The bits about breastfeeding and the other biological limiting factors (the indirect controls, basically) came to light during Richard Lee’s fieldwork with the San and Ju/’hoansi peoples of South Africa in the 1960s.
The bit about active measures is available if you peruse the anthropological literature on the subject (I don’t have a specific citation in mind), and the sort of thing covered in introductory classes to the field—it’s common knowledge within that domain.
The bits about breastfeeding and the other biological limiting factors (the indirect controls, basically) came to light during Richard Lee’s fieldwork with the San and Ju/’hoansi peoples of South Africa in the 1960s.
The bit about active measures is available if you peruse the anthropological literature on the subject (I don’t have a specific citation in mind), and the sort of thing covered in introductory classes to the field—it’s common knowledge within that domain.