The evolution of fatherhood
© 2010 Gwen Dewar, Ph.D., all rights reserved
In popular accounts of evolutionary psychology, men are cads.
Males--the story goes--maximize their reproductive success by mating with as many females as possible.
If they can’t get extra mating opportunities, then males might make the best of a “bad” situation by supporting their kids--assuming they can be sure of paternity.
But, as a rule, males are expected to invest more in mating than in parenting. By spending “too much” of their resources on kids, males lose opportunities to spread their genes far and wide.
Cynical? Silly? It isn’t complete nonsense.
It’s true that females—especially female mammals—invest more energy in parental care.
It’s true that female reproductive success is less limited by the number of partners a female has and more limited by the amount of food she can acquire.
It’s also true that females have little trouble identifying their own offspring, and that males are more likely to offer parental care when they can be confident of paternity.
But the pop psychology account of fatherhood –i.e., that males are designed by nature to avoid fatherly responsibilities—is simplistic and wrong.
Human fatherhood is extremely variable. In some societies, men provide very little parental care. Remove them altogether and little changes in the lives of their children.
In other societies, good fathers play a crucial role. Their economic support makes a big difference. Their emotional support can, too.
Furthermore, these men really want to support their children. And, not surprisingly,
men who like children are more attractive to women.
Are these human males an aberration of nature? Hardly.
Ninety percent of bird species are monogamous. In most of these species, males share equally in providing food and protection to their nestlings. Take these males away and the offspring usually suffer. The chicks are less likely to survive, and if they do survive, they don’t grow as large (Wolf et al 1988).
Paternal care among mammals is far less widespread. The weirdest, most newsworthy discovery is that some male fruit bats lactate. Do they actually feed infants? It’s plausible, but still unconfirmed (Kunz and Hosken 2008).
What’s not controversial is that helpful fathers are relatively common among certain groups of mammals. Among the primates and the carnivores, up to 40% of genera show some form of paternal care (Kleiman and Malcolm 1981).
In wolves, foxes, and wild dogs, this paternal care is direct and crucial. Fathers share with mothers the tasks of hunting, feeding, cleaning, and protecting the cubs. They play with their cubs, too (Malcolm 1985).
And among some monogamous New World monkeys, fathers perform similarly important roles. Marmoset and tamarin fathers carry their young on their backs and share food. Owl monkeys, titi monkeys, and Goeldi’s monkeys do the same (Shradin et al 2003).
Other cases of paternal care are less dramatic, but still notable.
Male Coquerel’s sifakas, made famous by the preschool TV show "Zooboomafoo," have been observed grooming and holding infants (Bastian and Brockman 2007).
In other lemur species, fathers guard and babysit their young (Vasey 2007; Fietz and Dausmann 2003).
--who aren't known for paternal care--fathers may protect infants from attack by other, infanticidal males.
Old World monkeys provide these protective services as well. And in one group of savannah baboons, researchers found that males were more likely to support youngsters involved in daily squabbles if they were the genetic fathers of those juveniles (Buchan et al 2003).
What about our closest living relatives--the African apes? Gorilla fathers are protective and playful with their offspring, but that's as far as it goes. Chimpanzee and bonobo males are uninvolved.
And that underscores an important lesson for understanding the evolution of fatherhood in humans:
When we look for comparative data about behavior, we don’t necessarily find the most instructive parallels amongst our closest living relatives.
Behavior evolves rapidly, so that two closely-related species may show dramatic differences in behavior. And quite distantly-related species may show remarkable behavioral similarities—if they encounter similar ecological conditions.
So when it comes to paternal care, the devoted dad who feeds his kids and walks them to school each day has more in common with a wolf than a chimpanzee.
Perhaps even more importantly, individuals can respond flexibly to local conditions. Some situations make it easier or more rewarding for men to support their children.
By studying different local environmental conditions, we may better understand why some men act like fatherly wolves and others act more like aloof chimpanzees.
This is the work of behavioral ecologists and biological anthropologists, and you can read about it in a new book by Peter Gray and Kermyt Anderson.
Fatherhood: Evolution and Human Paternal Behavior
In Fatherhood: Evolution and Human Paternal Behavior, Gray and Anderson review paternal behavior around the world and consider the patterns that emerge.
They begin with a brief overview of fatherhood in nonhuman primates and a discussion of how anthropologists are reconstructing the family life of our ancestors.
Then, with an emphasis on Western society, they cover topics like marriage, fertility, paternity, cross-cultural studies of father involvement, stepfathering, sexuality, health, and the biochemical changes that babies make to a father’s brain.
Gray and Anderson note that the old view of the hunter-gatherer family—that fathers hunt to provide meat for their kids—has been overturned by recent research on contemporary foragers.
Men hunt, but their kids don’t get any special benefits from it. The hunters share their meat equally with everyone in the camp. And a hunter’s motivation has more to do with building a reputation among other adults—and attracting potential mates—than with feeding their families.
Nevertheless, hunter-gatherer men are some of the most involved fathers in the world.
During the first year of an infant’s life, mothers are least able to forage for themselves.
Fathers bring home extra calories—including meat, honey, and plant foods—and their contributions may be crucial if the mother lacks the help of other close kin (Marlowe 2005).
Hunter-gatherer men are also relatively involved in child care, spending about 5% of their time holding infants.
Overall, hunter-gatherer fathers have more intimate (and less domineering) relationships with their kids than do men from horticultural, agricultural, and herding societies. These latter societies are not likely to meet with the approval of the modern, sensitive, involved dad. Fathers are distant. Their main roles seem to concern discipline, status, and providing vocational training to their sons.
They don't always provide much economic support, either.
In one analysis of cross-cultural data, researchers found that in 68% of the societies sampled, the death of a father had no impact on his children’s survival. In general, grandmothers were more important (Sear and Mace 2008).
So what accounts for the differences between hunter-gatherer men and men in other traditional societies?
Cross-cultural analysis (e.g., Katz and Konner 1981; Hewlett 1992; Marlowe 2000) suggests that hunter-gatherer men show higher father involvement because
• Females tend to contribute a large portion of calories to the diet (which among other things means that mothers need more help with child care)
• Husbands and wives spend more time together (foraging, sleeping together, eating together, etc.)
• Most marriages are monogamous (not polygynous, so children don’t have to share their fathers with children produced by other wives)
• Men spend less time engaged in warfare (which takes them away from their families and may socialize them in ways that are inconsistent with sensitive, involved fathering)
• Men don’t accumulate much wealth (when they do, they are more likely to take multiple wives and engage in warfare to defend their wealth)
Gray and Anderson don’t discuss all these factors in depth. But they give considerable attention to other issues, including these:
Men contribute less paternal care when they aren’t married to the children’s mothers. After a divorce, some men retreat from their children’s lives, but the stereotype of the deadbeat dad is misleading: The same dads that refuse to pay child support are usually men who provided little support before they got divorced.
Confidence of paternity
Contrary to what some studies have suggested, men who are confident about paternity are usually correct. And not surprisingly, American men who have doubts about paternity are less likely to support the kids.
What might interest you more is the way that some cultures have adapted to the problem of low paternity confidence. In cultures were men are less likely to be the genetic fathers of their wives’ children, men channel their wealth to their nephews or nieces, not their putative offspring (e.g., Hartung 1985).
Even more remarkable is the tradition of “partible paternity,” in which
“primary” fathers share paternal responsibility with other, “secondary” fathers.
Hormones don’t affect mothers only. Fatherhood is associated with hormonal changes, too.
Studies suggest that men involved with the care of young children experience a drop in testosterone levels. Men exposed to infants may also experience elevated levels of prolactin, the hormone that stimulates parental behavior in a variety of birds and mammals. And dads with higher prolactin levels are more responsive to babies (Fleming et al 2002). So it seems that there is a positive feedback loop. Fathers who live intimately with children become more biologically prepared and willing to take care of them.
If hormones intrigue you, you’ll enjoy Gray and Anderson’s chapter on the ways that parenthood and infants alter a man’s brain. And of course the transition to parenting isn’t only about happy effects. Gray and Anderson discuss disruptions, too. Like mothers, fathers may suffer from postpartum depression, especially if their spouses are depressed. There is also evidence that living with an infant inhibits a man’s sex drive.
More about the evolution of fatherhood
Gray and Anderson’s accessible, conversational book will appeal to readers interested in a broad look at the consequences of fatherhood for both children and men, particularly if your focus is on men living in modern Western societies.
And there's more good stuff to read about the anthropology and evolution of fatherhood.
Behavioral ecologist Sarah Blaffer Hrdy is renowned for her cooperative breeding hypothesis. She is also an outstandingly clear and engaging writer.
In her book Mothers and Others: The Evolutionary Origins of Mutual Understanding (Belknap Press), Hrdy presents a compelling argument for the idea that humans evolved in the context of communal child care.
Her chapter “Will the real Pleistocene family please step forward?” is an excellent overview of the variable role of fathers and includes an extended discussion of the physiological effects of child care on men.
There you will also find a fascinating discussion of “partible paternity” in more than one man claims paternal responsibility for the same child. This occurs among several different peoples of the Amazon basin, in societies where fathers contribute crucial calories to their children and also protect them from high rates of intergroup violence. In these situations, it seems, fathers are so important, kids benefit from having more than one!
Anthropologist Barry Hewlett has devoted his career to studying childhood and fatherhood. He discusses partible paternity--and many other topics concerning the evolution of fatherhood--in "Fathers in forager, farmer, and pastoral cultures," a chapter appearing in the multidisciplinary academic anthology The Role of the Father in Child Development, 4th edition (2004).
I also highly recommend Hewlett’s excellent review of the anthropology of father involvement,"Culture, history and sex: Anthropological perspectives on father involvement,"
which you can download by clicking here.
For a concise, well-organized overview of male parental care in nonhuman mammals and different human societies, check out Chapter 17 in Melvin Konner’s The Evolution of Childhood: Relationships, Emotion, Mind. Like Hewlett, Konner is an expert on infancy and child care among hunter-gatherers.
And if you have a background in biology and evolution—and are seriously interested in the evolution of parenting in nonhuman animals—Clutton-Brock’s 20-year-old The Evolution of Parental Care still rates as an essential, comprehensive synthesis of the literature.
References: The evolution of fatherhood
Bastian ML and Brockman DK. 2007. Paternal Care in Propithecus verreauxi coquereli . International Journal of Primatology 28(7): 305-313.
Buchan JC, Alberts SC, Silk JB, and Altmann J. 2003. True paternal care in a multi-male primate society. Nature. 425(6954):179-81.
Fietz J and Dausmann KH. 2003. Costs and potential benefits of parental care in the nocturnal fat-tailed dwarf lemur (Cheirogaleus medius). Folia Primatol (Basel). 2003 74(5-6):246-58.
Hartung J. 1985. Matrilineal inheritance: New theory and analysis. Behavioral and Brain Sciences 8:661-688.
Hewlett BS 2000. Culture, history and sex: Anthrpological perspectives on father involvement. Marriage and Family Review, 29, 324-340.
Kleiman DG and Malcolm JR. 1981. The evolution of male parental investment in mammals. In: DJ Gubernick and PH Klopfer (eds), Parental care in mammals, pp. 347-387. Plenum Press: New York.
Kunz TH and Hosken DJ. 2008. Male lactation: why, why not and is it care? Trends in Ecology and Evolution 24(2): 80-85.Malcolm JR. 1985. Paternal care in canids. American Zoologist 25(3):853-856.
Marlowe, F.W. 2005. Who tends Hadza children? In: B. Hewlett and M. Lamb (eds), Hunter-Gatherer Childhoods: Evolutionary, Developmental and Cultural Perspectives. New Brunswick: Transaction, pp 177-190.
Schradin C, Reeder DM, Mendoza SP, and Anzenberger G. 2003. Prolactin and paternal care: comparison of three species of monogamous new world monkeys (Callicebus cupreus, Callithrix jacchus, and Callimico goeldii). J Comp Psychol. 117(2):166-75.Schradin C. and Anzenberger G. 1999. Prolactin, the Hormone of Paternity News Physiol Sci 14: 223-231.
Sear R and Mace R. 2008. Who keeps children alive? A review of the effects of kin on child survival. Evolution and Human Behavior 29(1): 1-18.
Wolf LE, Ketterson ED, and Nolan V Jr. 1988. Paternal influence on growth and survival of dark-eyed junco young: Do parental males benefit? Animal Behaviour 36: 1601-1618.
Vasey N. 2007. The breeding system of wild red ruffed lemurs (Varecia rubra): a preliminary report. Primates 48: 41–54.
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