Caroline Tisdale

In many human households, the mother is the primary caretaker of the home and the children. But for a particular South American species of monkey, the Titi monkey, it is the father who plays the dominant role in child care, according to a recent Yale study.

Researchers conducted an observational study analyzing the behavioral patterns of the Titi monkey, also known as Callicebus discolor, during and after infant care. The study, published in September in the international journal Primates, is part of a 12-year project that focuses on multiple social groups of wild Titi monkeys that inhabit the Tiputini Biodiversity Station in the Ecuadorian Amazon. The study found that Titi monkey partners spend less time with one another after the birth of their offspring and that male Titi monkeys are more likely than females to take care of the infants.

According to Karen Bales, psychology professor at the University of California, Davis, and associate editor of the American Journal of Primatology, this work is crucial for scientists who work with captive monkeys as it teaches them not only how the wild monkeys act, but also how to promote the welfare of captive monkeys. The findings provide information on the Titi monkey’s natural habitat and enable scientists to better interpret their behavior, Bales said.

“The thing that is extra special about [fellow researcher Eduardo Fernandez-Duque’s] field study is that he’s been there for a really long time,” Bales said. “If you go there for a summer you have a really tiny peek into the animal’s lives. Whereas being there for 12 years, he gets to follow the animals from birth to becoming an adult.”

The researchers had two goals in mind when they conducted the study. The first was to describe infant-care behavior and the differences in male and female interaction during and after the birth of infants, and the second was to evaluate the possible repercussions infant care had on social interactions of parent couples, as well as parents’ activity level.

What made this research significant in the fields of anthropology and primatology was the fact that it was the first study of its kind to work with male and female Titi monkeys “unequivocally identified” by gender, researcher Andrea Spence-Aizenberg, a graduate student in the Department of Anthropology at the University of Pennsylvania, said. Spence-Aizenberg added that the males and females were collared throughout the study so their genders could always be identified, even when they were observed at faraway distances through binoculars.

The research also showed a clear decrease in the amount of time each pair of primate parents spent in contact after an infant was born, also suggesting that this may occur because females actively avoid the infants after their birth. Research indicated that males were primarily responsible for keeping close proximity to females, but with an infant present, female Titis tended to keep their distance as males became the main caretakers.

Researchers were surprised to find that not only was the male the main caretaker, but that the male monkeys did not expend as much energy as expected when performing infant care.

Bales said the study’s findings are particularly divergent from her own results, which suggest that other animal species, including prairie wolves, have a high energy cost for infant care.

But according to Fernandez-Duque, a male parent taking the lead in infant care is not at all surprising. A study Fernandez-Duque performed on owl monkeys found that owl monkeys are not just socially monogamous, but also practice “genetic monogamy,” a behavior in which a species only mates with one partner.

“Evolutionarily speaking, now [paternal care] makes sense because now we understand why the male is putting so much time into the infant. It is his baby. It is his infant,” he said.

Titi monkeys are one of a small number of mammals that are socially monogamous — “a paradox in evolution and biology,” Fernandez-Duque said.

According to Fernandez-Duque, this research has implications beyond just shedding light on the social behavior of a specific species of monkey — these findings are a gateway to understanding the influence of biology in love, social monogamy and human relationships.

“It is impossible, when trying to understand the role of biology in human love, to disentangle biological influences from the influences of culture, religion, social norms, government,” he said. “These [Titi monkeys] open a window into the past to try to understand the biological baseline over which humans developed their social relationships in a cultural and social context.”

There are number more than 30 species of Titi monkey across South America, according to National Geographic.