The increase in estradiol may help prepare the lemurs for fatherhood:
Red-bellied lemurs are one of only a handful of mammal species in which the males are active participants in caring for their young. New University of Arizona-led research suggests that expectant lemur dads may experience hormonal changes during their mates' pregnancies that help prepare them for parenting.
Red-bellied lemurs are monogamous, tree-dwelling primates found throughout Madagascar's eastern rainforests. They live together in close family units, with offspring going off on their own at about 3 to 4 years old.
When a female is pregnant, researchers have found, her male partner sees a significant increase in estradiol – an estrogen steroid hormone and major female sex hormone that, in several mammalian species, is associated with increased maternal sensitivity and responsiveness.
[...] "Males, when they're expecting, even when they're not carrying the infant, are responding to the developing fetus," said Tecot, who is also a member of the university's BIO5 Institute. "I was shocked by how much of a change there is in estradiol when their partner is pregnant."
Tecot and her colleagues suspect that the hormonal shift is part of nature's way of preparing male lemurs for fatherhood.
[...] Previous research has shown that expectant human, tamarin monkey and certain rodent fathers also undergo hormonal changes that appear to occur in response to their partners' pregnancies. During the last trimester and shortly after the birth of an infant, cortisol, oxytocin, prolactin and androgen levels have been found to change significantly in these species. However, estradiol has not been studied extensively in males, Tecot said.
"We put a lot of pressure on pregnant individuals as the influencers of infant outcomes instead of thinking about the environment, including everyone who interacts with them," she said. "If male lemurs are interacting with the pregnant female and their hormones are responding, that suggests this is a group effort. Something is happening to both parents as they're all preparing for the baby to arrive."
Journal Reference: https://doi.org/10.1016/j.yhbeh.2023.105324
