A tragedy in Stamford brings an old mystery to the fore: Why are chimpanzees so fantastically strong, at least compared to their human brethren? The rule of thumb states that chimps are five-to-seven times stronger, pound-for-pound, than members of our species (with whom chimps share 99 percent of their DNA).
That’s a bit puzzling, since chimps don’t appear anymore ripped than your average human (especially below the waist). The Air Force spent years investigating, by strapping both humans and chimps into “immobilization chairs” and testing each muscle individually. But these quasi-sadistic tests led nowhere.
The best guess comes from a 2006 European study of bonobo jumping. The Belgians and Dutch biologists conclude:
In an explosive task, bonobo muscle performs superiorly to human muscle, most likely due to a higher specific force. Whether the difference is due to higher density of contractile material or due to differences in the contractile machinery per se (i.e. myosin heavy chain isoform) remains to be investigated.
Whatever the ultimate answer might be, it’s best to avoid keeping chimps as pets.