The pumped-up chimpanzees - who all suffer from the hair-loss condition alopecia - show just how ripped the burly beasts actually are.
It's no wonder biologists say the aggressive jungle creatures are at least FOUR TIMES stronger than their human "cousins".
Chimps are considered the closest living relative of humans, sharing between 95 to 98 percent of the same DNA.
However, when it comes to muscular strength there really is no comparison between the two, say wildlife experts.
And if it ever came to a one-on-one fight there would be only one winner, said Steve Ross of Chicago's Lincoln Park Zoo.
When they fight "it's the closest thing we know to human warfare," said Ross, director of the Study of Conservation of Apes.