Mysterious chimpanzee behaviour may be evidence of ‘sacred’ rituals [Video]

Laura Kehoe, Humboldt University of Berlin

I trampled clumsily through the dense undergrowth, attempting in vain to go a full five minutes without getting snarled in the thorns that threatened my every move. It was my first field mission in the savannahs of the Republic of Guinea. The aim was to record and understand a group of wild chimpanzees who had never been studied before. These chimps are not lucky enough to enjoy the comforts of a protected area, but instead carve out their existence in the patches of forests between farms and villages.

We paused at a clearing in the bush. I let out a sigh of relief that no thorns appeared to be within reach, but why had we stopped? I made my way to the front of the group to ask the chief of the village and our legendary guide, Mamadou Alioh Bah. He told me he had found something interesting – some innocuous markings on a tree trunk. Something that most of us wouldn’t have even noticed in the complex and messy environment of a savannah had stopped him in his tracks. Some in our group of six suggested that wild pigs had made these marks, while scratching up against the tree trunk, others suggested it was teenagers messing around.

But Alioh had a hunch – and when a man that can find a single fallen chimp hair on the forest floor and can spot chimps kilometres away with his naked eye better than you can (with expensive binoculars) as a hunch, you listen to that hunch. We set up a camera trap in the hope that whatever made these marks would come back and do it again, but this time we would catch it all on film.

A world first

Camera traps automatically start recording when any movement occurs in front of them. For this reason they are an ideal tool for recording wildlife doing its own thing without any disturbance. I made notes to return to the same spot in two weeks (as that’s roughly how long the batteries last) and we moved on, back into the wilderness.

Whenever you return to a camera trap there is always a sense of excitement in the air of the mysteries that it could hold – despite the fact that most of our videos consisted of branches swaying in strong winds or wandering farmers’ cows enthusiastically licking the camera lens, there is an uncontrollable anticipation that maybe something amazing has been captured.

What we saw on this camera was exhilarating – a large male chimp approaches our mystery tree and pauses for a second. He then quickly glances around, grabs a huge rock and flings it full force at the tree trunk.

Selection of stone throwing behaviour, from carefully placing stones inside hollow trunks to full-on hurling. Video credit: Kühl et al (2016)

Nothing like this had been seen before and it gave me goose bumps. Jane Goodall first discovered wild chimps using tools in the 1960s. Chimps use twigs, leaves, sticks and some groups even use spears in order to get food. Stones have also been used by chimps to crack open nuts and cut open large fruit. Occasionally, chimps throw rocks in displays of strength to establish their position in a community.

But what we discovered during our now-published study wasn’t a random, one-off event, it was a repeated activity with no clear link to gaining food or status – it could be a ritual. We searched the area and found many more sites where trees had similar markings and in many places piles of rocks had accumulated inside hollow tree trunks – reminiscent of the piles of rocks archaeologists have uncovered in human history.

Videos poured in. Other groups working in our project began searching for trees with tell-tale markings. We found the same mysterious behaviour in small pockets of Guinea Bissau, Liberia and Côte d’Ivoire but nothing east of this, despite searching across the entire chimp range from the western coasts of Guinea all the way to Tanzania.

Sacred trees

I spent many months in the field, along with many other researchers, trying to figure out what these chimps are up to. So far we have two main theories.
The behaviour could be part of a male display, where the loud bang made when a rock hits a hollow tree adds to the impressive nature of a display. This could be especially likely in areas where there are not many trees with large roots that chimps would normally drum on with their powerful hands and feet. If some trees produce an impressive bang, this could accompany or replace feet drumming in a display and trees with particularly good acoustics could become popular spots for revisits.

On the other hand, it could be more symbolic than that – and more reminiscent of our own past. Marking pathways and territories with signposts such as piles of rocks is an important step in human history. Figuring out where chimps’ territories are in relation to rock throwing sites could give us insights into whether this is the case here.

Even more intriguing than this, maybe we found the first evidence of chimpanzees creating a kind of shrine that could indicate sacred trees. Indigenous West African people have stone collections at “sacred” trees and such man-made stone collections are commonly observed across the world and look eerily similar to what we have discovered here.

Stone throwing – in action and on site. Top line: Adult male tossing, hurling and banging a stone. Bottom line: Stones accumulated in a hollow tree; typical stone throwing site; and stones in between large roots.
Kühl et al (2016), Author provided

A vanishing world

To unravel the mysteries of our closest living relatives, we must make space for them in the wild. In the Ivory Coast alone, chimpanzee populations have decreased by more than 90% in the past 17 years.

A devastating combination of increasing human numbers, habitat destruction, poaching and infectious disease severely endangers chimpanzees. Leading scientists warn us that, if nothing changes, chimps and other great apes will have only 30 years left in the wild. In the unprotected forests of Guinea, where we first discovered this enigmatic behaviour, rapid deforestation is rendering the area close to uninhabitable for the chimps that once lived and thrived there. Allowing chimpanzees in the wild to continue spiralling towards extinction will not only be a critical loss to biodiversity, but a tragic loss to our own heritage, too.

You can support chimps with your time, by instantly becoming a citizen scientist and spying on them at www.chimpandsee.org, and with your wallet by donating to the Wild Chimpanzee Foundation. Who knows what we might find next that could forever change our understanding of our closest relatives.

The ConversationLaura Kehoe, PhD researcher in wildlife conservation and land use, Humboldt University of Berlin

This article was originally published on The Conversation. Read the original article.

Featured Photo Credit:  Mark Linfield/Walt Disney Pictures, CC BY

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What clues does your dog’s spit hold for human mental health?

Elinor Karlsson, University of Massachusetts Medical School

Dogs were the first animals people domesticated, long before the earliest human civilizations appeared. Today, tens of thousands of years later, dogs have an unusually close relationship with us. They share our homes and steal our hearts – and have even evolved to love us back. Sadly, they also suffer from many of the same difficult-to-treat psychiatric and neurological diseases we do.


Beskow, in fine spirits.
Elinor Karlsson, CC BY-ND

I learned this firsthand about six years ago, when my sister Adria adopted Beskow, a beautiful, boisterous, black and white mutt. Beskow became my constant companion on my morning runs along the Charles River. Her joy in running was obvious to everyone we passed, and she kept me going mile after mile.

When not running, though, Beskow suffered from constant anxiety that left her stressed and unhappy – on edge around other dogs and prone to aggressive behavior. Beskow had trouble even playing outdoors, since she was compelled to attend to every sound and movement. Working one-on-one with skilled behaviorists and trainers helped immensely, but poor Beskow still never seemed able to relax. Eventually, Adria combined the intensive training with medication, which finally seemed to give Beskow some relief.

Beskow’s personality – her intelligence, her focus and her anxiety – was shaped not only by her own life experiences, but by thousands of years of evolution. Have you ever known a dog who would retrieve the same ball over and over again, for hours on end? Or just wouldn’t stay out of the water? Or wasn’t interested in balls, or water, but just wanted to follow her nose? These dogs are the result of hundreds of generations of artificial selection by human beings. By favoring useful behaviors when breeding dogs, we made the genetic changes responsible more common in their gene pool.

When a particular genetic change rapidly rises in prevalence in a population, it leaves a “signature of selection” that we can detect by sequencing the DNA of many individuals from the population. Essentially, around a selected gene, we find a region of the genome where one particular pattern of DNA – the variant linked to the favored version of the gene – is far more common than any of the alternative patterns. The stronger the selection, the bigger this region, and the easier it is to detect this signature of selection.

In dogs, genes shaping behaviors purposely bred by humans are marked with large signatures of selection. It’s a bit like evolution is shining a spotlight on parts of the dog genome and saying, “Look here for interesting stuff!” To figure out exactly how a particular gene influences a dog’s behavior or health, though, we need lots more information.

To try to unravel these connections, my colleagues and I are launching a new citizen science research project we’re calling Darwin’s Dogs. Together with animal behavior experts, we’ve put together a series of short surveys about everything from diet (does your dog eat grass?) to behavior (is your dog a foot sitter?) to personality (is your dog aloof or friendly?).

Any dog can participate in Darwin’s Dogs, including purebred dogs, mixed breed dogs, and mutts of no particular breed – our study’s participants will be very genetically diverse. We’re combining new DNA sequencing technology, which can give us much more genetic information from each dog, with powerful new analysis methods that can control for diverse ancestry. By including all dogs, we hope to be able to do much larger studies, and home in quickly on the important genes and genetic variants.

A beagle considers making the saliva donation.
Stephen Schaffner, CC BY-ND

Once an owner has filled out the survey, there’s a second, crucial step. We send an easy-to-use kit to collect a small dog saliva sample we can use for DNA analysis. There’s no cost, and we’ll share any information we find.

Our plan is to combine the genetic data from many dogs and look for changes in DNA that correlate with particular behaviors. It won’t be easy to match up DNA with an obsession with tennis balls, for instance. Behavior is a complex trait that relies on many genes. Simple Mendelian traits, like Beskow’s black and white coat, are controlled by a single gene which determines the observable characteristic. This kind of inherited trait is comparatively easy to map. Complex traits, on the other hand, may be shaped by tens or even hundreds of different genetic changes, each of which on its own only slightly alters the individual carrying it.

Adding to the complexity, environment often plays a big role. For example, Beskow may not have been as anxious if she’d lived with Adria from puppyhood, even though her genetics would be unchanged.


Darwin’s Dogs team member Jesse McClure extracts DNA from a sample.
Elinor Karlsson, CC BY-ND

To succeed, we need a lot of dogs to sign up. Initially, we’re aiming to enroll 5,000 dogs. If successful, we’ll keep growing. With bigger sample sizes, we’ll be able to tackle even more complex biological puzzles.

This is a huge effort, but could offer huge rewards. By figuring out how a genetic change leads to a change in behavior, we can decipher neural pathways involved in psychiatric and neurological diseases shared between people and dogs. We already know these include not just anxiety, but also PTSD, OCD, autism spectrum disorders, phobias, narcolepsia, epilepsy, dementia and Alzheimer’s disease.

Understanding the biology underlying a disease is the first step in developing more effective treatments – of both the canine and human variety. For example, genetic studies of narcolepsy in Doberman pinschers found the gene mutation causing the disease – but only in this one dog population. Researching the gene’s function, though, led to critical new insights into the molecular biology of sleep, and, eventually, to new treatment options for people suffering from this debilitating disease.

Darwin’s Dogs is investigating normal canine behaviors as well as diseases. We hypothesize that finding the small genetic changes that led to complex behaviors, like retrieving, or even personality characteristics, like playfulness, will help us figure out how brains work. We need this mechanistic understanding to design new, safe and more effective therapies for psychiatric diseases.


Beskow with one of her loving family members.
Adria Karlsson, CC BY-ND

And Beskow? Six years later, she is as wonderful as ever. While still anxious some of the time, the medication and training have paid off, and she enjoys her daily walks, training and playtime. She still gets very nervous around other dogs, but is a gentle, playful companion for my sister’s three young children.

We are now sequencing her genome. In the next few months, we should have our first glimpse into Beskow’s ancestry. We know she is a natural herder, so we’re curious to find out how much her genome matches up to herding breeds, and which genes are in that part of the genome.

Of course, we can’t figure out much from just one dog – if you are a dog owner, please enroll your dog today!

The Conversation

Elinor Karlsson, Assistant Professor of Bioinformatics and Integrative Biology, University of Massachusetts Medical School

This article was originally published on The Conversation. Read the original article.

Featured Photo Credit: John Haslam via flickr. CC BY 2.0

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Contribute to Science: Count Croaks

If you’re looking for a way that you can easily and satisfyingly contribute to scientific research without even having to spend a lot of time on it, then here’s a suggestion: count frog croaks.

We found an awesome article over on the Discover Magazine site that details the work that FrogWatch USA is doing to essentially crowdsource the measurement of frog species:

At dusk, Carolyn Rinaldi and her 14-year-old daughter sit silently on the shores of the lake at Wadsworth Falls State Park in Middletown, Conn. Then their ears go into overdrive. For three minutes they count the different grunts, gribbets, croaks and peeps emanating from frogs and toads resident in the wetlands.

They are just two of the volunteers that took part in FrogWatch USA during 2014, a citizen science program of the Association of Zoos and Aquariums (AZA). The name is somewhat of a misnomer. The program could be called FrogListen. Volunteers identify frogs by listening to their mating calls and indicating whether each was heard individually, in a group or in a full chorus.

Pretty cool that you can spend just three minutes to make a contribution to zoological science!

But why is researching the croaks of frogs important? See the next page for that answer…

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