When I wrote “Culture: A Human Domain” (1969), I was attempting to show that the cognitive processes involved in toolmaking (not tool using, as then known in several different animal species) and language were extremely similar, if not identical. If I understand Vaesen's thesis, he has a similar viewpoint (but I would keep toolmaking and tool use as separate processes), and I believe he has extended the analysis well beyond what I attempted and in a most admirable way. I particularly agree with his emphasis on social intelligence and learning, as I earlier suggested that toolmaking was an inherently social process (Reference Holloway1967; Reference Holloway1975; Reference Holloway1981; Reference Holloway, Lock and Peters1996; Holloway et al. Reference Holloway, Yuan, Broadfield, Schwartz and Tattersall2004), suggesting social consensus and standardization, and thus some element of social control. My emphasis and his differ in that I have always been struck by the arbitrariness of human symbol systems (i.e., language) and by how internal (“intrinsic”) symbols become transformed into the external (“extrinsic”) symbol systems that can literally define reality – whether it actually exists or not, such as various forms of religious doctrine, not to mention countless historical (and prehistorical) examples of “man's inhumanity to man,” such as the Holocaust. These are perhaps “spandrels” of the human dark side and language, and tangential here.

More to the point of language and toolmaking, and to provide a concrete example, I still believe that the transformation of a branch used by chimpanzees for termite fishing is an iconic transformation where the final product is immediately visible in the original product (i.e., stick without leaves visible in a stick with leaves). This contrasts with much of hominid toolmaking – possibly starting with developed Oldowan, and surely present with the Acheulean, Levalloisian, Mousterian, and all blade tools (for in these instances, the final product is an arbitrary transformation where the final product is not necessarily apparent in the prior form but, rather, is a template formed in a social environment). In 1969 I tried to show that the three “design features” (Hockett Reference Hockett1960) considered unique to human language – namely, duality of patterning, productivity, and traditional transmission (the last also present in chimpanzees) – could be assessed in careful analyses of the units making up to the tool making process. For example, the “test-operate-test-exit” (TOTE) paradigm used by Miller et al. (Reference Miller, Gallanter and Pribram1960) can provide a quantitative as well as qualitative description of making any stone tool, as well as many other activities. Therefore, as crude examples, an Oldowan chopper would be a one TOTE unit tool, if a pebble was hit twice to detach two flakes without rotation. Rotation would add another TOTE unit. An Acheulean hand axe would involve selection of the blank, detachment of flake(s), rotation to other side, detachment of flakes until criteria are met (exit), thus yielding four TOTE units, but with multiple steps in each. Levalloissian flakes would add addition TOTE units. The exact number depends on selection processes for raw materials, as well as the actual flaking and rotating processes. Needless to say, there are also many stone tools where a predetermined shape has been selected because it was very close to the final sought product, as well as properties inherent in stone materials.

After 42 years, I still believe that culture as I defined it then (“that complex whole … shared by man as a member of society … is also the imposition of arbitrary form upon the environment”; Holloway Reference Holloway1969, p. 395) is still an exclusively human domain. The word imposition reflects my belief that arbitrary symbol use is not a natural phenomenon and is learned and practiced against psychological and societal resistance. Newer brain imaging, and fMRI studies conducted by Schick and Toth (Reference Schick and Toth1993), Toth and Schick (Reference Toth, Schick, Broadfield, Yuan, Schick and Toth2010), and Stout et al. (Reference Stout, Toth, Schick, Chaminade, Renfrew, Frith and Malafouris2009; Reference Stout, Toth, Schick, Schick and Toth2010), provide some tantalizing co-occurrences between complex motor patterns for stone tool knapping and the motor areas for language in Broca's region as well as the occipital and parietal lobes.

Nevertheless, as our understanding of non-human animal behavior is enhanced with both field and laboratory studies, it is likely that only language will remain the essential divide between us and other animals.