Contrary to humans and chimpanzees bonobos retain elevated thyroid hormones well into adulthood

Despite the fact that chimpanzees and bonobos share similar starting conditions at birth they develop different behavioural patterns later in life. These differences might be caused by different hormone levels. Researchers of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, and the Royal Zoological Society of Antwerp in Belgium have analyzed thyroid hormones from urine samples of zoo-living chimpanzees and bonobos. They discovered that bonobos retain elevated thyroid hormone concentrations well into adulthood, whereas in humans and chimpanzees thyroid hormone concentrations decline after puberty. The late decline of thyroid hormones in bonobos might have consequences on their behaviour and might also indicate a delayed development of their mental capacities.