Perceived mate fidelity and paternal resemblance predict men's investment in children

Here, we investigate whether variation in male parental investment can be explained in terms of (1) men's perception of the degree of resemblance between themselves and their offspring and (2) men's perception of their mates' fidelity. In a sample of men from London's Heathrow airport, both variables were found to predict reported investment. We also examined whether the predictors of investment varied when men were no longer in a relationship with the mother of their children and are therefore no longer investing in mating effort with them. Among men no longer in a relationship with the mother of their children, resemblance became a stronger predictor of investment, while fidelity was no longer a significant predictor. Overall, men provided less investment to their children if they were no longer in a relationship with the mother of their children.     

Reading men's faces: women's mate attractiveness judgments track men's testosterone and interest in infants

This study investigated whether women track possible cues of paternal and genetic quality in men's faces and then map perception of those cues onto mate attractiveness judgments. Men's testosterone concentrations served as a proxy for genetic quality given evidence that this hormone signals immunocompetence, and men's scores on an interest in infants test were chosen as prima facie markers of paternal quality. Women's perceptions of facial photographs of these men were in fact sensitive to these two variables: men's scores on the interest in infants test significantly predicted women's ratings of the photos for how much the men like children, and men's testosterone concentrations significantly predicted women's ratings of the men's faces for masculinity. Furthermore, men's actual and perceived affinity for children predicted women's long-term mate attractiveness judgments, while men's testosterone and perceived masculinity predicted women's short-term mate attractiveness judgments. These results suggest that women can detect facial cues of men's hormone concentrations and affinity for children, and that women use perception of these cues to form mate attractiveness judgments.     

Whom are Mexican infants said to resemble? Monitoring and fostering paternal confidence in the Yucatan

It has been hypothesized (Daly and Wilson 1982) that resemblance claims about, and names given to, newborns will be biased in a paternal direction. There are also evolutionary reasons to expect that the magnitude of this bias will vary with the laterality of the speaker, the infants' birthorder, the duration of the parents' union, and the possibility that the pater might overhear the remarks. A series of 13 such predictions was examined in light of 198 interviews with the parents and relatives of a randomly selected sample of Mexican infants under the age of six months. The analyses indicate that, as hypothesized, paternal resemblance is alleged much more frequently than is maternal resemblance and that mothers and their relatives remark such resemblance more often than do paters and their relatives. In addition, allegations of paternal resemblance are more frequent for low-birthorder children and when the parents have been paired only briefly. Counter to expectations, the presence of the pater has no effect on mothers' tendencies to allege paternal resemblance, and children named after the pater are not more likely to be said to resemble him. Overall, our findings are in agreement with the assumption that evolved motives influence behavior.     

Paternity cues and mating opportunities: what makes fathers good?

Human males provide facultative paternal investment to their offspring; that is, the male care is not necessary for the survival of his offspring. It is expected that the degree of male investment (1) increases with growing paternity certainty, (2) increases when investment increases the survival and later reproductive prospect of offspring and (3) declines when there are opportunities to mate with multiple females. Using a large sample of adult offspring and their fathers (n = 245), we first investigated the role of two factors possibly involved in the assessment of paternity and subsequently regulating the level of paternal investment: (a) father–child facial resemblance and (b) assortative mating for eye colour. Second, because mating opportunities are inversely related to paternal investment, we also investigated how male facial attractiveness (a cue of mate opportunities) correlates with paternal investment. In line with paternal investment theory, male investment positively correlated with offspring facial resemblance. However, paternal investment were neither higher among blue-eyed couples, nor there were preferences of blue-eyed men to marry with blue-eyed women. Moreover, father facial attractiveness was unrelated to paternal investment. These results indicate that resemblance between offspring and their fathers still plays an important role in paternal investment decision later in offspring’s life.     

Reactions to children's faces: Resemblance affects males more than females

Since cuckoldry risk is asymmetrical, we hypothesized that parental investment would be more affected by paternal than maternal resemblance. To test this hypothesis, we asked subjects hypothetical questions about investing in children under conditions in which their faces or those of other people had been morphed with photographs of children. Males were more likely to choose a face they had been morphed with as the most attractive, the child they were most likely to adopt, the child they would like to spend the most time with, the child they would spend US$50 on, and the child they would least resent having to pay child support for. Reactions to children's faces by females were much less affected by resemblance.     

Differential facial resemblance of young children to their parents: who do children look like more?

In humans, paternal investment is highly variable and is modulated by paternity uncertainty. Facial phenotypic similarity between a father and a child is one possible paternity indicator. However, whether such paternal-biased traits are expressed in children is unclear, as previous empirical results are contradictory. Therefore, we quantified the facial resemblance between a child and each of his or her parents, from birth to 6 years old. Resemblance was assessed from pictures of the face by nonrelated judges. We found that, at all ages, children resemble both their parents more than would be expected by chance, although there is a differential resemblance toward one or the other parent depending on the age and sex of the child. For newborns, boys and girls resemble their mothers more, this differential resemblance persisting through time for girls. For boys, an inversion occurs and they resemble their fathers more between 2 and 3 years of age. The resemblance ascribed by the parents shows that, at birth, mothers ascribe a resemblance to the father, as previously found, although assessment by external judges revealed the opposite. These results suggest that facial appearance is a cue for kin recognition between a father and a child. Patterns of differential resemblance are discussed within the context of evolutionary theories on parental investment.     

Whom are newborn babies said to resemble?

We tested a series of hypotheses derived from the view that allegations of resemblance of newborns are motivated responses to the problem of uncertain paternity. Paternal resemblance was alleged far more often than maternal resemblance by videotaped mothers immediately after birth and by questionnaire respondents (mothers, fathers, and relatives on both sides). This bias was evident for infants of both sexes, albeit for sons more than for daughters. It is evidently normative to remark paternal similarity: 25 parents reported that “every-one,” “many people,” or the like had so commented, whereas there were no reports of similarly consensual allegations of maternal resemblance.Although fathers' questionnaire responses were themselves biased toward paternal resemblance, many fathers betrayed skepticism or reserve about such allegations, both by their comments when present at the birth and in their replies to the comments of relatives. Maternal allegations of paternal resemblance were significantly related to birth order and naming practices, in ways predicted from the proposition that mothers endeavor to promote paternity confidence.     

Are men really that bad as fathers? The role of men's investments

Human pair-bonding and paternal involvement have long been attributed to the need for biparental rearing of altricial offspring with extended periods of dependency. More recently, researchers have focused on the fertility benefits that pair-bonding offers men and have re-conceptualized paternal care as a stratagem designed to curry favor with the recipient children's mother. These models, however, fail to explain a number of puzzling empirical findings, namely the lack of a significant and robust effect of father-presence cross-culturally, despite what appears to be true paternal involvement. I argue that the record is better explained by conceptualizing reproduction within unions as a joint venture, in which men's contributions are not simply lumped onto women's invariant levels of parental investment, but one in which men's involvement allows wives to reduce their own allocations to parental investment and increase those to fertility (fertility model), thereby maximizing the production of the union, not simply child survivorship.     

Men’s reproductive investment decisions

Using questionnaire data completed by 170 men, we examine variation in paternal investment in relation to the trade-off between mating and parenting. We found that as men’s self-perceived mate value increases, so does their mating effort, and in turn, as mating effort increases, paternal investment decreases. This study also simultaneously examined the influence on parental investment of men’s mating effort, men’s perception of their mates’ fidelity, and their perceived resemblance to their offspring. All predicted investment. The predictors of investment are also tested independently for men who are still in a relationship with the mother of their children and those that are separated from her. Finally we examine how self-perceived mate value affects how men respond to variation in paternity confidence. Men with a self-perceived low mate value were less likely to respond to lowered mate fidelity by reducing their parental investment compared with men with a self-perceived high mate value.     

Short-term changes in fathers' hormones during father-child play: impacts of paternal attitudes and experience

Hormonal differences between fathers and non-fathers may reflect an effect of paternal care on hormones. However, few studies have evaluated the hormonal responses of fathers after interacting with their offspring. Here we report results of a 30-minute in-home experiment in which Filipino fathers played with their toddlers and consider whether paternal experience and men's perceptions of themselves as fathers affect hormonal changes. Fathers provided saliva and dried blood spot samples at baseline (B) and 30 (P30) and 60 (P60, saliva only) minutes after the interaction. We tested whether testosterone (T), cortisol (CORT), and prolactin (PRL) shifted after the intervention. In the total sample, T did not vary over the study period, while CORT declined from B to P30 and P60, and PRL also declined from B to P30. Fathers who spent more time in daily caregiving and men who thought their spouses evaluated them positively as parental caregivers experienced a larger decline in PRL (B to P30) compared to other fathers. First-time fathers also had larger declines in PRL compared to experienced fathers. Experienced fathers also showed a greater decline in CORT (B to P60) compared to first-time fathers. These results suggest that males' paternal experience and age of offspring affect hormonal responses to father–child play and that there is a psychobiological connection between men's perceptions of themselves as fathers and their hormonal responsivity to childcare.     

Why babies look like their daddies: paternity uncertainty and the evolution of self-deception in evaluating family resemblance

It has been suggested that in a socially monogamous system where fathers invest in their mate's offspring but paternity is far from certain, it will be adaptive on the part of infants to conceal their father's identity; but the opposite claim has also been made that this is against the genetic interests of the fathers, and a high frequency of adulterine births will select instead for paternal resemblance. In this article, I present a simple theoretical model that suggests that neonatal anonymity benefits fathers, mothers, and children. Once anonymity becomes established, however, all babies start paying the cost of paternity uncertainty, that is, the reduction in paternal care due to fathers not knowing whether they have truly sired their mate's offspring. By diminishing the fitness of babies, such a cost bounces back as lowered fitness for parents as well. We should then expect the evolution of maternal strategies directed to decrease paternity uncertainty, in the form of instinctive and unsolicited comments on babies' resemblance to their putative fathers. In contradiction to the widespread belief that it would be in fathers' interest to be skeptical of these allegations, the model suggests that, under conditions of infant anonymity, fathers will actually promote their own fitness by believing their spouses. Received in revised form: 5 September 2001 Electronic Publication     

Facial resemblance of Japanese children to their parents

Facial resemblance between parents and their children could be an indicator of genetic relationship, and selective pressure could bias the resemblance of appearance. We assessed the degree of resemblance of 38 Japanese children (3–6 years old) to each of their parents using photographs. We asked nonrelatives to assess which of the parents each child resembled, manipulating indications of the sex of the children. Variance in the degree of resemblance between the children and their fathers was very large. Although the basic facial appearance of each parent can be reflected in each child with 50% probability, the children did not equally show the facial characteristics of each parent at the individual level. The indication of sex had no significant effect on the assessment of resemblance. On the other hand, a questionnaire given to the assessors revealed that, as children, they tended to be said to resemble the opposite-sex parent. This result indicates that alleged resemblance does not reflect an actual condition but rather might have cultural meaning. Electronic Publication     

Why do men marry and why do they stray?

Humans are quite unusual compared to other great apes in that reproduction typically takes place within long-term, iteroparous pairings--social arrangements that have been culturally reified as the institution of marriage. With respect to male behaviour, explanations of marriage fall into two major schools of thought. One holds that marriage facilitates a sexual division of labour and paternal investment, both important to the rearing of offspring that are born helpless and remain dependent for remarkably long periods (provisioning model). And the other suggests that the main benefits which men receive from entering into marriage derive from monopolizing access to women's fertility (mating effort model). In this paper, we explore extramarital sexual relationships and the conditions under which they occur as a means of testing predictions derived from these two models. Using data on men's extramarital sexual relationships among Tsimane forager-horticulturists in lowland Bolivia, we tested whether infidelity was more common when men had less of an opportunity to invest in their children or when they risked losing less fertility. We found that Tsimane men appear to be biasing the timing of their affairs to when they are younger and have fewer children, supporting the provisioning model.     

Facialmetric similarities mediate mate choice: sexual imprinting on opposite-sex parents

Former studies have suggested that imprinting-like processes influence the shaping of human mate preferences. In this study, we provide more direct evidence for assessing facial resemblance between subjects' partner and subjects' parents. Fourteen facial proportions were measured on 312 adults belonging to 52 families, and the correlations between family members were compared with those of pairs randomly selected from the population. Spouses proved to be assortatively mated in the majority of measured facial proportions. Significant correlations have been found between the young men and their partner's father (but not his mother), especially on facial proportions belonging to the central area of the face. Women also showed resemblance to their partner's mother (but not to their father) in the facial characteristics of their lower face. Replicating our previous studies, facial photographs of participants were also matched by independent judges who ascribed higher resemblance between partners, and subjects and their partners' opposite-sex parents, compared with controls. Our results support the sexual imprinting hypothesis which states that children shape a mental template of their opposite-sex parents and search for a partner who resembles that perceptual schema. The fact that only the facial metrics of opposite-sex parents showed resemblance to the partner's face tends to rule out the role of familiarity in shaping mating preferences. Our findings also reject several other rival hypotheses. The adaptive value of imprinting-related human mating is discussed, and a hypothesis is made of why different facial areas are involved in males' and females' search for resemblance.     

Family resemblance for anthropometric and blood pressure measurements in Black Caribs and Creoles from St. Vincent Island

This paper examines family resemblance for five anthropometric measurements (height, weight, triceps skinfold, upper arm circumference relaxed [UACR] and flexed [UACF] and for systolic and diastolic blood pressure in a group of adult Caribbean islanders of primarily African ancestry. Six hypotheses about family resemblance are tested by using path analysis and likelihood ratios. Significant intergenerational transmission is found only for height and UACR. For weight, UACF, and diastolic blood pressure, non-transmissible sibling resemblance is the primary component of family resemblance, although significant marital resemblance exists for diastolic blood pressure. Triceps skinfold and systolic blood pressure show no evidence of any family resemblance. Although results for highly heritable traits such as height are comparable to reports from other populations, measurements with a large contribution from common family environment or residual environmental effects, such as triceps skinfold or blood pressure, have much lower family resemblance in this population than in other populations. We hypothesize that this difference is due to the fact that adult children and their parents do not share a common household in this culture and to the presence of major nonfamilial environmental factors contributing to obesity and hypertension in this population.     

Different numbers of maternal and paternal siblings of cystic fibrosis patients

Summary When 458 parents of children suffering from cystic fibrosis (CF) from all over the German Democratic Republic were interviewed to determine the number of their siblings, it was found that the maternal families had a total of 1369 children and the paternal, 1220. While the fathers of CF patients tended to originate from families with one or two children, more mothers than fathers came from families with three to twelve children (P=0.01). The average number of children in the maternal families was 2.99; in the paternal families, only 2.66. To rule out any methodological errors, sibs of mothers and fathers of various control groups were studied. We found that the number of siblings in these groups was balanced. The differences in our findings are probably due to CF heterozygosity. The underlying mechanism is unknown.     

The dose and dose-rate effects of paternal irradiation on transgenerational instability in mice: a radiotherapy connection

The non-targeted effects of human exposure to ionising radiation, including transgenerational instability manifesting in the children of irradiated parents, remains poorly understood. Employing a mouse model, we have analysed whether low-dose acute or low-dose-rate chronic paternal γ-irradiation can destabilise the genomes of their first-generation offspring. Using single-molecule PCR, the frequency of mutation at the mouse expanded simple tandem repeat (ESTR) locus Ms6-hm was established in DNA samples extracted from sperm of directly exposed BALB/c male mice, as well as from sperm and the brain of their first-generation offspring. For acute γ-irradiation from 10-100 cGy a linear dose-response for ESTR mutation induction was found in the germ line of directly exposed mice, with a doubling dose of 57 cGy. The mutagenicity of acute exposure to 100 cGy was more pronounced than that for chronic low-dose-rate irradiation. The analysis of transgenerational effects of paternal irradiation revealed that ESTR mutation frequencies were equally elevated in the germ line (sperm) and brain of the offspring of fathers exposed to 50 and 100 cGy of acute γ-rays. In contrast, neither paternal acute irradiation at lower doses (10-25 cGy), nor low-dose-rate exposure to 100 cGy affected stability of their offspring. Our data imply that the manifestation of transgenerational instability is triggered by a threshold dose of acute paternal irradiation. The results of our study also suggest that most doses of human exposure to ionising radiation, including radiotherapy regimens, may be unlikely to result in transgenerational instability in the offspring children of irradiated fathers.     

Expression of lactate dehydrogenase phenotypes in intraspecific and interspecific matings of two species of Xenopus

Starch gel electrophoresis has been used to examine lactate dehydrogenase phenotypes in two species of Xenopus and their hybrids obtained from reciprocal crosses. The patterns are complex, consisting of as many as 18 bands in some material. Differences between laevis and mulleri isozymes allow an evaluation of the contribution of both parents to the phenotypes of their hybrid offspring, and the determination of approximate times of paternal allele expression. The phenotype of early embryos resembles that of the maternal parent until hatching, when evidence of paternal influence is first apparent. Regardless of the early appearance of paternal enzyme, reciprocal hybrids bear a stronger resemblance to the maternal parent until well after tadpole growth begins. Once this maternal effect disappears, both laevis and mulleri appear to contribute to the LDH phenotype without predominance of the isozymes of either species. Evidence for the possible formation of “hybrid” enzymes consisting of subunits of both species in one active enzyme molecule is presented. Expression of LDH phenotype is variable in the unfertilized eggs of fertile hybrid females.     

Testosterone levels correlate with the number of children in human males,but the direction of the relationship depends on paternal education

Most research shows that fatherhood is related to reduced testosterone (T) levels, but relationships between the number of children and T levels are not addressed. In humans, paternal care usually involves obtaining adequate resources to support children, which may require engaging in male–male competition and maintaining high T levels. We hypothesize that T levels in fathers should increase with increasing family size. In 78 Polish men, aged 30 to 77 years, the number of children was significantly correlated with paternal T levels, but the direction of this relationship was dependent on the fathers' education. In agreement with our hypothesis, in men with below-college education, T levels increased with increasing number of children. In contrast, in men with college education, the number of children was negatively related to paternal T levels. Drop in T levels throughout the day tended to be less pronounced the more children fathers had, irrespective of their educational level. Our results suggest that a hypothesis of simple trade-offs between mating and parenting effort may be too simplistic to explain changes in testosterone response to parenting in human males. In order to understand functional response of changes in T levels, it is crucial to account for family size and socioeconomic factors. However, due to the cross-sectional study design, we cannot exclude the possibility that T levels influenced reproductive behavior (rather than vice versa) and thus the number of children produced by men.