Data shows that male animals are not naturally promiscuous, nor are females naturally reticent

It's a commonplace that in the natural world, males attempt to mate with multiple females, while females attempt to entice males into being monogamous; this is attributed to the high cost of producing an egg and bearing children (or laying eggs) for females, and the low cost of sperm production for males.

It's also — not coincidentally — offered as an explanation for social inequalities and injustices, held up as proof that these are reflections of the "natural order" and not an oppressive, morally indefensible state of affairs perpetuated to the enduring advantage of the men who advocate it over the women who are kept down by it.

This theory, called "anisogamy," is part of a fabric of "evolutionary psychology" fairy-tales that hold up unfalsifiable hypotheses as science, cherry-picking examples of animal behavior to prove that human injustices are not the fault of their perpetrators, but rather, the inevitable result of our animal natures. As pioneering biologist Anne Innis Dagg wrote in her essential "Love of Shopping" is Not a Gene, the science behind this received wisdom is paper-thin, and the only thing thinner than the science is the skin of the scientists who advocate it, and go on the attack any time someone subjects their work to adversarial peer-review.

In a fantastic essay in The Conversation, University of Missouri-St. Louis Professor Emerita of Biology Zuleyma Tang-Martinez describes the inability of anyone to reproduce the 1948 experiments by botanist Angus Bateman that established the evidence in support of anisogamy, and the mounting body of empirical research — grounded in molecular paternity analysis — to show that sexual promiscuity and reticence are distributed evenly among males and females of different species, each of which has hit on its own strategy for evolutionary and reproductive success.

Unconscious biases and expectations can influence the questions scientists ask and also their interpretations of data. Behavioral biologist Marcy Lawton and colleagues describe a fascinating example. In 1992, eminent male scientists studying a species of bird wrote an excellent book on the species – but were mystified by the lack of aggression in males. They did report violent and frequent clashes among females, but dismissed their importance. These scientists expected males to be combative and females to be passive – when observations failed to meet their expectations, they were unable to envision alternative possibilities, or realize the potential significance of what they were seeing.

The same likely happened with regard to sexual behavior: Many scientists saw promiscuity in males and coyness in females because that is what they expected to see and what theory – and societal attitudes – told them they should see.

In fairness, prior to the advent of molecular paternity analysis, it was extremely difficult to accurately ascertain how many mates an individual actually had. Likewise, only in modern times has it been possible to accurately measure sperm counts, which led to the realization that sperm competition, sperm allocation and sperm depletion are important phenomena in nature. Thus, these modern techniques also contributed to overturning stereotypes of male and female sexual behavior that had been accepted for more than a century.

Data should smash the biological myth of promiscuous males and sexually coy females
[Zuleyma Tang-Martinez/The Conversation]

(Image: Where Did I Come From?, Peter Mayle and Arthur Robbins, Lyle Stuart Inc)