Rule Animal Animal Majority of Species Humans Suffer Mature from Early Challenges

Majority of Species Humans Suffer Mature from Early Challenges



There is something that most species — from baboons to humans to horses – have in common: if you have serious difficulties early in life, you are more likely to have difficulties after in life.

When researchers from the Dian Fossey Gorilla Fund and the University of Michigan decided to study this question in gorillas, they didn’t know what they would find.

Previous studies by the Fossey Fund have shown that young gorillas are surprisingly resistant to the loss of their mother, unlike many other species. But losing your mother is just one of many possible bad things that can happen to young animals.

“Assuming that they survive something that we consider an adversity at the beginning of life, it is often still that they are less healthy or have fewer children, or that their lifespan is shorter — regardless of the species to which they belong,” said anthropologist Stacy Rosenbaum, lead author of “There is this whole series of things that happen to you that seem to only make your life worse as an mature.”

Instead, the researchers found that the gorillas that survived to the age of six were largely unaffected by the difficulties they experienced as infants or teenagers. The study is published in the journal Current Biology.

Like other species, humans also face adversity early in life, and the effects of it can follow us into maturehood, such as a shorter lifespan or health complications, Rosenbaum said. But in humans, it is difficult to know if we develop cancer, for example, or if we passed away early in maturehood due to an adverse event early in life, or if this is due to a variety of behavioral, environmental and cultural factors— or a combination of all of the above.

Studying these early adverse events in non-human species could help researchers understand how such events affect humans and how to mitigate them.

“If you look at animals, you remove a lot of the variation that we have in humans. For example, they all eat similar diets, they all exercise as part of their daily lives, they don’t have the opportunity to engage in behaviors with negative health consequences such as smoking,” said Robin Morrison, researcher at the Dian Fossey Gorilla Fund and lead author of the study.

Despite this, in most species it is still true that early adversity can have negative effects in maturehood, which suggests that there is a deeper biological mechanism that we do not quite understand, Morrison said. The fact that gorillas show a different pattern suggests that these adversities can be overcome early in life. Understanding why and how this happens can have important implications for our own species, she said.

Like humans, gorillas live for a long time and have a small number of descendants in which they invest heavily. This makes it a good comparative animal model for understanding the effects of adverse events in early life. The researchers examined 55-year long-term data collected from 253 wild mountain gorillas, including 135 males and 118 females. These gorillas live in the Volcanoes National Park in Rwanda and have been monitored by the Dian Fossey Gorilla Fund for more than five decades.

The researchers identified six different types of adversity at the beginning of life: the loss of a father or mother, the passed away of a group member by infanticide, The instability of the social group, a few peers in the social group and a competing brother or sister born shortly after them. The data included information on how many of these first adversities each gorilla experienced at what age and how long each gorilla lived.

The researchers examined what happens when a gorilla does not experience, one, two or three or more adverse events. They found that the more adverse events the gorillas had experienced before the age of 6, the more likely they were to die in adolescence. But if they survived until the age of 6 — after their juvenile stage – despite the early adversity, the researchers found no evidence that their lifespan was shorter, regardless of the number of adverse events suffered by the gorillas.

In fact, if a gorilla has experienced three or more forms of adversity, it has actually lived longer; this group of animals had a 70% reduction in the risk of passed away in maturehood. However, this has been particularly caused by a longer life expectancy in men, and the researchers doubtful that the trend is due to something called viability selection. This means that if a gorilla was strong enough to survive difficult events at the beginning of life, he could simply be a “higher quality individual” and therefore more likely to have a longer lifespan.

“I expected these gorillas to have a short lifespan and not develop very well as matures,” Rosenbaum said. “We found that these events are definitely associated with a much higher risk of passed away at a young age. But if they survive to the age of 6, there is no evidence that these shorten their lifespan. This is very different from what we see in other species.”

The researchers have some theories about why these mountain gorillas were so resistant. Gorillas have very close social groups and previous studies have shown that when a young gorilla loses its mother, it does not really become more isolated: Other gorillas fill the void of social camaraderie.

“The boy is actually extending his time with other gorillas after the loss of his mother, and in particular the top-ranked mature male, even though he is not their biological father,” Morrison said. “These strong networks could provide a critical social buffer, as has been demonstrated in humans. The quality of our social relationships is a very important predictor of our health and longevity — more important than genetics or lifestyle in some matters.”

Another reason why they can be relatively buffered by the consequences of adversity is that mountain gorillas live in a resource-rich environment compared to many other wild primates. It might be easier for a gorilla to survive difficult circumstances if it doesn’t also constantly struggle with the Stress of finding enough food and water, Rosenbaum said.

“For comparison, the baboons of the savannah — which were the Inspiration for this Analysis — live in this very seasonal environment where they go through extreme droughts. Sometimes you have to walk for miles to get to a watering hole. They often action for every calorie they take in,” she said. “This is not the world in which mountain gorillas live. They are often described as living in a giant salad bowl.”

The researchers’ results suggest that species similar to ours may have significant resistance to adversity at the beginning of life. The results also raise important questions about the biological roots of sensitivity to first experiences and the protective mechanisms that contribute to gorilla resilience.

“I don’t think we should assume that the long-term negative effects of early life adversity are universal,” Rosenbaum said. “We tend to talk about it as if it were a pervasive experience and a fact that if you go through early adversity, your maturehood will be in peril.

“But I don’t think it’s that dry, even in human literature. I think the data is much more complex for humans and this research would suggest that it could also be more complex for other animals. And I actually think it’s a hopeful story.”

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