Given her work in the 1970’s with Hanuman langurs, Sarah Blaffer Hrdy (graduate student, now Dr.) showed that infanticide was rife with males who had assumed the alpha role in a new troop. The monkeys in question lived in troops of females and a single male. However, when another male drove away the patriarch monkey he often went after the infants to “good” result.

Infanticide: Humans Take Heart, Lots Of Mammals Kill Their Offspring

Infanticide: Monkey business

Ms. Hrdy, who became Dr. Hrdy and lectured at the University of California, Davis extended her analysis and prompted many to follow her in her belief that this behavior extends well beyond her specific monkeys. She argued in 1974, that infanticide is simple evolution (mammalian) and exists when a male wants nothing to do with step-children. Yes, redheads, he wants his own.

“She’s the goddess of all this stuff,” said Kit Opie, a primatologist at University College London.

In a report published on Thursday in the Science, Dr. Dieter Lukas and Dr. Elise Huchard suggest that of the 260 mammalian species they studied, 119 exhibited examples of males killing their young. Their work was accomplished by plowing into available studies by others before them.

Sex all year long

“When we started, we weren’t sure if infanticide was present in some ancestral mammal and is just more pronounced in some species and is lost in other species,” said Dr. Lukas. “Or maybe it just evolved in those species where the conditions were right.”

The two posit that infanticide evolved with the mammal. And occurred as a result of a single male being surrounded by females who give birth year round.

“There’s no sense for a male to kill the offspring in the previous year, because he has to wait anyway,” said Dr. Lukas.

Adding to that…“In effect, whenever promiscuity is high enough, it does not pay for males to commit infanticide,” said Carel P. Van Schaik, a primatologist at the University of Zurich. “This new study beautifully confirms the major role of sexual behavior.”