On the playground, girls are the keener climbers. In a set of four studies, girls climbed jungle gyms and monkey bars more often than boys, lingered longer at the top, and tackled an indoor rock wall with a different technique.
The work comes from Richard G. Coss, Victor K. Geisler and Michael Newmann of the Department of Psychology at the University of California, Davis. It was published in Evolutionary Psychology on July 15, 2025.
The authors frame their results as a possible echo of human evolution. In early hominins, males were much larger than females, which would have made tree climbing riskier for heavy males. The team asked whether traces of that difference still show up in how children climb.
Injury records and recess counts point the same way
Study 1 used an archival national injury database covering 1985 to 1989, which recorded emergency room visits for falls from stand-alone metal jungle gyms and monkey bars. Among 3,755 injuries to children aged 3 to 13, boys outnumbered girls before age 7, but from about age 8 more girls than boys were hurt.
Study 2 counted children actually climbing during two recess periods at 13 elementary schools, with data collected in the late 1980s and early 1990s. Overall, 3.14% of enrolled girls were on climbing structures at the moment of sampling, compared with 1.45% of enrolled boys.
The gap widened with age. In kindergarten to 2nd grade, 70 girls and 44 boys were climbing. In 3rd to 6th grade, the count was 47 girls and just 12 boys, as older boys largely abandoned the equipment.
Girls perch, boys keep moving
Observers in Study 2 noticed that girls on the equipment seemed more stationary. Study 3 tested that in a quiet community park, timing 6 to 8 year olds who climbed three jungle gyms alone.
Girls spent a much larger share of their climbing time perched at the top. On a dome structure, girls perched for about 75% of their climbing time versus about 35% for boys. On a pyramid, the figures were about 53% and 22%. On the shortest structure, there was no clear difference.
The authors suggest the perching may reflect a stronger interest in surveying the surroundings from a safe height, something that would have been useful for spotting danger.
Study 4 moved indoors to a beginners rock climbing class at a gym in Davis, California, filming 28 children aged 7 to 12. Girls clasped holds with both hands far more often (22.4% of reaches versus 7.3% for boys) and more often crossed one leg over the other to reach a hold. Boys more often dragged a foot and looked down to place their feet. Using four movement measures, a statistical model correctly sorted 84.6% of girls and 86.7% of boys by sex.
The authors are careful about the limits. Tree climbing itself was not studied, the playground data come from equipment that has since largely been replaced for safety reasons, and they write that their main explanation for the decline in climbing with age is the pull of other social and sports activities. They describe the findings as “though incomplete” support for their evolutionary idea.
They propose that future work use standardized climbing gym challenges, since the old metal jungle gyms that made these observations possible have mostly vanished from schools and parks.
Study Details:
- Title: Sex Differences in Children’s Motivation and Action Patterns for Climbing as Behavioral Relicts of Ancestral Sexual-Size Dimorphism
- Authors: Richard G. Coss, Victor K. Geisler, Michael Newmann
- Journal: Evolutionary Psychology
- Publication Date: July 15, 2025
- DOI: 10.1177/14747049251358630