Men Look For Fertility While Women Look For Fitness
What is the exact influence of genes on mate choices of humans? Does it affect males and females differently? Does the affect change based on whether the mate is for a short term relationship or long term relationship?
It is well known that genes located at the major histocompatibility complex (MHC) have a strong influence on human mate choices. The MHC is the densest part of the human genome and plays significant role in the auto immune system of humans. In order to improve the immunity capabilities, the MHC is believed to affect the mate choices, looking out for more a more different/diverse genetic partner, as this brings more new auto immune capabilities to their offspring. However this affect has not been analyzed across different sexes and for different relationship contexts.
Researchers from Australia recruited participants who were told to rate a huge collection of facial photos of the opposite sex for which genetic information was available. The rating was done on a scale of 1 to 10, with 1 being not attractive at all. The rating was done both for a short-term and a long-term relationship. All of the photos were with neutral facial expression and with hair and rest of the body not shown.
All participants were gene typed at 12 MHC and 11 non-MHC microsatellite loci. For every participant in the study, their genetic dissimilarity between him/her and every photo of the opposite sex was calculated. Genetic dissimilarity – a measure of shared alleles (a form of genes) was calculated. If two individuals had identical alleles at a locus, it was counted as a shared allele. Genetic diversity was measured for MHC and non-MHC loci separately. The diversity was measured in terms of heterozygosity (whether the two alleles at a given locus of two individuals are the same or not) and standardized mean (reflecting the genetic distance between two alleles at a locus, averaged across the measured loci).
Intensive statistical analysis on the data collected, after controlling non-MHC-dissimilarity showed that males prefer faces of females that are MHC-dissimilar, implying that faces contain cues to genetic dissimilarity. This was true for both long-term and short-term relationships. However females did not show any effect of MHC dissimilarity affecting the male face choices. This finding goes along with earlier research that, females did not show any preference for the odor of MHC similar males, whiles males preferred the odor of MHC-dissimilar females. Researchers identify that, males reproductive success is highly based on the fertility of the partner, irrespective of their mating strategy. Thus the males look out for MHC dissimilarity, as fertility problems such as longer birth intervals, recurrent abortions and fetal loss in humans are associated with increased MHC allele sharing.
When it came to genetic diversity, heterozygosity directly affected the choices made by females for both short-term and long-term relationships, however only the standardized mean measure of genetic diversity affected the choices made by males. MHC diversity is usually associated with fitness and choosing a MHC diverse mate would provide increased resources, reduction of contagions and high quality parental care in long-term relationships.
The researchers however point out that; this research is limited to mate choices (among the given photos) as opposed to mate preferences. Further research into mate preferences controlled by genetics, should bring more interesting information.
Image Credit: Flickr
Journal Reference: doi:10.1016/j.evolhumbehav.2009.07.001
What is the exact influence of genes on mate choices of humans? Does it affect males and females differently? Does the affect change based on whether the mate is for a short term relationship or long term relationship?
It is well known that genes located at the major histocompatibility complex (MHC) have a strong influence on human mate choices. The MHC is the densest part of the human genome and plays significant role in the auto immune system of humans. In order to improve the immunity capabilities, the MHC is believed to affect the mate choices, looking out for more a more different/diverse genetic partner, as this brings more new auto immune capabilities to the offspring. However this affect has not been analyzed across different sexes and for different relationship contexts.
Researchers from Australia recruited participants who were told to rate a huge collection of facial photos of the opposite sex for which genetic information was available. The rating was done on a scale of 1 to 10, with 1 being not attractive at all. All of the photos were with neutral facial expression and with hair and rest of the body not shown.
All participants were gene typed at 12 MHC and 11 non-MHC microsatellite loci. For every participant in the study, their genetic dissimilarity between him/her and every photo of the opposite sex was calculated. Genetic dissimilarity – a measure of shared alleles (a form of genes) was calculated. If two individuals had identical alleles at a locus, it was counted as a shared allele. Genetic diversity was measured for MHC and non-MHC loci separately. The diversity was measured in terms of heterozygosity (whether the two alleles at a given locus of two individuals are the same or not) and standardized mean (reflecting the genetic distance between two alleles at a locus, averaged across the measured loci).
Intensive statistical analysis on the data collected, after controlling non-MHC-dissimilarity showed that males prefer faces of females that are MHC-dissimilar, implying that faces contain cues to genetic dissimilarity. This was true for both long-term and short-term relationships. However females did not show any effect of MHC dissimilarity affecting the male face choices. This finding goes along with earlier research that, females did not show any preference for the odor of MHC similar males, whiles males preferred the odor of MHC-dissimilar females. Researchers identify that, males reproductive success is highly based on the fertility of the partner, irrespective of their mating strategy. Thus the males look out for MHC dissimilarity, as fertility problems such as longer birth intervals, recurrent abortions and fetal loss in humans are associated with increased MHC allele sharing.
When it came to genetic diversity, heterozygosity directly affected the choices made by females, however only the standardized mean measure of genetic diversity affected the choices made by males. MHC diversity is usually associated with fitness and choosing a MHC diverse mate would provide increased resources, reduction of contagions and high quality parental care in long-term relationships.
The researchers however point out that; this research is limited to mate choices (among the given photos) as opposed to mate preferences. Further research into mate preferences controlled by genetics, should bring more interesting information.
