Did Lower Testosterone Help Civilize Humanity?

A new study appearing Aug. 1 in the journal Current Anthropology finds that human skulls changed in ways that indicate a lowering of testosterone levels at around the same time that culture was blossoming. “The modern human behaviors of technological innovation, making art and rapid cultural exchange probably came at the same time that we developed a more cooperative temperament,” said lead author Robert Cieri, a biology graduate student at the University of Utah who began this work as a sen...

 Testosterone's Effect on Memory

Like many other areas of development, memory generally matures more rapidly in girls than boys. Beginning in the womb, female fetuses are known to habituate to auditory stimuli about two weeks earlier than males. After birth, they are more advanced at visual habituation. Toward the end of the first year, girls are about a month ahead in tests of short-term, explicit memory, like remembering, after a few seconds' distraction, where they just saw a toy being hidden. Girls also outperform boys o...

 How Testosterone Affects the Brain

We last met the steroid hormone testosterone in fish and birds where it was rendering them more vulnerable to parasites by exaggerating their sexual ornaments. In recent years more and more evidence has been found that testosterone affects not just ornaments and bodies but also brains. Testosterone is an ancient chemical. found in much the same form throughout the vertebrates. Its concentration determines aggressiveness so exactly that in birds with reversed sex roles, such as phalaropes and ...