Cultural complexity is a central facet of cultural evolution research, and the term ‘complexity’ is frequently used to describe behaviours & artefacts which are products of culture. However, exactly what we are trying to describe and capture with this description is not clear.

In defining Cumulative Cultural Evolution (CCE) an increase in complexity (and also efficiency) of the behavioural trait in question is fundamental to our understanding of the phenomenon (Dean et al, 2014). Most, if not all, animal cultural behaviours are not considered cumulative, due to a lack of improvement (in complexity or efficiency) over successive generations, and the likelihood that they could be invented by a single individual. Does this mean that the increases in complexity observed in human culture have resulted in our placing it on a pedestal? And has this been done without adequately defining or operationalising complexity?

We therefore believe it is important to address the subject of complexity further, particularly in light of recent work which, according to current criteria, claims to have found evidence for CCE in non-humans (Sasaki & Biro, 2017; Schofield et al, 2017).

During the conference we hope to address key questions such as:

• What is the most useful way to conceptualise complexity across humans and non-humans?
• How can complexity be measured and operationalised in empirical experiments? E.g. absolute number of elements of a trait, or the structure of those elements?
• Are increases in complexity the only drivers of cumulative cultural evolution, or also efficiency?
• Is complex cognition required for CCE?