In rock climbing, the sport considers the Ape Index when evaluating the factors critical for success.
However, the majority of successful climbers are lithe and slim with less than 8% body fat. As one professional described it
“I feel very pressured to be thinner for climbing. I’m very strong, but I will likely never be thin, and I think that it holds me back…I don’t have that classic thin, long-limbed climber body…”
However, this seems completely at odds with the primates that we see on documentaries and in zoos which appear to be heavy, muscular, powerful and with considerable upper body strength.
Professional human climbers, while strong, rarely have significant quantities of muscle (Bodybuilder-esque) on their skeleton. They seek a power to weight ratio through weight-loss.
What accounts for this difference in development? How do primates move such heavy masses through the upper canopy and why have they not evolved slimmer, smaller or more lithe frames?