Newly published research has revealed that when walking with female romantic partners, males tend to slow down by about seven percent.

Everyone has an optimal walking speed that minimizes how much energy they use. This optimal speed varies, depending on physical features such as mass and lower limb length, and so males in any given population tend to have faster optimal walking speeds than females. Given this difference, it is not exactly clear what happens in walking groups containing mixed sexes. In order to walk together, someone within the group will have to pay the energetic cost of deviating from their own optimal speed.

The authors of this study examined speed choices when people walked around a track alone, with a significant other (with and without holding hands), and with friends of the same and opposite sex.  Their study included 22 people, 11 men and 11 women which made up 11 romantically involved couples. They discovered that males walk at a much slower pace to match the females’ paces, only when the female is their romantic partner. The paces of friends of  either sex walking together did not significantly change,which suggests that pace adjustments occur only for romantic partners.

Surprisingly, when the females walked together, they walked even slower than they did with their partner. Researchers say this could relate to previous work showing that women report feeling very close to their female friends. On the other hand, men report not feeling as close to their friends of the same sex and tend to walk even faster when grouped with them.

These findings could have implications for both mobility and reproductive strategies of groups, and could help interpret fossil footprint trails and hunter gatherer strategies.

This research was conducted by Cara Wall-Scheffler and colleagues at Seattle Pacific University and published in the open-access journal PLOS ONE.