Search research articles

ABOUT JoVE

Overview Leadership Blog JoVE Help Center

AUTHORS

Publishing Process Editorial Board Scope & Policies Peer Review FAQ Submit

LIBRARIANS

Testimonials Subscriptions Access Resources Library Advisory Board FAQ

RESEARCH

JoVE Journal Methods Collections JoVE Encyclopedia of Experiments Archive

EDUCATION

JoVE Core JoVE Business JoVE Science Education JoVE Lab Manual Faculty Resource Center Faculty Site

Terms & Conditions of Use

Related Concept Videos

Natural Selection and Mating Preferences

Natural Selection and Mating Preferences

The principle of natural selection posits that organisms better adapted to their environment are more likely to survive and reproduce. This principle is closely intertwined with mating preferences, a key aspect of sexual selection, which evolutionary psychologists believe is driven by instincts to propagate one's genes. Such instincts significantly influence mating behaviors and preferences between genders.
Females, due to their biological roles in conception, pregnancy, and nursing,...

What is Natural Selection?

What is Natural Selection?

Natural selection is an evolutionary process in which individuals with survival-promoting traits reproduce at higher rates. These favorable traits become more common within a population or species. Naturally selected traits initially arise via random genetic mutations. In order for selection to occur, there must be variation within a population, the trait controlling the variation must be heritable, and there must be an evolutionary advantage for variation in the trait.

Natural Selection and Adaptation

Natural Selection and Adaptation

Natural selection, a fundamental concept in evolutionary biology, is the mechanism by which evolution is driven, favoring organisms that are best adapted to their environments. This process enhances their chances of survival and reproduction. Adaptation, a key outcome of this process, involves genetic modifications that optimize an organism's functionality under specific environmental challenges, such as extreme cold or thinner air at high altitudes.
Beyond physical adaptations,...

Friendships and Close Friendships

Friendships and Close Friendships

Friendship formation is a dynamic process shaped by psychological, cultural, and social factors. Friendships play a crucial role in emotional well-being, social development, and personal identity from childhood to adulthood.Childhood and Early FriendshipsFriendships in childhood often arise due to shared environments, such as school or neighborhood interactions. At this stage, proximity and common interests serve as the primary basis for connection. As children grow, their friendships evolve...

Relationship Formation

Relationship Formation

What do you think is the single most influential factor in determining with whom you become friends and whom you form romantic relationships? You might be surprised to learn that the answer is simple: the people with whom you have the most contact. This most important factor is proximity. You are more likely to be friends with people you have regular contact with. For example, there are decades of research that shows that you are more likely to become friends with people who live in your dorm,...

Inclusive Fitness

Inclusive Fitness

Most altruistic behavior—in which one animal helps another at a cost to themselves—occurs between relatives. Scientists think these altruistic behaviors evolved because they increase the inclusive fitness of the animal providing help.

You might also read

Related Articles

Articles linked to this work by shared authors, journal, and citation graph.

Sort by

Same author

Social network structure and depression by gender in rural Honduras: a cross-sectional study.

BMJ open·2026

Same author

Metagenomic polymorphic toxin effector and immunity profiling predicts microbiome development and disease-related dysbiosis.

mSystems·2026

Same author

Measuring intellectual humility through situated behavior: An alternative to dispositional self-reports.

Behavior research methods·2026

Same author

On the optimal integration of intelligent agents into network systems to steer cooperation.

Proceedings of the National Academy of Sciences of the United States of America·2026

Same author

Modeling roles and trade-offs in multiplex networks.

Nature communications·2026

Same author

Countering the forgetting of novel health information with 'social boosting'.

SSM - population health·2026

Search research articles

Related Experiment Video

Updated: Apr 27, 2026

Daily Transfers, Archiving Populations, and Measuring Fitness in the Long-Term Evolution Experiment with Escherichia coli

Daily Transfers, Archiving Populations, and Measuring Fitness in the Long-Term Evolution Experiment with Escherichia coli

Published on: August 18, 2023

Friendship and natural selection.

Nicholas A Christakis¹, James H Fowler²

¹Departments of Sociology,Ecology and Evolutionary Biology, andMedicine, Yale University, New Haven, CT 06520; and.

Proceedings of the National Academy of Sciences of the United States of America

|July 16, 2014

Summary

This summary is machine-generated.

Humans share similar genotypes with friends, extending beyond genetic similarity to strangers. This genetic homophily suggests friends may function as "functional kin," influencing human evolution.

Keywords:

genetics kinship detection social networks

More Related Videos

Using the FishSim Animation Toolchain to Investigate Fish Behavior: A Case Study on Mate-Choice Copying In Sailfin Mollies

Using the FishSim Animation Toolchain to Investigate Fish Behavior: A Case Study on Mate-Choice Copying In Sailfin Mollies

Published on: November 8, 2018

Monitoring Spatial Segregation in Surface Colonizing Microbial Populations

Monitoring Spatial Segregation in Surface Colonizing Microbial Populations

Published on: October 29, 2016

Related Experiment Videos

Last Updated: Apr 27, 2026

Daily Transfers, Archiving Populations, and Measuring Fitness in the Long-Term Evolution Experiment with Escherichia coli

Daily Transfers, Archiving Populations, and Measuring Fitness in the Long-Term Evolution Experiment with Escherichia coli

Published on: August 18, 2023

Using the FishSim Animation Toolchain to Investigate Fish Behavior: A Case Study on Mate-Choice Copying In Sailfin Mollies

Using the FishSim Animation Toolchain to Investigate Fish Behavior: A Case Study on Mate-Choice Copying In Sailfin Mollies

Published on: November 8, 2018

Monitoring Spatial Segregation in Surface Colonizing Microbial Populations

Monitoring Spatial Segregation in Surface Colonizing Microbial Populations

Published on: October 29, 2016

Area of Science:

Genetics
Social Sciences
Evolutionary Biology

Background:

Humans uniquely form social ties with non-kin/non-mates.
These social ties often form between similar individuals.

Purpose of the Study:

To investigate if genetic similarity extends to human friendships.
To explore the role of specific gene sets in friendship formation.
To understand the evolutionary implications of genetic similarity in friendships.

Main Methods:

Genome-wide analysis of single nucleotide polymorphism (SNP) correlations in friends versus strangers.
Development of a "friendship score" based on genotype correlations.
Gene-set enrichment analysis focusing on olfactory and immune system genes.

Main Results:

Friends exhibit significant genome-wide genotype correlations (homophily), comparable to fourth cousins.
Certain gene sets, like olfactory, are homophilic, while others, like immune genes, are heterophilic.
A "friendship score" derived from genotype correlations accurately predicts friendship ties.
Homophilic genotypes show higher positive selection, indicating potential fitness advantages.

Conclusions:

Genetic similarity (homophily) is a significant factor in human friendships.
Specific biological systems, such as olfaction and immunity, may influence friendship dynamics.
Genetic homophily in friendships may have played a role in recent human evolution, suggesting friends act as "functional kin".