Norm reinforcement, not conformity or environmental factors, is predicted to sustain cultural variation.

The maintenance of cross-cultural variation and arbitrary traditions in human populations is a key question in cultural evolution. Conformist transmission, the tendency to follow the majority, was previously considered central to this phenomenon. However, recent theory indicates that cognitive biases can greatly reduce its ability to maintain traditions.

Parental khat use and early childhood growth status in Eastern Ethiopia.

Background: Adult chewing of the stimulant plant khat ( has an unclear relationship with child growth outcomes. Contradictory study conclusions because habitual khat chewing covary with increased household income from khat production.

Aim: Disentangling the association of parental khat use, household khat production, and child nutritional status and growth markers.