To understand exactly what we mean by cultural evolution, first we need to define ‘culture’ and ‘evolution’.

When we use the term culture we don’t mean art, opera and novels like you find in the ‘Culture’ section of a newspaper. We mean something much broader. We define culture as any information that is passed from one individual to another via social learning, rather than genetically. Social learning (aka cultural transmission) can take the form of observation and imitation, spoken or written language, or teaching.

Culture therefore encompasses all of the knowledge, ideas, attitudes, opinions, languages, norms, institutions, music, art and technology that people learn from other people. Culture in this sense is not limited to humans. For example, chimpanzees have culture when they learn how to crack nuts by watching other chimpanzees, while birds and whales have culture when they learn songs from other members of their species.

Charles Darwin is celebrated because he came up with the first workable theory of evolution. In The Origin of Species, Darwin laid out three key principles for evolution: variation, inheritance and selection. He applied these three principles to biological organisms. First, there is variation amongst individuals. For example, different finches might have differently shaped beaks. Second, this variation is inherited genetically. For example, a finch’s beak shape resembles that of its parents because of the transmission of genes. And third, there is sometimes selection of certain variants. For example, finches with larger beaks might out-reproduce smaller-beaked finches when a drought reduces the availability of smaller seeds in the environment.

Over time, this process leads to adaptation, as organisms become better suited to their environments, and diversification into different species, as different environments favour different forms. For example, some finches might evolve large beaks to open nuts and other finches evolve small beaks to feed on insects. Eventually the two populations might become different species. Darwin therefore saw evolution as tree-like, with different forms diversifying over time. Evolution is not progress along a linear ladder of increasing complexity or perfection.

Combining these two concepts gives us cultural evolution. When cultural information varies, when it is inherited via social learning, and when sometimes certain cultural variants spread more effectively than others, then we can say that culture evolves.

For example, say there are different forms of the past tense of the verb ‘to chide’ (principle of variation). Some people say ‘chid’, others say ‘chided’. These forms are socially transmitted as people hear others say one or the other form and copy it (principle of inheritance). Then imagine that the regular form ‘chided’ is easier to remember than the irregular form ‘chid’ (principle of selection). Then the regular form ‘chided’ spreads over time. This is cultural evolution.