Meerkats are often portrayed as adorable and social creatures that live in tightly-knit packs. Their curious and lively demeanor has fascinated audiences in documentaries, movies, and advertisements. Yet, lurking beneath their charming facade is a menacing and assertive side that can catch you off guard.
Meerkats are the most murderous mammals on the planet, according to a study that ranked more than 1,000 mammal species based on how often they kill members of their own species. The meerkat had the highest rate of infanticide, with 19.4 per cent of all deaths caused by another meerkat, mostly due to the dominant female killing the offspring of subordinate females.
“It is surprising that a priori cute and pacific animals, like meerkats, marmots and ground squirrels, have high levels of mortality to conspecifics [members of the same species],” said Dr José María Gómez, lead author of the study.
Infanticide in meerkats is linked to wet-nursing, a behavior where females lactate and nurse the offspring of another female. Subordinate females who try to breed often lose their offspring or are evicted from the group. These recently bereaved or ostracised mothers may then become wet-nurses for the dominant female’s pups as a way of paying rent to stay in the group and avoid further aggression.
“Wet-nursing by formerly evicted meerkats may be a way of ‘paying rent’ to be allowed back into the group without receiving further aggression,” said Kirsty MacLeod, co-author of another study on wet-nursing in meerkats.
Infanticide by the dominant female might have two evolutionary advantages for her–she reduces competition for care for her own pups, and is more likely to secure allolactation for her litter, MacLeod added.
Infanticide is not only practiced by females, but also by males in some mammal species. The study found that infanticide is more common in mammals where males and females live together and a few males dominate as mates, but only for brief periods of time. This creates a strong sexual conflict and an incentive for males to kill the offspring of their rivals and mate with the females sooner.
Infanticide is also associated with non-annual or seasonal reproduction cycles, meaning females can mate whenever. This increases the chances of males encountering unrelated offspring that are not their own and eliminating them to increase their own reproductive success.
“Infanticide is probably the most extreme manifestation of sexual conflict in mammals, with a major fitness cost for mothers who lose their offspring, in which they have already invested lots of time and energy,” said Elise Huchard, co-author of the study on infanticide in mammals.
Infanticide can have evolutionary consequences for the species that practice it, such as influencing social structure, mating system, parental care, lactation and life history.
“Infanticide can be an evolved reproductive strategy in males, and sometimes females as well,” said Sarah Hrdy, an anthropologist who first proposed the idea in the 1970s.
The next time you see a meerkat on screen or in real life, remember that there is more to them than meets the eye. They may look cute and cuddly, but they are also killers who murder their own babies.
– Meerkats revealed as most murderous mammal known to science, The Independent, Thursday 29 September 2016
– Infanticide linked to wet-nursing in meerkats, University of Cambridge, 7 October 2013
– Why Some Mammals Kill Babies of Their Own Kind, Smithsonian Magazine, 13 November 2014
– Baby-Murdering Meerkat Alpha Females Enslave Subordinates As Wet Nurses, Smithsonian Magazine, 10 October 2013