Cooperative Breeding as a Likely Early Catalyst of Human Evolution

Area of Science:

• Human evolution
• Primatology
• Developmental psychology

Background:

• Humans exhibit unique traits like large, altricial infants, precocial social development, and large brains requiring long maturation.
• These traits are interconnected and likely coevolved over evolutionary time.
• Cooperative breeding (CB) is a key human adaptive complex involving extensive allomaternal care.

Purpose of the Study:

• To investigate the trigger for the coevolutionary feedback loop of human adaptive traits.
• To evaluate potential catalysts including bipedality, selection on altriciality, diet quality, and cooperative breeding.

Main Methods:

• Analysis of recent evidence from paleontology, developmental psychology, and pediatrics.
• Comparative analyses across species and evolutionary timelines.

Main Results:

• The cooperative breeding-first (CB-first) model provides the best fit for the available data.
• CB acted as a catalyst for increased brain size by mitigating the demographic challenges associated with prolonged neurodevelopment.

Conclusions:

• Extensive allomaternal care (cooperative breeding) was an early and crucial factor in human evolution.
• CB enabled increased birth rates, overcoming the demographic dilemma posed by larger, slower-developing brains.