hormone that controls the "fight or flight" response—and they found they were far lower than normal.

RAY COPPINGER: That would explain the tameness, they're just not afraid because they're not producing as much adrenaline. But where does the multi-colored coat come from? And somebody says right off the bat, "Hey, adrenaline's on a biochemical pathway that also goes to melanin, also has something to do with the animal's coat color." So there's a correlation between coat color now and the adrenal gland.

NARRATOR: Suddenly, it all started to make sense. As Belyaev bred his foxes for tameness, over the generations their bodies began producing different levels of a whole range of hormones. These hormones, in turn, set off a cascade of changes that somehow triggered a surprising degree of genetic variation.

JAMES SERPELL: Just the simple act of selecting for tameness destabilized the genetic make up of these animals in such a way that all sorts of stuff that you would never normally see in a wild population suddenly appeared.

NARRATOR: Most dog biologists now believe something very similar to what happened to these foxes also happened to a population of wolves more than 10,000 years ago. And the rest, as they say, is history: the world's first domestic animal.

The results of Belyaev's experiment in tranquil fox breeding tell a cautionary tale. Evidently the Law of Unintended Consequences applies to genetic engineering as well.

The full transcript of the program can be found on NOVA’s website.

Was Boas Bogus?

A reanalysis of the data used in the landmark study of craniometry by the now legendary Franz Boas shows that Boas fudged his figures.

Dr. Jantz said that Boas "was intent on showing that the scientific racism of the day had no basis, but he did have to shade his data some to make it work that way."

Nicolas Wade reported in the New York Times that Dr. Corey S. Sparks of Pennsylvania State University and Dr. Richard L. Jantz of the University of Tennessee reanalyzed the original data and were unable to arrive at the original conclusion made by Boas.

Two physical anthropologists have reanalyzed data gathered by Franz Boas, a founder of American anthropology, and report that he erred in saying environment influenced human head shape. Boas's data, the two scientists say, show almost no such effect

....

Boas measured the heads of 13,000 European-born immigrants and their American-born children in 1909 and 1910 and reported striking effects on cranial form, depending on the length of exposure to the American environment.

But in re-examining his published data, Dr. Corey S. Sparks of Pennsylvania State University and Dr. Richard L. Jantz of the University of Tennessee find that the effects of the new environment were "insignificant" and that the differences between parents and children and between European- and American-born children were "negligible in comparison to the differentiation between ethnic groups," they are reporting today in The Proceedings of the National Academy of Sciences.

Here is the full text of the PNAS study.

Here is the full text of the NYT article.

Sexes Do Not Exist

Pick sex and height. The average male is taller than the average female. Yet the variation in height in men or the variation in height in women is several times greater that the difference between the averages.

Saying that “races don’t exist as a biological fact because the variation within a race is greater than the variation between races” is like saying that sexes don’t exist as a biological fact for the same reason. (It is also oddly self-refuting because it relies on a use of the idea of “race” in order to refute the same idea). The conclusion simply does not follow from the observation – even if we assume a univariate distinction to an inherently multivariate nexus of facts.

Researchers Try to Get into British Genes

Researchers will take blood from thousands of volunteers from Cornwall to Shetland and from Kent to Tyrone. The samples will then be used to isolate key pieces of DNA that best identify how the different races, tribes and invaders have influenced the country's modern population.

This data will not only be used to create a genetic history; it will generate vital information about patterns of diseases such as diabetes, Alzheimer's, heart disease and other conditions in various parts of the country. Such data could also provide researchers with ways of identifying people at risk of succumbing to common illnesses.

…

Scientists used two key pieces of DNA to get the answer. First, they used mitochondrial DNA which is passed on only by mothers; second, they exploited the Y chromosome, inherited only from fathers. The mitochondrial DNA of Orkney people was found to be similar to that of people in the rest of Britain, but the Y chromosomes of Orkney men were found to be Scandinavian. Thus science suggests that Viking raiders took local brides. By contrast, the Roman invasion is reckoned to have had only a minor genetic impact because few Romans settled in Britain.

It's in the Guardian so you know it's true.

Animal Rites

Animals have no rights for the same reasons they have no responsibilities. If you can figure out a way to sue a cat for trespassing, vandalism, or rodenticide, then we can talk.

Fat-Heads are More Clever

American Scientist has a readable review by Nathan Emery of Intelligence of Apes and Other Rational Beings by Rumbaugh and Washburn.

Here is a provocative piece from the middle of the review:

Rumbaugh was one of the pioneers of this research. He invented an apparatus featuring a keyboard monitored by a computer, which primates could use to communicate by means of a system of symbolic language. By striking special keys marked with lexigrams (symbols that represent a word), chimpanzees formed sentences ordering a vending-type machine to supply them food, drink, moving pictures and music. The use of automated systems has dominated Rumbaugh's thinking about animal intelligence ever since his early training in the theory of animal learning.

The sections of the text in which Rumbaugh and Washburn give a detailed account of technological advances in the testing of primate learning and cognition are perhaps the most rewarding in the book. Here are described Rumbaugh's Herculean efforts to test different primate species with discrimination learning problems and discrimination reversal tests (so-called learning sets), which test how a subject "learns to learn." The animal is repeatedly presented with a pair of stimuli, such as a red square and a yellow triangle, and always rewarded with food for choosing one—the red square, say—and not the other. Then an entirely new pair of stimuli are presented, with only one member of the pair being rewarded. A subject who, after seeing on that first presentation which stimulus is rewarded, always chooses it on subsequent trials has learned a rule and can transfer it to new stimuli. Rumbaugh found that the ability to transfer rules correlates with brain size in primates.

Someone needs to exhume Stephen Jay Gould and give him the bad news.

The full review can be found at the American Scientist Online.