Gorillas are very social animals -- up to a point. Crowded areas can make silverbacks more violent, scientists say.Silverbacks are adult male mountain gorillas that often have a white area across their backs.They are the leaders of gorilla families.Mountain gorillas are genetically similar to humans.The large animals spend most of their time sleeping, eating, and cleaning each other. They are mostly peaceful creatures.They live in parts of Uganda, the Democratic Republic of Congo, and Rwanda.Researchers recently studied 50 years of data from Rwanda.They found that as the number of gorilla family groups increased, so too did the of violent fights between them.Most often, silverbacks led the fights.Some gorillas died, especially infants, or babies. These deaths, in turn, slowed population growth.Damien Caillaud of the University of California, Davis, was a co-writer of the new study, published in Science Advances.