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)

Tuesday, June 3, 2014

On the Encephalization Quotient of Neanderthals

Image via the Smithsonian.
And since we're on the topic of encephalization quotients (EQ) I just came across a new study comparing the EQ of Neanderthals to anatomically modern humans. Typically, previous work in this area has shown that even though some Neanderthals had brains which were larger than the average modern human brain, Neanderthals still had smaller EQ. One of the supposed implications being that Homo sapiens were smarter than Homo neanderthalensis.

In a new study Andrew Gallagher (2014) argues that previous comparisons between Homo sapiens and Eurasian Homo neanderthalensis  have been flawed because a "demonstrable male bias in the available postcranial, not cranial, series has skewed perceptions of Neandertal brain-to-body size scaling toward a rejection of the null hypothesis".

Gallagher's work suggests that once this sampling bias is controlled for by using the appropriate statistical methods of analysis, the difference in Homo sapiens and Homo neanderthalensis EQ disappears. Thus, the implication is that Neanderthals weren't the dumb dumb they are often made out to be. I think this also points out that we need to look outside the skull if we are to ever determine the reasons behind Neanderthal extinction. Hominins are much more than floating skulls, they have bodies and there are a lot of clear morphological differences to be found in the postcrania of Homo sapiens and Homo neanderthalensis.

But, more to point, there's also the possibility that intelligence and cognition, at this fine a scale, are not simply reducible to EQ. Brains are complicated things, and one thing the archaeological record does seem to suggest, is that late Pleistocene humans were much more artistic and creative than Neanderthals. I can't help shake the feeling that our innate artistic nature helped us survive when biology just wasn't enough to cut it.

The Cost of Muscles and Brains

Brains are expensive machines. They require a lot of energy if they are operate properly. Humans are giant brains, especially when you compare them to other mammalian species. One way you can quantify the size of our brains, in a manner that allows you compare them with other species while accounting for allometric differences, is by using an encephalization quotient (EQ). Here's what wikipedia has to say about it:
Encephalization Quotient (EQ), or encephalization level is a measure of relative brain size defined as the ratio between actual brain mass and predicted brain mass for an animal of a given size, which is hypothesized to be a rough estimate of the intelligence of the animal.This is a more refined measurement than the raw brain-to-body mass ratio, as it takes into account allometric effects. The relationship, expressed as a formula, has been developed for mammals, and may not yield relevant results when applied outside this group.
Just to give you an idea where humans stand, our species has an EQ that ranges between 7.4 and 7.8. Our closest living relative, the chimpanzee, has an EQ range of 2.2 to 2.5. Dogs have an EQ of 1.1 and a mice clock-in with an EQ of 0.5. One of the questions this raises is of course; how did our brains get so big?

This relatively hairless chimp has some big muscles
Photo via Faybalina (flickr)
Well, a new study published in PLOS ONE suggests that our large brains came as an evolutionary trade off (Bozek et al., 2014). See, chimpanzees are a lot stronger than humans. They have big powerful arm muscles which allow them to climb through trees with relative ease. Their muscles also enable them to be able to run much faster than humans. Any time a chimp and human engage in hand to hand combat, the safe money is always on the chimp. Okay, with all that being said, sometimes the strength of chimpanzees has been greatly exaggerated (see this short article by John Hawkes). Regardless, those big powerful chimp muscles require a lot of energy, just as a human brain does.

The common ancestor of chimpanzees and humans, which was far more chimp-like than human-like, was probably a pretty strong little bugger. If Bozek et al. (2014) are correct, this means that as our bipedal hominin ancestors evolved we lost these large powerful muscles, but gained our large powerful brains. Given that large brains can come with some large benefits, benefits which can help an individual pass on their genes to future generations, the idea seems quite plausible. Looking over their paper they seem to have some pretty decent evidence to back up these claims. It will be interesting to see if more follow up studies are able to reproduce similar results.

Monday, June 2, 2014

Oh looky there, an old Sasquatch mask

Last week my friendly neighborhood bartender told me about a new Sasquatch story he had heard earlier that day. Apparently, a Sasquatch enthusiast named J.W. Burns stole a Bigfoot mask from some natives in British Columbia about 75 years ago. Not a very nice thing to do, but by the beginning of the twentieth century I think we can all agree that natives were probably used to having items removed from their possession in the name of academia. Well, it turns out this mask was just recently returned to it's original owners, or at least the descendants of the original owners.

As you may know, I'm a bit of a Sasquatch enthusiast myself. The primary difference between people like J.W. Burns and myself is that I'm not convinced Sasquatches exist, but I would be willing to change my mind should sufficient evidence be presented to me. J.W. Burns, on the other hand, was already convinced such creatures did exist, regardless of how little evidence he could muster to support such claims.

Still, the mask story seemed rather interesting and I decided to investigate. I wanted to know: 1. What does the mask look like?, and 2. When was the mask made? If the mask actually looked like an ape and was made prior to European contact (before any New World natives knew what apes looked like) this might give the old native Sasquatch stories a bit more credibility.

As far as imaginary creatures go, they can look like anything you want them to look like. So long as you have an imagination that hasn't been dulled into conformity by popular pseudoscience. Back in the 1950s whenever anyone reported seeing a UFO or an alien there was a great deal of variety in these reports. Overtime as the myth spread across the world the tale became standardized, UFOs became flying saucers and aliens became "Greys". Prior to the emergence of a cultural idea of what an alien should be, the imagination of the individuals fabricating such stories was allowed to run wildly.

It's easy to graft old mythologies onto new mythologies, as neither is usually firmly rooted in facts or reality. Nearly all cultures around the world have some nebulous wildman story, be it the Sasquatches of British Columbia, Orang Pendek of Indonesia, or the feral wolf children of Europe.  In the case of the modern imagining of what Bigfoot looks like, we've merged an old North American wildman story with some late nineteenth century anthropology and a light dusting of white guilt. Essentially, we've crafted an image of giant bipedal ape that roams the the forest acting as a blood-thirsty environmentalist.

After reading a half dozen news reports on this story I'm yet to find any date that can firmly tell me that this particular mask was made prior to European contact. But, after seeing the mask myself I'm not really that interested anymore. It kinda looks like a ape, but it also kinda looks like a human. Given that such masks are typically stylized humanoids or animal-human hybrids, it's quite difficult to say that this particular mask has any features which are diagnostically unique to non-human apes. Now I'm beginning to think it looks like a dude in a parka.

It's nice that the folks who originally owned this mask got it back, but it doesn't really give us any new data on Bigfoot. I guess we'll just have to keep waiting for that.