Monday, December 8, 2014

Monday Primate: Mangabeys

Red capped mangabeys (Cercocebus torquatus)
Mangabeys are old world monkeys that primarily live in West and Central Africa. They are a medium sized monkey, being larger than guenons, but smaller than baboons. They are primarily herbivores, but also consume small invertebrates. Mangabeys tend to live in habitats which overlap with other primates. There are some mangabey species which primatologists have studied intensely for decades, and other species which are almost virtually unknown. Over the next few weeks I'd like to take a closer look at some of the different species, but before we get to that there's some important taxonomic distinctions which need to be made.

Taxonomically understanding mangabeys  can be a bit confusing. Crested mangabeys form the genus Lophocebus, which contains at least four different species: Lophocebus albigena (gray-cheeked mangabey), Lophocebus aterrimus (black mangabey) Lophocebus kipunji (highland mangabey) Lophocebus opdenboschi (Opdenbosch's mangabey). These can be distinguished from the white-eyelid mangabeys which are placed within the Cercocebus genus (. It used to be that all mangabeys were contained within the same genus, Cercocebus, but thanks to genetic studies, we now know that Lophocebus are more closely related to baboons (Papio) whereas Cercocebus are more closely related to Mandrills (Mandrillus). The following figure will helpfully illustrate this a little bit better.

And just to make things a bit more confusing, one particular crested mangabey, Lophocebus kipunji, is classified by some primatologists as belonging to its own distinct genus, Rungwecebus kipunji.

Left: A white-eyelid mangabey (Cercocebus atys), Right: A crested mangabey (Lophocebus aterrimus)

Luckily, crested mangabeys and white-eyelid mangabeys are rather easy to visually distinguish: crested mangabeys have dark eyelids and large crests atop their heads. White eyelid mangabeys lack such crests and have, you guessed it, white eyelids.

Next week we'll take a closer look at a member of the Cercocebus genus, Cercocebus atys, the sooty mangabey.

Tuesday, November 18, 2014

Figuring out climate change, part 1

Like I said yesterday, I want to better understand the evidence for global anthropogenic climate change. I tend to find that that the best place to start is at the beginning. As far as I can tell, when it comes to understanding climate change, that means understanding the greenhouse effect. I also have a deep love of science history and sometimes I get side-tracked into exploring how modern scientific theories originate, develop, and influence the work of other scientists and their own ideas. Let's begin.

Okay, the sun gives off radiation that travels through the atmosphere to reach planet Earth. The radiation warms up our planet and then travels back into the atmosphere. The gases that make up our atmosphere trap some of this heat and prevent it from escaping back into outer space. These gases are called greenhouse gases. Quite simply, this whole process is called the greenhouse effect.

The Greenhouse effect was originally proposed by the French mathematician and physicist Jean-Baptiste Joseph Fourier in two articles published in 1824 and 1827. Fourier was a pretty important physicist that did a lot of fundamental work in developing our modern understanding heat transfer, thermal conduction, and vibrations. In Fourier's (1824;1827) articles, he referred to an experiment by the Swiss physicist Horace-Bénédict de Saussurede...
de Saussure had lined a vase with blackened cork. Into the cork, he inserted several panes of transparent glass, separated by intervals of air. Midday sunlight was allowed to enter at the top of the vase through the glass panes. The temperature became more elevated in the more interior compartments of this device. Fourier concluded that gases in the atmosphere could form a stable barrier like the glass panes. This conclusion may have contributed to the later use of the metaphor of the 'greenhouse effect' to refer to the processes that determine atmospheric temperatures. Fourier noted that the actual mechanisms that determine the temperatures of the atmosphere included convection, which was not present in de Saussure's experimental device.
Fourier's work came at a very important time because it was also in the early 19th century that geologists were beginning to develop a more complex understanding of the Earth's geologic history. In 1815 Jean-Pierre Perraudin proposed the idea that glaciers might be responsible for the giant boulders seen in alpine valleys. Although originally dismissed by many scientists of his day, Perraudin's idea eventually gained traction and were largely responsible for influencing Swiss biologist Louis Agassiz. Agassiz was, of course, the man who coined the term "Ice Age" and further developed these idea to propose that during the past Europe had once been covered with glaciers. In turn this influenced the work of geologist Charles Lyell, whose geological work laid the foundation for Charles Darwin's theory of natural selection.

But, back to the greenhouse effect...

In order for the Earth's temperature to remain constant, the balance of the greenhouse gases has to remain constant. Primarily, the most important and abundant greenhouse gases are water vapor, carbon dioxide, methane, nitrous oxide, and ozone. The burning fossil fuels such as oil, coal, and natural gas release carbon dioxide into the atmosphere which upsets this balance causing more heat to be trapped inside the proverbial greenhouse. This is what causes global warming. There are plenty of well documented periods in the Earth's history in which natural forces have caused disruptions in the balance of greenhouse gases (I plan to explore some of these as I continue this series), but here in the 21st century it really seems as though the climate change we are currently experiencing is largely being driven by human factors.

I think this all pretty straight forward and I think most people would agree. The only point of contention among climate change deniers might be that the amount of carbon dioxide being released by the burning of fossil fuels is not be enough to disrupt the natural greenhouse effect of our planet. Thus, they would disagree with the statement that our current climatic changes are being caused by humans. Personally, I think we have some pretty good evidence to suggest that global climate change is real and caused by humans. Tomorrow, I'll begin to explore that evidence.

Monday, November 17, 2014

Time to get back to it

I know it's been awhile. What can I say? I've been busy. First, there was a summer of fieldwork in France and Hungary, then I had to finish my Masters of Science research, then I had to get a CRM archaeology job in order to pay the bills, then I had to put together a talk for the 2014 CAPA conference (Canadian Association of Physical Anthropologists), then I had to reunite my old mutant rock band, Atomic Machetes, to play two shows in New Brunswick, then I had to travel back to Toronto, and now that's where I am.

Currently, I'm putting together phD applications in the hopes of continuing my research into the wild and fascinating world of primate evolution. I'm interested in studying the link between bone morphology and function, relating the shape of bones to locomotion, movement, and behavior. Who knows where I'll end up, but I can tell you it's been a hell of a lot of fun so far, so I plan to continue down this road to see what else I can discover.

But now it's time to return to regular blog writing. This blog helps me organize my thoughts. It helps me learn more about things I don't know very much about. Recently, I discovered one of things I know very little about is climate change. I found this out by discussing the subject with someone most of my colleagues would call a "climate change denier". Personally, I used to sit in that camp myself a long time ago. Primarily, I think it was because I really dislike Al Gore. I've never forgave him and his ex-wife's attempts to destroy rock and roll in the mid 1980s via censorship and the establishment of the PMRC. Eventually, after looking more closely at the science, I came to accept the fact of climate change as something which is undeniably caused by humans.

In my recent discussions with said "climate change denier" I realized two things. First, I realized I was much less informed on the subject than I thought I was. Secondly, I realized it was my own personal responsibility to be better informed. Why? Because I'm the person making the claim. As one of my literary heroes, Christopher Hitchens, once wrote, "that which can be asserted without evidence can be dismissed without evidence". The truth is that I don't know what the best evidence for climate change actually is. In order to rectify this I plan to write a series of blog posts where I examine the evidence in defense of climate change. I plan to do with with an open mind. Although I already strongly believe that climate change is real and man-made I have to be willing to accept that I could be wrong should the evidence lead me in that direction.

That's where you come in my dear readers. Do you have any burning questions about climate change? Anything you'd like to know? Do you think it is real? Do you have some evidence in support of climate change that you'd like to share? Do you have evidence which casts doubt on anthropogenic climate change? Please share your ideas with me, regardless of where you sit on the subject.

And don't worry, I'll still be writing about primates, evolution, rock and roll, and other cool science news. It's good to be back. Let's get this thing going...

Saturday, June 14, 2014

Gone Fishing

Okay. I gotta go jump on the subway to the bus to the airport to France to the subway to the train to the archaeological site, work there for a few weeks, catch the train to the subway to the airport to Hungary, do some paleontology, archaeology, teaching assistant type work for about a month, then go to the airport to the Netherlands, switch planes, fly back to Toronto, take the bus to the subway, take the subway home. I'll be done that by early August. Have a great summer. See y'all later.

Monday, June 9, 2014

Monday Primate: Pygathrix

Image by Jurgen & Christine Sohns @ Arkive.
Primates of the genus Pygathrix are commonly referred to as douc langurs (or just doucs for short). This is bit of a confusing name from a phylogenetic perspective because there are another group of monkeys which are simply called langurs. Although these two groups are both members of the Colobinae subfamily, douc langurs are members of the odd-nosed monkey group and therefore more closely related to monkeys like the Proboscis monkey (Nasalis larvatus) and the Snub-nosed monkey (Rhinopithecus roxellana) than they are the langurs (Semnopithecus and Trachypithecus).

Within the Pygathrix genus there are three distinct species: the Gray-shanked douc (Pygathrix cinerea), the Red-shanked douc (Pygathrix nemaeus), and the Black-shanked douc (Pygathrix nigripes). Generally speaking doucs have grey bodies, but they can be distinguished from one another by colour differences in their face and legs.  P. cinerea has speckled grey legs and orange markings on its face, .P. nemaues has bright maroon legs and reddish patches around its eyes, and P. nigripes has black legs and a darker face.

Gray-shanked douc (P. cinerea), Red-shanked douc (P. nemaeus), Black-shanked douc (P. nigripes).
Geographic Range: Doucs are native to Southeast Asia, or more specifically, in Indochina, east of the Mekong River (Vietnam, Laos, and Cambodia). Some of these species can be found inhabiting the same regions, but the exact boundaries between all species are unclear. In part this is because the existence of hybrid forms of the three species do exist. In addition to this doucs are also found to live sympatrically with other primates like the pygmy loris (Nycticebus pygmaeus), Macaques (Macaca mulatta, Macaca fascicularis, and Macaca arctoides), Silvered langurs (Trachypithecus germaini), and Yellow-cheeked crested gibbons (Nomascus gabriellae).

Habitat: Doucs are highly arboreal species, and thus, they are only found in forest habitats. In fact, P. nigripes has never been observed on the ground.

Locomotion: Arboreal quadrupeds.

Diet: Primarily folivorous (leaf-eaters).

Social Organization: Multi-male/multi-female (multiple sexually mature males and multiple sexually mature females and young of all ages). Group size can vary considerably based upon the location and the availability of food resources (from a small handful to over 50 individuals). Adult males are dominant to all other members of a group and a dominance hierarchy is primarily sustained between individuals through displays or acts of aggression. Not to suggest the doucs are all a bunch of meanies, in fact they appear to considerably  enjoy playful activities. When a douc wants to play it will open its mouth, partially bear its teeth, and thrust its chin forward. Primatologists refer to this gesture as play-face. Sub-adults engage in play more than adults, but play-face is exhibited by doucs of all ages and sex.

This will likely be the last Monday Primate for the next month or two. This coming Saturday I'll be heading across the ocean to do some archaeology/paleontology for the next six weeks in France and Hungary. So have a fun summer everybody.

Wednesday, June 4, 2014

Afropithecus and the evolution of prolonged hominoid life history

Afropithecus turkanensis was an ape that lived in Kenya around 17.5 million years ago. Like other apes from the early Miocene, Afropithecus was considerably smaller than most modern apes. And even though Afropithecus was arboreal species, it moved atop the tree branches, rather than swinging below the branches like chimpanzee or gibbon. It also had thickly enameled teeth, a long snout, and dental morphology which suggests it may have been a hard-object feeder, like modern orangutans.

I think one the most interesting thing about this species is that it has allowed researchers to gain some insight into the life history of early apes. See, a few years ago Kelley and Smith (2003) examined the dentition of a sub-adult Afropithecus specimen, KNM-MO 26. KNM-MO 26 had an unerupted upper first molar (M1), so Kelley and Smith counted the number and periodicity of it's lateral perikymata. Perikymata are incremental growth lines that form as grooves on the enamel surface of teeth as they growth. As perikymata form at a fairly standard rate (8-10 days) measuring them allowed Kelley and Smith to determine KNM-MO 26's age at death: 28.2 to 43.5 months.

Comparing at the age of M1 eruption in extant species, Afropithecus fell outside the range of Old World monkeys, but within the range of chimpanzees. Then, by combining this data with that from similar study on Sivapithecus Kelley and Smith were able to determine "that the prolonged life histories characteristic of extant apes were achieved early in the evolutionary history of the group." Basically, apes have had long lives characterized by slow periods of development for at least 17.5 million years.

Afropithecus by Viktor Deak (Anatomical Origins)