Like humans, apes communicate to start and end social interactions


Date:
August 11, 2021
Source:
Cell Press
Summary:
When we're talking to another person, we probably wouldn't leave
without saying goodbye; that would just be impolite. Apes seem to
do something similar, researchers report in a study, in which they
documented apes purposefully using signals to start and then end
interactions -- a behavior not seen outside of the human species
until now. They also found that the social and power dynamics
between the interacting apes affected the communication efforts
used, which the researchers say mirrors patterns similar to human
politeness.



FULL STORY ==========================================================================
When we're talking to another person, we probably wouldn't leave without
saying goodbye; that would just be impolite. Apes seem to do something
similar, researchers report in a study publishing August 11 in the journal iScience, in which they documented apes purposefully using signals to
start and then end interactions -- a behavior not seen outside of the
human species until now.

They also found that the social and power dynamics between the interacting
apes affected the communication efforts used, which the researchers say
mirrors patterns similar to human politeness.


==========================================================================
"We were able to launch rockets and land on the moon because we have
the ability to share our intentions, which allows us to achieve things
so much bigger than a single individual can achieve alone. This ability
has been suggested to be at the heart of human nature," says Raphaela
Heesen, a postdoctoral researcher at Durham University in the United
Kingdom. Sharing intentions and working together on a common goal leads
to a mutual sense of obligation otherwise known as joint commitment --
and now, she and her team are seeing evidence in great apes that might challenge the long-held claim that joint commitment is unique to humans.

In previous experiments of joint commitment, human children protested
when an experimenter abruptly stopped playing with them. Offering toys
or vocalizing, the children tried to re-engage the experimenter in their previously agreed- upon play. After witnessing a similar situation between
two bonobos -- who were interrupted while grooming but then used gestures
to resume the interaction with each other -- Heesen and colleagues became curious to learn more about how and when joint commitment first emerged
in the human lineage.

But unlike previous scientists, Heesen and her team proposed that joint commitment isn't solely based on the feeling of obligation between two participants to fulfill a shared promise. Instead, it also involves the
process of setting up the agreement and mutually deciding afterward that
the agreement has been fulfilled.

That means something as simple as entering a conversational commitment
with eye contact and a "hello" and then signaling that a conversation is wrapping up with repeating "okay, sounds good" or a "goodbye" could be
an example of this process. So Heesen and her colleagues set out to see
if great apes had a similar interaction entry and exit process, which
she and her team argued would demonstrate the process of joint commitment.

After analyzing 1,242 interactions within groups of bonobos and
chimpanzees in zoos, they found that the apes did in fact frequently gaze
at and communicate with each other to start and end interactions. Bonobos exchanged entry signals and mutual gaze prior to playing 90% of the time
and chimps 69% of the time.

Exit phases were even more common, with 92% of bonobo and 86% of
chimpanzee interactions involving exits. The signals included gestures
like touching each other, holding hands or butting heads, or gazing at
each other, before and after encounters like grooming or play.

The researchers also considered factors like how close the apes were to
each other socially or who had more power over the other. Interestingly,
the closer bonobos were to each other, the shorter the duration of their
entry and exit phases, if they existed after at all. The authors say
this pattern is similar to how we, as humans, communicate with others,
too. "When you're interacting with a good friend, you're less likely to
put in a lot of effort in communicating politely," Heesen says.

However, the level of friendship and strength of social bonds didn't
seem to affect the chimpanzees' entries and exits at all. This could
be because in comparison to chimps' despotic power hierarchies,
bonobo societies in general are documented to be more egalitarian,
with emphasis on friendships and alliances between females and close
mother-son relationships.

As for understanding the origin and evolution of joint commitment, this
study is another step forward -- but Heesen says there's a still a lot
to do.

"Behavior doesn't fossilize. You can't dig up bones to look at how
behavior has evolved. But you can study our closest living relatives:
great apes like chimpanzees and bonobos," says Heesen. "Whether this type
of communication is present in other species will also be interesting
to study in the future." This work was funded by the Swiss National
Science Foundation.

========================================================================== Story Source: Materials provided by Cell_Press. Note: Content may be
edited for style and length.


========================================================================== Journal Reference:
1. Raphaela Heesen, Adrian Bangerter, Klaus Zuberbu"hler, Katia
Iglesias,
Christof Neumann, Aude Pajot, Laura Perrenoud, Jean-Pascal Gue'ry,
Federico Rossano, Emilie Genty. Assessing joint commitment
as a process in great apes. iScience, 2021; 102872 DOI:
10.1016/j.isci.2021.102872 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/08/210811113148.htm

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