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Natural Selection and Friendship - Coggle Diagram
Natural Selection and Friendship
Over time, friendship has been observed to be of great importance to human social environments. These social environments include other individuals chosen to interact with and be around. The reasoning behind the individuals chosen to be in this social environment is dug deeper into in this study.
Homophily is the tendency to pick others of similar genotypes by selecting individuals with similar phenotypes while heterophily is the tendence of picking dissimilar genotypes based on differing phenotypical traits.
Homophily
There are four main reasons why organisms may choose individuals with similar traits. These include:
1.Relationships are formed in result of making acquaintances in their same geographic location or setting.
Relationships are formed in result of choosing individuals to be friends with based on picking out similar phenotypical traits.
Relationships built in result of choosing specific environments to make friends in.
4.Relationships formed as a result of third parties choosing to be in specific settings to interact with similar individuals.
Homophily has a slight advantage in the sense that it is easier to find a successful interaction in a population of like individuals than it is to make a successful interaction with a dissimilar individual in a population of dissimilar people.
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Heterophily
There are two main reasons described to explain why humans may choose interactions with others that have genotypes dissimilar to their own.
1.Relationships built in result of choosing specific settings to choose to interact with dissimilar individuals.
Interactions based on specifically choosing dissimilar phenotypic individuals.
Advantages of chosen interactions with those of which have genotypes dissimilar to the subject's include benefits of any advantages there may be of having different immune systems around and differing resistances to pathogens relays into lack of transmission between individuals.
Testing was done to determine if friendship pairs have greater similarities in genotypes than dissimilarities. The specific testing included a genome-wide association study using the provided data from the Framingham Heart Study.
This initial test included 1,932 individuals in a singular or multiple friendship pairs. To prevent errors, a split-sample test was also preformed using strangers that had no kinship.
With this test of homophily, the kinship coefficient was measured. This ideally should show that positive correlated similarity will reap positive values as well as negatively correlated dissimilarity will result in negative values.
To test heterophily, the empirical probability was measured to observe the difference in single nucleotide polymorphisms (SNPs) in genomes.
In this test of heterophily, the scientists were looking for differences in SNPs of friend pairs with opposing genotypes.
This test showed that friend pairs had fewer differing SNPs than when compared to strangers.
The test of homophily in friends vs strangers showed the kinship coefficient shifting positively compared to the strangers. The friends showed a greater amount of "relatedness" in comparison to the strangers. The specific amount of kinship can be related to the kinship found in fourth cousins.
A secondary test was conducted to categorize genotypes into either being homophilic or heterophilic. The test compared a friend's expected genotype for 1,468,013 SNPs commonly found.
The first 10 primary component SNPs were compared between friend genomes and the subject's genome.
Only 907 friendship pairs had kinship less than or equal to zero so these were the pairs tested. The other 458 were used in a split-sample test.
The results of the test concluded the friend pairs had both greater amounts of homophily and heterophily than the compared strangers.
A third test was conducted using friendship scores of similarity in genotypes to see how correlated the genotypes really are.
This test utilizes 458 friend pairs and 458 stranger pairs.
The likelihood of a specific SNP occurring within 50 kb of each other was tested within 17,413 genes.
The next objective of this test was to see if any of the traits were overrepresented in specific databases.
The overrepresented genes were olfactory transduction, linoleic acid metabolism, and immune system processes.