On the island of Cayo Santiago, a few mile off the coast of jap Puerto Rico, the everyday relationship between people and different primates will get turned on its head. The 1,700 rhesus macaque monkeys (Macaca mulatta) residing on that island have free rein to maneuver round wherever and each time they please. People don’t. 

The Cayo macaque inhabitants got here to be in 1938 when primatologist and explorer Clarence Carpenter captured about 500 rhesus macaques in India. He and the monkeys sailed from Calcutta through Boston and New York to San Juan, and from there to Cayo Santiago, a 15-hectare island that had just lately been leased to the College of Tropical Medication on the College of Puerto Rico.

Lauren Brent started working with macaques on Cayo Santiago when her Ph.D. adviser prompt she think about happening to the island to take a look on the social dynamics of the monkeys. She instantly fell in love with every thing about her examine topics, the island, and the questions she was quickly addressing. “Cayo is a reasonably good examine system,” Brent says, “and the macaques  are such extremely social little dudes.” 

The extra buddies of buddies a feminine has, the extra offspring she produces.

The macaques on Cayo Santiago could be a handful to work with, partly due to the big measurement of their social teams. The monkeys are sometimes shifting, and even when not, the tattoos and ear-notch marks they’ve been tagged with could also be hidden by the bush or obscured by the angle between monkey and researcher. What meaning is that Brent and others working with macaques not solely have to keep up information on each monkey’s fur coloration and sample, eye options, and different traits that may assist distinguish the island’s residents from each other, however they need to additionally memorize that info and be capable to make split-second identifications amongst a gaggle that may quantity from just a few dozen to greater than 100 people.

Considered one of Brent’s early research targeted on females in two teams of macaques, one in all which had 58 females and the opposite about 20. She’d choose a macaque from her listing, discover it, comply with it, file what it was doing, after which choose one other monkey and repeat the method. Macaques groom each other typically, which serves not solely to take away parasites from the recipient however to decrease stress ranges in all events. Brent was particularly excited about grooming networks in females, in addition to networks primarily based on the proximity of people after they weren’t grooming. She wished to see what the networks appeared like and whether or not they modified over time.

In Body Image
THE TIES THAT BIND: Grooming is a crucial a part of social bonding for rhesus macaque monkeys. What number of buddies—and buddies of a pal—a monkey has determines her social standing. Photograph by BasPhoto / Shutterstock.

When Brent and her group appeared on the information from 2010 to 2017, they discovered that females who had sturdy friendships (tight connections) with their favored companions in a community had increased survival chances than different females. One other method for a feminine to extend her probabilities of survival was by way of weaker connections however with tons of grooming companions. It wasn’t solely the variety of buddies or the energy of particular favored friendships: Buddies of buddies additionally matter to feminine macaques. The extra buddies of buddies a feminine has, the extra offspring she produces.

By 2017, Brent and her colleagues—together with analysis assistants like Daniel Phillips, who was on Cayo Santiago on daily basis—had a deep understanding of the best way that the social networks of macaques on Cayo labored and what they meant. There was, after all, all the time extra to be taught, however a lot of that will probably contain filling within the particulars.

Then Hurricane Maria struck, devastating every thing in its path, together with the social networks the macaques had been rooted in.

When Hurricane Maria hit Cayo full drive in September 2017, Brent’s first ideas had been of the workers and analysis assistants, like Phillips, who stay there year-round. “[I] couldn’t get in contact as a result of all of the cell towers had been down. … Nobody heard from Danny for 2, possibly three weeks after Hurricane Maria. … It was fairly horrible.” Ultimately although, she discovered that Phillips and everybody on the mission had been secure. Then her ideas turned to the macaques and the island itself. “Once we noticed the satellite tv for pc tracker … I simply thought, ‘This discipline website is gone; these monkeys are all lifeless. … It’s a Class 4 hurricane, and these animals had been simply sitting on the bottom on this little chunk of rock in the course of the ocean.’”

They weren’t all lifeless, however Hurricane Maria turned the monkeys’ world the other way up and meant they wanted to reestablish their society, with all its intricate and sophisticated working elements. And rapidly. For Brent and her group, Hurricane Maria meant many issues, together with determining new methods to consider the consequences of large-scale pure disasters on social networks.

What occurred to the networks of the extremely social little macaque dudes and dudettes?

Greater than 60 p.c of the inexperienced vegetation on Cayo Santiago, together with plenty of the infrastructure that the Cayo group had put in place—together with feeders that provided the animals with a few of their meals, which they now wanted greater than ever—was decimated by Hurricane Maria. However not a single macaque was killed throughout the hurricane, and solely about 2 p.c of the animals died shortly thereafter, in all probability because of hunger.

Hurricane Maria had essentially altered the social networks of the monkeys.

“It’s fully unimaginable,” Brent says. “They’re not that massive, proper? And all their timber had been being blown over. It’s not like you possibly can maintain on to one thing.” At first Brent thought that possibly the macaques hid in a spot referred to as Glad Valley, which is partially protected against wind, however usually Glad Valley holds 50 macaques, and there was no method it might have supplied shelter for 1,700 monkeys. She and her group are working onerous to piece collectively what occurred, however nonetheless haven’t been in a position to determine how each single macaque survived the total brunt of a Class 4 hurricane.

About three months after Maria, Brent started pondering severely once more in regards to the dynamics of macaque social networks, primarily due to what she was listening to from Phillips and the opposite discipline assistants who had been again on the island. They’d inform her, “the monkeys are appearing bizarre,” and when Brent would ask how so, the on-the-ground group advised her that they appeared to be particularly pleasant towards each other. In early 2018, about 5 months after the hurricane, she went all the way down to verify for herself. The island was nonetheless reeling from Maria (as was most of Puerto Rico). “However once I received to Cayo,” Brent says, “I used to be like ‘Yeah, I see it.’ … They appear extra tolerant. … Monkeys I by no means anticipated to be cool simply sitting subsequent to one another.”

On the time, little or no was identified about how animals adjusted their social dynamics after full-scale pure catastrophes, and as terrible as the implications of Hurricane Maria had been for Puerto Rico, maybe, Brent thought, the catastrophe make clear these dynamics. When she and her group appeared extra deeply on the instantly way more pleasant macaques, what they discovered was that Maria had essentially altered the social networks of the monkeys.

For one, after they in contrast the grooming and proximity networks in two teams of macaques throughout the three years previous to Maria versus the one 12 months instantly after the hurricane, the info confirmed the anecdotal observations in regards to the monkeys being nicer to one another: Macaques had been 4 instances as more likely to be discovered shut to 1 one other after the hurricane, and so they had been 50 p.c extra more likely to groom each other. What’s extra, monkeys who groomed least and had spent the least time close to others earlier than Maria had been those who confirmed the best enhance in these behaviors after the hurricane.

Focusing their evaluation on grooming conduct, Brent and her colleagues thought that the adjustments in community construction is perhaps because of both a rise within the variety of companions or a rise in time spent with particular companions. Or maybe a bit of every. What they discovered was that post-Maria, macaques had extra social companions, however the common energy of a grooming relationship with a companion had not modified. The monkeys had shaped extra friendships of their community, not strengthened already current ones: Maria had introduced the macaques in a gaggle nearer collectively, with further grooming companions buffering them from the devastating results that the hurricane left in its path.

And once more, buddies of buddies mattered: Monkeys took the trail of least resistance in forming new relationships. If monkey 1 had been in a grooming relationship with monkey 2 earlier than Maria, it was extra more likely to enter a grooming relationship with one in all monkey 2’s grooming companions after the storm. Catastrophe, within the type of Maria, had introduced the monkeys nearer to 1 one other, and social community evaluation confirmed how.

Learn Lee Alan Dugatkin’s “3 Best Revelations” whereas writing his new e-book right here.

Reprinted with permission from The Properly-Related Animal: Social Networks and the Wondrous Complexity of Animal Societies by Lee Alan Dugatkin, printed by The College of Chicago Press. © 2024 by Lee Alan Dugatkin. All rights reserved.

Lead picture: Dmitry Strizhakov / Shutterstock


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