 Human offspring do not fall neatly into the dichotomous categorization of precocial versus altricial, and instead Portmann proposes they are "secondarily altricial" at birth due to the underdevelopment of neurological and cognitive capabilities.Therefore, human offspring are highly dependent on caregiver investment, a necessity that serves as the precursor for theories on the development of pair-bonding, alloparenting, and cooperative breeding.The evolution of cooperative breeding in early "Homo" species also promoted other pro-social behaviors such as social learning, increased social tolerance, and shared intentionality especially in food acquisition.