By Steph Yin
Elizabeth Hunt Burrett, a mother from Australia, experienced a moment with an orangutan while breast-feeding her son at Melbourne Zoo last year.
While it may be impossible to know exactly what this orangutan was thinking, it’s true that the critically endangered apes are exceptionally dedicated mothers. They give birth to one baby at a time, raising each for six to nine years, until it’s time to rear another. Mother and young sleep and spend most of their time with only each other. And young orangutans nurse longer than any other mammal — sometimes into their ninth year of life, according to a study published in Science Advances on Wednesday.
Because observing wild orangutans can be difficult, the authors recreated the nursing history of four orangutans by analyzing barium, an element absorbed from maternal milk, in teeth taken from museum collections. In doing so, the scientists also discovered a possible clue why the apes nurse for so long: The teeth showed cycles in barium, which might correspond to environmental fluctuations in food.
Continue reading by clicking the name of the source below.