Recent studies have shown that it his highly beneficial to both species when these cross species friendships are made. Indeed, it is not merely a question of chance encounters, instead each species will actively search out the other.
Benefits include protection from predators, increased social skills and finding fruiting trees.
Risks (which will not be obvious to chimpanzees or gorillas) is increased disease transmission. From Ebola and other diseases, transmission becomes more of a problem as the numbers of each species fall – due to human destruction of rainforest and direct hunting.
Researchers have watched significant time spent together between eastern chimpanzees and western lowland gorillas in Nouabale-Ndoki national park. Youngsters play together in these places, and observers noticed a young chimp beating its chest – an action usually restricted to Gorillas.
It was not all plain sailing, with occasional violent interactions – though the study never saw any of these result in death.
