Humans lived as hunter-gatherers for more than 95% of our evolutionary history, thus studying contemporary hunter-gatherer populations offers insight into the conditions children may be psychologically adapted to. Here, we contrast hunter-gatherer childhoods with those of WEIRD (Western Educated Industrialised Rich Democratic) societies and consider the implications for children's mental health. Hunter-gatherer infants receive continuous physical contact and more sensitive and responsive caregiving than is typical of WEIRD societies, due to the extensive involvement of alloparents (non-parental caregivers) who generally provide 40-50% of their care. Alongside positive attachment outcomes, alloparenting likely reduces the harms of family adversity and risk of abuse/neglect. From late infancy, hunter-gatherers spend their time in mixed-age 'playgroups' where they learn via active play and exploration without adult supervision. This contrasts with WEIRD norms surrounding the need for adult supervision of children, as well as with the passive teacher-led classrooms, which could potentially lead to suboptimal learning outcomes and pose difficulties to children with ADHD. Based on this preliminary comparison, we consider practical solutions to potential harms arising from discordance between what children are adapted to and exposed to. These include infant massage and babywearing; increased sibling and extra-familial involvement in childcare; and educational adjustments.