The end of brain growth when Homo sapiens appeared
about 250,000 years ago has nothing to do with the fact that the brain, unlike the earlier hominid brains, would have been perfect (Mayr). I also consider the idea of a seamless transition from genetic adaptation to cultural tradition (Habermas) to be an unacceptable simplification,
one that does not take sufficient account of the change of era at the end of the growth in size of the human brain. Here further intermediate steps, which make this type of development plausible, are mentally necessary and are still to be described.
The prolongation of brain growth into the first year after birth makes the human brain even more expensive and leads to the problem of who can afford the costs.
The mother alone probably cannot afford the increased costs; further helpers are required. If we assume pair bonding and family structures, the father and other family members, such as older siblings, can be considered additional helpers.
Kristen Hawkes examined the role of grandmothers and drew attention to the importance of menopause. As a result of their own infertility after menopause, grandmothers are able to give their labour to their grandchildren.
Carel van Schaik and Karin Isler see in their essay that has already been quoted a central element in community care for children in order to bear the increased costs of brain growth and long childhood.