Do insects have emotions in the same way humans and mammals do? For example, would a fly feel sad if it saw its brother die?
Jonathan Wallace, Newcastle upon Tyne, UK
There is nothing in the behaviour of insects that suggests any kind of emotional life that resembles that of humans. Insects have very simple brains compared with mammals, and much of their behaviour is produced by simple reflex responses to stimuli.
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The second question assumes that a fly would recognise its brother, which is doubtful. There is plenty of evidence that many insects have little or no sense of family bond.
The female praying mantis, for example, famously cannibalises her mate during the act of copulation. The orange tip butterfly normally lays just one egg per plant, but if she lays two by chance, then one of the resulting caterpillars will probably eat the other, sibling or not.
The social insects do, of course, cooperate closely with their family members and demonstrate high levels of self-sacrifice in the interest of their colony. But there is no evidence that this behaviour is regulated through emotions.
Stefan Badham, Portsmouth, Hampshire, UK
Anyone who has ever disturbed a wasp or ant nest will certainly know that insects feel anger, probably triggered by fear. They obviously procreate, and are extremely social with their own species, though this is probably born more out of a mechanical precondition than sexual arousal or a need for company.
So, while insects evidently possess base emotions, the question of whether they feel empathy, sympathy, love and grief is another matter. Although a human is capable of feeling and demonstrating kindness to an insect, it remains unknown if such emotions are ever reciprocated.
Venkata Sri Sai, Vellore, Tamil Nadu, India
In his book The Expression of the Emotions in Man and Animals, Charles Darwin suggested that animal emotions include anger, terror, jealousy and love.
Recent research has found that insects have the cognitive and physiological building blocks that might give rise to complex phenomena such as emotion. For example, bees that were given rewards when they reached a certain site became more optimistic than other bees (8 October 2016, p 9).
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