New research based on the latest technology shows that orangutan mothers breastfeed their babies for a longer period than any other mammal species. The most recent study found that young orangutans continue being breastfed even as they are eight or even nine years old.
Previous studies approximated that orangutans weaned their young until these reached about seven years old. Now, it seems that they lactate for even longer. The estimate differences can be explained by the difficulty in tracking nursing behavior for animals in the wild.
Orangutan Mothers are the Ape Breastfeeding Leaders
The results of this latest study were released in the Science Advances. Research team members used a novel technique for carrying out this study. They did not rely on observations of the species in the wild. Instead, they chose to measure barium deposits on the orangutans’ teeth.
By doing so, the team was able to determine and compile a history of their dietary habits. Barium is one of the elements absorbed in teeth while sucking on breast milk. The team measured these shifting levels in the teeth of four wild orangutans killed in Borneo several years ago.
Observations suggest that baby orangutans rely solely on breast milk during the first year of their life. Then, they seem to slowly begin incorporating other food sources as well, such as fruits.
However, mother orangutans still ensure their breast milk even as the offspring is 8 or nine years old. This places them as the lactate leads among apes. Other studies found that gorillas generally wean for four years while chimps breastfeed for about five.
“Having a long period of nursing may be a way for juveniles to learn the ins and outs of living in a challenging environment with limited and unpredictable food resources,” states Tanya Smith.
She is part of the Australian Research Centre for Human Evolution at Griffith University and also the lead author of the study.
In contrast, humans have one of the lowest breastfeeding periods, when compared to other primates. Some researchers even considered that this helped ensure humanity’s success as a species. Still, they are unsure when this weaning shift took place.
So the study team is set on taking a closer look at ancient human teeth and studying their enamel, just as they did with the orangutans.
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