Eve: How the Female Body Drove 200 Million Years of Human Evolution

by Cat Bohannon

While chimp males rarely kill chimp babies in their own troop, when they war with other troops, males regularly kill their enemies’ babies, since babies produced by the enemy males’ sperm are no benefit to them. They also have a habit of raping—or at least violently coercing—their female enemies, presumably to both enforce their dominance and potentially father new kids.[*14] Thus, many argue, the main thing keeping chimp males from killing babies in their own troop is that they’re never really sure the kid isn’t theirs. That’s not true in harem-based societies. Among mountain gorillas, over 20 percent of child deaths happen at the hands of an adult male—gorillas have harems, so paternity is more certain.[*15] That’s the big problem with the monogamy argument.