Apes Walking Upright: That's Just How They Roll (or Walk).

Orangutans, gorillas and chimpanzees do it. Bonobos seem to love doing it. Apparently gibbons do it really well. Indeed, bipedalism is not unique to humans and is quite common among apes. Apes are known to walk upright once in awhile, although bonobos seem to do it more frequently than other apes. Bipedalism is just one of the natural repertoire of ape locomotion.

(From left to right) Upright Apes Brigade: Gibbon, Orangutan, Gorilla, Chimpanzee and Bonobo. Click photo for larger image.

Upright Gorilla Goes Viral: 

Ambam the gorilla. Photo from Dailymail.

Currently going viral on the internet is a video of Ambam, a Western lowland gorilla (Gorilla gorilla gorilla) that was filmed walking upright in his enclosure. This 21 year-old, 485 lb. ape currently resides at Port Lympne wild animal park in Kent, England.

If you have not heard of Ambam or caught on to this internet sensation, you can read about him on :
Ambam, the swaggering silverback gorilla who walks around his pen on two legs (DailyMail)
Yes, he can walk. But just how close IS he to being human? (DailyMail)
Walk like a man: Gorilla strolls on hind legs (MSNBC).

It is not uncommon to see a gorilla walk upright but what's unique about Ambam is that he seems to walk upright quite frequently and good at it too. Bipedal locomotion is common in gorillas but they spend most of their time knuckle-walking. Ambam's upright gait and locomotion is definitely not an upright display to intimidate. Instead, it is most probably in response to curiosity and foraging in his enclosure. One of his keeper, Phil Ridges said:

"We think he might use it to get a height advantage to look over the wall when keepers come to feed him and standing up can also help him in looking for food generally in his enclosure as it gives him a better vantage point." Ridges added that Ambam could also carry more food if his hands were freed from walking and it also meant "he doesn't get his hands wet when it is raining."

It seems that the penchant for bipedalism runs deep in Ambam's family. His father, sister and half-sister (same father) prefer to walk upright and stand the same way as Ambam.

Ambam standing upright. Photo from Dailymail.

Is this a novel behavior in response to being in captivity? Is his skeletal and muscular structure (and in some sense his father, sister and half-sister) different than other gorillas? I think it would be interesting to see a behavioral study and an ethogram on Ambam's choice of locomotion. What are the percentage (or time spent) of him walking upright compared to knuckle-walking. Will his offspring be a fan of bipedality as well?

The Other Upright Ape:
While Ambam seem to prefer walking upright once in awhile, there is another ape that came before him who is a habitual biped. This ape is a chimpanzee named Oliver.

Oliver was a media (and science) sensation in the 60s and 70s for his preferred upright locomotion, having 47 chromosomes and a less prognathic face compared to other chimpanzees. Humans have 46 chromosomes while chimpanzees have 48 chromosomes. It was thought that Oliver is a "missing link" between chimpanzees and humans, thus nicknamed the "humanzee". While Oliver is not the missing link (Ely et al.,1998), he is truly a habitual biped.

The 52 year-old Oliver currently resides at Primarily Primates, a sanctuary in San Antonio, Texas. Below is a really good video of Oliver from his early years to his retirement. Seeing what happened to Oliver, I hope that they will not parade Ambam around like a freak of nature.

UPDATE: Oliver passed away on June 2nd 2012 at Primarily Primates. Read more here.

Reference:
Ely, J.J. Leland, M. Martino, M. Swett, W. Moore, C.M. 1998. Technical note: Chromosomal and mtDNA analysis of Oliver. American Journal of Physical Anthropology 105(3) 395-403. DOI: http://www3.interscience.wiley.com/journal/28165/abstract?CRETRY=1&SRETRY=0

When Is A Monkey Really A Monkey?

A little boy pressed his nose on the glass where a Western Lowland Gorilla is interacting with the zoo-goers. He turns around to his parents with a big smile. “Oh look, the monkey wants to kiss you”, said his mother.

At the lemur exhibit, a girl asks her parents what those black and white primates were. Her dad picks her up and said, “It’s a monkey, sweetie … let’s go”.

A pair of gibbons gracefully swings around in their exhibit. Excited, a group of kindergarteners cheered as these gibbons maneuver around its habitat with great agility. “These monkeys are so active”, said the teacher.

If this sounds familiar to you then you are not alone. I spent a great deal of time near primate exhibits mainly because I love to observe their behaviors. I also enjoy watching interaction between humans and primates. However, there are times when I just can’t control myself and felt compelled to walk over to these people and explain to them that the word “monkey” is not a general term for primates (politely, of course). It shocks me that most of the time people do not read the information panel at the exhibit (aren’t zoo trips for educational purposes?). So when is a monkey really a monkey?

Monkey is a colloquial term for any cercopithecoids (Old World monkey) and platyrrhines (New World monkey). Monkeys are not hominoids (apes) or prosimians. One of the most distinctive characteristic that differentiate monkeys and apes is the presence of a tail in monkeys. Gibbons, siamangs, orangutans, gorilla, chimpanzees and bonobos are apes because they do not have a tail.

Gorillas do not have tails, so they are not monkeys but apes.

Differentiating monkeys and prosimians are a little tricky; all prosimians have grooming claws (toilet claws) but it is generally not visible within zoo exhibits. Prosimians include lemurs, lorises, galagos, aye-ayes and tarsiers.

A ring-tailed lemur is a prosimian. Although it has a tail, it also have grooming claws so lemurs are not monkeys.

A hamadryas baboon is technically a monkey because it has a tail but has no grooming claws.

The Barbary Macaque, Macaca sylvanus, was formerly named Barbary Ape due to the absence of a tail (to be more precise, they have a vestigial tail that looks like a stump). However, we know now that it is more closely related to macaques than to apes so its name was changed to correctly reflect what they are.

A Barbary Ape (notice the lack of tail). Flickr photo from Gerald Davison.

This brings us back to the question, “when is a monkey really a monkey’? The most straightforward answer would be “when it has a tail but doesn’t have grooming claws”. However, the most convenient answer usually lies in front of you … on the information panel.

Flickr photo taken by tim ellis at the Twycross Zoo, England.
The sign reads "Who are you calling a monkey?"

Contagious Yawning in Chimpanzees

Animation of chimpanzee yawning from Emory University. Illustration from BBC News.

I'm sure we are all familiar with this scenario: Someone yawns and we would "catch" it or vice versa. This is the phenomenon of contagious yawning.

A new paper from The Proceedings of The Royal Society "Computer animations stimulate contagious yawning in chimpanzees" suggests that the phenomenon of contagious yawning and empathic response to animation occurs in chimpanzees. Computer animations of yawning chimpanzees (see illustration above) can be use to stimulate contagious yawning in chimpanzees. Previous researches have documented contagious yawning in chimpanzees through video-recorded footage.

Dr. Matthew Campbell, lead author of the paper from Emory University's Yerkes National Primate Research Center said that they would also like to learn more about behaviors that are related to empathy such as consolation (when an individual does something nice to the victim of aggression). They want to know if individuals that are good contagious yawners are also good consolers. Understanding how chimpanzees empathize and imitate animations can help us understand how we, as human beings, empathize and imitate animations as well, said Dr. Campbell.

New Study Suggests That Humans are More Closely Related to Orangutans, Not Chimps

Sorry, been traveling here and there lately so don't really have time to post blog updates. Found this interesting article on EurekAlert!

A new study suggests that humans share a common ancestor with orangutans, not chimpanzees according to shared physical characteristics.

Comparing physical characteristics instead of DNA, researchers Jeffrey H. Schwartz and John Grehan found that humans shared 28 unique physical characteristics with orangutans, share only two features with chimpanzees and seven with gorillas. Humans share seven characteristics with all three apes (chimpanzees, gorillas, and orangutans). Gorillas and chimpanzees shared 11 unique characteristics.

Schwartz and Grehan proposed to have a new "grouping" or classification for humans, orangutans and last common ancestor call "dental hominoids" because they all share similar thick-enameled dental.

Read more about this study at EurekAlert! Humans related to orangutans, not chimps, says new Pitt, Buffalo Museum of Science study.

Human Ancestors Were Not Good Tree Climbers, Said Researcher

A new study by Jeremy DeSilva, anthropologist at Worcester State College in Massachusetts suggests that human ancestors may not have been good tree climbers. He suggests that our ancestors traded in arboreal adaptations to evolve bipedality.

By recording how wild chimpanzees climb tree in Uganda's Kibale National Park, DeSilva found that chimpanzees flex their ankles 45 degrees from normal resting position while modern humans flex their ankles a maximum of 20 degrees while walking. Flexing any more than that and a modern human's ankle will suffer serious injuries.

DeSilva then compared the ankle joint, the tibia and the talus, in great apes and fossil hominins between 4.12 million to 1.53 million years old. He found that all of the hominin ankle joints resembled those of modern humans rather than those of apes, suggesting that this joint "form" took on its current configuration early in human evolution.

Read the full ScienceNOW article.