Who knew that male chimpanzees’ testicles were only a smidgen smaller than their brains? Chimps might be our closest relatives, but relative to body size, the average male of the species has nuts that are 10 times larger than humans’. Why, and why would we care?

Prodigious size, in this case, reflects (or is reflected by) prodigious sperm production. This is important if you’re Chimpanova because, unlike human females, chimpanzees are rather promiscuous. For a male chimp to be the first to the prize, as it were, he wants to have a bigger and better army of swimmers in order to pass ...

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