Decline in testosterone levels led to the rise in modern culture among ancient humans, according to a new study.

Findings of the study have been published in the journal Current Anthropology.

For the study, which was conducted by a University of Utah biology graduate student, saw examination of over 1,400 ancient and modern human skulls.

Robert Cieri and his colleagues found that as time passed by, characteristics of humans became more feminine, a clear indication of lowering testosterone levels, according to the study.

Levels of testosterone started to feel at a time when humans started to develop technology and culture some 50,000 years ago.

The appearance of modern humans was showed by the fossil record about 200,000 years ago.

"A reduction in testosterone makes people more socially tolerant. It makes them more cooperative and, as a result, people can more easily learn from and teach one another," Cieri said, according to the study.

Researchers noticed in the skulls that brow ridges receded and the length of the face between the eyes at the top of the jaw shortened around 50,000 years ago.

This doesn't mean that lower levels of testosterone were intended to make people more feminine, but it did help eliminate the hyper-masculine ones.

Reduced levels of testosterone played a positive influence on human beings as they no longer behaved overly aggressive. This helped humans create innovative technology.

Humans developed bone and antler tools, projectile weapons, grindstones, fishing and birding equipment, and a command of fire some 50,000 years ago.

"Human fossils from after modern behavior became common have more feminine faces, and differences between the younger and older fossils are similar to those between faces of people with higher and lower testosterone levels living today," Cieri said.

Humans also started to stay closer with one another, which helped them have a culture and learn from one another. 

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