Sociality in animals: how widespread is it? And how important is it?

In typical installments of this newsletter, I name a specific issue or question, then discuss some recent findings that help illuminate it, and then present the provisional conclusions from the new findings. In other words, these articles try to function as rather focused reports, based on some new findings. This week, however, the form will be a little different. This piece will be more of a meditative ramble around a question, although it will reach a tentative conclusion.
The subject is the sociality of mammals though the issue is relevant to all vertebrates, especially the long-lived ones. The question motivating this discursive ramble is: how wide-spread is sociality in mammals and does it serve any real purpose? As we will see, these matters connect to those of ageing and health.

I am using the word “sociality” rather than the more commonly used word “sociability”. These two words could be, and often are, used interchangeably but I regard them as having different shades of meaning. To me “sociability” involves the desire to actively interact with other people and the enjoyment that comes with that interaction. In (mild) distinction, “sociality” is somewhat more diffuse, being simply the wish to be around others, whether or not there is much active interaction. In company, there is often just a sense of comfort in their being other people around.

If I am in a restaurant, for instance, having a meal and there is no one else there or only one other customer, it seems kind of lonely and bleak in a way not compensated by the quality of the food, even if the latter is very good. However, if there are more customers, especially if there are one or more couples talking to one another, it seems like a friendlier, warmer environment to me, even if I am not interacting with the other customers.

Do any of our fellow mammals feel similarly about company? Apart from any direct benefit from being around one’s fellow species members, one’s “conspecifics”, is there some degree of psychological comfort in their presence? And, if so, does that feeling have any larger significance or is it just an interesting fact in itself without larger implications? This pertains particularly to gregarious animals such as those that live in herds, such as domestic sheep or, in the wild, antelopes or water buffalo. The members of such a herd may seem to be paying no attention to each other but are they actually getting some quiet benefit from the presence of their fellows?

Furthermore, if such feelings in other mammals exist, are they only engendered by members of one’s own species? For most of those of us with pets, just having one’s cat or dog near one in the same room is pleasant, even if they are just sleeping and not interacting with us. Hence, for this situation, we know that sociality can extend beyond one’s conspecifics. But what about animals in the wild? I remember wondering about this on several trips to the great African plains that I have made. On the savannahs, there are often, within relatively short distances of one another, groups of different species of antelopes, along with zebras, giraffes, sometimes a few rhinoceroses, water buffalo, all quietly going about their business (mostly grazing). For such animals, there is safety in numbers, in such situations, should a lion or a leopard suddenly charge, and this extra degree of protection probably may well produce more relaxed, less stressed animals. My question, however, was about a different kind of benefit, whether these animals actually enjoy each other’s presence to some degree?

With people, you can directly ask them about their feelings and reactions and if they do not mind being asked, you will get some information. With animals, of course, you cannot do the equivalent of man-on-the-street interviews and it is probably impossible ever to know from just watching. To explore animal sociality, you have to make careful observations after something has changed in the social environment and then make inferences about the animals’ psychology from their ensuing behaviors.

Two news stories about animals this past week revived such questions for me. One had to do with one of our nearest animal relatives, the mountain gorilla, the other with a very unusual animal odd couple. I will describe the latter situation first.

This odd couple pairing involved an ocelot (a wild cat, somewhat larger than a typical house cat) and an opossum (definitely smaller than the ocelot) in the Amazon forest. Normally, the cat would regard the possum as potential dinner and the opossum would keep its distance from the ocelot but these two mammals were caught on video at night peacefully walking along a path, like old friends after a night out. The investigators contacted other researchers and found that there were three other videos showing similar behavior between an ocelot and an opossum at other locations and times in the forest. They also did some tests of scent preference or at least interest and found that ocelot scent was distinctly more interesting or appealing to possums than that of another wild cat, the puma, or a control non-cat scent. Altogether, it looks as if there is some propensity for ocelots and opossums to hang out together ¹.

This behavior does not demonstrate that ocelots and opossums bond or have a special social affinity for each other but it does suggest it. Animals that spend time together and travel together, of their own volition, must have engaged in some prior familiarization with each other without fear and that they at least tolerate each other. The fact that at least four pairs took walks with each other for company is consistent with their being some purpose in it, perhaps scent masking (both have strong and distinctive scents) or perhaps something else providing an advantage if they go hunting together. Hence, ocelots and opossums keeping company with each other may not be pure socializing for its own sake. Then again, friendship between pairs of humans is not always just based entirely on affection but has some elements of self-interest or mutual helping.

The other recent story concerned mountain gorillas, who are generally regarded as only of middling sociality amongst the primates, somewhere between bonobos, at the higher end, and orangutans at the lower end. The new findings come after more than 20 years of observation of the social lives of these animals in Rwanda, a research program whose roots lie in the 1960s with the work of the late Dian Fossey (1932-1985) (which was immortalized in the film “Gorillas in the Mist”). The findings concern the relationships amongst the adult females in these populations.

Female gorillas often travel between and take up residence in new groups. This lowers the risk of inbreeding and is therefore a good thing for the genetic health of the different sub-populations; of course, it is unknown what gorilla-type thoughts or feelings prompt the animals to move to new groups. These populations have been so well studied that it is possible to identify and track individuals, both those doing the shifting between groups and those in the groups they join. That ability of the researchers to identify individuals made possible this research on the relationships between females.

The basic finding was that new female pair associations was preferentially between female mountain gorillas who had previously known each other, even if the earlier association had been several years in the past. Groups in another gorilla species, the lowland western gorillas, were also observed and monitored and a similar pattern of preferential female association with females previously known was observed for them though it was statistically stronger for the mountain gorillas.

A question concerns the role of the alpha males in these groups and whether the females’ social behavior with each other reflected the influence of the males. The evidence indicated that the presence or the absence of the male was not the driver of the females’ association patterns. The simplest conclusion is that female gorillas prefer the company of other females whom they had known and interacted with previously, even if this had been some years in the past. ²

If these had been small human groups we had been discussing, we would not hesitate to discuss this phenomenon in terms of “friendship”, while acknowledging the complexity of friendship and the different factors that can either contribute to or detract from it. The only reason to hesitate to do so is to avoid the charge of anthropocentrism, namely projecting human qualities on to animals without sufficient evidence. Yet as I have pointed out in this newsletter several times in the past, the history of research into animal behavior in the past 100 years, though most strongly in the last 20-30 years, has been a history of finding that certain behavioral and mental characteristics assumed to be unique to humans can be found in various animals, when looked for with the appropriate tests and procedures (see, for instance, Do non-human animals see other members of their species as individuals?) I think that female friendship between females who are not closely related might be, on the basis of this long study, about to join this list of special qualities now known to be shared with non-humans.

Of course, finding something in one group or species of animals, in this instance mountain gorillas, does not mean that it will be found in all the species of the larger taxonomic group to which they belong, in this case the primates or even mammals as a whole. Yet, if the propensity for a behavioral trait is found in one kind of animal, it is quite likely that it is found far more broadly. Gorillas are gregarious animals and if something like friendship exists amongst females in them, it seems not unreasonable that it exists in other gregarious mammals. This, however, will have to be looked for, on a case-by-case basis. A lot of the history in which various cognitive traits were assumed to be absent in animals involved simply the absence of evidence, which in turn reflected the failure to search for it. That in turn was based on the assumption of a great divide between humans and the rest of the animal kingdom, a feature of Western thinking dating back at least to the 18^th century.

Yet, as our knowledge of and understanding of evolution has grown in the past 160 years or so, the grounds for the assumption of human biological uniqueness have become weaker and weaker. In terms of both basic evolutionary thinking and growing biological knowledge, it is becoming increasingly reasonable to ask about any trait of humans, to what extent or in what form it might exist in at least our closest animal relatives, the primates, or more widely, in the mammals or even the vertebrates as a whole. Female bonding and friendship may be a case in point.

Nevertheless, for every trait that exists, it is reasonable to ask, from an evolutionary point of view, what advantage(s) does it confer. Why does it exist? In this case, what is the long-term value of friendship?

I would suggest, without claiming any originality in this, that the advantages of friendship are broadly of two kinds. First, there are the practical benefits: friends often help you with things that you cannot manage on your own or, at least, not as well. Sometimes that help can be of tremendous advantage, extending even to saving one’s life or preventing some terrible harm. Everyone knows this in principle and nearly everyone, at least people who are adults, have experienced such help at times.

Second, there are the more intangible emotional-psychological benefits. People who have friends are generally less likely to get highly stressed, at least over long periods, and are usually happier than people who lead largely solitary lives. Married people live longer, by two to three years, than unmarried people. There are undoubtedly several factors involved in that last fact but increased sociality, and decreased loneliness, in marriages almost certainly contribute.

Furthermore, some recent information suggests that increased sociality may actually slow ageing. The evidence comes from studies of so called “super-agers”. These are people in their 80s and 90s, who are generally similar in their mental functioning – speed, accuracy, memory – to people decades younger. Their brains often do not show the reduction of brain size typical of ageing seen in their age cohorts nor the signs of Alzheimer’s, in particular amyloid plaque accumulation (see The terrible tangle of Alzheimer’s disease) that are typically seen in the brains of people their age, irrespective of whether there are any clinical signs of Alzheimer’s. Of course, many factors can and do contribute to ageing and avoiding any of them probably favors a slower rate of ageing and prolonged life. Yet, a recent study has identified a common factor that may outweigh all the others in explaining the super-agers: they show more sociality and interact with more and diverse people than those typical of their age. ³

All of the studies mentioned here raise more questions than they resolve but they point in a similar direction (along with many other studies), that social contacts, perhaps even fairly brief ones, are good for one, first for one’s contentment in life and second, for one’s health. Other observations, which space and time limits do not allow me to go into, suggest that many animals have an untapped or underutilized potential sociality. In particular, gregarious animals, such as those that live in herds or large groups but which seem to be paying little attention to one another may actually be getting more out of the presence of their fellows, psychologically and physically, than is apparent. I intend to come back to this topic in a future essay.

1. This was a short science news item in the New York Times. Brincat, C. As long as one partner does get too hungry, it’s a fine friendship. The New York Times (Int’l Edition), 2-3 August, 2025, p. 13

2. For a short report, see Gill, V. (2025). Gorillas seek out old female friends even after years apart. www. bbc.com/news/articles/c80d17194yvro. For the detailed scientific report, see Young, C., M.M. Robbins (2022). Association patterns of female gorillas. Phil. Trans. B Roy. Soc. 378. 20210429.

3. See Smith, D.G. (2025). The one quality most super-agers share. The New York Times, 09/08/25. www.nytimes.com/2025/08/07/well/mind/super-agers-social-connections.