In a heated 1860 exchange between Bishop Wilberforce and TH Huxley, Wilberforce supposedly asked Huxley whether it was through his grandmother or grandfather that he claimed to have descended from a monkey. Huxley is said to have responded that he held no shame to have a monkey as an ancestor, but that he would be ashamed to be connected to a man who used his gifts to obscure the truth. Now, if you were interested in the details of paternal care across many monkeys (and apes and humans), then it would matter greatly which monkey through which you reckoned your descent. Among mammals, paternal care is most commonly found in primates, carnivores, and rodents, but even among primates the practice of intense paternal care is still something of a rarity.
A chapter by Maren Huck and Eduardo Fernandez-Duque in a new edited book, Building Babies: Primate Development in Proximate and Ultimate Perspective, reviews the world of primate paternal care and features one of the most involved set of primate dads, found among various species of owl monkeys.
Across primates, males provide relatively little direct care. While species of gibbons may be monogamous, male gibbons rarely provide direct care, such as holding or carrying offspring, while in siamangs, males do sometimes carry their weight in infant care. Baboon males may offer some more protection to offspring they are more likely to have sired. Among Barbary macaques, males remain in proximity to infants and help with their care more than in any other species of monkey from Africa or Asia. Apart from some highly invested humans, the all-stars of primate paternal care tend to be found among several groups of small-bodied monkeys in the Americas. Callitrichids, such as cotton-top tamarins, regularly give birth to twins in the wild; weighing about 15 to 20 percent of a mother’s body weight at birth, those twins are often carried around by older males, particularly fathers. Among titi monkey infants in captivity, the removal of dad elicits a stronger stress response than removal of mom, one indicator of the powerful bond between baby and dad.
It’s through their recent research on owl monkeys that Huck and Duque-Fernandez shed some of the most interesting light on comparative primate studies. And that’s no easy feat, since owl monkeys are the only group of monkeys in the Americas that are most active at night rather than day (when most primatologists would rather be sleeping). Owl monkeys are socially monogamous, living in pairs with typically an infant and one or two older juveniles. They are sexually monomorphic in body size, meaning that males and females are of the same body size; indeed, male and female offspring grow at similar rates during infancy and as juveniles. Owl monkey males (presumed to be the fathers, though confirming that requires DNA testing) groom and clean the babies, though they groom them less in the wild than in captivity. While moms initially care for owl monkey babies, males take over, performing the majority of infant carrying during successive months. Although genetic studies confirm the paternity of some adult males, others move in after another male has disappeared, making some males “step-fathers.” Owl monkey infants have similar rates of survival/disappearance whether they’re living with presumed genetic fathers or other males, and the offspring leave their group at similar ages regardless of the presumed paternity of the group male.
What do we take away from these comparative insights into primate male care? We learn that there are many ways to nurture babies, ways that may involve fathers in some species of primates, and ways that don’t. We also learn that some of the closest parallels (“analogies”) to highly invested human fathers are found in South American forests rather than among our closest living relatives, chimpanzees and bonobos. Huxley may have been proud to call a monkey a relative, but which monkey he thought of would have influenced his imagined degree of paternal care.
Huck M. and Fernandez-Duque E. 2012. When dads help: Male behavioral care during primate infant development. In Building Babies: Primate Development in Proximate and Ultimate Perspective, eds. KBH Clancy, K Hinde and JN Rutherford, pp. 361-385. New York: Springer.