Bonobos have a track record among the great apes as “hippie chimps,” and new study hints that high levels of an essential thyroid hormone could play a duty in keeping the animals’ aggression in check.
Found in the lowland forests of the Democratic Republic of the Congo, bonobos (Pan troglodytes) are closely associated with chimpanzees (Pan troglodytes) however the two diverge in behavior.
Bonobos seem to diffuse social stress with an outstanding repertoire of sex acts rather than physical battles. Males in particular show low levels of hostility– they even maintain platonic friendships with females and stick by their moms into adulthood. The life of male chimpanzees, meanwhile, focuses on climbing the social ladder (or at least hanging onto their present rung), and browsing cooperative and aggressive relationships with various other males.
Experts just recently discovered an additional big distinction between the two Pan types: A key thyroid hormone lowers at a much later age in bonobos compared to chimps.
For their research, researchers took urine samples from about 100 chimpanzees and 96 bonobos living in zoos. The analysts particularly took a look at the apes’ levels of triiodothyronine (T3), a hormone in the thyroid gland that is vital for development in all vertebrates (animals with foundations).
In human beings, T3 levels normally decrease after puberty. For chimpanzees, this drop comes when the animals are around 10 years old, but in bonobos, T3 levels remains high till they are about 20, the research study discovered.
“We never anticipated the long delay in thyroid hormone level reduction in bonobos,” stated research analyst Verena Behringer of limit Planck Institute for Evolutionary Anthropology.
Compared with chimpanzees, bonobos likewise reveal a developmental delay in cognitive tasks and in body growth. Given that T3 levels have been associateded with brain and skeletal development, the analysts had actually anticipated a matching hold-up in the beginning of the reduction in thyroid hormone levels in bonobos compared to chimps, Behringer described in an email to LiveScience. But it was unusual that the hold-up was so long.
“Human beings have the lengthiest growth duration in contrast to the two Pan types, therefore we expected the beginning of the decrease in thyroid hormones in human beings to occur later on than in the 2 Panspecies,” Behringer wrote. “So it was unexpected to see that the beginning of the reduction in thyroid hormone levels in people is between bonobos and chimpanzees. This offers speculation about which developing thyroid hormone pattern took place in the common forefather.”.
The research researchers also discovered that male bonobos throughout their lives had lower levels of T3 than their female peers, which can contribute to the male apes’ fairly reduced levels of aggression.
The researchers write that thyroid hormones could influence the apes’ behavioral responses to stress, as has been revealed in other animals, like rodents, human beings and dogs.
Behringer stated further study will be aimed discovering more about “how thyroid hormones are associated with the development of bonobos and chimpanzees to maybe discover a description for our result.”.