First report of “referential gesturing” in any animal other than humans

November 25, 2022 • 9:15 am

Here’s a short new paper from Proc. Nat. Acad. Sci. that, in fact, reports just a single gesture of one chimpanzee towards another. Was that worth a whole paper? Well, it appears to document the first example of “referential gesturing” in any animal other than humans.

What is a “referential gesture”? It’s a gesture that one individual could make to call attention of another individual to something, usually involving an object, an action, or a third party. (This is how humans use such gestures.) Pointing is one of these actions (you all know that when you point at something to a dog or cat, they look at your hand, not what you’re pointing at!).

In this case, one chimp held out a leaf to another chimp, and when the second chimp didn’t respond, the leaf-holder moved it towards the other’s face to call more attention to it.  Click on the screenshot below to see the paper, which has free access, and you can find the pdf here.

The behavior is connected with the way chimps groom themselves to get rid of parasites and keep themselves clean. Sometimes they also appear to groom leaves—for reasons unknown.  I’ll reproduce the report of the one gesture involving a chimp who was grooming a leaf.

We recorded an instance of a referential showing gesture between conspecifics in the context of leaf grooming in the Ngogo chimpanzee community, Kibale National Park, Uganda that seems to be produced declaratively. During self-grooming or social grooming, groomers occasionally pluck leaves that they manipulate with their fingers and mouths as if grooming them while also peering closely at them. They may be inspecting ectoparasites (e.g., ticks) they have placed on the leaves, but the function of leaf grooming remains unexplored in this community. The event described here involved a mother/adult daughter dyad. Adult female Fiona was sitting next to her mother Sutherland, whom she had been grooming. Fiona plucked a leaf from a small sapling and started leaf grooming. Sutherland’s attention was focused elsewhere while Fiona did this (Fig. 1 and Video S1), and after grooming the leaf for several seconds, Fiona held it out toward Sutherland. She repositioned her arm when the initial holdout did not elicit a response (Fig. 1). Once Sutherland attended to the leaf by fully orienting her eyes and head toward it, Fiona retracted it and continued leaf grooming.

It’s already known that chimps (and other species) use gestures to indicate what they want from others, like food or grooming, and here’s a video of such gestures:

But these aren’t referential gestures showing something to another chimp just to get its attention. As we’ll see shortly, Fiona apparently wasn’t offering the leaf to her mother to say, “here’s something for you to eat” or “here’s something we can eat”, but, according to the authors, the gesture was meant to get Sutherland’s attention, meaning roughly, “Have a look at this.” Fortunately, the gesture was filmed by the researchers, and here it is. Note how Fiona moves the leaf around until the object has Sutherland’s full attention.

The authors dissect this gesture to show that it’s truly referential:

The movements of this behavior are in line with the definition of showing or “holdouts” in human infant literature. Using the operational definitions of the most recent research on infant showing and giving, this gesture would be coded at least as an incipient show and potentially, as a fully formed conventional show. Incipient gestures are those that are plausibly part of the developmental trajectory toward the emergence of the conventional gesture form. Moreover, Fiona showed persistence with her gesturing (indicative of intentional signaling) (12), moving the leaf closer to Sutherland and more into her line of sight until Sutherland clearly adjusted her head to follow the movement of the leaf. Although Sutherland dropped her gaze to the leaf when Fiona first extended her arm, this may not have been clear from Fiona’s perspective, and head direction could have been a more reliable indicator for her. Once Sutherland had clearly seen the leaf, Fiona ceased gesturing, suggesting that the goal of Fiona’s gesturing behavior was simply to get Sutherland to attend to the leaf.

However, there are two alternative explanations for the gesture, all of which the authors find implausible (my paraphrasing):

1). Fiona was trying to share the leaf (and/or any parasites on it) with her mother as food. This seems unlikely because Fiona did not surrender the leaf to her mother. Further, chimps at Ngogo don’t eat this species of leaf. In sixty-six other observations of chimps grooming leaves near other chimps, there were no cases in which the nearby chimp took or ate any part of the leaf.

2.) Fiona’s leaf play was meant to induce some other “dyadic social activity” like grooming or playing. But chimps already show, as we see in the first video, different gestures to initiate these activities, and Fiona’s display gesture was different from these. And in 58 other observations of leaf grooming involving 30 chimps, only 5 such behavior—none showing “declarative referential gesturing”—produced immediate social grooming or play. This is the case even though three quarters of all leaf grooming events got the attention of other chimps (this was absent in the one above, making Fiona produce the referential gesture). The authors conclude:

Overall, there were no consistent differences between the leaf groomer’s behavior before and after leaf grooming, with social behaviors (social grooming, play) being more frequent before than after. This indicates that leaf grooming is not reliably used imperatively to elicit grooming or play from a partner, making it unlikely that Fiona gestured to request such an outcome.

The upshot: In my view, Fiona was indeed calling attention to the leaf (as the author say, Fiona was “sharing attention for sharing’s sake”), though we don’t know why. The fact that this is the first time such a gesture has been observed despite chimps being observed for decades AG (“after Goodall”) also suggests that referential gesturing is not common in this species. Perhaps it occurs only under very special and specific conditions, but we’ll need a lot more observations to reach this conclusion.

However, if we do find that referential gesturing in chimps is part of their behavioral repertoire, it leads to one inference, an inference that was the subject of Darwin’s book The Expression of the Emotions in Man and Animals (1872). Darwin found (or thought he found) similarities in how humans and other species express emotions, leading him to conclude, as part of his Big Game Plan, that our emotional expressions evolve from precursors present in our common ancestors with other species, and that other living species have inherited expressions resembling ours from those ancestors.

In this case, it’s not really the expression of an emotion that Fiona shared with humans, but a referential gesture. But the implication is the same. As the authors say, the analogy to human behavior is critical here:

Several aspects of the Fiona–Sutherland interaction provide hints as to where such future research may find further examples of showing and other protodeclarative gestures in one of our closest living relatives. . . Additionally, Fiona was interacting with her mother, with whom she shared a close social bond. Our observation suggests that in highly specific social conditions, wild chimpanzees, like humans, may be motivated to communicate cooperatively and share interest and attention simply for the sake of sharing. If so, this raises the question of whether differences between humans and chimpanzees in the ability to engage in cooperative communication are quantitative rather than qualitative, with ramifications for our understanding of the evolution of human social cognition.

I presume, though, that animals like cats and dogs could be trained to respond to referential gestures. (They’re already trained to make them to humans, like pointer dogs assuming a stance pointing to human prey.) Has anybody trained of observed their pets respond to a referential gesture, like looking at something you’re pointing at rather than at your hand?

Readers’ wildlife photos

October 18, 2022 • 8:00 am

Today’s batch of bird photos, plus a primate and a stanchion, comes from Bernie Grossman, whose notes are indented. Click on the photos to enlarge them:

We took a guided tour in 2014 to Japan in winter to see resident and migrant birds, particularly the cranes. We traveled first to the area called the Japanese Alps, which is an east -west band north of Tokyo. The famous Snow Monkeys are found here (Tourist Trap). Then we went to the southernmost island (Kyushu) and the city, Kagoshima, where the Hooded and White-naped Cranes winter. The last stop was Hokkaido, which was having its worst winter in years. Most of the island except the eastern coast was blocked. The best birds here were the Red-crowned Cranes and White-tailed and Steller’s Sea Eagles. We missed the Blakiston’s Fish Owl, the world’s largest owl.

Varied Tit (Poecile varius varius):

Eurasian Nuthatch (Sitta europaeca amurensis)  This taxon is found in the Japanese Alps and south:

Japanese Macaque (Macaca fuscata)  Also accompanied by a similarly furred member of genus Homo. The apes bath in artificial pools fed by nearby hot spring. The pools are located in a national park and required a long walk along an icy road:

Hooded Crane  (Grus monacha)  These and the next crane species migrate into southern Kyushu for the winter and feed in large numbers in agricultural fields. The local government established a crane feeding center where grain and corn is spread. This attracts thousands of cranes which are viewed from the visitors’ center:

White-naped Crane  (Grus vipio)  This species was the less abundant of the two at the center. Also present were three Sandhill Cranes (Grus canadensis) and two Common Cranes (Grus grus):

Japanese White-eye (Zosterops japonicus)  We were surprised to see fruit trees in bloom is southern Kyushu in February. The White-eye was photographed in a flowering hedge in a farming area:

Red-crowned Crane (Grus japonensis)  This is the national bird of Japan and is found in numbers near Kushiro in Hokkaido. They are large, graceful birds which we saw mostly at feeding stations where grain was spread on the snow. We saw others feeding in streams, etc. There is a famous bridge over a small stream that attracts large numbers of photographers with big 600mm prime lenses and other kit.  The government built a second, parallel bridge strictly for photographers and safety. If it is cold enough (<20F), a fog forms above the warm water. The cameras have remote triggering and fast frame settings, so when a crane emerges from the mist and/or does its dance, the cameras are fired. It sounds like a whole machine gun squad shooting. I asked one guy how much time it takes to process all the pictures. He responded, “Who processes!” On a second trip five years later taken in the spring, we saw a few of the cranes in Hokkaido including a pair with two chicks:

Hawfinch (Coccothraustes coccothraustus)  Photographed in snowy woods in the northeast peninsula of Hokkaido:

Brown-eared Bulbul (Hypispetes amaurotis amaurotis)  The only bulbul in Japan and fairly widespread:

Ural Owl (Strix uralensis)  A winter resident. This shot required a slog down a hill through deep snow to a tree with a big hole in the trunk. The owl  was calmly sunning itself and giving great views:

White-tailed Eagle  (Haliaeectus albicilla)  While this species can be found in the whole of northern Eurasia, they are concentrated on the Notsuke Peninsula in northeastern. Hokkaido. This is a cold, windswept point of land used mostly by commercial fishermen. We found it empty and snow covered. These eagles were perched along the shore:

Steller’s Sea-eagle  (Heliaeetus pelagicus)  This is the wold’s largest eagle and is usually found along the northeastern edge of Asia (Manchuria and Russia). Some move south to Hokkaido in the winter. One was sitting on a power pole along the Notsuke road. We were able to approach fairly closely by very slowly walking toward it. It was huge with a magnificent beak:

Eurasian Jay  (Garrulus glandarius brandtii)  This taxon was seen in Hokkaido and has a dark eye. Another taxon, japonicus, has a pale eye. The species is seen across Eurasia.

Bunny Stanchion  (Stanchion stanchicus bunni)  These stanchions as well as others shaped like monkeys, raccoons, and others were seen all around Japan. They usually supported galvanized pipe.

Readers’ wildlife photos

August 10, 2022 • 8:00 am

Today’s batch of photos come from Costa Rica, and were taken by Fred Dyer. His notes and captions are indented, and you can enlarge the photos by clicking on them:

Some Photos from Costa Rica 10-20 July 2022

I recently traveled around Costa Rica with my family for about 10 days prior to a conference.  Our itinerary included a day in the capital city of San Jose, a couple of days in the mountainous/volcanic region northwest of San Jose, and then several days along the central Pacific coast. Costa Rica is an amazing place, geologically, biologically, and culturally.  Almost everything you see is beautiful.  These photographs are a grab bag that don’t have much in common except that they were the ones that came out looking pretty good.

First, a few photos from near the town of La Fortuna and the Arenal volcano, including from a guided walk through a private rainforest reserve.  On the walk we saw toucans, howler monkeys, army ants, leaf cutter ants and morpho butterflies, plus these (I welcome corrections on the species identifications):

Python Millipede (Nyssodesmus python). This one was about 8 cm long.

Eyelash pit viper (Bothriechis schlegelii), which gets its common name from the hairlike scales protruding over each eye. It is a small snake, but one of the most dangerous in Costa Rica.

Stingless bees (Apidae : Apinae : Meloponini: Perhaps Tetragonisca sp?) guarding their nest entrance tube. There are something like 60 species of stingless bees in Costa Rica. These guard bees were 4-5 mm in length. The colony is enclosed in a cavity so its size is hard to know, but some species have several thousand workers in each colony.

View of the Arenal Volcano from the north. This volcano began erupting violently in 1968 and continued until 2010. Vapors still issue from the peak, although this picture shows only clouds:

Golden-bellied Flycatchers (Myiodynastes hemichrysus) perching behind our rental house in El Castillo (south of Arenal):

From La Fortuna/Arenal we drove toward the Pacific coast, and stopped at a wildlife rescue center (Santuario Las Palmas) near the town of Cañas in Guanacaste province.  The enclosures held rescued jaguars, pumas, ocelots, monkeys and several species of parrots.  We also spotted some wildlife outside the enclosures:

Automeris metzli caterpillar (larva of a Saturniid moth—in the same genus as the North American Io moth). This beauty was about 10 cm long

Same caterpillar after it moved onto a twig. The urticating spines supposedly produce a nasty venom. Here is what an adult Automeris metzli looks like. Whereas the larva relies upon aposematic signals and spines to deter potential predators from attacking, the adult is cryptic in the resting position, and exposes eyespots as a startle cue.
You can read more on Automeris here.

Black Ctenosaur (Ctenosaura similis), also known as the black spiny-tailed iguana, grazing at Las Palmas. These large lizards are extremely common along the Pacific slope:

On the coast our home base was the resort town of Manuel Antonio, which is next to the wonderful Manuel Antonio National Park.

Ponies for the tourists:

In Manuel Antonio National Park, stingless bees (species unknown) on a Heliconia sp.:

Also in the park, Panamanian white-faced capuchins (Capuchin imitator) engaged in a groomfest, while baby looks on. These were part of a larger group of a dozen or so monkeys in a grove of trees about 3 meters above the ground:

Same monkeys, still grooming.

Back in town, a Groove-billed Ani (Crotophaga sulcirostris) with some insect yumminess for its nestling(s). These are large birds (a bit bigger than a grackle) in the cuckoo family.  They often nest communally but this seemed to be a single mated pair.  The nest was in a tree across the street from our rental house in Manuel Antonio. Pictures of the nestling(s) and the other parent didn’t come out so great.

Playa Hermosa, a black-sand beach about an hour north of Manuel Antonio. This is a destination for expert surfers, and the surf was really intense the day we were there.

American Crocodiles (Crocodylus acutus) basking next to the Tárcoles River below the “Crocodile Bridge.” This is a tourist attraction on the main coastal highway (Route 34). The travel guidebook said that there is a population of 2000 or more crocs in this river and the nearby Carara National Park. Crocodiles often rest with their mouths open to dissipate heat.

Readers’ wildlife photos

May 27, 2022 • 8:00 am

Don’t forget to send your photos in! There’s a prize! (You get to show them off to a lot of people).

Today’s batch comes from Daniel Shoskes, whose captions and IDs are indented. Click on the photos to enlarge them.

It’s been a few years since my last submission so I thought I would share a few photos from a recent trip to Belize. Brown Iguana, Toucan (the national bird of Belize), Howler monkeys, nurse sharks and a Roseate Spoonbill. [JAC: not in order, but I trust you won’t be confused.]


Readers’ wildlife photos

November 25, 2021 • 8:00 am

Today I’ll show my own “wildlife” photos just for fun, but keep sending yours in.  Click the pictures below to enlarge them.

Feeding wild cats at a nunnery in Mystras, Greece, 2002. I always carry a box of dry cat food in my backpack in places like this.

A rare bloom in Death Valley, California, 2005. I don’t know what the moth is, and I’m baffled about where the many pollinating insects come from in those very occasional wet years. They just appear from out of nowhere.

Me feeding a grape (with permission) to a ring-tailed lemur (Lemur catta) at the Duke Lemur Center, 2006. Note the baby clinging to its belly.

Another ringtail with child:

Sifakas (lemurs, Propithecus sp.):

Cepea nemoralis snails on a fencepost, Dorset, England, 2006. The riot of colors and banding in this species was subject to a lot of investigation when I was in college, but evolutionary geneticists still don’t have an explanation for why the variation persists:

A butterfly (I don’t know the species) in the garden at Thomas Hardy’s boyhood home, 2006:

Snail and fly near Clouds Hill (T. E. Lawrence’s cottage), Wareham, Dorset, 2006:

Gooseneck barnacle, a rare and expensive delicacy. Galicia, Spain, 2006:

The one above was found on the rocks at low tide. Here are some for sale in the market. You eat the meat underneath the leather skin. It’s very good.

Me feeding a Texas longhorn on David Hillis’s and Jim Bull’s Double Helix ranch outside Austin, 2007:

Groundhog (Marmota monax), Capitol grounds, Ottawa, Canada, 2007:

Greg Mayer’s pet common snapping turtle (Chelydra serpentina); I believe its name was “Snappy”), Kenosha, Wisconsin, 2008:

Butterfly and orchids (species unknown), Guatemala, 2009:

Statue dedicated to all the lab cats “sacrificed” in medical research. St. Petersburg, 2011:

Gulls, Lake Geneva, Switzerland, 2011

Trees in autumn, Switzerland 2011:

I have many more, and perhaps I’ll post some of them on another holiday (Chanukah, Christmas, and Coynezaa are coming up).

Readers’ wildlife photos

October 11, 2021 • 8:00 am

Please send in your good photos, as the tank is depleting faster than I’d like. Thanks.

Today we have a potpourri of photos from various readers and contributors. Their captions are indented, and you can enlarge the photos by clicking on them.

The first photo is by Jamie Blilie:

Winter plumage American Goldfinch (Spinus tristis) in the middle of a snowstorm.  Taken Dec 23, 2020, in a tree in our back yard, Minnesota.  We have many winter resident birds.  We have many feeders in our yard to help them through the winter (we feed much less in summer).

Reader Bryan found slugs making The Beast with Two Backs in Middlesex County, Massachusetts:

I saw this the other day (cool fall day in N. hemisphere).Reading a bit tells me it is gastropod copulation involving Spanish slugs, Arion vulgaris.  It was satisfying to know I stumbled (figuratively!) on a fascinating biology topic.

From Thomas Czarny, sent September 8:

Yesterday an epic line storm coming across Lake Michigan slammed into the Traverse City, MI area causing widespread wind, rain and hail damage.  Below is a sequence of photos of the advancing front as it swept inland from the Sleeping Bear Dunes National Shoreline.  Only the first one is my photo, the rest are from friends and other local sources.  At last report the Cherry Hut in Beulah is still intact.🍒

From Divy:

 We went to the Ubud Monkey Forest in Bali a couple of years ago.  If I remember correctly, this was a tourist conservation, owned by the local community.  There were several Hindu temples within the forest which were closed-off to the public; only the monkeys could enter. I believe these were Balinese long-tailed macaques (Macaca fascicularis).

Reader Reese sent in some photos he got from a friend who tends ducks in a pond by his house. I’m going to show these photos to Honey.

From my friend John Williamson who feeds ducks and other wildlife on a resaca in Brownsville, Texas.  I hope some of your pals are planning on wintering there.  His house backs up to Town Resaca (which appears to be a body of water that goes nowhere) in Brownsville, not far from the Gladys Porter Zoo.  I attach a few more photos so your ducks have a better idea of the winter spa awaiting them:

Note that he has built a duck-feeding platform (and also a Buddha platform).

Nutria (rodents also known as coypu; Myocaster coypus) also appreciate the duck corn.  There also seem to be duck pellets:

Readers’ wildlife photos

September 6, 2021 • 8:00 am

Today I’m showing a melange of photos contributed by readers who sent in just one or a few photos. Their captions are indented, and you can enlarge the photos by clicking on them.

Here’s a Canada Goose family (Branta canadensis) from Laurie Berg:

From Joe Dickinson:

These bats are spectacled flying foxes (Pteropus conspicillatus) seen by the thousands in downtown Cairns, Australia.

This monkey is certainly in the genus Ateles, likely Ateles chamek, the Peruvian spider monkey.

From Ken Phelps:

Caught some early morning light on an Arbutus tree whose peeling bark seems to be sending out a message. About what I can’t say, but they have been stressed by fungal organisms and warmer, drier weather in recent years. Ours seem to be doing pretty well, but we do see a lot of mangy looking trees in the area.

And some travel photos by Jean Greenberg:

We went to Tibet in the summer of 2009. It was when Michael Jackson died, because we learned about it while we were there. We traveled with my former postdoc and her husband, who was all about taking fancy pictures and connecting with people everywhere even though he could not speak the language. To get pictures of people, he often posed with them. The pictures below, except for a few, were taken by my late husband Adam Driks.


A yak with a fancy saddle:

Nomad lady:

A sheltered prayer wheel:

Readers’ wildlife photos

June 25, 2021 • 8:15 am

Thanks to a slew of readers, we have enough photos for several potpourri features, but do send in your long-form contributions when you can. Thanks!

We’ll have two contributors today, the first being physicist and origami master Robert Lang from Altadena, California.  Like all photos below, the captions are indented and you can enlarge the pictures by clicking on them:

I saw today you asked for a few topping-off photos, so I thought I’d send the below, from recent mornings’ hikes.

First, we have the common American Crow (Corvus brachyrhynchos). A group of these started hanging around my place for a few days; I suspect, coincidentally (and sadly) with the disappearance of the contents of a mourning dove nest I’d been monitoring in a nook above the back porch.

And now for a few hiking photos. The Whipple Yucca (Hesperoyucca whipplei) blooms in June, studding the mountains with cream-colored candlesticks. They bloom only once, then die, but there’s plenty of slightly younger ones to fill in each year.

Darkling Beetles (Eleodes sp., possibly armata) are fairly common around here. When disturbed, they stick their butt up in the air. This one was just going about its business.

And last, a new and uncommon critter: the Southern California legless lizard (Anniella stebbinsi). At first glance I thought it was an earthworm from its size and shape and the way it was twitching from side to side, but given the heat and dryness, any earthworm wouldn’t have been long for the world! A closer look revealed its reptilian scales, and then its stumpy tail and lizard-like head helped narrow it down.

Here are two photos by regular Joe Dickinson. He didn’t supply the IDs, but it’s clear that one is a flying fox and the other a primate. I’ll add the IDs when he responds to my query. In the meantime, you can guess!

Interspecies primate love

May 26, 2021 • 2:00 pm

This is an ineffably sweet video from The Dodo, showing a gorilla mother, with her own young baby, fascinated by a human relative with her human baby on the other side of the glass. Four minutes in the video, the gorilla mom fetches and displays her own infant to the human. I cannot help but feel, anthropomorphic though it may be, that this is a moment of maternal bonding.

Here’s The Dodo‘s text:

Sometimes, a difference really isn’t a difference at all — especially when it comes to the bonds of a mother’s love.

Just ask Emmelina Austin and her new friend, this gorilla mom named Kiki.

The other day, Austin and her family decided to pay a visit to the Franklin Park Zoo in Boston with their 1-month-old son, Canyon.

It was there, while stopping by the gorilla enclosure, that the Austins spotted Kiki in the company of her own child, a 7-month-old baby gorilla named Pablo.

“My wife mentioned that she felt like she could understand their bond and could see how much she cared for Pablo, since she is a mother now herself,” Michael Austin, Canyon’s dad, told The Dodo.

“My wife held up our son to show to Kiki, who was on the other side of the enclosure … then Kiki grabbed Pablo and put him on her leg to carry him over to us.”

For the next several minutes, Emmelina and Kiki sat with their babies inches apart — bonding as mothers, despite the barrier between them, in a language as old as time:

“[Kiki] was talking to us with her hands,” Michael said. “Pablo even pushed his face up to the glass at one point and they watched him, noses touching, together. My wife and I both had tears in our eyes.”

It was a moment the young family won’t soon forget.

“It was one of the most amazing experiences,” Michael said. “Such an incredible memory to share with our son someday!”

Do watch the whole thing:

The naked ape family (photo by Michael Austin):

Readers’ wildlife photos

December 24, 2020 • 8:00 am

I think we’ll take a break from the photos tomorrow, as people will be celebrating and the photographer’s work may be overlooked. But do send your photos in!

Today’s photos were taken in Tanzania by Daniel Shoskes. His commentary is indented; click on the photos to enlarge them.

These should be self explanatory. The baby wildebeest was a few minutes old. It’s amazing to me how a giraffe can bend down so low to drink and then raise up their head to full height and not stroke out.