Davide Piffer is an Italian evolutionary anthropologist. He received a BA in Anthropology from the University of Bologna and a Master of Science in Evolutionary Anthropology from Durham University in England. His Master’s thesis was on the sexual selection of sleep patterns among humans, and was the first to link mating behavior to chronotype (sleep patterns during a 24-hour period) within an evolutionary framework. His research later shifted to quantitative genetics, and he published one of the first studies of the heritability of creative achievement. In 2013, he switched to molecular genetics, focusing on the polygenic evolution of educational achievement and intelligence, and this remains his main focus. Within this area, his main finding is that ethnic differences in intelligence are largely explained by the thousands of genetic variants that predict cognitive abilities within populations.
Grégoire Canlorbe: You have made a well-known attempt to provide a theoretical framework within which creativity in science, philosophy, technology, music, mathematics, or literature can be defined and measured. How does your theory now stand?
Davide Piffer: Creativity is not a single cognitive function or ability. Hence, it is not possible to measure creativity with paper and pencil or computer tests, unlike, for example, intelligence, or working memory. Creativity is the capacity to produce creative products, such as scientific theories, poems, paintings, sculptures, inventions that are novel and useful or meaningful. Hence, the only way to measure a person’s creativity is by his creative output, which is the sum of the creative products over the lifetime of an individual (or a society or race).
A lot of cognitive abilities contribute to creativity, and in my paper (Piffer, 2012) I argued that the widespread assumption by researchers that divergent thinking is the sole measure of creativity is a mistake. In fact, there are many cognitive and personality predictors of creative achievement besides divergent thinking, such as IQ or general mental ability, working memory, openness to experience, and non-clinical schizophrenic tendencies (i.e. “shizotypy” to use the psychiatrist’s jargon). Hypomania, or the tendency to feel positive emotions, has been linked to creativity, as has bipolar disorder. All of these factors constitute what I call “cognitive potential.”
Divergent thinking (DT) is actually an important cognitive function which has generally been studied only as part of creativity research. However, studying it would benefit other areas of psychology as well. My opinion is that it would be better to regard DT as a form of intelligence, and to include divergent thinking measures in psychometric batteries and standardized intelligence tests, such as the WAIS. Since psychometrically it is correlated to general cognitive ability but it taps into different neurological substrates, it would provide a more complete picture of one’s mental power, possibly less tied to academic intelligence and more to artistic or daily-life accomplishments.
From an evolutionary perspective, the ability to come up with many original ideas and find a novel way to light a fire or kill an animal would have increased someone’s fitness more than the ability to, say, learn a mathematical equation or find the next number in a sequence. Moreover, divergent thinking predicts creative accomplishments above and beyond general intelligence, so the usual counter-argument by hard core “generalists,” that it’s all about g, doesn’t stand up from an evolutionary perspective.
As an anthropologist, I find it remarkable that a man’s intelligence as measured by IQ tests has practically no effect in increasing his attractiveness to women, whereas originality, sense of humor, and other creativity-related features can increase a man’s attractiveness. This is possibly because such things were better predictors of survival in the ancestral environment than conventional IQ, which taps into academic abilities that were not important for survival up until the creation of states with a high level of bureaucracy and the introduction of compulsory schooling. Another possibility is that artistic pursuits (which tap more heavily into divergent thinking abilities) were used by men to attract women. The sexy-brain hypothesis — that intelligence is attractive to women — has failed to find substantial support, but it does not necessarily have to be discarded, since it could have validity with regards to some specific cognitive abilities.
Another drawback of limiting creativity research is that the traditional measurements used in this field, such as divergent thinking or creative achievement, have been ignored by the currently hottest line of research, namely, behavioral genetics and genome-wide association studies. For example, the UK Biobank, which has been a rich resource for many studies, contains hundreds of anthropometric and psychometric measures but it totally ignores creative achievement or divergent thinking.
Grégoire Canlorbe: As Leonardo da Vinci pointed out in his notebooks, “The black races of Ethiopia are not products of the sun, for if in Scythia a black man makes a child to a black woman, the offspring is black; but if a black man inseminates a white woman, the offspring is gray. Proof that the race of the mother has as much power over the fetus as that of the father.” Besides skin color, how do you sum up what we know — or appear to know — about heritable racial differences in traits such as intelligence, creativity, or even the rate of maturation of male voices?
Davide Piffer: As I said, creativity has been neglected by geneticists and many psychologists, so unfortunately we know next to nothing about race or individual genetic differences in creativity. With regards to intelligence, there is a growing consensus, thanks to the work of myself and colleagues, that racial differences have a genetic basis. This comes from different lines of evidence, using the most recent methods of population genetics: admixture analysis and polygenic scores.
As for voice maturation, Philippe Rusthon proposed the theory that the Mongoloids are the most K-evolved and the Negroids are the least K-evolved, while the Caucasoids fall between the two, although closer to the Mongoloids. This theory is supported by a large amount of data. I made a new contribution to Rushton’s theory by presenting data on race differences in the age at which the voice breaks in boys. The prediction from Rushton’s theory and the hypothesis to be tested is that the voice should break at a younger age in Negroids than in Caucasoids. The hypothesis was successfully corroborated.
Grégoire Canlorbe: Your most conclusive investigations in behavioral genetics deal with the connection between sexual selection and sleep patterns — or that between sexual selection and both sex- and country-level differences in performance on tests of fluid intelligence. Could you tell us more about it?
Davide Piffer: I was the first to investigate the relationship between sleep patterns and sexual behavior among humans as part of my MSc’s dissertation at Durham University. My original work was later replicated by a researcher from Sri Lanka and a group from Germany. Sleep is well known to affect mating behavior in many animal species, and some heritable differences in chronotype also predict mating success among men, both in Western and non-Western societies.
The effect seems to go above and beyond personality (extraversion) and the propensity to engage in social activities at night. Being a night owl is associated with going out at night, thus increasing the chances of meeting a member of the other sex, but also with testosterone levels. We still don’t know if it is also perceived as an attractive feature in males, but it has significant sex differences, with males across different societies being more likely to be night owls than females, so it is a candidate target for sexual selection.
Some years ago, I published a paper in which I proposed an explanation of the paradox that more developed countries, with higher equality of the sexes, had a higher sex inequality in IQ scores. That is, in more developed countries, men are smarter than women, but this sex difference is much smaller or absent in less developed countries. For example, in Muslim countries, women have higher ability than men, so we could call this the Muslim paradox. This is the opposite of what one would expect from a purely environmental perspective, because women get more education in sex-equal countries. What I found was that smarter countries had higher sex differences independent of GDP or equality of the sexes.
A potential mechanism that I did not mention in the paper but that occurred to me later is that in industrialized countries, dysgenic fertility is mainly driven by highly educated females having fewer children and later in life, whereas male intelligence is not generally related to reproductive success. This sex disparity in dysgenic fertility would cause women to decline in intelligence relative to men.
This may not seem obvious. Because both men and women contribute to the genotypes of children, the fact that high-IQ women have few children should depress the IQ of both sexes, not that of women only. The question is more subtle, however, because many complex traits have sex-specific mechanism of expression, so that the same allele has different effects in males and females, even if the genes are not located on the sex chromosomes.
Grégoire Canlorbe: You devised a methodology to detect polygenic selection, a mechanism that acts on many genetic variants simultaneously. You have done this in particular with educational attainment. How do you summarize your approach?
Davide Piffer: My approach moves away from classical methods that focused on a single gene, because most traits are polygenic — the result of contributions of many alleles, or gene variants — and the effect of each is so diluted that you need to study many genetic variants in order to detect a pattern of selection. The frequency of a single allele is mainly affected by genetic drift unless that allele has a very strong effect on a trait such as, for example, sickle-cell anemia. Natural selection also affects population frequencies of alleles, but the effect on a single allele is typically so small that it can go unnoticed. However, when you simultaneously look at hundreds or thousands of alleles, you start seeing a pattern because the effects of random drift on each allele cancel each another out, and what is left is the directional effect of natural selection, which acts more strongly on some populations than on others, according to the environmental conditions or the sexual dynamics across the millennia.
Of course, these alleles are not picked at random from the genome. They come from studies called GWAS (“genome-wide association study”) which explore the correlation between millions of genetic variants or SNPs (single-nucleotide polymorphisms) and some phenotype or trait, such as years of education or height, using very large samples (from 100,000 to over a million individuals). These studies then find the SNPs with the strongest phenotypic effect, that is those that can increase an individual’s IQ by half an IQ point or increase height by as much as a centimeter. [Editor’s note: A good explanation of GWAS methods is included in this book review.]
The average frequency of alleles weighted by their effect on the phenotype (e.g. IQ) is called the polygenic score. Polygenic scores can be used to predict how well individuals do in school, or their height, or risk for cardiovascular disease. These scores are based on direct biological evaluation of a subject’s genome, so they are unaffected by culture, family differences, or any other factor that is commonly claimed to invalidate traditional IQ testing. I calculated polygenic scores for populations by averaging the scores of samples from different ethnic groups available on public databases. In the case of educational attainment and intelligence, I used between 2,400 and 3,500 of the most significant SNPs to compute polygenic scores.
What I found was that these population-level polygenic scores had a very high correlation of r=0.9 with scores on standardized intelligence tests. Ashkenazi Jews have the highest polygenic scores, followed by East Asians, then Europeans, South Asians, Native Americans and Blacks. A correlation this high would occur at odds of only one in 46,000 if the SNPs had been chosen at random. Furthermore, the SNPs associated with the greatest intelligence differences between populations were also associated with the greatest differences between individuals within a single population. This supports the view that both kinds of difference were the result of selection.
Grégoire Canlorbe: It may be worthwhile to try to measure race differences in imagination, perhaps by comparing the abundance and inventiveness of metaphors in a nation’s poetic production. It may be worthwhile to investigate the correlation between scientific progress and what may be called the infrastructure of fantasy: the stock of dreams and legends each nation has. Do you think such an inquiry would confirm Albert Einstein’s notion that “imagination is more important than knowledge” for scientific progress?
Davide Piffer: I think imagination is more important than knowledge for scientific breakthroughs or revolutionary science, but in most labs around the world, scientific progress is 99 percent perspiration and 1 percent inspiration. A more systematic approach would be to measure divergent thinking or creative achievement scores across ethnic groups, but unfortunately no one has made a systematic attempt at this.
Grégoire Canlorbe: You made the claim that the north-south difference in Italy in fluid intelligence should be understood in terms of genetic differences between the populations. What data corroborate that hypothesis?
Davide Piffer: Historically, literacy levels and economic prosperity have been higher in the north than in the south. Data collected by Richard Lynn have shown that these differences are reflected in scores on tests of intelligence and scholastic aptitude (PISA and INVALSI).
There are strong genetic differences within Italy, recently corroborated by an in-depth study (Raveane at al., 2019). These differences were mostly established in pre-Roman times: Bronze-Age migrations from the Eastern European steppes (Indo-Aryans) in the north and West Asians from the Caucasus in the south. The Latin people who founded ancient Rome belonged to the Indo-European/Aryan group, along with other Italic tribes, such as the Veneti who later founded Venice.
Later migrations strengthened the pre-existing differences. In the first millennium BC, groups of Celtic people (originating from Indo-Aryans, like the native northern Italians such as the Veneti and the Ligurians) settled in the north and mixed with their ethnic cousins (that is why the Roman name for northern Italy was Gallia Cisalpina), and the Greeks heavily colonized the South (Magna Graecia) in the 1st millennium BC. In the Middle Ages, Germanic people invaded Italy and mostly added to the genetic pool of northern Italy (mostly Lombards and Gothic peoples) with some pockets in central and southern Italy (the Lombards in the Ducato di Benevento and the Normans in Palermo), whereas the south was conquered by Arabs.
Grégoire Canlorbe: It has been hypothesized that race differences in ethnocentrism can affect the number of geniuses in a society. High ethnocentrism would preserve genetic homogeneity but keep the gene pool from becoming diverse enough to allow for the emergence of genius; lower ethnocentrism would sacrifice kin solidarity for a more diversified gene pool that would make the appearance of genius more likely.
Since the days of Ancient Rome, Italians have maintained kin solidarity (through the persistence of extended, instead of nuclear, families) and high levels of ethnocentrism, but also created a “culture of genius” from which sprang some of the greatest minds in history. Do Italian achievements refute this theory?
Davide Piffer: I am not very familiar with this theory but I am not sure that ethnocentrism would necessarily hinder the development of a sufficiently diverse gene pool to allow for the emergence of geniuses. Jews are highly ethnocentric but they have the highest percentage of geniuses of any ethnicity, as shown by Richard Lynn (2011). Also, let’s not forget that Italy was settled throughout history by people of different ethnic backgrounds: Neolithic farmers, Bronze Age steppe pastoralists, Celtic and Germanic tribes, Arabs, etc. Moreover, Italy reached political unity only relatively recently and each region had developed its own genetic landscape thanks to drift, migrations, and local selection. A very recent study found that Italy has the largest degree of genetic population variation so far detected in Europe (Raveane at al., 2019). So, thanks to its geographic position and historical events, Italy had both a relatively high degree of kin solidarity and an extremely diverse gene pool. I think this solves your paradox.
Grégoire Canlorbe: Besides your scientific inquiries, you have a keen interest in Renaissance poetry, and even wrote a book of poems titled “Note d’Alambicco.” Galileo compared your two favorite poets of that period — Tasso and Ariosto — in his work Considerazioni al Tasso. How do you rank Tasso and Ariosto?
Davide Piffer: Galileo considered Ariosto’s work superior to that of Tasso. In retrospect, his analysis was correct because literary critics and the public at large today usually prefer Ariosto. This is because Galileo the scientist liked the less flamboyant writing style and the ironical skepticism of Ariosto, as opposed to Tasso’s taste for words for their own sake and lack of realism. I think Galileo’s critique of Tasso was too harsh, since his poetry also had merit. Galileo knew the whole Orlando Furioso by heart, a “poem” of over 38,000 verses divided into 46 canti. I found this impressive; I quit my attempt at memorizing it before I reached the end of the first canto.
Memory and intelligence are positively but not highly correlated. It also seems that pre-modern people had much better memories, perhaps for genetic reasons or because they had no technology and had to depend on memory alone. Nowadays, we can google anything we can’t remember so there is not much pressure to learn things by heart.
Grégoire Canlorbe: Thank you for your time.
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Piffer, D. (2012). “Can creativity be measured? An attempt to clarify the notion of creativity and general directions for future research.” Thinking Skills and Creativity, 7, 258-264.
Raveane et al. (2019). “Population structure of modern-day Italians reveals patterns of ancient and archaic ancestries in Southern Europe.” Science Advances, DOI: 10.1126/sciadv.aaw3492
Lynn, R. (2011). The Chosen People: A Study of Jewish Intelligence and Achievements. Augusta, GA: Washington Summit Publishers.