Paragraph 1：Some insects contain poisons that do not affect an insect-eating bird until after the bird has swallowed one of them. Being swallowed is almost always fatal for these insects. How does an insect benefit by containing a poison that is effective only after it has been killed and eaten? This paradox is resolved once we realize that birds, which are made ill by the poison but are rarely killed by it, soon learn to recognize the warning signals of poisonous insects and reject them on sight. Eating a poisonous insect is an educational experience for predators, and thus the death of the insect victim serves to protect other members of its own species. If these other members of the species are relatives of the victim — perhaps its own offspring, siblings, or first cousins — their genetic makeup will be similar to the victim’s, and many of the victim’s genes will survive in them. In almost all organisms, including most insects other than bees or wasps, half of a victim’s genes will survive in any one of its offspring, half in a sister or brother, a quarter in a nephew or niece, and an eighth in a first cousin. Thus by sacrificing itself, a victim enhances the chances that its own genes will survive by improving the chances of the survival of its relatives.
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