In the present study, we found age-dependent differences between wolves and dogs in the success to utilize human pointing and in their willingness to cooperate with the experimenter. The latter included differences in struggling and biting when held at a fixed position and attentiveness to a human experimenter. These detailed behavioural analyses offer a novel approach in pointing tests, and help to reconcile previously contradicting views on the effects of evolutionary and developmental processes.
At the age of 8 weeks, it was very difficult to make wolves attend to the human signal despite facing a relatively simple form of the task, namely proximal pointing. Even those wolf pups that could be tested had a higher latency for eye contact with the pointing E, struggled in the hands of the handler and bit her more often than dogs of the same age. The success of the two groups did not differ at this age. These results suggest that the tameness of the subjects and attention paid to the human experimenter do not influence the usage of this simple gesture. This is supported by the findings that socialized fox cubs are also able to utilize similar type of pointing gestures independently of having been selected for tameness or not 
In Study 2, using the more demanding, distal momentary pointing gesture, we found a marked difference in the performance of 4-month-old wolves and same-aged dogs. Importantly, these results confirmed previous findings that at this age only dogs are able to rely on this signal 
. Though higher attentiveness was paralleled with increased willingness to cooperate in wolves by this age, the results show that even early and intensive socialisation of dogs and wolves in human environment is not sufficient to diminish differences in the performance in distal momentary pointing, as it has been suggested recently 
In Study 3, we provided evidence that socialised adult wolves are as successful in relying on distal momentary pointing as adult pet dogs. Adult wolves' success was paralleled with minimal struggling (and no biting) and high variability in the latency of eye contact at the group level. Importantly, success at the individual level in wolves correlated with the readiness to look at the pointing human. Dogs seemed to show a ceiling effect in this respect and this may explain the lack of correlation in their case.
The behavioural changes in wolves that paralleled the success in utilizing human distal pointing seem to support the hypotheses arguing for indirect selection during domestication 
. It seems, however, that selection for decreased levels of fear and aggression toward humans, as proposed by the emotional reactivity hypothesis, may be insufficient in accounting for higher interest in and cooperation with humans 
. In addition a recent study revealed that selection for two factors under genetic influence (visual cooperation and focused attention) may have led independently to increased comprehension of human communicational cues in dogs 
. Thus, the tendency for looking at humans in a communicative situation seems to be a genetic predisposition in dogs, while it is difficult to induce this behaviour in young wolves even after intense socialization 
. However, intensive socialization could “mimic” the evolutionary effect at the individual level in wolves by lowering emotionality and leading to increased performance in some human controlled communicative situations.
Observations in an operant learning context 
suggest that, compared to wolves, dogs have a better control of the suppression of immediate drives in favour of delayed rewards and show higher attentiveness to humans already at the age of 9 weeks. These differences give dogs a head-start in utilising human gestural signals, while delaying similar performance even in hand-reared and extensively socialised wolves.
We agree with Udell et al. 
that in adult wolves an alternative route, predominated by extensive learning experiences about humans, can lead to similar performance in some human pointing tasks. In nature, during maturation wolves learn to take into account the behaviour of their pack mates in a feeding context. In addition, for being effective in this test, wolves have to learn about humans as social partners. This does not need to be in a special context, such as observing human visual gestures, but rather a general understanding that humans can provide useful information.
However, due to their less specific species recognition system and unique attachment behaviour, dogs are at an advantage to include humans in their social environment, and even intensively socialized wolves do not regard their caretakers as attachment figures 
. This indicates that despite similar amount of early social interaction the role of humans as social partners is different in wolves and dogs. This is supported by results of Study 3, in which adult wolves still struggled significantly more and had longer eye-contact latency than dogs, though this difference was already relatively small at this age. This indicates that both learning processes described above have taken place during the first 3 years, and individuals who modulate their agonistic behaviour and cooperate with humans as social partners, performed indistinguishable from dogs in this task.
Note, that although in the present study we did not find differences in the success of socialized adult dogs and wolves, it does not necessarily follow that the ability of socialized wolves and dogs is the same with respect to other instances of communication with humans. Adult dogs are able to rely on even more demanding pointing types, which require the ability to generalize among contexts (cross body and asymmetric pointing: 
), or lack any discriminative component 
. It may well be the case that wolves should reach a threshold in the latency/duration of attention, and then they can solve a given task. There could be different thresholds for different types of tasks. Dogs could be at an advantage in more complex tasks in social contexts, and further studies applying more subtle tests should be necessary to reveal such potential effects.
In sum, in dogs the necessary social skills for utilizing human pointing signals or the preparedness for their rapid development have been selected for in the domestication process. For wolves, a compensating developmental route might enable the establishment of the behavioural basis of successful communication and cooperation with humans in some tasks. Wolves, however, react to a lesser degree to socialisation in contrast to dogs, which are able to display control of agonistic behaviours and inhibition of actions in a food related task early in development. The synergistic hypothesis suggests that the dog-wolf difference in the sensitivity for human gestural cues emerges both at the evolutionary and developmental level. Further studies are needed to investigate whether this can be interpreted in the phenotype as a developmental change in the timing (heterochrony) of some social skills in dogs.