As humans, we *think* too much about the *proper age* of weaning, versus the need our children have to suckle. Though the following research information is based upon information regarding weaning a child from the breast, the same timing would hold true to bottle feeding when thinking in terms of the psychological advantages that suckling has for our young children.
1. In a group of 21 species of non-human primates (monkeys and apes) studied by Holly Smith, she found that the offspring were weaned at the same time they were getting their first permanent molars. In humans, that would be: 5.5-6.0 years.
2. It has been common for pediatricians to claim that length of gestation is approximately equal to length of nursing in many species, suggesting a weaning age of 9 months for humans. However, this relationship turns out to be affected by how large the adult animals are -- the larger the adults, the longer the length of breastfeeding relative to gestation. For chimpanzees and gorillas, the two primates closest in size to humans and also the most closely genetically related, the relationship is 6 to 1. That is to say, they nurse their offspring for SIX times the length of gestation (actually 6.1 for chimps and 6.4 for gorillas, with humans mid-way in size between these two). In humans, that would be: 4.5 years of nursing (six times the 9 months of gestation).
3. It has been common for pediatricians to claim that most mammals wean their offspring when they have tripled their birth weight, suggesting a weaning age of 1 year in humans. Again though, this is affected by body weight, with larger mammals nursing their offspring until they have quadrupled their birth weight. In humans, quadrupling of birth weight occurs between 2.5 and 3.5 years, usually.
4. One study of primates showed that the offspring were weaned when they had reached about 1/3 their adult weight. This happens in humans at about 5-7 years.
5. A comparison of weaning age and sexual maturity in non-human primates suggests a weaning age of 6-7 for humans (about half-way to reproductive maturity).
6. Studies have shown that a child's immune system doesn't completely mature until about 6 years of age, and it is well established that breast milk helps develop the immune system and augment it with maternal antibodies as long as breast milk is produced (up to two years, no studies have been done on breast milk composition after two years post partum).
And on and on. The minimum predicted age for a natural age of weaning in humans is 2.5 years, with a maximum of 7.0 years. So *truly* there is no rush and this allows you more time to respect the *need* of your child!
Kind regards,
Dr. Tamara