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Friendship & natural selection - Coggle Diagram
Friendship & natural selection
Humans exhibit homophily in the friendships - meaning we're more likely to form friendships with people that are similar to us.
Deeper than just common interests - genetic are at play
At least 4 reasons homophily may exist:
Environment may be at play as we tend to form friendships with people who are geographically close or even related to us.
People choose to maintain friendships with those that are similar while not maintaining a relationship with those who aren't.
People choose their environment and meet people who chose the same environment.
People can be chosen to be in a specific environment.
Most likely all of these processes are happening at the same time.
Even if heterophily has more favorable fitness, humans tend to act on homophily because it is easier.
Heterophily can also exist.
2 processes can cause heterophily in friendships:
Participation in certain environments can bring different people together.
Some may choose to live by the "opposites attract" theory and seek out friendships with people that are different.
Study Procedures
Analyzed the friendships of 1,932 people in which they were a part of at least one of 1,367 friendship pairs.
calculated the kinship coefficient for homophilic friendships
calculated the probability of opposite genotypes for heterophilic friendships
This is the first study of this type (that they know of) so they don't have much data to analyze.
Conclusions
Pairs of friends show a relatedness at the fourth cousin level.
The genetic structure of the human population is a result of both reproduction and the formation of friendships.
Reference
Christakis NA, Fowler JH. Friendship and natural selection. Proc National Acad Sci. 2014 Jul 14 [accessed 2023 Oct 3];111(Supplement_3):10796–10801.
https://doi.org/10.1073/pnas.1400825111
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There are a lot of unknowns when it comes to this study and much more to be studied and learned.