Behavioral Ecology Blog

Woman’s fertility cycle affects brain- (Didn’t we always know this)

A woman’s hormones affect specific parts of the brain called the reward pathway, researchers said on Monday in a finding that could offer insight into treating drug abuse and mood disorders.

A study of women playing an imaginary slot machine game showed their brain responses changed in anticipation of a payout depending on the phases of their menstrual cycles.

This might help explain other studies that show women get a bigger kick from cocaine and amphetamines during one phase of the fertility cycle — and perhaps why women are less vulnerable to schizophrenia than men are, the researchers said.

Anthropologist confirms ‘Hobbit’ indeed a separate species

After the skeletal remains of an 18,000-year-old, Hobbit-sized human were discovered on the Indonesian island of Flores in 2003, some scientists thought that the specimen must have been a pygmy or a microcephalic — a human with an abnormally small skull.

Not so, said Dean Falk, a world-renowned paleoneurologist and chair of Florida State University’s anthropology department, who along with an international team of experts created detailed maps of imprints left on the ancient hominid’s braincase and concluded that the so-called Hobbit was actually a new species closely related to Homo sapiens.

How does one sex grow larger than the other?

A group of 13 researchers from 10 countries investigated the latter questions using comparative data on 155 species of insects and spiders (arthropods) from 7 major groups.

The results, published in the February issue of The American Naturalist, suggest that, generally, growth rate differences between the sexes are more important than growth period differences in mediating size dimorphism in arthropods.

Does Evolution Select For Faster Evolvers?

It’s a mystery why the speed and complexity of evolution appear to increase with time. For example, the fossil record indicates that single-celled life first appeared about 3.5 billion years ago, and it then took about 2.5 billion more years for multi-cellular life to evolve. That leaves just a billion years or so for the evolution of the diverse menagerie of plants, mammals, insects, birds and other species that populate the earth.