Original articlesPaternal Care by Genetic Fathers and Stepfathers I: Reports from Albuquerque Men
Section snippets
Theory
Most evolutionary approaches to male parental care begin with the notion that organisms must allocate reproductive effort among two competing forms of investment: parental effort (the summed investments in offspring that increase their fitness) and mating effort (the summed investments that increase future fertility) Low 1978, Trivers 1972. In most sexually reproducing species, males allocate more of their reproductive budget to mating effort than females, whereas females allocate more to
Male parental care as relationship effort
The standard evolutionary model of male parental care needs to be expanded for humans, because of the variation in the relationships between men and the children to whom they provide care. In addition to the so-called “traditional” human family form in which a husband and wife both provide care for their common genetic offspring, men often provide care to unrelated offspring—specifically, to stepchildren, i.e., offspring conceived during a mate's previous relationship. Many studies have
Classifications of male parental care
We have argued that male parental care is influenced by both relationship effort and parental effort. We now will specify how these forms of reproductive effort influence men's decisions to allocate parental care to the children they have parented. Table 1 presents four classes of male/child relationships, defined by the male's relatedness to the child and the male's relationship with the child's mother. Class 1 relationships involve a genetic offspring whose mother is the man's current mate.
Proximate influences on male parental care
The model as we have articulated it does not directly address the proximate mechanisms by which men bond with children or choose to invest in them. This is not necessarily the fatal flaw that one reviewer implied: one can legitimately analyze the outcomes of men's decision-making processes without necessarily fully understanding the psychological mechanisms that informed and influenced those processes. These decisions are not consciously made by men, nor are these decisions made in an
The Albuquerque Men Data Set
The data we use to test our hypotheses are derived from a sample of men from Albuquerque, New Mexico, U.S.A., collected by Kaplan and Lancaster from 1990 to 1993. Two complementary interviews were administered to participants recruited at the Bernalillo County (New Mexico) Motor Vehicle Division (MVD). The short interview took about 7 minutes to administer; approximately 7,100 participants were given this interview in a private area at the MVD. All men who appeared to be over 18 years of age
Results
Table 2 presents descriptive statistics for each measure of male parental care, by class of father-child relationship. The table shows that, not controlling for education, income, ethnicity, or other socioeconomic variables, male investment does vary across the four classes of offspring presented in Table 1. For each measure of investment, genetic children of men's current mates receive the highest levels of investment, whereas stepchildren of previous mates receive the least, consistent with
Discussion
The pattern presented by these results is similar for each measure of parental care and conforms to the model presented in Table 1. In general, genetic offspring of current mates receive the highest levels of investment, step offspring of former mates receive the least, and genetic offspring of former mates and step offspring of current mates receive similar levels of investment, allowing for the effects of coresidence.
To the best of our knowledge, no other investigators compared children in
Conclusion
We present a biosocial model of male parental care that incorporates the dual effect of mating and parental benefits on male parental allocation decisions. Using several measures of parental care by men living in Albuquerque, New Mexico, U.S.A., we present results that are consistent with the model: men invest more in the offspring of their current mates, even when residency is not an important influence. We also report that although stepchildren of current mates generally receive lower
Acknowledgements
Funding for the Albuquerque Men project on male fertility and parenting was provided by the National Science Foundation (#BNS-9011723 and #DBS-911552) and the William T. Grant Foundation (#89135089 and #91130501), as well as by the University of New Mexico Research Allocations Committee and the University of New Mexico Biomedical Research Grant. Kermyt Anderson was supported during part of the writing of this paper by a National Science Foundation Graduate Research Fellowship. Martin Daly, Phil
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