Orangutans nurse their pups longer than any other mammal. This was known, but as far as it went, it was not yet known. Instead of trying to answer by sighting the animals in the trees, the primatologists at Icahn School of Medicine at Mount Sinai (New York) and Griffith University (Australia) have chosen a different approach: they have studied the composition of the teeth of some orangutans of various ages .

Does breast milk make you smarter?

biographical memory. During lactation, some important chemical elements - such as calcium - transfer, and accumulate, in the bones and teeth of the puppy. Their analysis can be as revealing as that of tree rings. From the quantity of an element in particular, the barium, in the teeth of the orangutan-children, the researchers deduced how long, and with what continuity, the animals had been suckled.

A quarter of life. It emerged that the orangutans consume almost exclusively breast milk for the first year of life, and then the percentage of this food decreases, but not entirely: an analyzed specimen was nursed until shortly before death, at 9 years of life ( an orangutan from Borneo, Pongo pygmaeus, lives about 35-40 years).

Filling. The amount of milk taken seems to fluctuate based on the availability of food from the natural habitat. When fruit is scarce, mothers provide an extra supplement to feeding their children. This long relationship of dependence could make the orangutans even more fragile in the face of the destruction of the forests in which they live. The study could also provide details on the evolution of breastfeeding in other mammals, including humans.