Where are kin recognition signals in the human face?
MF Dal Martello and LT Maloney; 2006
http://www.journalofvision.org/content/6/12/2.long
Abstract
We report two experiments that aimed to determine where in the face the cues that signal kinship fall. In both experiments, participants were shown 30 pairs of photographs of children's faces. Half of the pairs portrayed siblings and half did not. The 220 participants were asked to judge whether each pair of photographs portrayed siblings. We measured the effect on kin recognition performance of masks that covered the upper half or the lower half of the face (Experiment 1) and the eye region or the mouth region (Experiment 2). In Experiment 1, we found that the signal detection estimate of performance d' decreased only 5.3% (ns) when the lower face was masked but by more than 65% when the upper face was masked. We tested whether the combination of kinship information from the two halves of the face can be treated as optimal combination of independent cues and found that it could be. In Experiment 2, we found that masking the eye region led to only a 20% reduction (ns) in performance whereas masking the mouth region led to a nonsignificant increase in performance. We also found that the eye region contains only slightly more information about kinship than the upper half of the face outside of the eye region.
Samstag, 2. November 2013
Freitag, 1. November 2013
Human Beings as Evolved Nepotists - Exceptions to the Rule and Effects of Cost of Help
Human Beings as Evolved Nepotists - Exceptions to the Rule and Effects of Cost of Help
Steve Stewart-Williams; 2008
Abstract
Inclusive fitness theory provides a compelling explanation for the evolution of altruism among kin. However, a completely satisfactory account of non-kin altruism is still lacking. The present study compared the level of altruism found among siblings with that found among friends and mates and sought to reconcile the findings with an evolutionary explanation for human altruism. Participants (163 males and 156 females) completed a questionnaire about help given to a sibling, friend, or mate. Overall, participants gave friends and mates as much or more help than they gave siblings. However, as the cost of help increased, siblings received a progressively larger share of the help, whereas friends and mates received a progressively smaller share, despite the fact that participants were closer emotionally to friends and mates than they were to siblings. These findings help to explain the relative standing of friends and mates as recipients of altruistic aid.
Steve Stewart-Williams; 2008
Abstract
Inclusive fitness theory provides a compelling explanation for the evolution of altruism among kin. However, a completely satisfactory account of non-kin altruism is still lacking. The present study compared the level of altruism found among siblings with that found among friends and mates and sought to reconcile the findings with an evolutionary explanation for human altruism. Participants (163 males and 156 females) completed a questionnaire about help given to a sibling, friend, or mate. Overall, participants gave friends and mates as much or more help than they gave siblings. However, as the cost of help increased, siblings received a progressively larger share of the help, whereas friends and mates received a progressively smaller share, despite the fact that participants were closer emotionally to friends and mates than they were to siblings. These findings help to explain the relative standing of friends and mates as recipients of altruistic aid.
Estimating ethnic genetic interests: Is it adaptive to resist replacement migration?
Estimating ethnic genetic interests: Is it adaptive to resist replacement migration?
Frank K Salter; 2002
Abstract
Analyses of the costs and benefits of immigration have not considered the dependence of an ethny’s reproductive fitness on its monopoly of a demarcated territory. Global assays of human genetic variation allow estimation of the genetic losses incurred by a member of a population when random fellow ethnics are replaced by immigrants from different ethnies. This potential loss defines an individual’s ethnic genetic interest as a quantity that varies with the genetic distance of potential immigrants. W. D. Hamilton showed that self-sacrificial altruism is adaptive when it preserves the genetic interests of a population of genetically similar individuals. Ethnic genetic interest can be so large that altruism on behalf of one’s ethny—‘ethnic nepotism’—can be adaptive when it prevents replacement. It follows that ethnies usually have an interest in securing and maintaining a monopoly over a demarcated territory, an idea consonant with the universal nationalism of Bismarck and Woodrow Wilson.
[See also: http://www.humanbiologicaldiversity.com/]
Frank K Salter; 2002
Abstract
Analyses of the costs and benefits of immigration have not considered the dependence of an ethny’s reproductive fitness on its monopoly of a demarcated territory. Global assays of human genetic variation allow estimation of the genetic losses incurred by a member of a population when random fellow ethnics are replaced by immigrants from different ethnies. This potential loss defines an individual’s ethnic genetic interest as a quantity that varies with the genetic distance of potential immigrants. W. D. Hamilton showed that self-sacrificial altruism is adaptive when it preserves the genetic interests of a population of genetically similar individuals. Ethnic genetic interest can be so large that altruism on behalf of one’s ethny—‘ethnic nepotism’—can be adaptive when it prevents replacement. It follows that ethnies usually have an interest in securing and maintaining a monopoly over a demarcated territory, an idea consonant with the universal nationalism of Bismarck and Woodrow Wilson.
[See also: http://www.humanbiologicaldiversity.com/]
Intelligence tests with higher g-loadings show higher correlations with body symmetry
Intelligence tests with higher g-loadings show higher correlations with body symmetry: Evidence for a general fitness factor mediated by developmental stability
Mark D Prokosch, Ronald A Yeo and Geoffrey F Miller; 2005
Abstract
Just as body symmetry reveals developmental stability at the morphological level, general intelligence may reveal developmental stability at the level of brain development and cognitive functioning. These two forms of developmental stability may overlap by tapping into a bgeneral fitness factor.Q If so, then intellectual tests with higher g-loadings should show higher correlations with a composite measure of body symmetry. We tested this prediction in 78 young males by measuring their left–right symmetry at 10 body points, and by administering five cognitive tests with diverse g-loadings. As predicted, we found a significant (z=3.64, p<0.003) relationship between each test’s rank order g-loading and its body symmetry association. We also found a substantial correlation (r=0.39, p<0.01) between body symmetry and our most highly g-loaded test (Ravens Advanced Progressive Matrices). General intelligence is apparently a valid indicator of general developmental stability and heritable fitness, which may partly explain its social and sexual attractiveness.
Mark D Prokosch, Ronald A Yeo and Geoffrey F Miller; 2005
Abstract
Just as body symmetry reveals developmental stability at the morphological level, general intelligence may reveal developmental stability at the level of brain development and cognitive functioning. These two forms of developmental stability may overlap by tapping into a bgeneral fitness factor.Q If so, then intellectual tests with higher g-loadings should show higher correlations with a composite measure of body symmetry. We tested this prediction in 78 young males by measuring their left–right symmetry at 10 body points, and by administering five cognitive tests with diverse g-loadings. As predicted, we found a significant (z=3.64, p<0.003) relationship between each test’s rank order g-loading and its body symmetry association. We also found a substantial correlation (r=0.39, p<0.01) between body symmetry and our most highly g-loaded test (Ravens Advanced Progressive Matrices). General intelligence is apparently a valid indicator of general developmental stability and heritable fitness, which may partly explain its social and sexual attractiveness.
Life history traits of humans compared with chimpanzees:
(full size: click at the image)
Source:
Patterns and processes of human life history evolution. MP Muehlenbein & MV Flinn; 2011
Mittwoch, 30. Oktober 2013
Human Ability to Recognize Kin Visually Within Primates
Human Ability to Recognize Kin Visually Within Primates
Alexandra Avergne et al.; 2009
http://link.springer.com/article/10.1007/s10764-009-9339-0/fulltext.html
Abstract
The assessment of relatedness is a key determinant in the evolution of social behavior in primates. Humans are able to detect kin visually in their own species using facial phenotypes, and facial resemblance in turn influences both prosocial behaviors and mating decisions. This suggests that cognitive abilities that allow facial kin detection in conspecifics have been favored in the species by kin selection. We investigated the extent to which humans are able to recognize kin visually by asking human judges to assess facial resemblance in 4 other primate species (common chimpanzees, western lowland gorillas, mandrills, and chacma baboons) on the basis of pictures of faces. Humans achieved facial interspecific kin recognition in all species except baboons. Facial resemblance is a reliable indicator of relatedness in at least chimpanzees, gorillas, and mandrills, and future work should explore if the primates themselves also share the ability to detect kin facially.
Alexandra Avergne et al.; 2009
http://link.springer.com/article/10.1007/s10764-009-9339-0/fulltext.html
Abstract
The assessment of relatedness is a key determinant in the evolution of social behavior in primates. Humans are able to detect kin visually in their own species using facial phenotypes, and facial resemblance in turn influences both prosocial behaviors and mating decisions. This suggests that cognitive abilities that allow facial kin detection in conspecifics have been favored in the species by kin selection. We investigated the extent to which humans are able to recognize kin visually by asking human judges to assess facial resemblance in 4 other primate species (common chimpanzees, western lowland gorillas, mandrills, and chacma baboons) on the basis of pictures of faces. Humans achieved facial interspecific kin recognition in all species except baboons. Facial resemblance is a reliable indicator of relatedness in at least chimpanzees, gorillas, and mandrills, and future work should explore if the primates themselves also share the ability to detect kin facially.
Low fertility increases descendant socioeconomic position but reduces long-term fitness in a modern post-industrial society
Low fertility increases descendant socioeconomic position but reduces long-term fitness in a modern post-industrial society
Anna Goodman et al.; 2012
Abstract
Adaptive accounts of modern low human fertility argue that small family size maximises the inheritance of socioeconomic resources across generations and may consequently increase long-term fitness. This paper explores the long-term impacts of fertility and socioeconomic position (SEP) on multiple dimensions of descendant success in a unique Swedish cohort of 14,000 individuals born 1915-1929. We show that low fertility and high SEP predict increased descendant socioeconomic success across four generations. Furthermore, these effects are multiplicative, with the greatest benefits of low fertility observed when SEP is high. Low fertility and high SEP do not, however, predict increased descendant reproductive success. Our results are therefore consistent with the idea that modern fertility limitation represents a strategic response to the local costs of rearing socioeconomically competitive offspring, but contradict adaptive models suggesting that it maximises long-term fitness. This indicates a conflict in modern societies between behaviours promoting socioeconomic versus biological success. This paper also makes a methodological contribution, demonstrating that number of offspring strongly predicts long-term fitness and thereby validating use of fertility data to estimate current selective pressures in modern populations. Finally our findings highlight that differences in fertility and SEP have important long-term effects on the persistence of social inequalities across generations.
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"We do, however, find strong support for the prediction that fertility limitation in modern societies enhances descendant socioeconomic success. Thus, our results indicate that reproductive behaviours that promote biological success (i.e. long-term genetic fitness) are in conflict with those that promote descendant socioeconomic success in modern populations. Specifically, we find that both low parental fertility and high parental SEP independently predict higher schoolmarks, educational level and income, and this is generally true in male and female descendants alike ... . Moreover, these associations persist up to at least the great-grandchild generation, reflecting the advantage of starting one’s own offspring on a favourable socioeconomic trajectory.
We also demonstrate for the first time a multigenerational interaction between SEP and fertility, such that the socioeconomic benefit of low fertility was especially large in groups that already had high SEP. This finding adds to a number of recent studies indicating that demographic modernization is associated with increased socioeconomic pay-offs to fertility limitation for the wealthiest families ... ."
Anna Goodman et al.; 2012
Abstract
Adaptive accounts of modern low human fertility argue that small family size maximises the inheritance of socioeconomic resources across generations and may consequently increase long-term fitness. This paper explores the long-term impacts of fertility and socioeconomic position (SEP) on multiple dimensions of descendant success in a unique Swedish cohort of 14,000 individuals born 1915-1929. We show that low fertility and high SEP predict increased descendant socioeconomic success across four generations. Furthermore, these effects are multiplicative, with the greatest benefits of low fertility observed when SEP is high. Low fertility and high SEP do not, however, predict increased descendant reproductive success. Our results are therefore consistent with the idea that modern fertility limitation represents a strategic response to the local costs of rearing socioeconomically competitive offspring, but contradict adaptive models suggesting that it maximises long-term fitness. This indicates a conflict in modern societies between behaviours promoting socioeconomic versus biological success. This paper also makes a methodological contribution, demonstrating that number of offspring strongly predicts long-term fitness and thereby validating use of fertility data to estimate current selective pressures in modern populations. Finally our findings highlight that differences in fertility and SEP have important long-term effects on the persistence of social inequalities across generations.
-------------------------------------------------------------------------------------------------------------
"We do, however, find strong support for the prediction that fertility limitation in modern societies enhances descendant socioeconomic success. Thus, our results indicate that reproductive behaviours that promote biological success (i.e. long-term genetic fitness) are in conflict with those that promote descendant socioeconomic success in modern populations. Specifically, we find that both low parental fertility and high parental SEP independently predict higher schoolmarks, educational level and income, and this is generally true in male and female descendants alike ... . Moreover, these associations persist up to at least the great-grandchild generation, reflecting the advantage of starting one’s own offspring on a favourable socioeconomic trajectory.
We also demonstrate for the first time a multigenerational interaction between SEP and fertility, such that the socioeconomic benefit of low fertility was especially large in groups that already had high SEP. This finding adds to a number of recent studies indicating that demographic modernization is associated with increased socioeconomic pay-offs to fertility limitation for the wealthiest families ... ."
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