Lead author Lynne Isbell, a professor of anthropology at the University of California, Davis, said she initiated the study after noticing the paucity of female speakers at the annual meeting in April of the American Association of Physical Anthropology.
"I started wondering if this was a fluke, or something we hadn't noticed before," Isbell said in a statement.
Isbell and fellow anthropology Professor Alexander Harcourt and Truman Young, a professor of plant sciences, also at the University of California, Davis, analyzed programs from 21 annual meetings of the association, focusing on sessions on Isbell's own field, primatology -- the study of lemurs, monkeys and apes.
They tallied the genders of speakers at symposiums, which are generally viewed as more prestigious; those giving shorter oral presentations; and those presenting posters, which are often given by junior researchers and graduate students and seen as the least prestigious.
The study, published in the journal Plos One, found symposiums organized by men had half the number of female speakers (29 percent0 as those organized by women (64 percent) or by men and women (58 percent).
Women were far more likely to make poster presentations than give talks, while men presented more talks than posters, the study said.
The findings were surprising, Isbell said, because primatology is dominated by women, and there are many senior women, following pioneers such as Diane Fossey and Jane Goodall, with long and distinguished careers.
"If it can happen in primatology, what's happening in other fields with fewer women?" Isbell asked.