When male chimps go hunting, they sometimes use spears, but their own bodies, bigger and stronger than the females’, are often weapon enough. Even if they’re injured as a result, no offspring will starve. From an evolutionary point of view, their injuries aren’t as costly, because males aren’t caretakers in chimp society. Generally speaking, innovation is something that weaker individuals do in order to overcome their relative disadvantage. As a primatologist in Kenya told me years ago, “Women do clever things because we have to.”
