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Letter: How altruism shapes our biological fitness

Published 1 April 2026

From James Stone, Buxton, Derbyshire, UK

Regarding David Robson’s piece, “Why are we so suspicious of do-gooders?”, in terms of evolutionary theory, altruism increases biological fitness if the cost of altruism is less than the benefit to my relatives, where the currency of cost and benefit is measured in terms of the future spread of my genes in the population. This is Hamilton’s rule, which has been tested in animal populations, where unfettered signals regarding costs, benefits and relatedness aren’t mediated by human communication systems (21 March, p 17).

In contrast, because humans in most societies are influenced by unreliable information sources (such as fashion or propaganda), when estimating the value of costs, benefits and relatedness, we constantly break Hamilton’s rule, which undermines our biological fitness, among other things.

Issue no. 3589 published 4 April 2026

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