Great-grandfathers were smarter than us
Geneticists have elevated the intelligence of Victorians over modern
Denis Strigun, Naked Science
The most important microevolutionary, social and economic changes of mankind are associated with the Holocene – an epoch that began about 11.7 thousand years ago. The emergence of the first cities, the invention of many new agricultural tools, monotheism, aristocracy and money date back to this time. It is assumed that in the Holocene Homo sapiens also received lactase persistence (high enzyme activity in adulthood), relative resistance to hypoxia in the mountains and general cognitive ability (GCA), or intelligence. The development of the latter determined military and technical superiority, and therefore survival, and had to be determined genetically.
The high heritability of GCA is confirmed by genetic studies: according to various estimates, the indicator is 22-88 percent. Moreover, genome-wide association search (GWAS) has repeatedly revealed a correlation between specific snips (single nucleotide polymorphisms, SNPs) associated primarily with the central nervous system (CNS) and academic performance. In particular, such variations – they are combined into polygenic indices, POLYCOG – explain 60 percent of the individual variability of intelligence. Until now, however, there has been no reliable evidence that population growth and cultural boom in the Holocene were accompanied by an increase in genetic variations of GCA.
To fill the gap, experts from Chemnitz Technical University, the Free University of Brussels and other institutions compared 99 samples of ancient (from Eurasia) and 503 modern people (from Europe). The age of the first was 1208-4557 years. The authors compared three POLYCOGS. The results showed that the number of specific alleles in Holocene samples did increase over time, and the modern human genome contains more GCA-associated variations than in the Bronze Age. At the same time, the sign seems to have reached its peak in the Victorian era, and in the XX century the growth of its diversity not only slowed down, but also reversed.
The occurrence of the most common group of "cognitive" SNPs
depending on the year (Woodley et al., bioRxiv, 2017).
According to the authors, despite the increase in the average level of intelligence relative to earlier periods, the modern European is probably inferior to the Victorians. The reason for this may be natural selection: in the XV–XIX centuries, a high social status (correlated with GCA) helped to ensure survival, the owners of which, thus, had a demographic advantage. With a decrease in social mobility among carriers of a larger number of variations, competition increased, which actively drove progress – it was reflected in the industrial revolution. However, with the growth of the population, the availability of medicine and the restriction of fertility in favor of long-term education, the trend has changed.
It is worth noting that the article Holocene selection for variants associated with cognitive ability: Comparing ancient and modern genomes is published on the preprint server bioRxiv.org and has not yet been reviewed for publication in a scientific journal. In addition, earlier, the lead author of the study, Michael A. Woodley, stated that modern man would also lose to Victorians in reaction speed, and co-author David Piaffe (Davide Piffer) he argued in favor of the hypothesis that Africans have, on average, a lower level of intelligence than Europeans.
Meanwhile, scientists have recently found that a high IQ is associated with a reduced risk of death from most common causes.
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19.07.2017