Where can I find studies done on the strength dimorphism between male chimps and female chimps?
For example, "one-arm pull strength is 300 pounds for male chimps and 200 pounds for female chimps"
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$\begingroup$ try google scholar or pub med. Nothing obvious here: scholar.google.ca/… ... maybe useful references here? pnas.org/content/114/28/7343.long $\endgroup$– Ben BolkerSep 16, 2019 at 18:00
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$\begingroup$ Note this is likely do to the difference in size between male and female chimps more than anything else. $\endgroup$– JohnSep 16, 2019 at 19:41
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$\begingroup$ not necessarily entirely; the (very small!) sample I show in my answer does show 2 males that both have higher weight-specific strength than 3 females ... (p-value=0.1 ...) $\endgroup$– Ben BolkerSep 16, 2019 at 21:32
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1 Answer
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I searched for "chimpanzee strength" on PubMed and followed links from
- O'Neill et al. PNAS 2017 "Chimpanzee Super Strength and Human Skeletal Muscle Evolution"
to
- Bozek et al. PloS Biology 2014 "Exceptional evolutionary divergence of human muscle and brain metabolomes parallels human cognitive and physical uniqueness" where I found this figure:
which shows pulling strength normalized by individual body weight, with circles for females and diamonds for males. In fact, the Excel spreadsheet given in supplementary materials shows there were two males and three females, tested in three sessions; in each session weight and pull strength were listed. The ratios of max pull to weight for males were 3.44 and 3.49, for females were 2.9, 3.14, and 3.25 (one of the males was quite small ...)
O'Neill et al. give a few other references, you could follow those as well and see what you come up with. (I found that "chimpanzee strength" gave better results as a search term than terms including "sexual dimorphism", which tended to be swamped by more general discussions of the evolution of dimorphism in apes.)
@jackaidley notes in a comment that
extreme caution is needed in interpreting these results for Chimp sexual dimorphism, quite apart from the very low number of individuals, there is a significant problem with these measurements - as the paper itself notes "The inability to control nonhuman primates' motivation hinders the exact quantification of the muscular strength difference between humans and nonhuman primates, even in a highly controlled experimental setup." This problem equally applies to male/female differences.
In other words, male chimpanzees might pull harder at least in part because they are more motivated than females in this particular setting, rather than because of intrinsic differences in strength. (That may or may not matter for what you are trying to do with this information.)
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6$\begingroup$ Good find, and I suspect this is about as good as it gets. But I think extreme caution is needed in interpreting these results for Chimp sexual dimorphism, quite apart from the very low number of individuals, there is a significant problem with these measurements - as the paper itself notes "The inability to control nonhuman primates' motivation hinders the exact quantification of the muscular strength difference between humans and nonhuman primates, even in a highly controlled experimental setup." This problem equally applies to male/female differences. $\endgroup$ Sep 17, 2019 at 8:15
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$\begingroup$ Is the x-axis individuals? It seems to not be equally-spaced for some reason. $\endgroup$ Sep 17, 2019 at 13:27
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3$\begingroup$ What is the x-axis even? Some human-chimp-macaque function? $\endgroup$ Sep 17, 2019 at 14:16
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1$\begingroup$ I believe the x-axis just represents individuals (individuals are measured in 1-4 sessions). Don't know about uneven spacing. The data are there if you want to draw your own version ... $\endgroup$ Sep 17, 2019 at 15:05