In red-bellied lemurs, the hormonal background changes during the pregnancy of the partners. Reported by the University of Arizona.
Red-bellied lemurs are one of the few mammalian species in which males are actively involved in the care of their young. These animals live in Madagascar, grow up to 40 centimeters and weigh 2.5 kg, feed on leaves and flowers.
These animals are characterized by monogamous behavior, live together in close families, and the cubs begin to live independently at the age of 3-4 years. The researchers found that when a female is pregnant, her male partner has a significant increase in levels of estradiol, an estrogenic steroid hormone, and the main female sex hormone, which in some mammalian species is associated with increased maternal sensitivity and responsiveness. This was determined by analyzing the feces of wild lemurs in Ranomafana National Park in Madagascar.
A typical lemur gestation period lasts about 126 days, or a little over four months. At the same time, a four-fold increase in estradiol level is observed in the last trimester in men. After the calf is born, the estradiol level does not drop, but fluctuates high until the female stops feeding it with milk.
“Males react to a developing fetus, even though they do not give birth to an offspring,” the authors explain. “We were shocked by how much the fathers’ estradiol levels changed while their wives were pregnant.”
Scientists suspect that hormonal changes are part of the natural process of preparing male lemurs for paternity.