Researchers have found social bonds between specific chimpanzees and gorillas that endured over years and in many circumstances at Nouabalé-Ndoki National Park in the Republic of Congo. These observations span more than 20 years. The bulk of the remaining wild gorillas and chimpanzees live in close proximity, something most people are unaware of. Few studies of interactions between primate species have been able to account for inter-species relationships in the wild, but it is well known that these primates can recognize individuals within their own species and establish enduring connections. However, we did not know that this ability extended to other species. The study's findings were published in the journal iScience

Large areas of forest in the Congo Basin provide a stronghold for conservation for many species, in addition to these two types of endangered great apes. For nearly three decades, the Wildlife Conservation Society and the government of the Republic of Congo have collaborated to maintain wild areas that provide for the needs of the local population, safeguard natural resources, and mitigate climate change. Scientists observed chimpanzees and gorillas in the Goualougo Triangle daily from 1999 to 2020. They reviewed published reports and synthesized previously unreported data to show a wide variety of social behaviors, from play to aggressiveness.

Researchers looked into a number of potential advantages of these interspecies interactions, including as protection from predators, better feeding opportunities, and other social advantages from information exchange. Their discoveries demonstrate that no ape live alone on an island. Instead of focusing solely each species and their groups, it is important to remember that they coexist actively with other species in a variety of dynamic settings and are essential to the survival of the distinct ecosystems in which they dwell.

Predators are one of the main explanations put up for why apes might seek to socialize with people of other species… Because of the threat of predation in this area is very real — leopard for example prey on chimpanzees. However, the data from this study indicate that threat reduction cannot be attributed to these social interactions. The theory that chimpanzees or gorillas band together to lessen leopard, snake, or raptor predation efforts received no support from the researchers.

It appears, instead, that improved foraging opportunities are more crucial. The researchers discovered that 34% of the interspecific interactions they recorded involved co-feeding at the same tree, and another 18% of observations were apes foraging nearby but using different foods. In this study, apes targeted at least 20 different plant species during co-feeding occasions, considerably enhancing researchers' understanding of the variety of resources that chimpanzees and gorillas are willing to pool together and share.

This study demonstrated social bonds between members of various species that endured for years, in addition to a wider diversity of interactions than previously recorded among sympatric apes. For instance, the study's authors stated that they frequently saw juvenile gorillas and chimpanzees picking out specific partners to play with at food sources. These contacts may present special possibilities for growth that increase an ape’s social, physical, and cognitive abilities.

We can no longer presume that all of an individual ape's social neighbors are also of that species. The apes' strong social bonds and ability to maintain them over time reveal a level of social awareness and a variety of never-before-seen social transmission mechanisms. Such understandings are essential because interspecies social contacts have the potential to act as channels for the spread of both contagious diseases and positive socially learnt cultural habits.

Certainly, there are dangers involved with apes' social interactions.

The possibility of disease transmission is one. While habitat loss and poaching continue to be the biggest dangers to apes, infectious disease has just lately come to light as a threat of comparable size. Due to their close kinship, chimps and gorillas can share a variety of infections. For instance, the extremely contagious Ebola virus has wreaked havoc on the populations of apes in central Africa. Ebola first appeared in wild ape populations just over 20 years ago, then it migrated to human populations. Some estimates place the death toll from that Ebola virus wave at one-third of all chimpanzees and gorillas worldwide. These viruses' origins and methods of transmission within and across species, including humans, are now more better understood.

The degree of previously undetected and unreported overlap and interaction between these apes was a surprise in the study. We all assume that the apes would avoid one another, but that occasionally it appeared to be the opposite. In paleoanthropology, it has long been assumed that early hominins would compete with one another for access to the same resources in the same regions.

However, if current research on non-human apes may provide insight into early modern human behavior, then our study shows that these interactions would have most likely taken place in tolerant social settings. There is still much to learn about these interesting apes despite more than 60 years of chimpanzee and gorilla research; the key problem at the moment is to ensure the protection of these endangered species so that such chances are available for future generations.