اعتماد به نفس پدری، طلاق، و سرمایه گذاری در کودکان توسط مردان آلبوکرک

Abstract Using a sample of men living in Albuquerque, NM, we examined the relationship between paternity confidence and men's investment in children. In humans, men may reduce their investment in a child in two ways: indirectly, by ending their relationship with the child's mother and ceasing to cohabit with the child (e.g., divorce), and directly, by allocating less time and fewer resources to the child. In this article, we tested two hypotheses regarding the effect of paternity confidence on investment in children: (1) men will be more likely to divorce women if they suspect or are sure that they are not the father of their wife's child, and (2) controlling for divorce, men will reduce direct investments in low paternity confidence children relative to high paternity confidence children. The first hypothesis was supported by the data. The second hypothesis was supported for two out of three measures of paternal investment we examined; low paternity confidence reduces the time men spend with a child in a group with other children or adults, and it reduces extensive involvement with the child's educational progress; there was no effect of paternity confidence on the amount of time men spend with children in one-on-one interactions. We also examined the effects of unstated paternity confidence (e.g., when men decline to answer the question) on divorce and paternal investment. Overall, the results suggested that paternity confidence plays an important role in shaping men's relationships with women and with their putative genetic children.

. Introduction Asymmetry of parental investment is a fundamental feature of sexual reproduction (e.g., Clutton-Brock, 1991 and Low, 2000). In the vast majority of species, female gametes are larger than male gametes and provide the initial energy plant for development. Moreover, when investment extends beyond the initial energetic input into gametes, it is often the female that provides the extra care or resources. In some cases, however, males do provide substantial inputs into offspring, rarely more than females but sometimes as much as females. Therefore, paternal care is much more variable across species than maternal care. While among birds and mammals, most females engage in extensive parental investment, male care of offspring is rather rare among mammals, common in birds, and highly variable among fish (Clutton-Brock, 1991). Because parental care is costly, evolution predicts that males will provide less parental investment for putative genetic offspring who are unlikely to be their actual offspring (e.g., Alexander, 1974, Trivers, 1972 and Xia, 1992). The distinctions between actual paternity, nonpaternity, and paternity confidence are often confounded or overlooked in the literature (Anderson et al., in press and Schwagmeyer & Mock, 1993). Paternity refers to the actual likelihood that a man is (or is not) the biological father of a particular child. Nonpaternity is the exclusion of paternity and refers to the likelihood that a man is not the genetic father of a particular child. Modern paternity tests do not prove paternity; rather, they demonstrate nonpaternity by showing that a given man is exceedingly unlikely to have fathered a particular child. In contrast, paternity confidence refers to a man's internal (not necessarily conscious or articulated) assessment of his paternity. Among humans, beliefs about paternity and men's responsibility for children vary greatly cross-culturally (e.g., Beckerman et al., 1998, Hrdy, 2000 and Levine, 1987), though men in many different cultures pay great attention to paternity (e.g., Betzig, 1989 and Daly & Wilson, 1988). In Western legal tradition, men are generally not held responsible for putative children who are in fact not theirs (Rudavsky, 1999 and Wilson, 1987), and American men who refuse to pay child support often cite suspected nonpaternity as justification (Dubey, 1995). The mechanics of internal fertilization and live birth mean that while women are always sure of maternity, men can never be fully positive of paternity. Men must rely instead on indirect cues such as mate fidelity or child resemblance to assess whether they are likely to be the father of a particular child (e.g., Davis & Daly, 1997). Most research on paternity confidence has focused on men's resemblance to children and their ability to detect it (reviewed in Anderson et al., in press). In contrast, Anderson et al. (in press) examined demographic correlates of paternity confidence, using data on men in Albuquerque, NM. They reported that men were more likely to report low paternity confidence in a pregnancy if the man was not married to the child's mother or if the pregnancy was unplanned. Both of these factors are likely to correlate to some extent with the potential for mate infidelity. No research has directly examined how accurately men assess paternity confidence, though indirect evidence suggests that men with high paternity confidence may be more accurate in their assessment than men with low paternity confidence (Anderson, 2006). The prediction that males will invest less in offspring who are unlikely to be theirs has received limited empirical examination. For avian species, the prediction is generally met, although the effect is not as strong or as universal as originally predicted (Møller & Birkhead, 1993, Schwagmeyer et al., 1999 and Whittingham & Dunn, 2001), and many of the avian studies have been criticized on methodological grounds (Kempenaers & Sheldon, 1997, Schwagmeyer & Mock, 1993 and Sheldon, 2002). Among nonhuman primates, it has been questioned whether paternal care ever reflects paternity (e.g., Van Schaik & Paul, 1996). Among humans, analyses of qualitative cross-cultural data suggest that paternity confidence is positively associated with men's involvement with children, or with investment or inheritance from paternal kin (Diamond & Lorcay, 1989, Flinn, 1981, Gaulin & Schlegel, 1980, Greene, 1979, Hartung, 1985 and Kurland, 1979). Within societies, greater investment by matrilineal than patrilineal kin suggests significant levels of nonpaternity, or more precisely, it suggests reduced levels of paternity confidence (Euler & Weitzel, 1996, Gaulin et al., 1997 and McBurney et al., 2002; but see Pashos, 2000, for mixed results). Relatively, little is known about the rates of actual paternity cross-culturally (see Anderson, 2006, for a detailed analysis). Fox and Bruce (2001) used a sample of men in Knoxville County, TN, to examine the relationship between confidence of paternity and (a) a measure of men's affective involvement with children, and (b) a composite fathering variable. They found a positive relationship for both outcomes, but paternity confidence was unrelated to several other measures of fathering (responsivity, harshness, and behavioral engagement). However, Fox and Bruce (2001) provided no substantive information on how they measured paternity confidence, making the interpretation and contextualization of their results difficult. No study has directly examined the quantitative relationship between actual paternity and investment in or involvement with children. In the current study, we propose to examine how self-reported paternity confidence influences men's investment in their putative genetic offspring. We analyze how paternity confidence influences paternal investment indirectly, through the likelihood that men may abandon low paternity confidence children, and directly, through reduced direct male involvement with low paternity confidence children after controlling for divorce status. 1.1. Hypotheses We proposed two routes through which low paternity confidence may reduce paternal investment. One route is through divorce or separation from the child's mother, which often results in men ceasing to live with the child. In many cultures, divorce results in reduced male investment in children from previous relationships (e.g., Amato, 1987, Anderson et al., 1999, Anderson et al., 1999, Hofferth & Anderson, 2003, Simpson, 1997, Teachman, 1991, Weiss & Willis, 1985 and Weiss & Willis, 1993). This reduction in investment occurs in part not only because of reduced contact between men and children, but also because men have reallocated resources toward new avenues of mating effort, as well as perhaps into new children or stepchildren (Anderson, 2000). Divorce can be considered an indirect form of reduced investment in children and results in our first hypothesis: (1) Men will be more likely to divorce women if they suspect or are sure that they are not the father of their partner's child. Whether or not divorce has occurred, men may reduce direct investment in low paternity confidence children. Controlling for paternal coresidence in this analysis is crucial. We expected to find an effect of paternity confidence on men's investments in children, above and beyond the effects of divorce on investment. This led to our second hypothesis: (2) Controlling for divorce, men will reduce direct investments in low paternity confidence children relative to high paternity confidence children.

3. Results 3.1. Divorce Table 1 presents descriptive statistics, by level of paternity confidence, for the variables used in the analysis of divorce. For this table only, each variable is assessed for the focal child's year of birth. The final column of the table presents the F statistic and p value associated with an analysis of variance for each variable, indicating whether there is a significant variation across different levels of paternity confidence. Table 1. Descriptive statistics for variables used to predict union dissolution, by paternity confidence Paternity confidence F2,2579 p High Low Unstated Mean SD Mean SD Mean SD Respondent's age (years) 28.56 5.87 27.16 5.98 28.38 6.33 0.92 .4000 Logged income (in 1990 dollars) 9.87 1.61 9.45 2.59 9.65 0.73 1.39 .2490 Respondent's education (years) 15.70 3.53 15.28 4.06 10.26 4.02 39.6 .0000 Mother's education (years) 13.99 3.71 11.91 3.49 11.82 4.22 10.54 .0000 Calendar year of pregnancy 1962.70 12.61 1965.00 13.73 1955.00 12.90 6.81 .0011 Couple ever legally married 0.98 0.14 0.78 0.42 0.97 0.17 29.74 .0000 No. of children the couple has together 1.16 1.44 0.75 0.98 2.65 2.46 19.01 .0000 Respondent is Anglo 0.58 0.49 0.69 0.47 0.06 0.24 19.98 .0000 Respondent is Hispanic 0.37 0.48 0.31 0.47 0.94 0.24 23.92 .0000 Respondent is other ethnicity 0.05 0.21 0.00 0.00 0.00 0.00 1.59 .2035 Child is male 0.52 0.50 0.63 0.49 0.59 0.50 1.05 .3484 N (no. of children) 2516 32 34 Statistics calculated for the focal child's year of birth. Table options Neither the man's age nor his logged income at the time the child was born varied significantly by confidence of paternity. The education levels of each parent showed highly significant variation, with men whose paternity confidence was unstated having less education than other men, and mothers of high paternity confidence children having more education than other mothers. Children whose paternity confidence was unstated tended to be born in earlier calendar years than other children, while children whose paternity confidence was low were less likely to have parents who were married at the time of their birth. Low paternity confidence children had the fewest siblings, and unstated paternity confidence children had the most. Ethnicity varied by confidence of paternity, with Anglos the least likely not to state paternity confidence and Hispanics the most. There was no significant variation by paternity confidence for men of other ethnicities (reflecting their relative scarcity in the data set), nor did the child's gender vary significantly. (For further details on the demographic correlates of paternity confidence among Albuquerque men, see Anderson et al., in press). Confidence of paternity was related to the probability of divorce, as illustrated in Fig. 1, which shows life table survival curves to union dissolution following birth. Men with high and unstated levels of paternity confidence in children had very similar survival curves, and both were unlikely to divorce following the birth of a child. Men with low paternity confidence were much more likely to experience union dissolution; less than half of these men were still in relationships with the child's mother when the child was 4 years old, as opposed to about 90% of men with high or unstated levels of paternity confidence. Time until union dissolution following birth, by paternity confidence. Fig. 1. Time until union dissolution following birth, by paternity confidence. Figure options A multivariate Cox proportional hazards model of the probability of divorce is presented in Table 2. The coefficient is presented as a hazards ratio: values greater than 1.0 indicate that the outcome is more likely to happen as the value of the independent variable increases, while values less than 1.0 indicate that the outcome is less likely to happen as the value of the independent variable increases. All else being equal, divorce is less likely to occur following the birth of a child if the man is older or more educated, if the child's mother is more educated, or if the couple is legally married. Union dissolution is more likely to occur in recent calendar years. Income and the couple's previous fertility have no significant effect on union dissolution. With respect to ethnicity, Hispanics are significantly less likely to divorce than Anglos, but there is no significant difference between Anglos and other (non-Hispanic) ethnic groups. Additionally, the child's gender has no effect on parental divorce. Table 2. Cox proportional hazards analysis of the probability of union dissolution within 10 years following birth Hazards ratio SD p Respondent's age 0.942 0.014 .000 Logged income 1.033 0.053 .522 Respondent's education (years) 0.941 0.024 .016 Mother's education (years) 0.939 0.023 .009 Calendar year 1.052 0.007 .000 Couple ever legally married 0.313 0.083 .000 No. of children the couple has together 0.939 0.072 .413 Anglo (reference group) – – – Hispanic 0.620 0.104 .004 Other ethnicity 1.158 0.349 .626 Child is male 0.986 0.094 .883 High paternity confidence (reference group) – – – Low paternity confidence 4.935 1.417 .000 Unstated paternity confidence 0.861 0.804 .873 χ2 173.35 p .0000 n=22677 person-years from 2582 children parented by 1000 men. Standard errors are adjusted to control for multiple children per respondent. Table options Consistent with the pattern depicted in Fig. 1, low paternity confidence has a tremendous effect on the probability of divorce. All else being equal, union dissolution is 4.9 times more likely to occur following a child's birth if the man has low paternity confidence in a child than if he has high paternity confidence. The probability of union dissolution is not significantly different for children whose paternity confidence was unstated than children in whom men have high paternity confidence. This model does not test for a difference between low and unknown paternity confidence. In an identical model with low paternity confidence as the omitted baseline, divorce is marginally less likely following the birth of a child whose paternity confidence is unstated vs. one with low paternity confidence (p=.071). 3.2. Investment in children Examination of the median or mean time involvement with children, as measured retrospectively for children aged 5 through 12 years, suggested that paternal investment varied significantly by paternity confidence in this sample. The median time spent with a child in one-on-one interactions was 3 to 5 h per week for high paternity confidence children and less than 2 h per week for both low and unknown paternity confidence children. Wilcoxon rank-sum tests, used because the dependent variable was neither continuous nor normally distributed, showed that the median time spent one-on-one with high paternity confidence children was significantly greater than the median for low paternity confidence children (z=2.357, p=.0184) and for children whose paternity confidence was unstated (z=2.753, p=.0059). The medians for low and unstated paternity confidence children were not significantly different from each other (z=−0.300, p=.7644). The median amount of time per week men reported spending with a child in a group with other children or adults was 16 h or more for both high and unknown paternity confidence children, and 6 to 15 h for low paternity confidence children. According to Wilcoxon rank-sum tests, the medians for these distributions were all significantly different from each other (z=3.956, p=.0001 for high vs. low paternity confidence; z=−2.126, p=.0335 for high vs. unstated paternity confidence; and z=−3.896, p=.0001 for low vs. unstated paternity confidence). Lastly, men reported extensive educational involvement with 60.4% of high paternity confidence children, as do 66.7% of men with unstated paternity confidence; in an analysis of variance, these mean proportions were not significantly different (F1,1958=0.34, p=.5620). Men were extensively involved with schooling for only 29.2% of low paternity confidence children, which was significantly less than the level of involvement with either high (F1,1961=9.71, p=.0019) or unstated (F1,43=7.04, p=.0111) paternity confidence children. For all three measures of paternal investment, low paternity confidence children received less investment than high paternity confidence children. The descriptive statistics for other variables used in analysis by paternity confidence were essentially identical to those presented for the divorce sample ( Table 1) and thus was not repeated here. Ordered logistic models of the time men spend one-on-one with children are presented in Table 3. There are two models in the table. Model 1 does not control for parental divorce or separation, and Model 2 adds a variable indicating whether the man had divorced or broken up with the child's mother by the time the child was 5 years old. Many of the control variables in Model 1 have significant effects on men's involvement with children. The mother's education, the calendar year, being legally married, being Hispanic, and the child being male all have significant positive effects on men's involvement with children, while the number of children the couple has together has a significantly negative effect on men's one-on-one interactions with a child. Men spend marginally more time with children if they were ever legally married to the child's mother. The man's age, income, and education, as well as being of other (non-Anglo, non-Hispanic) ethnicity, were not significant predictors of the time spent alone with children. All else being equal, men spend significantly less time with low paternity confidence children than with high paternity confidence children, while unstated paternity confidence has no significant effect. Relationship status, when added (Model 2), has a significant effect; not surprisingly, men spend less time with children if they are no longer in a relationship with the child's mother. The effect of low paternity confidence loses statistical significance. Thus, the reduction in time spent one-on-one with low paternity confidence children reported above is apparently a result of the parents being divorced. In an identical model with low paternity confidence as the omitted baseline (not shown), no significant difference was found between time spent alone with low and unknown paternity confidence children. Table 3. Ordered logistic models of time men spent with a child in one-on-one interactions, aged 5 to 12 years Model 1 Model 2 Coefficient SD p Coefficient SD p Respondent's age 0.007 0.009 .456 0.012 0.009 .189 Logged income 0.053 0.040 .192 0.055 0.039 .164 Respondent's education (years) 0.013 0.023 .573 0.010 0.023 .649 Mother's education (years) 0.058 0.023 .012 0.042 0.024 .072 Calendar year 0.012 0.005 .013 0.014 0.005 .004 Couple ever legally married 0.974 0.540 .071 0.589 0.391 .133 No. of children the couple has together −0.281 0.042 .000 −0.409 0.045 .000 Anglo (reference group) – – – – – – Respondent is Hispanic 0.366 0.149 .014 0.422 0.149 .005 Respondent is other ethnicity −0.108 0.230 .639 −0.055 0.231 .812 Child is male 0.262 0.071 .000 0.257 0.073 .000 Respondent and child's mother divorced/broke up – – – −2.189 0.304 .000 High paternity confidence (reference group) – – – – – – Low paternity confidence −1.429 0.643 .026 −0.736 0.624 .238 Unstated paternity confidence −0.717 0.620 .247 −0.522 0.640 .415 χ2 107.99 167.36 p .0000 .0000 n=2581 children parented by 973 men. Time-variant variables calculated for when child was 5 years old. Table options Table 4 presents multivariate ordered logistic models of the time men spend with a child in a group with other children or adults, for children aged 5 through 12 years. Among the background variables in Model 1, being legally married and being Hispanic both have significant positive effects on group time involvement with children, while being of non-Anglo non-Hispanic ethnicity has a marginally significant negative effect. Men spend significantly less time in a group with low paternity confidence than high paternity confidence children, and they spend more time (though the effect is only marginally significant) with children whose paternity confidence is unstated than with high paternity confidence children. Furthermore, these patterns remain after controlling for whether the parents divorced or broke up by the time the child was 5 years old (Model 2). Divorce has a significantly negative effect on time involvement in a group with children, but even controlling for this, men report spending significantly less time with low paternity confidence children, and significantly more time with unstated paternity confidence children. In an identical model with low paternity confidence as the omitted baseline (not shown), men spent significantly less time with low than with unknown paternity confidence children, even when divorce is controlled for. Table 4. Ordered logistic models of time men spent with a child in a group with others, aged 5 to 12 years Model 1 Model 2 Coefficient SD p Coefficient SD p Respondent's age 0.004 0.010 .695 0.009 0.010 .366 Logged income −0.002 0.052 .970 −0.002 0.050 .964 Respondent's education (years) −0.013 0.026 .616 −0.017 0.026 .503 Mother's education (years) 0.023 0.023 .325 0.007 0.024 .759 Calendar year 0.004 0.005 .472 0.006 0.006 .258 Couple ever legally married 1.102 0.554 .047 0.786 0.471 .095 No. of children the couple has together 0.047 0.068 .487 −0.069 0.062 .268 Anglo (reference group) – – – – – – Respondent is Hispanic 0.355 0.171 .038 0.412 0.172 .017 Respondent is other ethnicity −0.547 0.290 .059 −0.490 0.279 .080 Child is male 0.073 0.079 .357 0.089 0.081 .271 Respondent and child's mother divorced/broke up – – – −1.997 0.340 .000 High paternity confidence (reference group) – – – – – – Low paternity confidence −1.248 0.375 .001 −0.764 0.338 .024 Unstated paternity confidence 0.859 0.488 .079 1.020 0.497 .040 χ2 39.82 79.67 p .0000 .0000 n=2581 children parented by 973 men. Time-variant variables calculated for when child was 5 years old. Table options Lastly, Table 5 presents logistic regression models of the probability that men were extensively involved with children's educational progress between the age of 5 and 12 years. Model 1 shows that the education of the respondent and of the child's mother have significantly positive effects on educational involvement, as do being legally married or being Hispanic. The calendar year has a marginally significant negative effect, while the respondent's income has a marginally significant positive effect. Controlling for these background factors, men are significantly less likely to be extensively involved with the schooling of low paternity confidence children than high paternity confidence children. Children whose paternity confidence is unstated are not significantly different from high paternity confidence children. The effect of low paternity confidence on educational involvement persists after parental relationship status is added to the model (Model 2). Although divorce has a significantly negative effect on being extensively involved with schooling, men are still less likely to report high educational involvement with low paternity confidence children. The effect of unstated paternity confidence remained nonsignificant after divorce was added to the model. In an identical model with low paternity confidence as the omitted baseline (not shown), no significant difference was found between low and unknown paternity confidence children in terms of paternal involvement in education. Table 5. Logistic models of whether men were extensively involved in children's educational progress, aged 5 to 12 years Model 1 Model 2 Coefficient SD p Coefficient SD p Intercept 18.573 12.701 .144 17.970 13.051 .169 Respondent's age 0.014 0.012 .261 0.017 0.012 .164 Logged income 0.075 0.041 .069 0.073 0.041 .077 Respondent's education (years) 0.082 0.028 .004 0.080 0.028 .004 Mother's education (years) 0.059 0.028 .035 0.046 0.028 .106 Calendar year −0.012 0.007 .078 −0.011 0.007 .108 Couple ever legally married 1.014 0.459 .027 0.664 0.451 .141 Number of children the couple has together −0.021 0.057 .709 −0.111 0.062 .073 Anglo (reference group) – – – – – – Respondent is Hispanic 1.024 0.208 .000 1.045 0.210 .000 Respondent is other ethnicity −0.243 0.373 .514 −0.218 0.372 .558 Child is male 0.027 0.095 .776 0.019 0.096 .846 Respondent and child's mother divorced/broke up – – – −1.242 0.263 0.000 High paternity confidence (reference group) – – – – – – Low paternity confidence −1.214 0.460 .008 −0.984 0.468 .036 Unstated paternity confidence 0.269 1.027 .793 0.395 1.032 .702 χ2 48.89 75.87 p .0000 .0000 n=1984 children parented by 778 men. Standard errors are adjusted to control for multiple children per respondent.