3. Relatedness, time and bacteria

In Part 1, we saw that cooperative behaviour is rife in the world of microorganisms. The fruiting bodies of myxobacteria and social amoebas are famous, but any bacterial biofilm is held together by vast amounts of discreet cooperation—the bacteria emit all kinds of molecular ‘public goods’ to their neighbours. This …

2. Relatedness and altruism

Haldane’s quip In what circumstances might natural selection favour self-sacrifice? As legend has it, the best known answer to this question was first spoken in a London pub called the Orange Tree. One night in the 1950s, after “calculating on the back of an envelope for some minutes”, J.B.S. Haldane remarked …

1. Altruism in nature

What is biological altruism? We tend to think of altruism as action motivated by concern for others. Biologists, however, use the term in a different way. In biology, altruism is, roughly speaking, behaviour that has two distinctive consequences for reproduction: it reduces the chances of reproduction of the organism that performs the behaviour, …

6. Descriptive names

Consider the following example: Case 1: ‘Tremulous Hand’ ‘Tremulous Hand’ is used to refer to the otherwise unidentified author of around 50,000 Thirteenth Century glosses in manuscripts. Palaeographical analysis provides strong evidence that these glosses are the work of a single person with distinctive (tremulous and left-leaning) handwriting. All that …

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