A new study of violent behavior in more than 1,000 mammal species found the meerkat is the mammal most likely to be murdered by one of its own kind.

About 20 percent of meerkat deaths are murders. Their violence has been documented; a 2006 study described in National Geographic documented meerkat mothers killing the offspring of other females to maintain dominance.

Some of the animals with reputations for docility are actually more dangerous to each other than creatures known for their aggression. Chinchillas kill each other more often than brown bears turn on their own kind. New Zealand sea lions are more murderous than actual lions.