Males have been found to kill infants in many mammalian species in order to maintain their chances of successful reproduction. Scientists say this behavior has influenced the evolution of mammals.
A study was made with 260 mammalian species out of which the males from 119 species were found to kill infants. About a quarter of the entire species of mammals is related to infanticide.
The male’s actions have been pointed out as being a sexual strategy by Elise Huchard from the National Center for Scientific Research’s Center for Evolutionary and Functional Ecology, the co-author of the study. It is thought that by killing the infants from other males the female would be again sexually active to other males. Species that don’t maintain groups or are monogamous rarely practice this method. Animals having a set mating season also don’t practice infanticide because the males would have to wait for the next mating season anyway.
Dieter Lukas from the University of Cambridge, another co-author of the study claims females of some of the species also have a way to counter the practice. The females mate with several males in order to confuse the males of who the off springs belong to. As a result of the female strategy, males tend to compete in sperm quality, which leads to the production of a large amount of sperm thus increasing the size of their testis.
“While it had previously been suggested that infanticide might be an evolutionary driver in mammalian societies – leading to females allying themselves with other females or forming bonds with a specific male in order to defend their offspring – we’ve now shown that this isn’t the case: male infanticide is a consequence of variation in sociality, most commonly occurring in species where both sexes live together in stable groups.”
The research findings show that infanticide is not passed down genetically but is simply a strategy practiced where it brings advantages to males.
“Male infanticide appears and disappears over evolutionary times according to the state of the evolutionary arms race between the sexes. Although infanticide may not have contributed to shape the diversity of mammalian social systems, it has deeply influenced the evolution of sexual behaviour and sex roles.”
Said Elise Huchard.