Which Animal Murders The Most?

We hear news of people killing one another every other day. 
Have you ever wondered why are we so violent towards one another? Comparing ourselves to other animals in the animal kingdom, are we, Homo sapiens, any more murderous than say, dogs, rats, or lions?

The answer may surprise you.

A team of researchers in Spain (note: the paper is locked behind paywall) studied data for more than 1000 mammal species and they found out that killing is pretty rare. Sure, predators kill their prey to survive, but most predators are lousy hunters--lions, for example, have a success rate of only 19%.In addition, less than half of the species studied commit murder (defined as the act of killing members of their own kind).

And we humans are nowhere near the top of the chart of the most murderous mammals. In fact we're not even in the top 30. Of course, the obvious ones like lions, wolves and bears are there in the chart. But there are also unexpected members like the adorable ground squirrels, wild horses and deer.
And the most murderous mammal of all?

The meerkat.

About 20% of Timons lose their lives to other Timons.

Image: disney.wikia.com

Putting the number into perspective, if humans lived in a society as violent as the meerkats', the human population today would be reduced by 1.4 billion. That's more than the entire population of China, or twice the population of the ten countries in South East Asia.

Primates, the group we belong to, turn out to be an unusually violent bunch. Primates are eight times more likely to kill a member of their kind than other mammals are. This number is driven by the fact that primates are both territorial and social--the two factors that provide the motive and opportunity for murder.

However, are humans the most murderous member of the primate group?
We're responsible for the two world wars, after all.

The researchers combed through historical records and archeological data and found that during paleolithic time, lethal violence caused 3.5% of all human deaths--which makes us only slightly more violent than the average primate. But as our society grew, our rate of violence increased, rising to around 12% during the medieval time. Since then, organized statehood and the advent of modern law enforcement reduced the rate of murder to around 1.2%.

Some researchers argue that the way an animal murders its own kind matters more than the rate at which it does the killing. For primates, the most common form of murder is infanticide by aggressive males. For humans, however, we kill each other as adults at an exceptionally high rate--putting us in the exclusive adult-murder-club alongside animals like wolves, lions and spotted hyenas.

Are humans really superior to animals when it comes to murder?

Malcolm