One claim to such disparity has been attributed to biology. The idea there’s some kind of ‘superdiversity’ among male brains has been repeatedly cited in the scientific literature in recent decades; but according to a newly published meta-analysis, this argument for male success is entirely unsupported by evidence.
“Based on our data, if we assume that humans are like other animals, there is equal chance of having a similar number of high-achieving women as there are high-achieving men in this world,” says biologist and lead author Lauren Harrison from the Australian National University (ANU).
“Based on this logic, there is also just as great a chance of having a similar number of men and women that are low achievers.”
Most research on diversity within various species tends to focus on differences between the sexes. It’s not hard to find numerous and extreme examples of dimorphism; even within our own species, contrasts in sex chromosomes are responsible for exaggerating a litany of anatomical characteristics, such as beards or boobs.
Since the late 19th century, with the writings of the famous English sexologist Havelock Ellis, the assumption that larger male brains equal greater potential for cognitive prowess has been used to explain why men ‘deserve’ positions of influence and command.
Much has since been written on whether statistical differences across the sex divide translate into anything truly significant (short answer – they don’t), but few studies have looked into whether anatomical diversity within one sex provides for a greater spectrum of behavior.
Generalizing the assertion towards non-human animals, in this new meta-analysis the team investigated whether equivalents of our own personality traits across 220 species varied to any great extent within either of the sexes.
In spite of a thorough search of some 10,000 studies, the team couldn’t find any compelling evidence demonstrating greater richness of variability within the personality traits of males or females of any of the species included.
That’s not to say there were no differences across species as a whole. Some select characteristics, such as immunity or certain morphological traits, were also found to vary considerably within sexes in particular species.
But if we’re to use nature as a proxy for our own expanse of variation within male brains as suggested in the past, we can only conclude the rich landscape of female brains provides just as much opportunity for genius (and nonsense) as the male’s.
“If males are more variable than females, it would mean there are more men than women with either very low or very high IQs,” says one of the authors, evolutionary biologist Michael Jennions from ANU.
“But our research in over 200 animal species shows variation in male and female behavior is very similar. Therefore, there is no reason to invoke this argument based on biology to explain why more men than women are Nobel laureates, for example, which we associate with high IQ.”
A lack of evidence in favor of behavioral variation among men doesn’t rule out other biological explanations for the shatter-proof glass ceiling that permeates so much of modern society.
It does, however, limit arguments for that ceiling being a result of our biological wiring, and thus being something that we can’t – or shouldn’t – do anything about.
Dismantling notions that male merit is cemented in biology might even help to break down the social structures that are actually responsible for gender biases.
“Instead of using biology to explain why there are more male CEOs or professors, we have to ask what role culture and upbringing play in pushing men and women down different pathways,” says Harrison.
This research was published in Biological Reviews.