Paternity Certainty and Paternal Care in Humans

This entry was written by Sophie Morrish as part of a project done in BIAN 2133 ‘Human Reproductive Strategies’ at The Australian National University in 2019 Semester 2.


Paternal certainty is when a father knows with certainty that it is his offspring. Paternal investment and care are the levels of care he provides to the offspring and how much time and energy is invested into looking after the child and ensuring the survival of the child. The hypothesis is that the level of paternal care is increased upon the certainty of paternity. This excludes adoption and fostering; as a willing choice was made to parent a child knowingly not of the same genetic line. Maternal figures demand certain levels of care in modern day whether that be in the form of a custody agreement, support in the home, or child support payments regulated by the law. It has become a matter of legality how much paternal investment/ care in the form of monetary contribution to the child’s welfare. Since the creation of paternity blood tests, the ease and thus demand for identifying paternal certainty has become much more prominent. Evolutionary psychologists have been able to trace the divide in parental care back to our earliest ancestors and definitively show the emphasis on maternal care. Mothers have always had to do the majority of the parental work, care and investment regardless of paternal certainty. The paternal care element is governed by an evolutionary need for males of a species genes to survive and be passed on, directly caring for the child ensures their survival. Paternal certainty is a way for the male to ensure the continuation of his genes and paternal investment is contributed on the basis that it is definitely his lineage being and his reproductive success being confirmed.

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How certainty affects investment

The evolution of human paternal care is affected greatly by the gender roles enforced on our societies historically (Geary 2005). It has historically not been expected for males to look after children, as women were seen as all the parental care needed and that men had other more important duties to attend to such as working to bring in money. As gender roles have begun to evolve more emphasis has been placed on equality in the home and the demand for paternal care and investment has risen. The introduction of the child support scheme in 1988, has seen a demand for paternal certainty as a claim for money from a parent requires proof of parentage. Trivers (1972) compares offspring to investments, giving more investment to one offspring decreases the likelihood of siring more offspring. Paternal certainty is viewed as a way to ensure the commitment to the investment (offspring) as it is continuing the paternal line. The relative cost benefit analysis that seems to be involved in paternal care versus mating effort seems to be applied combined with paternal certainty. Even if the child is certainly the male’s offspring paternal care is not guaranteed. The effort required to care for offspring often means putting further reproductive endeavours on hold, meaning less time and opportunity to find a new mate and produce more offspring. If the child is certainly fathered by the male, they will often more willingly sacrifice further reproductive opportunities to care for and assure their own offspring’s survival and inevitable reproductive efforts.

Cross cultural studies

It is clear that the universal standard for parental care is for the mother to do the majority of the care and give the most investment with the contribution from the father being none at all to the maximum amount possible, however paternal care has not universally evolved. It differs from places in the world and the societies within those places. Bogin (2014) discusses how the rules of marriage and kinship have altered the way in which humans care for their young. The marital dynamic enforces the caring for and obeying the husband on the woman, and thus she is given the responsibility to care for the children. Fernandez-Duque, Valeggia & Mendoza (2009) discuss how it has been discovered that outside of the realm of western society there are other cultures in which no paternal care is expected making the paternal certainty factor completely irrelevant. Hurtado & Hill studied the Aché fathers of Paraguay and found that they very rarely associate with the children or care for them. This is a stark contrast of what is expected of most modern western fathers and shows the varying level of care expected from paternal figures paternally certain of not. At the other end of the spectrum studied Aka males living in the southwestern Central African Republic and in northern Republic of the Congo reportedly spend up to 22% of their overall time holding infants and caring for them (Hewlett 1991). In Roopnarine’s (1997) study he showed that the structure of the average family changes across cultures and countries as well changing the expectation of paternal care. In Roopnarine’s study of African Caribbean families he found that mate - shifting (changing partners) and child- shifting (the child moving between guardians) were very common. Evans and Davies study showed that 15 to 30% percent of children grow up in homes without either parent. Brow et al’s (1997) study showed that in a study of 700 Jamaican men 37.5% had more than two “baby-mothers”. These studies show that the hypothesis that paternal certainty increases paternal care and investment cannot be universally applied.


Paternal certainty in humans in some societies sees an increase in paternal investment and care; when a man knows with certainty that he is the father he will look after them to ensure the survival of his genetic line. Although cross cultural studies show that this blanket hypothesis cannot be applied universally. The level of care expected of paternal figures around the world differs very severely. The hypothesis also limits our understanding of why paternal care is neglected in situations where paternal certainty is attained and care is expected.


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Fernandez-Duque. E. Valeggia. C. & Mendoza. S. (2009). The Biology of Paternal Care in Human and Nonhuman Primates. Annual Review of Anthropology, 38, 115-122.
Geary. D. C. (2005). Evolution of paternal investment. The evolutionary psychology handbook. 483-505, John Wiley & Sons, Hoboken, NJ,
Hewlett. B.S. (1991). Intimate fathers: The nature and context of Aka Pygmy paternal infant care. Ann Arbor, University of Michigan Press.

Huber. B & Breedlove. W (2007). Evolutionary Theory, Kinship, and Childbirth in Cross-Cultural Perspective. Cross-Cultural Research, 41(2), 196–219.

Langos. D. Kulik. L. Mundry. R. & Widdig. A. (2013). The impact of paternity on male–infant association in a primate with low paternity certainty. Molecular Ecology, 22(13), 3638-3651.

Roopnarine. J. & Hossain. Z. (2013). Chapter 13, African American and African Caribbean Fathers. Handbook of Father Involvement: Multidisciplinary Perspectives, Routledge, New York, 223-237

Trivers. R. (1972). Parental investment and sexual selection. Sexual Selection & the Descent of Man, Aldine de Gruyter, New York, 136-179.

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