Overstating What Science Tells Us About Gender

[Crossposted on Alas, TADA and Family Scholars Blog.]

Ronald Wilcox says that women should be in charge of long-term investments, while men should do the grocery shopping. It’s biology!

Just as men’s hunting instincts help make them inferior investors relative to women, women’s gathering instincts can wreck household finances as well. In the context of modern markets, women are aggressive shoppers. They enjoy shopping, spending money, and, unfortunately, do it to excess more often than men do. Men lose money at the stockbroker’s office; women lose it at the shopping mall.

It’s refreshing to see someone call upon our hunter-gatherer past to argue we should change our gender roles from the status quo. But apart from that, Wilcox’s article is an unfortunately typical example of how science is exaggerated, misused, and misinterpreted to argue that our behaviors are hardwired according to gender.

First point: We don’t even know if the earliest humans were hunter-gatherers. Many anthropologists now argue that early humans were scavengers, not hunters. (1 2 3 4) Like many “brain sex” writers, Wilcox doesn’t exhibit much knowledge of the science he refers to, treating currently active debates within the expert literature as if they were firm and settled conclusions.

Second point: The gender differences Wilcox points to, when they’re applicable, are tiny. The study of gender-and-investors Wilcox cites (pdf link) does find that men are more likely to be overconfident and to trade more often (leading to men paying more in fees). But how big a difference in returns did the study actually find?

…women earn net monthly returns that are 0.143 percent lower than those earned by the portfolio they held at the beginning of the year, while men earn net monthly returns that are 0.221 percent lower than those earned by the portfolio they held at the beginning of the year.

The difference was less than a tenth of one percent — and the differences between married men and women were even smaller. Furthermore, despite trading more often, the men in this study actually grossed slightly more than the women. Wilcox’s conclusion — that husbands shouldn’t make investments– is an entirely unreasonable conclusion, not supported by this evidence.

Since the evidence shows only a tiny difference between husbands and wives as investors, a more reasonable conclusion is that gender should be irrelevant when deciding who should be in charge of investments. Wives and husbands should divide this task up according to their individual talents, not based on what Mr. Wilcox imagines life on the Savannah was like.

Third point: Wilcox’s makes enormous logical leaps based on inapplicable evidence.

Wilcox argues that women — due to their evolutionary past as gatherers — are born shoppers, citing a 2007 study called “Spatial Adaptations for Plant Foraging: Women Excel and Calories Count.” (pdf link.) The study found that women were nine degrees (on a scale of zero to 180) better than men at remembering which direction particular food items were in, in a farmer’s market. In addition, both women and men remembered the locations of high-calorie foods (such as “olive oil, almonds, honey and avocados”) more accurately. Surprisingly, the researchers found no connection between what items people actually bought, and remembering where those items were located: “Participants did not point more accurately to foods that were more liked or eaten more often, nor to stalls that were liked more or shopped at more often.”

Nothing justifies leaping from this nuanced and subtle study to the sexist claim that “women’s gathering instincts can wreck household finances.” The study may have found interesting evidence of a gathering instinct that makes women slightly better at finding food, and makes both women and men better at remembering high-calorie foods — but the study also found a lack of connection between this ability and shopping decisions!

Perhaps the answer is in a study called “Tightwads and Spendthrifts” (pdf link), also cited by Wilcox, which found that men are more likely to be tightwads. But what the study’s numbers show is that the large majority of both men and women are neither tightwads nor spendthrifts. The main difference is that there are 9% more spendthrifts among women than men. It’s unreasonable to use 9% of women to generalize about all wives, but that’s what Wilcox does.

To extrapolate from this evidence to a declaration that husbands have a “natural aversion to [shopping] that is likely to lead to stronger household balance sheets,” while wives “can wreck household finances as well…. They enjoy shopping, spending money, and, unfortunately, do it to excess more often than men do…. women lose it at the shopping mall” is ridiculous. In the end, Wilcox is just arguing that sexist stereotypes about women and men are true — but if we look at the evidence Wilcox cites, his conclusions fall apart.

Unfortunately, this misuse of evidence is very common behavior in best-selling pop science writing about gender and behavior, from Leonard Sax to Louann Brizendine. In general, if you don’t have time to look up the original studies and see what they said, it’s probably best not to trust the pop science writers on this subject at all.