We welcome Reference Riesch, Barrett-Lennard, Ellis, Ford and DeeckeMoffett's linkage of shared group identification to the term “society.” The division of a population/species into groups within which there is mutual recognition has important ramifications for genetic and cultural structure, for population dynamics, ecological effects, and psychology. “Society” has largely been an amorphous term, sometimes synonymous with social structure or community, but more often undefined. Calling mutual recognition groups “societies” should bring them important attention, and increase rigour in their description and study.

Moffett requires that mutual recognition societies “maintain control over access to a physical space.” This has the intentional result that societies cannot overlap in membership, and individuals can only be a member of one society. We argue that this “territoriality” constraint is counterproductive as it excludes some situations where mutual recognition is an important element of social and population structure but there is no territoriality, and in others where overlapping or nested “societies” may be important factors in social and population structure. We particularly consider societies of the deep ocean.

Moffett notes that gelada baboons are problematic for his definition of society: Their “units” do have mutual recognition, but there is no control of physical space. However, he argues “for retaining control of space as part of the definition [of ‘society’] despite these outliers.” Among free-swimming social species of the deep ocean, the gelada scenario is not an outlier, it is the norm and perhaps universal. The deep ocean is fluid as well as three-dimensional, and resources are typically very patchy and often unpredictable (Inchausti & Halley, Reference Inchausti and Halley2002). The fluidity and increased dimensionality of the deep ocean mean that it is either impossible or uneconomical to defend anything (except possibly a mate), leading to scramble competition rather than contest competition for resources (Gowans, Würsig, & Karczmarski, Reference Gowans, Würsig and Karczmarski2007; Whitehead & Rendell, Reference Whitehead and Rendell2015, p. 55). With extreme patchiness, there are often enough resources for everyone in a given patch, reducing competition. In a few cases, ocean animals may actively recruit conspecifics to join them to feed on resources (blue whales; Cade et al., Reference Cade, Fahlbusch, Oestreich, Ryan, Calambokidis, Findlay and Goldbogen2021). Thus, territorial or resource defence is not an important feature of the deep ocean. The shallower continental shelves, and even much shallower coastal and estuarine waters, have less extreme versions of these same characteristics (Whitehead & Rendell, Reference Whitehead and Rendell2015, p. 56). However, the benthos, the bottom of the ocean, is more two-dimensional and solid, so benthic animals may be territorial (e.g., Roberts & Ormond, Reference Roberts and Ormond1992).

Despite this lack of territoriality, shared group identification is a well-documented attribute of a few deep-ocean animals and it may be quite common. Sperm whales, mostly open ocean nomads, have two primary social tiers: Stable communal matrilineally based family “units” with about 10 females and young, and “clans” which typically contain thousands of social units, and are distinguished by vocal dialects and distinctive culturally transmitted behaviour (Whitehead, Reference Whitehead2024). Units form temporary groups only with other units from their own clan, even though several clans often use the same waters (Whitehead, Reference Whitehead2024). The dialects seem to symbolically mark clan membership as the vocal repertoires of clans that use the same waters are less similar than those of clans that overlap little (Hersh et al., Reference Hersh, Gero, Rendell, Cantor, Weilgart, Amano and Whitehead2022). Thus, the sperm whale clans have the key attributes of Moffett's “anonymous societies” (except territoriality).

Killer whales exhibit multi-tiered social organization. Membership in the groups at each tier is usually stable, and different groups have different culturally inherited characteristic behaviour, including dialects (Ford, Ellis, & Balcomb, Reference Ford, Ellis and Balcomb2000; Riesch, Barrett-Lennard, Ellis, Ford, & Deecke, Reference Riesch, Barrett-Lennard, Ellis, Ford and Deecke2012). Group identification at the lower tiers (such as matrilines and pods with less than about thirty members in each) is likely often based on individual recognition, while the higher levels (communities, or ecotypes with hundreds or thousands of members in each) likely constitute anonymous societies (minus territoriality), with vocal dialect being the most probable marker.

Moffett dilutes the notion of territoriality to “include whatever land or stretch of sea a mobile society controls access to at a given time, through aggression or avoidance, and to allow for the possibility that visits from outsiders may be permitted.” However, the suggestion that sperm whales similarly rely on “mobile territories” (target article, sect. 3, para. 10) does not hold up to scrutiny. Though sperm whale units travel cohesively in the same areas, there is no evidence that they attempt to monopolize the space they travel through. Furthermore, if taken literally, this dilution undoes the purpose of adding territoriality to the definition of society. Nomadic groups that avoid one another in real time may include nested or overlapping societies, as in ethnically or religiously based identifiable groups of humans (or even symbolically marked supporters of different sports teams) wandering in an urban setting. Killer whales show avoidance at the level of both the community and ecotype but there is no indication of territoriality.

Nested and overlapping societies are quite common and important on both land and sea. While nation-states are the exemplar human societies, mutually recognizable religious, class, and ethnic divisions within or between nation-states, not based on territoriality, can have major impacts on mating patterns, cultural diffusion, and resource use. The tiers of killer whale society influence population biology: “resident” killer whales mate between but not within “clans,” while xenophobia separates “communities” and “ecotypes” (Barrett-Lennard, Reference Barrett-Lennard2011). We believe that such groups which are based on mutual recognition should be considered societies.

Crucially, the extent to which a society controls space seems to have little impact on the key distinction between societies and other groups, that is, a “bedrock sense of belonging.” For example, most of the social processes and psychological traits that Reference Riesch, Barrett-Lennard, Ellis, Ford and DeeckeMoffett links to a reliance on identity groups are unrelated to spatial exclusion.

We therefore propose that the definition of “society” not include territoriality, thus allowing for societies among non-territorial populations and species, as well as for overlapping and nested societies. However, space-use is important in how some societies function. We suggest that “territorial society” join other modifications such as “anonymous society” and “society in suspension” as important subcategories of “society.”