his theory of sexual selection (where females choose their mates based on how attractive they are) could not apply to caterpillars since they are immature and hence not sexually active. Wallace replied the next day with the suggestion that since some caterpillars "...are protected by a disagreeable taste or odour, it would be a positive advantage to them never to be mistaken for any of the palatable catterpillars [sic], because a slight wound such as would be caused by a peck of a bird’s bill almost always I believe kills a growing . Any gaudy & conspicuous colour therefore, that would plainly distinguish them from the brown & green eatable , would enable birds to recognise them easily as at a kind not fit for food, & thus they would escape seizure which is as bad as being eaten." Since Darwin was enthusiastic about the idea, Wallace asked the Entomological Society of London to test the hypothesis. In response, the entomologist John Jenner Weir conducted experiments with caterpillars and birds in his aviary, and in 1869 he provided the first experimental evidence for warning coloration in animals. The evolution of aposematism surprised 19th-century naturalists because the probability of its establishment in a population was presumed to be low, since a conspicuous signal suggested a higher chance of predation. Poulton, 1890 Wallace coined the term "warning colours" in an article about animal coloration in 1877. In 1890 Edward Bagnall Poulton renamed the concept aposematism in his book The Colours of Animals. He described the derivation of the term as follows: Evolution Aposematism is paradoxical in evolutionary terms, as it makes individuals conspicuous to predators, so they may be killed and the trait eliminated before predators learn to avoid it. If warning coloration puts the first few individuals at such a strong disadvantage, it would never last in the species long enough to become beneficial. Supported explanations There is evidence for explanations involving dietary conservatism, in which predators avoid new prey because it is an unknown quantity; this is a long-lasting effect. Dietary conservatism has been demonstrated experimentally in some species of birds and fish. Further, birds recall and avoid objects that are both conspicuous and foul-tasting longer than objects that are equally foul-tasting but cryptically coloured. This suggests that Wallace's original view, that warning coloration helped to teach predators to avoid prey thus coloured, was correct. However, some birds (inexperienced starlings