This 2015 California/Oxford review described the interplay between an individual and their group membership from an evolutionary biology viewpoint:

“Many central questions in evolutionary biology rely on understanding how individual-level and group-level selective processes interact to shape phenotypic variation and specialisation. Individuals can aggregate into groups, and the composition of these groups, populations, or communities (herein group phenotypic composition or GPC) can affect group-level dynamics and self-organisation.

Research across a range of disparate topics will benefit from simultaneously developing an understanding of how GPC affects individual fitness [genetic fitness, not physical fitness] and exerts selection on individual phenotypes, and assessing how individual phenotypes respond to GPC.

GPC can be a function of the phenotypes of its members or an emergent property that is not attributable to any single individual, such as the mating system. GPC is also an emergent property of genotypes and their patterns of expression.

GPC can affect individual fitness by influencing the overall performance of the group on collective tasks, affecting all the members of any given group equally, or by affecting the relative performance of different phenotypes within groups. For instance, a group with more aggressive individuals can be more successful at foraging, but aggressive individuals can have a higher fitness than non-aggressive individuals because they can monopolise a larger share of the total resources.

Individuals can respond to the effect of GPC by altering the phenotypic composition of the group (for example by controlling access to the group) and/or by changing their own phenotype.”

See my Individual evolution page for more on the topic of human individuals “changing their own phenotype.”

---

The review provided specific examples to illustrate each point of the overall framework. The authors seldom mentioned human examples, although many of the discussion items applied. Two of their points that weren’t necessarily applicable to human groups were:

• Benefits from reducing competition
• Altruism wasn’t viewed as an individual trait.

The authors didn’t use human-specific examples in their framework. For example, they mentioned division of labor, which benefits both animals and humans. There was no mention of applying capital to efforts, which is thought to be specific to humans, although reuse of tools by crows and chimpanzees may be animal examples.

I’d guess that the authors didn’t refer to humans often because that may have added the human trait of unforced individual choice. Unlike other species, we have the capability to direct much of our own lives, and choose the communities to which we belong.

---

A few questions about our group membership decisions:

• Do we choose group memberships based on how the group recognizes and facilitates the unique individual each of us is?
• How do we benefit as an individual when we become default members of communities by not making choices?
• What individual benefits may we receive by opting out of default groups?

http://www.sciencedirect.com/science/article/pii/S0169534715001846 “From Individuals to Groups and Back: The Evolutionary Implications of Group Phenotypic Composition”