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?

  • 3
    $\begingroup$ I don't understand. Monkeys that are particularly agile at climbing tend to be very thin as well. A famously agile monkey species is the spider monkey. $\endgroup$
    – Remi.b
    Feb 13, 2017 at 15:33
  • 5
    $\begingroup$ Gorillas typically are pretty bad at climbing. I think you make the mistake to put all primates into a single pack and assume they are all alike and are all good climbers and then you make comparison with humans. A human is probably a better climber than a gorilla. $\endgroup$
    – Remi.b
    Feb 13, 2017 at 17:42
  • 1
    $\begingroup$ Remi...please dont make uninformed comments. If you have an academic answer backed up with references then please make it otherwise assumptions benefit no one. berggorilla.org/en/gorillas/general/everyday-life/… Gorillas can spend 20% of their day climbing $\endgroup$ Feb 13, 2017 at 18:32
  • 1
    $\begingroup$ Venture, humans don't have exoskeletons (and you call others uninformed?) Please don't come here and be rude. We like questions, and we like answering good ones, but Remi.b is right that you've grouped a large number of species then compared them to one. You have your answer in your question. Finally, how closely related is climbing rocks to climbing trees? If trees disappear and primates have to resort to living on cliff faces, you'll have your definitive answer in a few million years maybe. $\endgroup$ Feb 13, 2017 at 18:51
  • 1
    $\begingroup$ Do gorillas spend their time rock climbing? $\endgroup$
    – Seeds
    Feb 13, 2017 at 18:51

1 Answer 1


As a rock-climber myself I’ll attempt to answer: The selection criteria for competitive rock-climbing is exclusively based on sustain non-resting, extremely challenging moves up a rock-face. The two most challenging aspects are 1) ability to ‘crimp’ (climbing term) on micro-holds without slipping and 2) being able to keep that up without resting throughout the climb. I personally have a real problem with the later, because of my weight.

Primates selection criteria is not isolated to non-resting climbs. They don’t get penalized for sitting on the branch.

  • $\begingroup$ I have to say, as someone who did a bit of climbing now & then, that the idea of competitive rock climbing just boggles my mind. It seems to run contrary to everything I enjoyed about climbing... $\endgroup$
    – jamesqf
    Feb 14, 2017 at 4:53
  • 1
    $\begingroup$ @Venture2099 If you think this answer answered your question then upvote and accept it instead of posting unnecessary comments. $\endgroup$
    Feb 14, 2017 at 14:18
  • 2
    $\begingroup$ I will post the comments that I see fit and I will mark the question as answered when I think it is appropriate. $\endgroup$ Feb 16, 2017 at 14:47

Not the answer you're looking for? Browse other questions tagged .