Nav: Home

Wild monkeys use loud calls to assess the relative strength of rivals

June 21, 2017

ANN ARBOR--Gelada males--a close relative to baboons--pay attention to the loud calls of a rival to gain information about his relative fighting ability compared to themselves, a new study indicated.

Researchers at the University of Michigan, Georgia State University and Princeton University found evidence that gelada males decide to escalate contests with their opponents based on their own condition relative to the condition of their opponent.

They appear to do this by using the acoustic quality of the loud calls of their rivals--long-distance vocalizations that carry honest information about the fighting ability of the caller.

There has been much debate on specifically how animals make competitive decisions during contests. Game theoretical models predict that animals should assess an opponent's condition relative to their own condition prior to engaging in combat to avoid costly fights they are unlikely to win, a strategy known as mutual assessment.

Despite the benefits of such mutual comparisons ("I am stronger than him"), remarkably few studies have been able to reject much simpler assessment strategies such as self-assessment ("I am strong and should fight") and opponent-only assessment ("he is strong and so I should not fight").

Researchers say one approach for distinguishing these strategies is to use animal displays (rather than aggressive contests) to examine how animals make informed decisions about rivals.

"Particularly for quality signals that contain honest information on the condition of its bearer, signals used in animal displays offer an ideal situation for examining mutual assessment because they are low cost and allow for experimental manipulation," said Marcela Benítez, a postdoctoral research associate at Georgia State University and the study's lead author.

In geladas, harem-holding "leader" males engage in loud call displays to deter challenges from "bachelor" males, who must compete with leaders to gain reproductive access to females. Supporting a mutual assessment strategy, gelada males responded to loud calls of different quality (in both playback experiments as well as in natural observations) according to attributes of themselves and their opponent.

"Previous studies in wild primates have shown that they use mutual assessment, but this was between animals that knew one other," said Jacinta Beehner, U-M associate professor of psychology and anthropology. "They see Kevin and they remember that they beat him in a previous fight. The novelty of our finding is that we have shown that primates can do this even for completely unfamiliar individuals--using signals."

Although primates routinely classify others relative to themselves using individual attributes, this represents some of the first direct evidence for mutual assessment in primate signaling contests, Benítez said.
-end-
The study's other co-authors include David Pappano, a postdoctoral research fellow at Princeton University, and Thore Bergman, U-M assistant professor of psychology and ecology and evolutionary biology.

The findings appear in Nature Scientific Reports.

University of Michigan

Related Primates Articles:

Research bias may leave some primates at risk
Recent primate research has had a heavy focus on a few charismatic species and nationally protected parks and forests, leaving some lesser known primates and their habitats at risk, according researchers at The University of Texas at Austin and Santa Clara University.
Showy primates have smaller testicles
Well-adorned or well-endowed -- but not both. Evolutionary biologists at the University of Zurich have for the first time demonstrated that male primates either have large testicles or showy ornaments.
Short birth intervals associated with higher offspring mortality in primates
Shorter intervals between primate births are associated with higher mortality rates in offspring, finds a new study of macaque monkeys.
HIV vaccine protects non-human primates from infection
New research shows that an experimental HIV vaccine strategy works in non-human primates.
Oldest-known ancestor of modern primates may have come from North America, not Asia
A new fossil analysis suggests the earliest-known ancestor of modern primates may have come from North America, not Asia, as previously thought.
Three previously unknown ancient primates identified
Biological anthropologists from The University of Texas at Austin have described three new species of fossil primates that were previously unknown to science.
Primates adjust grooming to their social environment
Researcher of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, show that wild chimpanzees and sooty mangabeys, two primate species who live in complex social groups, choose their grooming partners based on a variety of criteria, including their social relationship with them and their potential partner's dominance rank.
Fossils show ancient primates had grooming claws as well as nails
Humans and other primates are outliers among mammals for having nails instead of claws.
Primates in peril
International experts call for immediate action to protect endangered primate species.
Evolving sets of gene regulators explain some of our differences from other primates
Today, biologists add an important discovery to a growing body of data explaining why we're different from chimps and other primate relatives, despite the remarkable similarity of our genes.
More Primates News and Primates Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Teaching For Better Humans 2.0
More than test scores or good grades–what do kids need for the future? This hour, TED speakers explore how to help children grow into better humans, both during and after this time of crisis. Guests include educators Richard Culatta and Liz Kleinrock, psychologist Thomas Curran, and writer Jacqueline Woodson.
Now Playing: Science for the People

#556 The Power of Friendship
It's 2020 and times are tough. Maybe some of us are learning about social distancing the hard way. Maybe we just are all a little anxious. No matter what, we could probably use a friend. But what is a friend, exactly? And why do we need them so much? This week host Bethany Brookshire speaks with Lydia Denworth, author of the new book "Friendship: The Evolution, Biology, and Extraordinary Power of Life's Fundamental Bond". This episode is hosted by Bethany Brookshire, science writer from Science News.
Now Playing: Radiolab

Space
One of the most consistent questions we get at the show is from parents who want to know which episodes are kid-friendly and which aren't. So today, we're releasing a separate feed, Radiolab for Kids. To kick it off, we're rerunning an all-time favorite episode: Space. In the 60's, space exploration was an American obsession. This hour, we chart the path from romance to increasing cynicism. We begin with Ann Druyan, widow of Carl Sagan, with a story about the Voyager expedition, true love, and a golden record that travels through space. And astrophysicist Neil de Grasse Tyson explains the Coepernican Principle, and just how insignificant we are. Support Radiolab today at Radiolab.org/donate.