So when humans gather in a football huddle before a big match, hug a teammate, or offer a pat on a shoulder before a stressful event, they may be drawing on a social toolkit that is millions of years old. (10/10)

Tolerance, the capacity to share space without aggression, appears crucial to the foundation of cooperation and social learning across the animal kingdom. Our findings suggest that pre-emptive friendly touch may be part of how that tolerance is maintained in our ape cousins. (9/10)

The vulnerability may be the key. Offering such contact is only safe if you are confident the other animal won’t bite your fingers off. And this tolerance may feed back into the wider social environment, creating even more tolerance. (8/10)

In chimpanzees, who are often viewed as the more aggressive species, we also found intense reassurance behaviours that were never seen in bonobos. These behaviours involve great vulnerability, for instance placing one’s hand or fingers into another individual’s mouth (7/10)

The patterns followed the social structure of each species. In bonobos, female-female pairs reassured each other most. In chimpanzees, it was the males. For both apes, these patterns were clearest in the more tolerant groups. In groups with more authoritarian leaders, the pattern disappeared. (6/10)

We recorded all social contact and aggression that occurred before, during, and after the food arrived. Does more reassurance lead to more peace? In both species, the answer was clear. Apes who had more friendly contact before food arrived spent more time feeding peacefully afterwards. (5/10).

To test this, we used a cofeeding task the “peanut swing” in several groups of chimpanzees and bonobos at two sanctuaries (Chimfunshi & Lola Ya Bonobo). By spreading a desirable resource into only limited space, this method provides a competitive context and measure of co-feeding tolerance (4/10)

In humans, touch is one of our oldest forms of communication, crucial for forming attachments with infants, long before language develops. Touch can increase cooperation, prevent lying, and reduce threat-related brain activity. But is the reassuring nature of touch a unique trait to humans? (3/10)

With Edwin van Leeuwen, Stephanie Kordon, @christinewebb.bsky.social & @zannaclay.bsky.social, affiliated with among others @durham.ac.uk and @mpi-animalbehav.bsky.social, funded by @templetonworld.bsky.social. We tested if reassuring body contact before competition promotes peaceful feeding. (2/10)

Would chimpanzees or bonobos huddle before a penalty shootout in the World Cup? 🐵⚽ In both species, reassuring body contact promotes social tolerance, read more in our new study led by Jake Brooker out now in @royalsociety.org Proc B. (doi.org/10.1098/rspb...) A thread of the main findings 🧵 (1/10)

Want to know more about monkeys kidnapping other monkeys?🐒 I had an amazing chat together with @bjjbarrett.bsky.social on @sidedoorpod.bsky.social about the Coiban capuchins and their wild antics. Science really is stranger than fiction! Listen 👂 here: www.si.edu/sidedoor/mon...

~5 years, 5 chapters, and one real human baby later, my "academic" baby is finally done. After a defense in near-boiling conditions, where even the beamer quit halfway through, I am now officially Dr. Zoë 🎓🐒 I am so grateful for this experience, and all my friends and family lifting me up! #PhDone

Group level assessments of abnormal behavior overlook important qualitative variation between individuals. Chimpanzees are each abnormal in their own way, and in order to accurately assess their welfare, focus should lie on the individuals. (9/10)

Here we also found individual differences: some chimpanzees often scratched and consumed feces within the same 10 minutes; for them coprophagy may indicate poor welfare. For others this link was not present. Our analyses were exploratory, but our main takeaway is this: (8/10)

Chimpanzees can acquire AB via social learning from group members, or they may be remnants of a poor welfare situation in the past. We considered the co-occurrence of a known stress-related behavior (self-scratching) with the most common AB (feces-eating).(7/10)

Quantitative variation of AB (e.g. frequency) has been studied, but less is known about qualitative variation. To fill this gap, we considered the entire AB repertoire of each individual, and found that chimpanzees highly varied in which AB they showed and how often. (5/10)

With my co-authors Elisabeth Sterck, Frans de Waal, and Christine Webb, we explore how a group of captive chimpanzees varies in their expression of abnormal behavior (AB). AB, such as coprophagy (eating one’s feces 💩, see GIF) is often seen as a sign of poor welfare. (2/10)

Lastly, a very big thank you to @kaylakolff.bsky.social for helping with the data collection. We also wouldn't have been able to write this article without the zookeepers and their amazing records. And to the chimpanzees themselves of course! Especially Moni for inspiring two publications 🐵 (8/8)

Previous studies have shown chimpanzees adopting local conventions after migration, but in our report the speed at which Moni copied the behavior (within days after being exposed to it) is especially remarkable. (6/8)

When two new females (Moni, left, and Erika, right) were introduced to the group, Moni copied the crossed-arm walk days after meeting only the resident female in the gif above. Erika never showed the behavior during >1 year of observation. 3/8 📷: @kaylakolff.bsky.social

With my wonderful co-authors Edwin van Leeuwen, Christine Webb, and Frans de Waal, we provided the first report of this tradition, we dubbed the "crossed-arm walk" (see gif), which has been present in the chimpanzee group @burgerszoo.bsky.social for over 20 years. (2/8)

The GHC is a delightfully mysterious behavior: we still don't know why chimpanzees do it. Our findings show the GHC is a great context to study coordination, joint intentionality and communication in non-human animals, and increase our understanding of (non-)human culture. (10/10)

We found that chimpanzee pairs more experienced with GHCing with each other were more likely to communicate instead of shape. This suggests that how GHCs are initiated is variable and changing rather than fixed within an individual or a pair. (8/10)

GHC initiations were not one-sided, set sequences, but rather flexible interactions that showed great variation. This is best illustrated by this sunburst figure, showing which behavioral sequences initiators of GHCs showed (plus it’s interactive! see article supplements) (6/10)

We found that shaping was common (22% of initiations), but what was even more common (44%) was communication! Chimpanzees used several gestures (such as “hold” demonstrated by Debbie in the video below) to indicate their intention to GHC to a partner, who responded in turn. (5/10)

Now the science: imagine wanting to high-five someone ✋, but instead of raising your hand and waiting for them to raise theirs, you grab their elbow and force their arm up yourself. Weird as this may sound, this is how chimpanzees were thought to initiate most GHCs (3/10)

What can #chimpanzees clasping their hands teach us about human and non-human animal culture? Our study, published #openaccess in @royalsocietypublishing.org examines the role of communication in initiating this social custom, the grooming handclasp (GHC). doi.org/10.1098/rspb... a🧵 (1/10)

As usual, many questions remain, including how capuchins 🐒are aware of the tidal cycle. However, this study highlights the importance of the ocean as a rich, yet challenging, resource for island-living species and the role tool use may play in its efficient exploitation (9/9)

These findings show how tool use can permit niche expansion, and provide insight into hominin behavior. Archaeological evidence of tool use in coastal areas is rarely preserved, so studying living non-human primates is one way to gain understanding of our evolutionary past (8/9)

Tool-using 🔨 capuchins showed the strongest, most consistent coupling of coastal activity to the tidal cycles, in line with exploitation of tidal resources. Tool use may help capuchins process resources faster, and allows access to protected food 🦀(7/9) (photo Meredith Carlson)