Wednesday, April 9, 2014

Washington, DC

For the past ten days I've been down I. Washington, DC at the Smithsonian Museum of Natural History. I was measuring primate carpal bones for my Master's research project. It's been pretty fun (if you're into measuring bones, which I am). I've got a pretty good sample now, but the real work still lies ahead in sorting through this data with my various means of analysis. I'm leaving it rather vague on purpose, as I don't want anyone to steal my ideas quite yet.

The SMNH is an amazing museum. The exhibits are masterfully designed and the staff are all really nice people (both the researchers and the security guards). Being a visiting researcher I got the added benefit of being able to stroll through the museum on my own before it opened and after it closed. That's a luxury which is entirely new to me. As someone who has a deep seated and borderline irrational hatred of lines I couldn't ask for anything better. Still, even with other people milling about this is quite a beautiful establishment.

I found the city of Washington itself to be rather quiet, but I guess that's par for the course when it comes to capital cities. And like most other capital cities Washington is eerily clean. Too clean, much too clean. Even with my brand new Wal-Mart sneakers I felt as though I dirtying up the sidewalks as I strolled down to the museum every morning.

Getting to see all the famous landmarks which were familiar to me via popular American film and television was pretty cool. I even stumbled across a Marathon one morning. The thought of joining in and going for a 10 mile run with a cigarette hanging out of my mouth did cross my mind, but I'm pretty sure Eddie Izzard already did something like that.

Now it's time to pack up and fly home to Toronto. I've got that "Got Anthropology?" talk coming up soon (April 23: more details here). If you're in the area please come by check it out. It shall be both entertaining and enlightening.

Friday, March 28, 2014

Got Anthropology?

At the end of April I'll be giving a talk as part of the "Got Anthropology?" public lecture series at the University of Toronto. I'll be examining the about the age old question, "If humans evolved from monkeys, why are there still monkeys?" It's free and open to the public, so if you're Toronto come on out, okay?

FitzGerald Building
University of Toronto
150 College Street, Room 103.
Wednesday, April 23, 2014.
7:30 PM

"This commonly asked question is often met with a rehearsed monotonous response: humans didn’t evolve from modern day monkeys, humans and monkeys share a common ancestor. Although this statement is technically correct, it implies our common ancestor was neither monkey-like nor human-like. The fossil record, however, shows us that this earlier ancestor would undoubtedly be called a monkey by anyone who saw it. Why have human beings seemingly evolved so much while other primates remain so primitive? In this upcoming talk Andrew C. Holmes will answer these questions by exploring the primate fossil record."

More details can be found on the "Got Anthropology?" facebook event page. More details about other "Got Anthropology?" talks (including videos of past lectures) can be found here.

Tuesday, March 18, 2014

Hey Look! It's some dude who likes snakes!

Hello vagrants, dreamers and borderline sociopaths. My name is Rob, and I like reptiles, not just snakes but all reptiles. My buddy Andrew told me I should write for his blog, and after several dozen delays, forgetful moments and debaucherous sidelines I finally am getting to write my intro post. Although this blog primarily deals with primates, I will speak mostly about our reptilian counterparts on this planet (and no, I am not talking about the reptilian intruders that have infiltrated our society, although I wish I were). While I have no formal education on the subject matter I have been keeping, studying and loving reptiles for many years now. I write for an online herpetology magazine as well volunteer at the Maritime Reptile Zoo in halifax. These animals are not only my hobby but my passion. I have kept small lizards to monster snakes and everything in between. Keep your eyes and eyespots on this blog for my articles about extant species, and watch me get out of my comfort zone while chatting away on extinct reptiles and the evolutionary track they followed to get where they are today!

Monday, March 17, 2014

Primate Monday: Sapajus apella

Cebidae is one of the five families of New World monkeys (Platyrrhini). Until recently Cebidae was composed solely of two genera: capuchins (Cebus) and squirrel monkeys (Saimiri). Closer examination has lead researchers to the conclusion that Cebus should be split into two separate genera: gracile capuchins (Cebus) and robust capuchins (Sapajus). This argument was based upon three separate lines of evidence. First, genetic research suggests gracile and robust capuchins diverged over 6.2 million years ago, and then each clade when through a period of adaptive radiation during the Early Pliocene. Secondly, gracile and robust capuchins have distinct biogeographical ranges, which can be tied to this divergence. Gracile capuchins originated, and subsequently populated, the Amazon forest. Robust capuchins on the other hand, seem to have originated in the Atlantic forest. Third, and finally, gracile and robust capuchins genera are phenotypically distinct, in pelage, size, robusticity, and skeletal morphology (see Alfaro et al., 2012 for more details). Thus, this week's primate, once known as Cebus apella, is now recognized as Sapajus apella.

Description: S. apella is commonly known as the Tufted capuchin. If you haven't figured it out from the pictures, the name is refers their semi-obnoxious hairstyle. The tuft is usually dark brown or black and is sometimes accompanied by some pretty sweet monkey sideburns. Males tend to be larger, have more pronounced canines, and have darker faces as compared to females.

Geographical Distribution: Tufted capuchins are found in multiple forest types throughout Northeastern South America (Suriname, Guyana, French Guyana, Venezuela, Brazil, Colombia, Ecuador, and Peru). They are typically found in the understory and the lower levels of the tree canopy.

Diet: Omnivorous. The widespread distribution of C. apella is partially explained by their ability to exploit a wide range of foods. Their diet is primarly made up of s fruits, insects, leaves, nectar, nuts, and pith, but the actual propotions of each can vary greatly from region to region.

Locomotion: Tufted capuchins are above branch aborealists and use a combination of palmigrade and graspwalk locomotion.

Social structure: Tufted capuchins live in groups of 8-15 individuals which are lead by an alpha male. Both male and females have ranked hieraches based upon age. Generally speaking, the older the individual, the higher their social rank.

Capuchins are extremely intelligent, perhaps the smartest of the new world monkeys. They are known to use tools in the wild such as sponges to absorb liquid, hammerstones to smash nuts, sticks to dig in the ground, and containers to collect water. Researchers have also been able to figure out that some of their vocalizations have distinct meanings. Tufted capuchins use contact calls to reestablish contact with their group when separated. They also make distinct warning calls that will cause an entire group to disperse and flee when heard.

Due to their highly intelligent nature, tufted capuchins have been involved in numerous studies which have attempted to understand cognition in various animals. The research indicates that capuchins are able to develop and use new tools in order to solve novel problems. Interestingly, however, this same research also suggests they only really learn when one of their new ideas works and thus, they do not learn from their failures. This demonstrates some sort of disconnect in their understanding of cause and effect (see Visaberghi et al. 1994 for more details).

Sunday, March 16, 2014

Zhoukoudian Homo erectus and the use of fire

When Peking Man was first discovered in the 1920s by researchers working at the Zhoukoudian cave site in China it was suggested that Homo erectus had controlled use of fire. This was based upon the presence of ash samples found in close association with H. erectus remains. Some early twentieth researchers even proclaimed these samples could be used as evidence that H. erectus was engaging in cannibalism. As excavation methodology and chemical analysis improved over the twentieth century the claim that the Zhoukoudian ash samples demonstrated fire came into question. Siliceous aggregate, an insoluble phase of burned ash, was not found in the ash samples, and, thus, this suggested that they might not even actually be ash samples.

But now, here in twenty-first century, molecular archaeology is even stronger as an informative method of analysis. A new study by Zhong et al., 2014 which looks at newly recovered samples from Zhoukoudian has confirmed the use of controlled fire by H. erectus. Researchers detected a large number of sintered agglomerates in the insoluble residual phases of the samples. Additionally, elements associated with siliceous aggregates (Aluminum, Silicon, Potassium, and Iron) were present in all of the samples. So, after a century of research, we can now strongly confirm the original hypothesis that H. erectus used fire. 

Monday, March 10, 2014

Monday Primate: Hylobates lar

Although I've discussed gibbons in a previous installment of Monday Primate (back when it was called Sunday Primate), it was in very general sense. Gibbons (Hylobatidae) actually represent a very diverse group of primates which is composed off four genera (Hylobates, Hoolock, Nomascus, and Symphalangus) and 14 distinct species.

The evolutionary origins of Hylobatidae are still somewhat of a mystery. Some evolutionary anthropologists believe they represent a very primitive branch of the ape superfamily. Others have suggested gibbons actually evolved from larger apes and subsequently became smaller size through a process known as phyletic dwarfism. The fossil record doesn't actually leave us much to go on when it comes to gibbons, but molecular studies suggest that the four main genera diverged from one another sometime around 7 to 8 million years ago.

The white-handed gibbon, Hylobates lar, is probably the most well known Hylobatidae species. This is because it has been the subject of a great of primatological field research and it is the gibbon which is most commonly found in zoos around the world. Although the white-handed gibbon is one of the more populous wild gibbon species, they are still considered to be an endangered species by the IUCN Red List.

Description: The pelage of H. lar is light brown or black. Interestingly, these colour differences are not tied to sex, as either male or female can be either colour. This follows the general pattern of a lack of sexual dimorphic characters in gibbons. Based upon my own personal observations of Hylobatidae skeletal morphology that it is impossible to tell whether an individual was male or female simply by examining their skeleton. This is markedly different from the great apes (Orangutans, Chimpanzees, and Gorillas) which exhibit some of the most pronounced sexually dimorphic characters among all living primates. The colour differences in gibbons appear to be more closely linked to the specific population from which the gibbon comes from. Some groups are mostly light coloured, some groups are mostly dark coloured, but then there others groups which seem to be a fairly equal mix of white and dark coloured individuals. H. lar have white hands and feet, a white ring around their hairless face, and adults weigh about 5 to 8 kilograms.

Geographical Distribution: Southeast Asia (Indonesia, Laos, Malaysia, Myanmar and Thailand). Although there used to be some white-handed gibbons in Yunnan Province, China, it is thought that these populations are now extinct.

Habitat: White-handed gibbons are an extremely arboreally adapted primate and, thus, unsurprisingly, they spend most of their time in the trees. More specifically, they are partial to dipterocarp trees and rainforests, but they are also found in deciduous bamboo forests, and mix evergreen forests.

Diet: Fruit, leaves, flowers, and insects.

Locomotion: Brachiation. Gibbons have one of the most unique locomotor styles, not just among primates, but among all land animals. Their ability to move quickly and accurately through trees means they are virtually unaffected by predators. In fact, some gibbons even use their abilities to torment other animals for their own amusement (as seen in this video). The secret lies partly in their wrist. Apes have two carpal bones (scaphoid and lunate) which articulate with the radius of the forearm. In most apes these bones form something of flat articular surface, however, in gibbons the angle of articulation between the scaphoid and the radius are markedly different. Essentially, the scaphoid and lunate are oriented to form a sort of ball and socket joint with the raduis. And then to top it off, this joint can actually be painlessly dislocated to allow a even greater range of motion when needed.

Friday, March 7, 2014

Proconsul: seeing the forest and the trees

Proconsul is one of the earliest fossil primates which is generally considered to be an ape. It was originally discovered by a gold prospector in 1909 in Western Kenya. Since then a wide variety of Proconsul fossils have been found which have been placed into four different species (P. nyanzaeP. africanusP. heseloni, and P. major). As is to be expected, there are some paleontologists that disagree with the classification of Proconsul as an ape. Instead they suggest the various Proconsul species form a sister taxon to the apes (Hominoidea) which they call Proconsulidae.

Regardless, there are some things we know about Proconsul. It lacked a tail (a derived trait among apes), it lived between 25 and 18 million years ago, and it was much smaller than moderns apes. Its size and postcranial morphology suggests that unlike modern apes, Pronconsul was not suspensory. Instead it walked along the tops of tree branches as it moved through the forest.

And here we arrive at what has been something of dilemma for paleoanthropologists working on Proconsul. Because of the nature of the deposits in which Proconsul fossils have been found it's hard to determine what kind of trees and what kind of forest Proconsul lived in. Most of the fossil assemblages to which Proconsul belongs represent something of a time-averaged  accumulation.  This has lead to various contradictory interpretations of Proconsul's habitat. These interpretations range from "closed forested systems to mixed habitats of open and closed environments to open woodland or grassland environment" (Lauren et al., 2014). Not having a firm grasp on Proconsul's environment is problematic for determining the adaptive forces which shaped it's evolution. The loss of the tail is a really big deal from a functional/locomotor perspective. Thus, any information about the environment which lead to this loss is extremely important.

This problem may now be solved thanks some new finds which are reported in the latest issue of Nature (Lauren et al., 2013). Researchers working at the Rusinga Island site in Kenya found Proconsul fossils in a geological deposit along with tree stumps, leaves, and calcified roots. Unlike previously discovered deposits, this one clearly represents a specific period frozen in time. Now we clearly know that 20 million years ago Proconsul lived in a dense, multistoried, closed-canopy tropical seasonal forest with a warm and relatively wet climate. It probably looked a little something like this:

Image credit: Jason Brougham
Oh yeah, they found some Dendropithecus fossils too. Dendropithecus is a potential ancestor of modern gibbons that lived alongside Proconsul in Eastern Africa during the early Miocene. You can see Proconsul in the foreground and Dendropithecus in the background of this image being all gibbon-like.