Since nursing past infancy is no longer the norm in many cultures and is, in fact, often perceived as abnormal, we as Leaders can benefit by looking beyond our cultures and our time period to gain a more in- depth understanding of what is truly normal and natural human behavior. First permanent molar eruption occurs around 5.5 to 6.0 years in modern humans. Our evolutionary past has produced an organism that relies on breastfeeding to provide the context for physical, cognitive and emotional development. The non-human primate data suggest that human children are designed to receive all of the benefits of breast milk and breastfeeding for an absolute minimum of two and a half years, and an apparent upper limit of around seven years. Natural selection has favored those infants with a strong, genetically coded blueprint that programs them to expect nursing to continue for a number of years after birth and results in the urge to suckle remaining strong for this entire period.
Lactational duration is just one of many cultural variations in breastfeeding practices.
Kung of almost four years. Such frequent suckling may indeed be nature's norm, reports Sheila Kippley in her book, Breastfeeding and Natural Child Spacing, as it is true of both chimps and gorillas as well as representative of a number of human cultures living in natural conditions. The Gainj of New Guinea nurse their infants at an average interval of 24 minutes. It is interesting to compare these practices to the standard recommendation given to new mothers today of 8 to 12 nursings in a 24-hour period. She reports that according to a study of advice given to mothers by doctors from 1550 to 1900, It was not until 1800 that most of the popular English writings on child care recommended weaning as young as 12 months.