Table 1.

Comparison of methods and conclusions from published studies of ape gesture meaning (emphasis mine)

Study	Species	Conclusions	Methods
Hobaiter & Byrne (85)	Chimpanzee (Pan troglodytes)	“…found [gestures] to be used intentionally to achieve 15 purposes...”	“We examined whether different gestures were associated with a specific pattern of outcomes..” “… we therefore excluded data from play bouts to avoid masking the “real-world” meaning of gestures.”
Roberts et al. (104)	Chimpanzee (Pan troglodytes)	“...gestures were also strongly associated with specific responses and outcomes…”	“…consistent association between a given gesture type and particular behavioural change may be used to infer the meaning of different gestures” “…this necessarily excluded both actions that were not clearly directed…towards a specific recipient that could visually perceive the signaller's behaviour…and actions that could feasibly be readily explained in noncommunicative terms”
Cartmill & Byrne (84)	Orangutan (Pongo pygmaeus/abelii)	“…more than half of the orangutan gestures we were able to analyse had predictable intentional meanings”	“The aim is to identify gestures that are used predictably to elicit specific reactions...” “Only gestures that occurred singly or as the first gesture in a sequence were analysed for meaning. While this simplified the analysis by restricting it to a single signal and reaction in each case, it necessarily excluded some gestures from analysis.”
Graham et al. (105)	Bonobo (Pan paniscus)	“Bonobos intentionally deploy gestures to achieve at least 14 different intended outcomes”	“We are able to deduce the meaning of great ape gestures by looking at the ‘Apparently Satisfactory Outcome’ (ASO)…” “…Fifteen gesture types were suitable for analysis, having been used by at least 3 individuals at least 3 times to achieve an ASO.”

These studies represent a range of authors and study species and all employ methods frequently used in the field. Each study found that gestures were used to communicate specific meanings. Each also explained in the methods that the researchers were explicitly looking for code-like contingencies between signal and response and curated their data in particular ways that made these codes easier to find.