Chimpanzees help others with what they want, children with what they need; uniquely human socio‐ecologies based on interdependent cooperation gave rise to uniquely human prosocial motivations to help others paternalistically

Chimpanzees help others with what they want; Children help them with what they need. Robert Hepach, Leïla Benziad, Michael Tomasello. Developmental Science, November 11 2019. https://doi.org/10.1111/desc.12922

Abstract: Humans, including young children, are strongly motivated to help others, even paying a cost to do so. Humans’ nearest primate relatives, great apes, are likewise motivated to help others, raising the question of whether the motivations of humans and apes are the same. Here we compared the underlying motivation to help of human children and chimpanzees. Both species understood the situation and helped a conspecific in a straightforward situation. However, when they knew that what the other was requesting would not actually help her, only the children gave her not what she wanted but what she needed. These results suggest that both chimpanzees and human children help others but the underlying motivation for why they help differs. In comparison to chimpanzees, young children help in a paternalistic manner. The evolutionary hypothesis is that uniquely human socio‐ecologies based on interdependent cooperation gave rise to uniquely human prosocial motivations to help others paternalistically.




General Discussion

Previous experimental work had investigated the rate of helping in human and non-human
primates but has not directly compared the manner of helping. In the current studies we used a
novel paradigm giving both children and chimpanzees a choice not of whether to help but rather
how to respond to others’ needs. Our results replicate previous work in showing that both children
and chimpanzees show concern for others and comply with others’ request for help when these
align with the requester’s actual need (Warneken et al., 2007; Yamamoto et al., 2012). However,
the crucial difference between the two groups was evident in the nature of their tendency to be
paternalistic. Only human children showed paternalism and intervened for the benefit of the
recipient and corrected her behaviour. Crucially, children did not automatically correct others’
request for help but took into account how much better they could evaluate the situation.
Children’s paternalism was strongest when they shared the same view of the situation as the
requesting adult. Overall, children complied with the adult’s request in the majority of conditions
unless the requested tool did not serve to fulfil the adult’s actual need in which case children were
more motivated to correct the request. Chimpanzees, on the other hand, did not show preference
for either object and performed at chance across conditions unless the conspecific requested the
functional tool when that tool was needed to retrieve a reward. Together these results suggest that
while both children and chimpanzees show concern for others, the underlying manner in which
each group provides this help is different when their understandings of the situation differ.
The current results replicate previous work on chimpanzees’ helping behaviour, both with
regards to their response to others’ requests for help as well as their lack in concern to
systematically improve others’ long-term well-being. Chimpanzees are sensitive to others’
immediate needs and requests for help (Yamamoto et al., 2009, 2012). These previous findings
replicated in the current study where chimpanzees helped more in the need compared to the noneed
control condition when the conspecific requested the functional tool. However, in the
paternalism condition chimpanzees did not correct requests for help that were dysfunctional. In
other words, chimpanzees were not paternalistic to interfere ‘for the good of the recipient’ (Grill,
2007). This lack in paternalism to improve the requester’s well-being by means of correcting the
request for help is comparable to previous findings that chimpanzees do not systematically
improve a conspecific’s well-being in the so-called prosocial choice task in chimpanzees (House
et al., 2014; Jensen et al., 2006). The results of the current study with human children also
replicate and crucially extend previous work.
By age three children concern themselves with others’ long-term well-being and correct
dysfunctional requests for help (Hepach et al., 2013; Martin et al., 2016; Martin & Olson, 2013).
In one study, the authors found that 3-year-old children complied with the adult’s request less
often when this resulted in a negative consequence and half the children corrected the adult by
providing the intact tool instead (Martin & Olson, 2013). Note that the child and the adult did not
share the same perspective which may have put additional constraints on children’s decision
resulting in correction rates between 52 and 69 % (see Martin & Olson, 2013, for details). In the
current study, we found different rates of correcting in children between the occluded and nonoccluded
contexts. This allows us to specify that the rate of correcting others is greatest if both
parties share the same perspective, as is the case in the current study’s non-occluded context.
Children at the age of three may thus hesitate to override an adult’s request for help if they cannot
be certain that their view of the situations matches that of the adult. Therefore, in the current
study’s occluded context children may have complied with the adult’s request because, from their
perspective, the adult may have had a privileged view of the tools that children did not have. This
context sensitivity resonates with previous findings from a study in which children’s and the
adult’s perspective matched and children’s complying behaviour and responses to unjustified
requests for help were as low as 25 % (Hepach et al., 2013). Thus, based on the current results we
can conclude that children are less likely to correct the adult when they do not have the same view
of the situation as the adult (e.g., Martin & Olson, 2013) but, in contrast, correct the adult more
often when both the child and the adult share the same perspective (see also Hepach et al., 2013).
The current studies are the first to assess and directly compare the phenomenon of
paternalism between young children and chimpanzees. At the same time, there are a number of
methodological considerations of the current studies that warrant discussion. One crucial premise
of a paternalism context is that the potential helper knows that only the functional tool can fulfill
the requester’s need even if the requester reaches for the dysfunctional tool. Given the speciesunique
testing constraints we chose different approaches for chimpanzees and children.
Chimpanzees’ underwent extensive training in which subjects were exposed to multiple days of
using the functional tool to successfully obtain juice. Helpers only proceeded to the test phase if
they correctly identified the functional tool on multiple successive sessions during the training
phase. In this way, we sought to ensure that helpers had ample experience of using the functional
tool and thus, in the helping and paternalism context of the test phase, knew that only the
functional tool would fulfill the requester’s need. In contrast, young children were only tested in a
single session and thus the time we could allocate to training them on the apparatus and the tools
was more limited in comparison to chimpanzees. Therefore, we included control questions during
the training phase to ensure that all children knew that only the functional tool worked to retrieve
the reward from the box. During the test phase, we reminded children of the adult’s goal of
wanting to retrieve the reward from the box and of the fact that one tool was needed to
successfully to do so. To this end the adult experimenter pointed to both tools from a distance
saying: “Yes, I need that one”. Crucially, the adult pointed ambiguously and did not provide any
clues as to which tool he required. Together, the extensive multi-session training and testing for
chimpanzees could have made the functional tool more salient for chimpanzees than for children
who received a total of four reminders during a single testing session that one tool (not which) was
needed for the adult to successfully retrieve the reward. This would have resulted chimpanzees
overall choosing the functional tool more often than children (which is not what we found).
Together, these methodological differences between children and chimpanzees prompt a
more critical reflection on whether the differences in observed paternalism where a mere
consequence of methodological differences between the paradigms in which each group was
tested. It is important to point that children - in the paternalism context when the adult reached for
the dysfunctional tool but needed the functional tool - were not paternalistic per se but took into
account what view of the situation they had in comparison to the adult. Children’s paternalism was
rather selective and occurred significantly more often in the non-occluded context, where both
tools were fully visible, compared to the non-occluded context, where occluders changed the
visual perspective of the child and adult on the two tools. If the study’s procedure prompted
children to be paternalistic to correct the adult then one would have expected similar levels of
paternalism between the occluded and non-occluded contexts. But this is not what we found.
Children corrected the adult in the paternalism context significantly more often on the nonoccluded
compared to the occluded context. This suggests that asking children during the training
phase to identify the correct tool did not automatically result in them providing this tool. One
avenue for future research is to manipulate the conditions that result in paternalism in children.
Children’s paternalistic helping may depend on how certain they are that the adult’s request will
not sufficiently fulfill his/her need. In addition, it is important to investigate age effects whether
older children are more motivated to be paternalistic, even in occluded context, than the 3-year-old
children in our study (see also Martin et al., 2016). Similarly, additional research is needed to
follow up on the question of whether there are circumstances under which chimpanzees will show
paternalism. This could include varying the social relationship between the requester and the
helper to include mother-child dyads or dyads of close allies and friends (see also Engelmann &
Herrmann, 2016).
In addition to a difference in how chimpanzees and young children help others it is
important to consider other factors that may explain the species difference observed in the current
studies. It is possible that chimpanzees have greater difficulties taking the perspective of the
requester than young children, which could explain their lack of paternalistic helping. On such an
account both children and chimpanzees are motivated to help others and even help
paternalistically but chimpanzees may not be able to think about the requester’s goals and
constrains in ways that are comparable to young children. While ultimately more research is
needed to fully address this point, there are two reasons to think that a mere lack in a cognitive
ability to take others’ visual perspective is not the best explanation of the current pattern of results
for chimpanzee subjects. First, the extensive training in the current study ensured that subjects
proceeded to the test phase only if they had completed a training phase with the occluders during
which they themselves had to walk to the non-occluded side to identify the functional tool (so they
clearly knew the positions from which their own view was or was not occluded). Second, previous
work with comparable experimental set-ups shows that chimpanzees are able, in addition, to
discern the positions from which others can and cannot see things (Hare, Call, Agnetta, &
Tomasello, 2000; Kaminski, Call, & Tomasello, 2008) and can represent others’ false beliefs
(Krupenye, Kano, Hirata, Call, & Tomasello, 2016), suggesting that subjects in the occluded
context of the current study knew whether the requesting conspecific could or could not see the
functional tool.
It is important to emphasize that the lack of paternalism in the current sample of
chimpanzees does not indicate a lack of concern for others. On the contrary, the results from the
helping condition in the current study replicate previous work with chimpanzees who help
conspecifics to fulfill their instrumental goals in instrumental responding to others needs and
helping more in need compared to control scenario (Melis et al., 2011b; Warneken et al., 2007;
Yamamoto et al., 2012). The results of the current study add to our understanding of the
underlying motivation of chimpanzee helping behavior. Chimpanzees, as opposed to young
children, help others by fulfilling the request. This suggests that for chimpanzees the cost of
denying a conspecific the tool that he/she requested does not outweigh the benefits of having
corrected the request to provide the tool that is functional to fulfilling the actual need. One
interesting avenue for future research is the questions under which chimpanzees are paternalistic
and do correct others. Previous work has shown that chimpanzee helping behavior to increase
toward conspecifics who have benefitted the induvial in the past (Schmelz, Grueneisen, Kabalak,
Jost, & Tomasello, 2017). In such scenarios of dependence chimpanzees may correct others’
dysfunctional requests for help because they themselves want to be helped by having their need
rather than their request being fulfilled.
In summary, the current results suggest that while human children and chimpanzees share
a sensitivity to others’ immediate requests for help, humans additionally take into account others’
long-term well-being. Only human children showed evidence for paternalism. Such paternalistic
interference with another’s goal-directed behavior bears a cost given that it temporarily upsets and
frustrates the recipient who did not get what he requested. In a highly interdependent species this
cost is trumped by the benefit of correcting others’ ill-fated requests for help, given that there is a
mutual understanding among collaborating partners to care about each other’s needs above and
beyond fulfilling each other’s immediate requests for help. Our hypothesis, therefore, is that the
strongly interdependent nature of human social life has led, via natural selection, to helpful
individuals who are not so much interested in fulfilling a conspecific’s every wish and desire, but
rather at keeping them in good shape as potential collaborative partners for the future.