Social network size in humans.
Level 4 - case-series / case-control
Cross-sectional observational survey study (by design analogy)
PubMed 26189988 · doi:10.1007/s12110-003-1016-y
What was done
Social network size and structure in contemporary Western society were analyzed using Christmas card exchange lists as a proxy. The authors evaluated maximum and explicitly contacted network sizes, kin proportions, and how active factors (emotional closeness, genetic relatedness) and passive factors (distance, colleagues, overseas residence) influenced contact frequency.
What was found
Maximum network size averaged 153.5 individuals, and the mean size for individuals explicitly contacted was 124.9. Kin comprised a relatively constant proportion of networks at approximately 21%. Network structure varied with age, household type, and relationship type.
Why it matters
The study offers empirical field evidence consistent with the evolutionary hypothesis that human social network capacity is cognitively constrained around 150 individuals by neocortex size.
Limits
The abstract does not report the sample size (n), participant demographics, or measures of variance (e.g., standard deviations or confidence intervals). Using Christmas card exchange as a proxy for total social network size introduces cultural, seasonal, and behavioral biases.
Cited by
- supports Dunbar's number is 150, representing the approximate limit of people with whom a human can maintain stable social relationships.