Primate Locomotion

We all know that one thing that sets us apart from other primates is that as adults, the majority of our locomotion is upright on two legs.  The scientific term for this is "obligate bipedalism" -- obligate here meaning that our anatomy does not allow us to walk any other way, and bipedal meaning on two (bi) feet (ped).  We may be special in walking upright, but that definitely doesn't mean that all other primates move about in the same way!  Let's take a look at how some of the other primates we've seen on Chimp & See get around.  For each species below, we'll look at their most common form of locomotion.

Starting with the primates most distantly related to us, we have galagos and pottos.  These are both small, nocturnal, arboreal, solitary primates, but they have surprisingly different modes of locomotion.  Pottos generally move by climbing slowly and deliberately, using their arms and legs about equally.  Most galagos (though it differs somewhat by species) are great leapers, sometimes traveling more than 2.5 meters (8.2 ft) in one jump!  They get most of their power from strong legs, which are much longer than their arms.  Since they're a bit hard to see in the black and white videos, here are a couple pictures to help familiarize you with these primates.

 

 Potto photo credit: Josh More                                                Galago photo credit: Wegmann

This video shows a clip of a slow-moving potto, then a couple leaping galagos.

Original clips: ACP00058om, ACP000cb2b

Before we look at the next clips, a very quick side lesson in skeletal anatomy.  When humans walk, they contact the ground with the heel bone: the calcaneus, shown in yellow in the image on the left below.  Some animals, like your dog or cat, only contact the ground with the bones that make up the toes.  Their heel bone, shown again in yellow in the wolf skeleton on the right, remains off the ground throughout their stride.

 

Human foot image credit: DBCLS                                                                                   Wolf image credit: Royal Natural History Volume 1


That sets the stage for the the African monkeys.  We have seen over a dozen different species of monkey, but we mostly see them using one of two subtly different types of terrestrial locomotion.  The first is called palmigrade quadrupedalism -- palmigrade meaning that they place the whole palm on the ground as they walk, and quadrupedal meaning on four (quad) feet (ped).  This is equivalent to the way humans place their whole foot on the ground.  The other type of locomotion we see in African monkeys on Chimp & See is called digitigrade quadrupedalism, where digitigrade means on the fingers/toes (digits).  This is equivalent to the way your dog or cat would walk, without touching the heel bone to the ground and instead supporting the weight on the fingers/toes.  At first glance, both of these types of locomotion look quite similar in C&S clips, but when you look closely, you can see how the wrist/ankle are in different positions, either contacting the ground, or held above it.

The first clip in this video is a green monkey walking palmigrade.  With each step, the whole hand and foot contact the ground.  The second clip shows a patas monkey walking digitigrade.  Like your cat or dog, the palm and heel remain raised off the ground as the monkey walks.

Original clips: ACP0006fnm, ACP000638c

Last we have the chimps and gorillas.  As adults, both gorillas and chimps knuckle-walk for the majority of their locomotion, but there is some debate as to whether this evolved independently in each lineage, or just once in an ancestor.  Either way, they both curl their fingers under, contacting the ground with the knuckles.  This is actually a behavior that has to develop in infant chimps and gorillas.  When they take their first quadrupedal steps, they walk palmigrade, just like the green monkey in the previous video.  Gorillas make the switch to knuckle-walking earlier than chimps do: at 10 months of age about 70% of quadrupedalism is knuckle-walking in gorillas, while only about 20% is knuckle-walking in chimps.

This video shows two adult chimps knuckle-walking, followed by an infant chimp taking a few palmigrade steps.  Last, a handsome silverback gorilla knuckle-walks past the camera.

Original clips: ACP0004pfv, ACP0004pfx, ACP00078z2, ACP00078z3, ACP000bxr0

As you can see, we've been able to watch quite a variety of primates on Chimp & See, moving about in many different ways!  Join us and see if you can spot some of them yourself!


References:
Off, Eileen C., and Daniel L. Gebo. "Galago locomotion in Kibale National Park, Uganda." American journal of primatology 66.2 (2005): 189-195.
Butynski, Thomas M., and Yvonne A. de Jong. "Natural history of the Somali lesser galago (Galago gallarum)." Journal of East African Natural History 93.1 (2004): 23-38.
Schaefer, Melissa S., and Leanne T. Nash. "Limb growth in captive Galago senegalensis: getting in shape to be an adult." American journal of primatology 69.1 (2007): 104-112.
Gebo, Daniel L. "Locomotor diversity in prosimian primates." American Journal of Primatology 13.3 (1987): 271-281.
Patel, Biren A. "Functional morphology of cercopithecoid primate metacarpals." Journal of human evolution 58.4 (2010): 320-337.
Isbell, Lynne A., et al. "Locomotor activity differences between sympatric patas monkeys (Erythrocebus patas) and vervet monkeys (Cercopithecus aethiops): implications for the evolution of long hindlimb length in Homo." American Journal of Physical Anthropology 105.2 (1998): 199-207.
Kivell, Tracy L., and Daniel Schmitt. "Independent evolution of knuckle-walking in African apes shows that humans did not evolve from a knuckle-walking ancestor." Proceedings of the National Academy of Sciences 106.34 (2009): 14241-14246.
Doran, D. M. "Ontogeny of locomotion in mountain gorillas and chimpanzees." Journal of Human Evolution 32.4 (1997): 323-344.

Field Update: Camp in Sierra Leone

Kyle Yurkiw, temporary research site manager for the PanAfrican Programme: The Cultured Chimpanzee at one of our sites in Sierra Leone (and expert beard grower), gives a small tour of his home for the next 13 or so months!

Chimp ID: Pearl and her infant Flocke

During the year, I will introduce individual chimps and show how we came up with a specific match. Following is irregular series, you can learn what to look for when comparing two chimps, how to deal with different camera angles and black-and-white footage, and how hard it is to identify infants and often even juveniles. 

Today’s Chimp ID has been very easy matching as we almost immediately recognized this chimpanzee’s most characteristic trait. It all started with a discussion about a distant “pale female” with a dependent infant, mostly carried dorsally (i.e., on the back).

Chimpanzees are born with light-colored faces that darken with age unlike gorillas and bonobos who are born with their dark-colored faces. Depending on subspecies and region, we expect infants and juveniles to have light-colored faces (sometimes with darker eye-masks already early in life), but it is seen less often in adults. As we observed this “pale female” with an infant, this suggested that she was rather an adult. So, her light-colored face was unusual and something to look for.

The "pale" face

With the first close-up, it became clearer that the “paleness” seemed to be an extensive de-pigmentation of her face, brows and ears. It shines almost white with some bigger freckles. In a later video, we could see that both hands are affected too. Although her untypical face made several of us concerned, overall she did not look sick or suffering. Her baby appeared healthy and lively. Some of us noticed frequent slow-swinging head movements which could possibly indicate bad vision or perhaps are just caused by less protection against the glaring sun due to the skin condition or are from some other cause entirely. Unfortunately, her skin condition seems to be changing over the course of one year. While the de-pigmentation has already been fully present when video footage started; a year later one could see that the ears have thickened and crumpled. Yet, her appearance was still robust and she seems to be able to take care of her infant. We also did not notice any other chimps with similar symptoms suggesting that whatever is afflicting her, is not spreading across the community.

Because of her pale complexion, volunteer Snorticus named her Pearl. We named her infant Flocke (the German word for flake), because of its fluffy hair-do.

Another interesting point in this match is that – after an observation of citsci moderator jwidness – we were able to reliably identify Pearl and Flocke from the back view, i.e., without even seeing Pearl’s white face. Flocke has a very special way of riding on mom’s back, using always a protuberance from the female to support the right foot while they walk.

Back view (detail): notice Flocke's right foot seeking support

All videos of Pearl and Flocke can be found in this collection.

You can join the matching discussions at Chimp & See!

Field Update: a long awaited discovery in the Republic of Congo!

Our 2nd field update is from Mattia Bessone and Emmanuel Dilambaka from Conkouati-Douli National Park in the Republic of Congo. Mattia and Emmanuel are site managers for the MPI-EVA's Pan African Programme: The Cultured Chimpanzee's collaborative research site in Conkouati where we are partnered with the Wildlife Conservation Society - Congo.

Mattia takes a mid-day rest in a gorilla nest

Mattia writes:

I open my eyes. Several bulbuls are loudly singing all around my tent. It is dawn, time to wake up.

I force myself out of my “house” and head to the kitchen where Olivier has already lighted the fire to prepare our breakfast. Emmanuel and Old Nita join us and we fill our plastic cups with boiling river water, powdered milk and nescafé, Radio France International crackling the last news from Emma's old radio. Despite 10 hours of sleep, there is not much talking: we are all still very tired.This is the last day in the forest after three weeks of hard work, few rest and some thousands of trees visited, measured and, sometimes, identified for the habitat structure study. Tomorrow we will be back to base camp to transmit the results of the mission, my colleagues will have sometime to spend with their families and I will enjoy a proper bath and some good food. That gives us a bit of strength.

As we are all very tired, the plan is to only visit three camera-traps at the end of one of our transects, T3, the last ones missing. It won't take much and as we plan to be back around midday, we set off without food: we will eat back at camp.

We walk in silence, in single line, as we pass through the beach and enter the first patch of forest. After a 30 minutes walk we reach the savannah and eventually the path that will be our highway to the end of T3, a nicely fast shortcut.

The rainy season has started and the grass is wet with the night rains; it doesn't take long for our trousers and legs to get completely damp. Despite this unpleasant but familiar feeling we soon arrive at the entrance of the forest and the well known areas of our transect.

Making our way through a swamp we climb a little hill and we found ourselves surrounded by a large group of red-river hogs that noisily flee away, scattering in the forest.

Few hundred meters more and a familiar, unmistakable smell hit us: gorillas! We all start looking around and soon we found their fresh night nests, really close to our track, one of them even built on a tree we monitored for a year straight for the phenology study. That means good ape samples and it will be our job on the way back: there's still quite a long walk to arrive at the furthest camera and we want to be there before the rain.

When we eventually get to the spot “voilà”, it rains. We wear our rain-coats and download the videos. Nothing particularly exciting though, just like the second camera: a few duikers, some elephants but no chimps. We quickly move to the very last camera which is actually quite an interesting one, placed in front of a big log chosen by some stingless-bees to build their hive.

Not far from Conkouati, chimpanzee in other population from Congo and Gabon are known to use tools for different purposes but, after 18 months of PanAf work here and years of monitoring by our collaborators, the WCS-Congo, we still have no clues about our group and we are really struggling to find out the reason why.We arrive on the spot and we freeze. If you wanted to imagine the scenario of a tool-use site you would have pictured exactly what we are seeing: the hive is completely crashed and a couple of sticks are laying on the log. 

We try to be cool and switch off the camera before approaching and make sure that it has not been some villager or well...who knows. But there is no doubt, this was done by a chimpanzee!

The hive has been crashed with a rather big branch, used to pound the entrance. This was found just  next to the hive, leaning against the log. On the other side we found a second tool, a stick, that has been clearly inserted in the hole and still has several wax remains attached. And in front of the log a third, shorter, tool with clear signs of wear: one of the extremities looks exactly like a brush. This is not simply a tool, but a complete tool-set for honey extraction!We hug each other, shake hands, release ourselves in laughters and all the tiredness is replaced by excitement. We did it! We eventually found tool-use in our population.

The “crime scene”: a) the original, untouched bee-hive; b) crashed bee-hive; c) the log and

two of the tools laying beside the hive (pounder on the right and first inserted stick on the left). 

All we still have to do is check the incredible videos the camera has recorded and we eagerly arrange a cover for the laptop with my poncho to protect it from the rain. 

And then again, everything changes and our excitement is replaced by dismay. The camera did not record a single video except those about the installation and the removal for the downloading.

Speechless we examine the camera, trying to understand what on earth could have gone wrong. The device seems working and it ironically records my impression of a chimp walking around the hive.

With no answers but loaded with irritation and frustration we collect the tools, put up the camera again, turn our backs and move back to camp. We stop to collect the gorillas faeces and hair we left on the way, then rush back on our savannah path. Not a word is pronounced in the route and the silence is broken only at camp, for the basic communication to prepare lunch.

With some foufou in our mouths, a good fish soup in our plates and the sun finally shining above us, we eventually decide to discuss the day.It is true, we failed to record the behavior, we have lost an amazing chance, probably the only one we have. But on the other hand, after months of work, thoughts, efforts and frustration, we finally have the first evidence of tool-use in our population. The bees are still in the hive and the chimpanzees now know the place and are likely to come back and visit it again in the next months. In addition, we are now confident that, maybe, even the other bee-hive we are monitoring will be visited and the honey harvested. There is still hope. After all, it is a day worth celebrating! 

And we all help ourselves with another generous portion of soup. 

The team back at camp, proudly posing with the tool-set.
From left to right Emmanuel, Olivier, Nita and Mattia.

2 million classifications at Chimp & See!

Another milestone has been reached in almost no time and we are extremely proud of all volunteers who dedicate their time and passion to watch, annotate, and discuss videos from all over Africa. Your deep interest and engagement surprise us on a daily basis! 

What does it exactly mean to have 2 million classifications? 

Each volunteer watches videos – usually from only one research site at a time – in a random stream and is asked to annotate the species to see, the number of animals present, and their behavior from a predefined selection. A field guide explains clues for species identification and the behaviors the science team is interested in. Depending on what is seen and how hard the animal makes it, that takes 15 seconds to a few minutes. This is one classification.

A video is retired when agreement is reached. This agreement is reached pretty fast with the occasional empty video: when just three different persons say “nothing there”, it is taken out of circulation. If an animal is present, we need seven volunteers to agree on the aggregated species level. That is pretty easy for iconic species like chimpanzees and elephants, but we all have our weaknesses to reliably distinguish the duikers. Is it a small gray, red, or dark one? Or, even a small antelope? If no agreement is reached after 15 different annotations, the video will be retired nevertheless. But the classification did not fail here. The volunteers’ choices about the different duikers or small antelopes still tell us that there is a duiker-like or antelope-like animal present (and not an elephant). Additionally, a volunteer who is an expert in duikers might see the video as well and add the correct species tag in the comment section. So, no click is unnecessary or wasted time for the science project.

A Brooke's duiker - classified as "red duiker"

In numbers: In an average week more than 120 volunteers make over 30,000 classifications. Until now, volunteers annotated more than 370,000 videos from nine different research sites in West and Central Africa that are now completed

Three research sites are currently open. All three of them already presented themselves with great chimpanzee and elephant footage; and Restless Star in addition shines with gorillas.

A heartfelt thank you from everybody here at Chimp & See for your amazing work!

If you are interested, please join us at Chimp & See to watch and annotate videos from across Africa!

Stone throwing Gif :)

COOL! we got some new stone throwing gifs from this article: 
https://www.thedodo.com/mysterious-chimpanzee-behavior-gives-researcher-goose-bumps-1636949303.html

The great one of Dodge above can be found at:
https://assets-animated.rbl.ms/4316151/980x.gif

7000 citizen scientists on Chimp&See!!!

We just hit 7000 citizen scientists on chimpandsee.org and are close to our 2 millionth classification! Thanks to everyone who has been annotating videos and a very big welcome to all our new citizen scientists!