Previously trapped disagreement among scientists about the effects of brain volume decline experienced by modern humans when early humans evolved from. Disagreement began when it was discovered that mentions during the last 20,000 years, the average human male brain volume decreased from initially 1500 to 1350 cubic centimeters cubic centimeters. The decrease was equivalent to a tennis ball.
Kathleen McAuliffe writes in Discover magazine said conditions are also similar to the proportion of women experienced the same decline. McAuliffe writings refer to the opinion of an anthropologist from the University of Wiconsin, John Hawks who declared brain volume decrease is not accompanied by a decrease of intelligence.
Opinion was also in line with other meyimpulkan Palaentolog brain capacity is decreased causing more efficient performance. However, there are also Palaentolog that says humans continue to become more stupid because it has undergone a long evolutionary time.
Disagreement is colored a number of theories that attempt to explain the shrinkage of brain volume. One theory is that large volumes of brain early humans needed to survive in cold environments and lots of outdoor activities. Another theory says even large skull that is designed to deal with sources of food such as rabbit, deer, foxes and horses.
"Head of the skull which allows early humans to eat," commented scientists support this theory as quoted Dailymail, Monday (3 / 1). While other experts said the high death rate in childbirth due to the size of the skull that is too large. Therefore, the infant mortality rate immediately shrink due to lower proportion in the modern human brain size.
A recent study initiated by cognitive scientists from the University of Missouri, David Geary and Drew Bailey, investigating how the size of the skull changed as a consequence of adaptation of modern human embryo with an increasingly complex social environment between 1.9million and 10,000 ago.
Sstudi causes, the low population density resulted in an increase in the size of the skull. However, when the original population rarely turn into solid, skull size also decreased.
Both agreed as modern humans, the brain grows smaller because people do not have to be smart to stay alive. However, Geary cautioned against stereotyping as a human ancestor that is more intelligent than modern humans. "Practically speaking, our ancestors are not as smart or creative as modern society because they do not have the support of culture," he explained.
Geary explains the improvement of the life patterns and the emergence of economic specification has enabled intelligent human beings to focus their efforts on the sciences, arts and other fields. "Our ancestors did not have a strong infrastructure to support them. Therefore, they only strive to live a life cycle," says Geary.
On the other hand, the Hawks believe the decrease in the size of a modern human brain shows increased intelligence. The brain, he explained, uses 20 percent of all fuel consumed. Therefore, a larger brain would require more energy and takes longer to develop. Hawks noted that the explosion of human populations between 20,000 and 10,000 years ago lead to mutations - an unusual but lucrative - happen. He believes that's what causes the brain to become more streamlined.
Separately, anthropologist Richard Jantz of the University of Tennessee actually find the modern human brain size getting bigger. The fact was revealed after he measure and compare cranial African-American and Europe from the late colonial era of the 20th century. "In fact, our brains develop," he said.