The pace at which we choose to walk, or possibly the pace chosen for us many thousands of years ago, depends on if we are alone, the sex of the other walker, and our relationship to our walking partner, according to a study published Wednesday in the online journal PLOS ONE.
Researchers tracked 20 students walking around the track in five different scenarios: a man by himself, a man with a man, a man with a woman, a woman with a woman, and a woman by herself.
Results showed that males in general walked faster than females. Males tended to increase their pace when walking with other males. Female and male friends walking together struck a pace in the middle of their respective speeds. Males walking with a significant other slowed all the way down to the pace of their female counterparts. Females walking together walked slower than the pace they walked alone.
Researchers applied each finding to the hunter-gatherer society.
In the hunting and gathering way of life, males and females travel separately to maximize each other's walking speeds; men would be slowed down and women would get too tired if they mixed. Though women tend to walk slower when grouped together (due to more intimate feelings than male-male pairs), the effect is "minimal" according to researchers. Also, females walking together slow each other down less than they would if they walked with males.
"In indigenous, hunter-gatherer populations -- groups who are walking huge amounts -- we see females walking together with other females and we see men tending to walk by themselves or maybe with one other individual," anthropologist Cara M. Wall-Scheffler of the University of Washington, Seattle, who led the study, told the Los Angeles Times. "That's typical, cross-culturally."
Males may walk faster together, but that increased pace expends too much energy. Their optimal pace is achieved when walking alone, according to the research.
When men walk with a woman they are interested in sexually, researchers posit they're the ones to cede the pace in order to ensure all the women's resources are spent towards reproductive success. The male reproductive system is more resilient to physical exertion than the female's, according to the study.
"By men slowing down, the female reproduction is protected, and that's not something that is trivial," Wall-Scheffler said. "There is so much data that when women are able to reduce the amount of energy they spend walking, they have more children."
Men won't slow down as much for females they aren't attached to because they are less interested in reproductive outcomes, the study showed.
Wall-Scheffler believes in her team's comparison, but isn't sure if the results mean nature selected for male-female walking traits thousands of years ago.
"I definitely think there is an evolutionary outcome," Wall-Scheffler said. "Whether or not selection has acted on this behavior so that we still see it among men today -- I don't know if I could go that far."
