Explaining dog wolf differences in utilizing human pointing gestures: selection for synergistic shifts in the development of some social skills

Abstract

Background: The comparison of human related communication skills of socialized canids may help to understand the evolution and the epigenesis of gesture comprehension in humans. To reconcile previously contradicting views on the origin of dogs' outstanding performance in utilizing human gestures, we suggest that dog-wolf differences should be studied in a more complex way.

Methodology/principal findings: We present data both on the performance and the behaviour of dogs and wolves of different ages in a two-way object choice test. Characteristic behavioural differences showed that for wolves it took longer to establish eye contact with the pointing experimenter, they struggled more with the handler, and pups also bit her more before focusing on the human's signal. The performance of similarly hand-reared 8-week-old dogs and wolves did not differ in utilizing the simpler proximal momentary pointing. However, when tested with the distal momentary pointing, 4-month-old pet dogs outperformed the same aged hand reared wolves. Thus early and intensive socialisation does not diminish differences between young dogs and wolves in behaviour and performance. Socialised adult wolves performed similarly well as dogs in this task without pretraining. The success of adult wolves was accompanied with increased willingness to cooperate.

Conclusion/significance: Thus, we provide evidence for the first time that socialised adult wolves are as successful in relying on distal momentary pointing as adult pet dogs. However, the delayed emergence of utilising human distal momentary pointing in wolves shows that these wild canines react to a lesser degree to intensive socialisation in contrast to dogs, which are able to control agonistic behaviours and inhibition of actions in a food related task early in development. We suggest a "synergistic" hypothesis, claiming that positive feedback processes (both evolutionary and epigenetic) have increased the readiness of dogs to attend to humans, providing the basis for dog-human communication.

Figure 1. Study 2 and 3: The performance of young and adult wolves and dogs in distal momentary pointing trials.

In all groups, success was compared to random choice (50%) with one sample t test. * P<0.05, ** P<0.01.

Figure 2. Study 1: The behaviour of 8-week-old, hand-reared dogs (N = 7) and wolves (N = 9) in the proximal momentary pointing test.

* P<0.05, ** P<0.01.

Figure 3. Study 2 and 3: The behaviour of 4-month-old and adult pet dogs (N = 7 and N = 8) and hand-raised wolves (N = 7 and N = 7) in the distal momentary pointing test.

* P<0.05, ** P<0.01.