Why Adolescent Male Gorillas Rely on Their Mothers: Do They Face a Risk of Inbreeding with Close Relatives?
Author: Shi Lan
As is well-known, as primates of the family Hominidae, gorillas are extremely closely related to humans, becoming the animal closest to human bloodlines in the world. In fact, gorillas and humans only separated and evolved independently about 500 to 600 years ago, respectively, and then evolved into humans, as well as gorillas and dwarf gorillas living in the African forests. Over the past years of Earth's history, humans are known to be the most intelligent species, while gorillas represent the highest level of intelligence outside of humans.
It is certain that reproduction is an instinct for all living beings on Earth, including ourselves. Although gorillas live in the natural world and have little contact with humans, their lifestyles also show clustering. Incestuous marriage has long been a convention in human society, and mothers are indispensable to their young. So, why do adolescent gorillas rely on their mothers, do gorillas also have a risk of close-kin reproduction?
In the adolescent world of gorillas, whether the mothers accompany them will determine their survival rate. In a new study, scientists discovered that adolescent gorillas who lost their gorilla mothers had a higher survival rate than gorilla teenagers sheltered by gorilla mothers.
The study used data from approximately fifty years starting from 1960. Whether it is the death of gorillas or the birth of new gorillas, all were recorded in detail. When analyzing these decades of gorilla data, the influence of the gorilla's biological mother on the growth stages of the offspring caught the attention of scientists.
By adolescence, gorillas have already outgrown breastfeeding, at this time they can start to live independently. But adolescent gorillas who remained with their mothers still lived longer than their orphaned peers.
At the same time, there is a gender difference in this situation, adolescent males are more pronounced in this regard. In simple terms, 10 to 15-year-old male gorillas rely more on their mothers' companionship, which can significantly affect their survival.
Perhaps many people don't know that adolescent male gorillas live their entire lives in the group they were born into, they need to defend their territory together with other group members. But female gorillas are different, they often travel throughout their lives.
Unless the gorilla mother in the group has a high-level family dominance, the female gorilla born to her can choose to live in the same group. This leads to the problem that this female gorilla has a risk of breeding with close relatives after puberty.
Generally, the female offspring born by the gorilla mothers are often away from the place where they were born in adolescence, even though this departure is difficult. And when they arrive in a new group, they will be attacked by other female gorillas in that group.
Previously, some people speculated that it was because of food scarcity or intense competition within the group, so female gorillas wanted to migrate from their birthplaces. But from the research results, female gorillas who leave their birthplaces generally have more brothers, because this means they have a greater risk of close-kin reproduction.
According to the logic, gorilla mothers should be completely uninterested in each other, but there are examples of high-level male gorillas forcing their sisters to reproduce with them, and about four of the offspring they produce can survive to adulthood. There is no doubt that female gorillas and brother-breeding is a costly mistake, and this mistake will further lead to one gender establishing its own family group in another place.
