As media and social channels around the world recently contemplated the hypothetical scenario of 100 men facing one male gorilla, here at the Dian Fossey Gorilla Fund we know from our nearly 60 years of study that gorillas are really “gentle giants,” generally calm, affectionate and family oriented.
It’s true that male gorillas are the largest primate on the planet, weighing an average of 400 pounds and that they have incredible upper body strength and jaw muscles. But there are many factors that play a role in their lifetime success. Their size when compared to other silverbacks is important, as is their personality, background and relationships.
Not all silverbacks have the characteristics to become group leaders, but all have their place and role. And even among those reaching high positions, ambition, size and personality can be very different.
In this photo, dominant silverback Musilikale is managing an interaction with the large Susa group.
Growing up silverback: size is important
Gorilla males start developing a silver-colored back around the age of 12 but they continue growing until about age 18, developing massive muscles, powerful jaws and teeth, and large bones, making them extremely strong and much bigger than gorilla females or humans. Usually they maintain their large size in adulthood, until their muscle mass decreases in old age.
But measurements of living gorillas taken by our researchers through a non-invasive method called photogrammetry confirms significant differences in body size among males — not surprising given their genetic similarity to humans. Some males grow exceptionally large, while others remain on the smaller side, even when full grown.
Currently, two of the mountain gorilla silverbacks we monitor in Rwanda’s Volcanoes National Park highlight these extremes in body size. Musilikale, leader of his own group, remains the largest silverback we’ve measured, even now that he is beyond his peak. In contrast, Umuganda, a subordinate silverback in Ntambara’s group, at 15 years old, is notably small for his age. This may help explain his lower rank within that group.
Silverback size is important for climbing social ranks because females typically prefer larger males, since they offer better protection. And therefore these silverbacks have more chances to mate and produce offspring. Given this relationship between size and reproductive success, larger males generally have better chances of becoming dominant.
And personalities count too
However, size alone does not determine everything. Gorilla males who do not reach top positions also play meaningful roles. Our daily observations reveal clear personality differences among the adult male gorillas, which influence their relationships within groups and their status.
Some silverbacks are calm and tolerant, while others are aggressive and quick to engage in conflicts. Interestingly, being aggressive does not necessarily help a male rise to a high rank. In addition to large size, females often prefer stable, calm males over aggressive ones.
Our decades of observations have shown a wide range of personalities contributing to individual success. Among the most-successful silverbacks we’ve observed, Titus, who was a peaceful leader for over 20 years, rarely engaged in physical conflicts. Similarly, silverback Cantsbee, who led for 23 years, seldom joined fights, letting subordinate males handle conflicts. He remained centrally located, surrounded by females and offspring. In contrast, silverback Shinda led through dominance and aggression, frequently involving allied males in violent confrontations.
In the current Musilikale group, none of the three subordinates challenge the dominant silverback, likely due to his size and authoritarian leadership style. However, in today’s Titus group, dominance is unclear. Three silverbacks, particularly Pato and Urwibutso, regularly challenge each other. Observations of daily interactions and genetic studies of offspring show no clear winner, highlighting varying female preferences.
Historic silverback Cantsbee was one of the most successful ever observed.
The real challenge
This variety among silverbacks within gorilla societies offers valuable insights into how individual traits influence leadership styles and group dynamics, similar to variability found in human societies.
In the hypothetical scenario of the 100 men versus a silverback gorilla, the sheer number of humans would likely eventually wear down and strategically overcome the gorilla, despite its larger size and strength. However, we would definitely expect different reactions depending on which gorilla they are facing! Undoubtedly, the men would face a much tougher challenge against a gorilla with the size and temperament of Musilikale.
But, of course, the challenge that’s more important is the real one – the fight for survival that all gorillas face, as a critically endangered species with many threats to their future existence. It’s up to people to make sure gorillas are still around for generations to come.
This article is part of a series presented by the Fossey Fund’s gorilla program Senior Advisor Veronica Vecellio, focusing on the mountain gorillas the Fossey Fund protects and studies every day in Rwanda. Veronica has worked with these gorilla families for more than 20 years and shares her deep knowledge and insights about their lives.
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