Men can be choosy, women can get around according to UMSL biologist’s popular article on mating

J.C. Leyendecker "Easter" 1906. oil on canvas.

Victorian-era societal understandings of gender roles skewed scientific analysis of male and female sexual tendencies, assuming males to be promiscuous and females to be coy, according to Zuleyma Tang-Martinez. She’s a professor emerita of biology at UMSL. (Artwork by J.C. Leyendecker, CC)

It seems an age-old given – men are promiscuous, and women are coy. But are they really?

Zuleyma Tang-Martinez, a professor emerita of biology at the University of Missouri–St. Louis, recently tackled the theory in her article published in The Conversation online.

She notes that the first inklings of this assumption about males and females comes from the idea of anisogamy, or in plainer terms, the differences in size and presumed energy cost of producing sperm versus eggs. It seems right that females might be coy and selective in their mate choice when it takes so much energy to produce a single egg, while males produce millions of sperm to go around.

“In reality it makes little sense to compare the cost of one egg to one sperm,” writes Tang-Martinez, who points out that it takes millions of sperm to fertilize a single egg.

Charles Darwin was the first to make reference to anisogamy, falling in line with popular Victorian-era societal understandings of gender roles. Tang-Martinez argues that these understandings biased the research to come, specifically the 1948 research of botanist Angus Bateman.

Bateman attempted to prove with fruit flies that males have more mate variation while females are monogamous. The theory became known as Bateman’s Principle.

But science has come a long way since Bateman’s time. Not only does paternity analysis now exist, but accurate measurements of sperm count have offered concrete scientific evidence to the contrary.

Tang-Martinez notes that sperm counting shows that males practice mate choice by allocating more sperm for more desirable females.

And in songbirds, previously thought to be 90 percent monogamous, Tang-Martinez points to paternity tests showing multiple sires for offspring.

“Because of the assumption that reluctant females mate with only one male, many scientists initially assumed promiscuous males coerced reluctant females into engaging in sexual activity outside their home territory,” Tang-Martinez writes. “But behavioral observations quickly determined that females play an active role in searching for nonpair males and soliciting extra-pair copulations.”

She goes on to say that the number of offspring produced by a female increases with the number of mates. That in itself seems an obvious conclusion.

So maybe the age-old truth isn’t so true after all?

Read Tang-Martinez’s article for the more in-depth take and judge for yourself. Besides appearing in The Conversation, Tang-Martinez’s story has also run in Observer, Inverse Science, The Good Men Project and on Smithsonian.com.

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