Question

B. Data showing that only distantly related individuals are most likely to perform altruistic behaviors in order to protect each other

Answer 1

Short answer: That claim is not supported by the bulk of empirical and theoretical work. Across many species (including humans) altruistic helping tends to increase with genetic relatedness; apparent “non‑kin” cooperation is usually explained by reciprocity, mutual benefit, social bonds, or demographic/measurement issues rather than a rule that only distant relatives protect one another.

Key theory
- Hamilton’s rule (kin selection): an altruistic act that costs C to the actor and gives benefit B to the recipient will be favored if rB > C, where r is genetic relatedness. This predicts greater helping toward closer kin.
- Reciprocal altruism (Trivers): repeated interactions and the expectation of return favors cooperation among non‑kin who interact frequently.

Representative empirical patterns
- Humans: Numerous studies show higher probability of costly help and investment for closer relatives (parents → offspring, siblings, grandparents, etc.). In life‑or‑death or resource‑allocation contexts, people preferentially help closer kin. (Daly & Wilson’s work on parental investment and household risk is one example.)
- Social insects: workers overwhelmingly assist close kin (sisters/offspring), consistent with kin selection and relatedness asymmetries.
- Mammals/primates: cooperative breeding and alloparental care often concentrate on close kin; coalitionary support is stronger among kin in many species.
- Exceptions / non‑kin cooperation: vampire bats and some primates demonstrate extensive helping among non‑kin. In those cases, reciprocity (help among frequent roostmates), food‑sharing networks, or strong social bonds (friendships) explain cooperation without high r. Mutualism (immediate shared benefit) also produces cooperation among non‑kin.

What “data showing the opposite” would look like (and why it’s rare)
- The claim “only distantly related individuals are most likely to protect each other” predicts a negative relationship between r and probability/intensity of help (highest helping at low r, lowest at high r), and that this pattern would persist after controlling for proximity, repeated interactions, and immediate mutual benefits. Such a pattern is rare because kinship usually covaries with the factors that favor helping (shared location, shared genes, predictable future interactions).

How to test this claim properly (study design / analyses)
- Define altruistic acts (cost to actor, benefit to recipient).
- Measure genetic relatedness (pedigrees or genetic markers) and social variables (proximity, interaction frequency, reciprocity history, dominance, resource availability).
- Collect repeated observations or experiments of helping events.
- Model helping probability or rate as a function of r and covariates (mixed‑effects logistic/Poisson regression with individual and dyad random effects).
- Critical checks: control for spatial association, repeated interactions, and kin recognition errors; test for reciprocity effects and immediate mutual benefit; examine whether any negative r–help relationship remains after controls.

Bottom line
- The preponderance of theory and data supports greater altruism toward closer relatives. Cooperation among distant/non‑related individuals does occur but is generally explained by reciprocity, direct mutual benefits, or strong social bonds — not by a general tendency for distant relatives to be the main protectors. If you want, I can (a) list key empirical papers that document kin‑biased helping and non‑kin reciprocity, or (b) draft a study protocol and statistical model to test the exact claim. Which would you prefer?