Men do better than women at most tests of spatial awareness, but not all. A new study set in a farmer’s market shows that women outperform men at remembering the locations of food, particularly the most calorific ones.
When men and women do the grocery run, their evolutionary histories play out among the aisles of food in subtle ways. Women are more likely to remember where things are; men are better at plotting efficient paths through the smorgasbord of choice. These different abilities are the result of evolutionary adaptations that took place when we were still hunting and gathering.
The evolution of sex differences
The brains of men and women are clearly different, and rarely more so than in the realms of spatial awareness. In most tests of spatial ability, men routinely outperform women. But to Irvin Silverman and Marion Eals, this crude assertion crumbled under an evolutionary spotlight.
In 1992, the duo noted that our mental abilities were not created from a vacuum – they evolved to allow us to cope with different adaptive challenges. And for the men and women of our dim evolutionary past, these challenges were very different.
Back in the day, when we were still living as hunter-gatherers, men did most of the hunting while women excelled at gathering. And these jobs required very different spatial skills. Hunters, for example, needed to chase their prey over unfamiliar and winding routes; once they had killed, they needed to work out the quickest route home.
It’s makes sense then that men tend to be better than women at plotting out the quickest and most efficient route to a place they have been before, a skill called ‘vector integration’.
Gatherers use quite different spatial skills. They can afford to stick to familiar locales and their quarry – fruits, nuts and the like – sit still, but vary in quality throughout the year. As such, the brain of an efficient gatherer needs to store an accurate mental map of the best food sources in the local area, almost without thinking about it.
Many classic psychological tests for spatial awareness favour the male speciality of vector integration – including navigation and mental rotation tests. Some scientists have designed tests to look at the object-mapping that women should excel at. While some of these have shown hints of a sex difference, they have all been unrealistic in some way – it was a computer test, or the subjects were asked to look for irrelevant things.
A realistic test
Enter Joshua New and colleagues from Yale University and the University of California, Santa Barbara – they decided to test Silverman’s and Eal’s idea in a realistic setting, where subjects had to walk over a large space in order and search for food – a modern market.
They recruited 41 women and 45 men at the entrance to a farmer’s market, using a cover story of doing survey about the market. Each person was also asked to rate their own sense of direction (which other studies have found that people do with remarkable accuracy).
The researchers then led the volunteers on a circuitous route to six different food stalls, where they were given different foods to eat. They were then taken to the centre of the market, out of sight of all the stalls, and asked to aim a pointer at each of the different foods.
Sure enough, even though men claimed to have better senses of direction, the women outperformed them and pointed to the locations of the stalls with 27% greater accuracy.
This result is all the more striking because the task involved vector integration. That really ought to have favoured the men and indeed, in most similar tasks, men do enjoy the advantage. But New’s experiment shows that when food is involved, it’s the women who gain the upper hand.
The most calorific foods stuck most strongly in the women’s minds, a result that will surely worry but hardly surprise most female readers. The volunteers were much more likely to accurately pinpoint the location of high-calorie foods like almonds, honey and avocadoes, than low-calorie ones like cucumbers and lettuce.
It didn’t matter how much they liked these foods, or how often they’d eaten them before – nutritional value was the only thing that significantly affected their accuracy.
Could it be that the women simply had more experience with food shopping? Not according to New – in his test, the scores of both sexes were completely unrelated to the number of times they had been to the market before. And in other studies, women have shown no advantage over men where tasks involve generic non-food items, and men have proven to be better at memorising the layout of a shopping centre.
Certainly, the fact that nutritional foods were remembered more accurately suggests that the women’s proficiency in this area evolved in a foraging context. Foraging is a lifestyle that we relied on for the vast majority of our history as a species – it’s no wonder that it continues to shape our food-finding habits today.
More on gender differences:
More on the evolution of personality traits:
Reference: New, Krasnow, Truxaw & Gaulin. 2007. Spatial adaptations for plant foraging: women excel and calories count. Proc Roy Soc B doi:10.1098/rspb.2007.0826