Controversy about the intellectual decline of humanity

An American scientist asserts that the intelligence of humanity is decreasing, but many researchers oppose his hypothesis.

Gerald Crabtree, a researcher at Stanford University in the US, has published an article in Trends in Genetics magazine about human intellect. He thinks that people are becoming more and more intelligent thanks to the evolutionary pressure from the environment. For example, prehistoric people can only exist if they hunt or gather good. So they always have to think of ways to improve the efficiency of hunting and gathering. But since people lived in crowded populations a few thousand years ago, that pressure disappeared, Livescience reported.

'The intellectual development of mankind is likely to take place quite quickly when our ancestors have no language and live in groups scattered in Africa. After we know how to plant trees, raise cattle and live concentrated in residential areas, human intellect has grown more slowly, ' said Crabtree.

About 2,000 to 5,000 genes determine people's intelligence. Those genes are very easy to change before environmental changes. Crabtree and colleagues affirmed that, on average, each person suffered two intellectual-related mutations in the past 3,000 years.

Crabtree's hypothesis encounters opposition from many scientists. Some argue that human intelligence does not decrease, but that we are diversifying intelligence. For example, Thomas Hills, a psychologist at the University of Warwick in the US, says mutations in intellectual decision genes cannot reduce intelligence. Instead, today's comfortable life allows human intelligence to divide into many categories. People today have the intelligence of language, emotion, body, logic, space, music. Some people point out that the average human intelligence index has increased over the past 100 years.

However, Crabtree asserted that the intelligence index increased due to the achievements in maternity care, better nutrition and the fact that people rarely have to deal with harmful chemicals for the brain.