Traditional attempts to understand the evolution of human cognition compare
humans with other primates. This research showed that relative brain size
covaries with cognitive skills, while adaptations that buffer the developmental
and energetic costs of large brains (e.g. allomaternal care), and ecological or
social benefits of cognitive abilities, are critical for their evolution. To
understand the drivers of cognitive adaptations, it is profitable to consider
distant lineages with convergently evolved cognitions. Here, we examine the
facilitators of cognitive evolution in corvid birds, where some species display
cultural learning, with an emphasis on family life. We propose that extended
parenting (protracted parent–offspring association) is pivotal in the
evolution of cognition: it combines critical life-history, social and ecological
conditions allowing for the development and maintenance of cognitive skillsets
that confer fitness benefits to individuals. This novel hypothesis complements
the extended childhood idea by considering the parents' role in juvenile
development. Using phylogenetic comparative analyses, we show that corvids have
larger body sizes, longer development times, extended parenting and larger
relative brain sizes than other passerines. Case studies from two corvid species
with different ecologies and social systems highlight the critical role of
life-history features on juveniles’ cognitive development: extended
parenting provides a safe haven, access to tolerant role models, reliable
learning opportunities and food, resulting in higher survival. The benefits of
extended juvenile learning periods, over evolutionary time, lead to selection
for expanded cognitive skillsets. Similarly, in our ancestors, cooperative
breeding and increased group sizes facilitated learning and teaching. Our
analyses highlight the critical role of life-history, ecological and social
factors that underlie both extended parenting and expanded cognitive
skillsets.
This article is part of the theme issue ‘Life history and learning: how
childhood, caregiving and old age shape cognition and culture in humans and
other animals’.
Allometric Analysis Detects Brain Size-Independent Effects of Sex and Sex Chromosome Complement on Human Cerebellar Organization