Over the past half century, humanity as a whole has become stupid, scientists have found. Since the mid-1970s, IQs have fallen by an average of seven points for each subsequent generation. Some experts associate this with the ongoing human evolution, others with the laws of genetics, and still others with the rapid development of technology.
Measure volumes
Upper Paleolithic humans and Neanderthals had larger brains than ours. On average, in men, its volume was more than 1500 cubic centimeters versus modern 1425. Whether they were smarter than today's Homo sapiens is a big question, but some researchers find a positive correlation (albeit insignificant) between the size of this organ and the level of intelligence.
According to the Russian anthropologist Stanislav Drobyshevsky, the large brain size of ancient people is most likely due to the harsh conditions of existence. Cro-Magnons and Neanderthals had to keep all vital information in their heads, since artificial media, such as books, had not yet been invented, and old people, wise by experience, were extremely rare. After all, the average life expectancy was very short.
Modern people, on the contrary, find themselves practically in greenhouse conditions - they receive clothes, food, information in a ready-made form, and the knowledge accumulated by generations is stored on external media. In such an environment, a large, voracious brain, consuming up to 20 percent of the energy produced by the body, becomes unnecessary. This is probably why its gradual drying has been observed in the last 25 thousand years. Moreover, over the previous ten thousand years, it has shrunk by almost five percent.
Anthropologists at the University of Chicago associate such a marked decrease in the brain with a mutation that appeared in the farmers of the Middle East about six thousand years ago. Today, most of the representatives of the human population are its carriers, so the trend is likely to continue.
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Progress is not good
According to Gerald Crabtree, a geneticist at Stanford University (USA), over the past three thousand years, mankind has undergone at least two genetic mutations that have a negative effect on intelligence. There are likely to be several more similar changes in the future. He came to this conclusion based on the frequency with which harmful mutations occur in the human genome, and the estimated number of "smart" genes.
The scientist points out that the leap in the development of cognitive abilities and the optimization of the genes responsible for intelligence happened even before our ancestors left Africa. There they had to exist in rather harsh conditions, so the strongest, smartest and most adapted to the environment survived. In other words, natural selection worked to improve intelligence.
After migration to Europe, human life became much easier. The development of agriculture, the emergence of cities, the progress of medicine, virtually nullified natural selection. A large number of individuals with bad mutations in DNA appeared in the population. As a result, intelligence began to gradually decline.
Global drop in intelligence
Paradoxically, an increase in the level of intelligence was recorded in the twentieth century. This was discovered in 1984 by American psychologist James Flynn, who calculated that from 1932 to 1978 in the United States, the average IQ increased by almost 14 points. His data were subsequently confirmed in many countries.
However, last year, Norwegian scientists, after analyzing the test results of more than seven hundred thousand people, came to the conclusion that since the 1970s, average IQs have been gradually falling - by about seven points for each next generation. So, the IQ of people born in 1969 is about three points higher than that of people who are seven years older than them - 102.3 versus 99.5. But then the situation changes: the volunteers who passed the test, who were born in 1989, have an average result already less - 99.4 points.
This phenomenon can be traced even in individual families, where older brothers passed intelligence tests better than younger ones. This means that the matter, apparently, is not in the demographic situation or the spread of less successful genes in the population, the authors of the work note. Probably, the drop in IQ indicators, on the one hand, is influenced by a change in lifestyle - the development of technology, changes in education and upbringing, and on the other - the imperfection of the test itself, which is not able to assess the level of intelligence of a modern person.
Change in average IQ by year of birth. The data used were 700 thousand Norwegians born between 1962 and 1991.
In addition, the cognitive ability of people can be reduced due to severe environmental pollution, the Spanish researchers note. They measured the level of harmful impurities in the air in about 39 primary schools in Barcelona, and then tested the intelligence of the students. In ecologically safe areas, schoolchildren performed better on average.
Similar data were obtained by scientists from Lancaster University (UK), having analyzed a sample of 18 thousand little Britons. They found that children with mental retardation were more likely to live in areas with high air pollution than their peers.
Alfiya Enikeeva