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Tuesday, January 29, 2008

Zhe-Xi Luo Lecture Follow-up

As I mentioned a few days ago, Dr. Zhe-Xi Luo of the Carnegie Museum of Natural History gave two talks here yesterday, regarding paleontology in China. My apologies: first, I gave the wrong room # for his first talk, hopefully this didn't cause too much confusion. Second, when urging people to attend these lectures on mammalian origins, I neglected to mention monotremes and marsupials--hopefully I didn't offend any primitive-mammal-lovers.

Now to the lectures. The noon lecture was very interesting, and a bit more in depth than the evening talk. Luo discussed how fossil discoveries in China over the past few decades, but especially in the past 5-10 years, have addressed the issue of early mammalian diversity. He also discussed the discrepancy between molecular and fossil data, and ways to reconcile them (though I missed this important part because I had to go teach). His point was that there has been an incorrect notion that early mammals were not terribly diverse, and it wasn't until the extinction of the dinosaurs at the end of the Mesozoic that mammals were able to diversify ecologically, and therefore morphologically. Moreover, it was assumed that early, 'non-diversified' mammaliaformes were just generalized insectivores.

Recent discoveries in China, however, have revealed great diversity in Mesozoic mammals. Late Jurassic-early Triassic Docodonts display vertebral morphology similar to modern beavers and otters, and their appendicular skeleton apparently appears to have been adapted to swimming and digging, ultimately suggesting that around 200 Ma Docodont mammals occupied an aquatic niche. Late Cretaceous Fruitafossor had a 'primitive' mandible lined with peg-like, open-rooted teeth which apparently grew throughout life. Fruitafossor, at some 145 Ma, shows Mesozoic mammals occupied a niche similar to extant Xenarthrans (i.e. aardvarks). Repenomamus was a dog-sized carnivore/scavenger; there were even gliders comparable to modern flying squirrels. The point: Mesozoic mammals filled a variety of niches, alongside dinosaurs, and only in the past 5-6 years have we seen fossils showing the diversity that molecular studies have suggested. One interesting thing is that these Mesozoic mammals, like their dinosaur contemporaries, similarly suffered from the mass extinction at the end of the Cretaceous. So these fossils, at least what was presented, do not tell us about the common ancestor of modern mammals.

So, one important lesson coming from these talks is that convergent evolution is not uncommon in the organismal world, even in mammals. Of course, this isn't anything new: simply look at the convergence of forms of Australian marsupials with other placental mammals. The fact that convergence occurs, even though it's arguably not "parsimonious" has been recognized in paleoanthropology for a long time now, but it never hurts to repeat the lesson, especially when so many out there are still so reliant on parsimony, at the neglect of other data, for phylogenetic reconstruction. Also, Luo posited that molecules suggested earlier divergence than did the fossil record. This is symptomatic of two things: the sparseness of the fossil record, and the possibility (or probability?) that molecules are overestimating divergence times, at least with regard to morphological divergence. This interesting in light of recent genetic studies suggesting a hominin-chimpanzee divergence time of 4-5 Ma. I'm too out of it to get too much into it now, plus I have to go to class, but suffice it to say that perhaps chimpanzees aren't a good model for the last common ancestor of humans and chimps. Now I'm getting scatterbrain and am late for class. More organized and coherent thoughts on this later...

Monday, January 28, 2008

nostalgia

top things grad students spend their time doing:
1. complaining
2. drinking/making coffee
3. reading articles and immediately forgetting what they were about OR reading articles and not understanding anything in the entire article until the section "acknowledgements"
4. figuring out how many coffee cards you have from the coffee shop, and if you put them all together...can you get a free coffee? maybe if you had enough cards, they'd feel bad for you and give you the coffee anyway. i dont know, i haven't gotten to that point yet.
5. watching stupid things on the internets

as you can see...very little changes from being an undergrad to a grad student. except you can now say, "when i was in college..." indicating the past tense. and when you say it, you long so very much to be in college again. because college was easy. you never pulled all nighters, you never took too many classes, it was always sunny, and you barely remember the hell that was grad school applications.

Palaeontology Lectures

Ciao, ragazzi. Sorry for the late notice, but Chinese paleontologist Zhexi Luo is going to be speaking twice today (28 January) about Mesozoic mammals. At noon in room 1534 of the Natural History Museum, Luo will give a talk about aforesaid mammals (this might be intended for students and faculty?). At 8 pm in the 4th floor Rackham amphitheater he will give a talk entitled, "Palaeontology in China: Early Life to Feathered Dinosaurs and the Origins of Mammals." Everyone who loves life, especially placental life, should attend one or both of these. Sure, this isn't exactly anthropology, but being paleontological they should be informative and interesting to paleoanthropologists.
On a lighter note, I just returned from Tip-up-town 2008 in Houghton Lake, Michigan, and I can honestly say I learned two important life lessons. First, sometimes spin-tastic carnival rides make terrifying noises--noises that no machine should ever make in any circumstance--when it's freezing outside. But that doesn't necessarily mean that they imperil people's lives. More importantly, confidently asserting, "We're all gonna die" is "not funny," according to the mother of a bored-looking toddler sitting two cars behind me. Even though I was wrong in my claim, I think some good came out of it. If the lad did in fact hear and comprehend my pessimistic message, having survived the harrowing ordeal he probably has a new appreciation for life, as well as new dose of self-confidence.
Second, in Michigan it is a good idea not to move firewood, because it bugs some people. When I first read this message on a bumper-sticker, I marveled at human language. From a relatively finite number of meaningful sounds, people can construct myriad meaningful words; these words and sounds can further be combined into countless comprehensible conglomerations--even if the final products don't make sense. The italics are what I originally took away from the bumper sticker. But after doing a little research it turns out the sticker's message is part of a very important campaign. For Michigan trees are at risk of attack from the horrible Emerald Ash Borer (EAB), a voracious green beetle with an appetite for wreaking havoc on unsuspecting wood. Recent outbreaks have revealed the beetle's expanded its Wood War into the firewood theater. The point: moving firewood will spread the wildfire of EAB infestation. So, if you care about Michigan wildlife, do not move your firewood, even if your livelihood depends on it.

Friday, January 25, 2008

The Anthropocene

Jan Zalasiewicz and others at the Stratigraphy Commission of the Geological Society of London are initiating the naming of a new geologic age.

They are suggesting that human activities have changed the composition of ocean floors, altered the distribution and diversity of species, and altered the Earth's atmosphere enough to constitute a new geologic epoch: The Anthropocene.

What does this mean for the every day anthropologist?
Maybe the public will realize that "anthro" = people, and that anthropologists study people, and I won't have to answer any more questions about dinosaurs.

Thursday, January 24, 2008

Vegetarians are able to produce kids with brains

Archaeologist John Speth gave a very interesting Brown Bag presentation today entitled, "How important were large mammals, animal protein, and DHA in hominin evolution? 'Paleoanthropology still ain't heard the news'."

In it, he discussed why the aquatic theory that human evolution was driven by a need for DHA fatty acids for brain function was probably wrong. His reasoning was that if humans needed to consume DHA (which is found in seafoods) to get enough of it, then populations that didn't eat seafood would not have "proper" brains, which is of course not what is observed. This is where the title-quote about vegetarians comes in. It turns out many of the previous studies on humans producing DHA were done solely on males, and it wasn't until recently that females were studied as well. It turns out females are more efficient at bio-synthesizing DHA than males, and that DHA is stored in adipose tissues, which females tend to have more of.

So, does anyone know if this means I can stop buying expensive OJ with Omega-3's added in?

LCA: the new movement

hello,

if you're reading this, you probably know one of us. but just in case you don't (and since we hope to have an ever-expanding fan base), i wanted to introduce you to the lawn chair anthropology blog.

lawn chair anthropology is...

crystal aka "big chief" on drums
caroline aka "shirley" on bass
zach aka "tate" on some form of guitar
dana aka "danabag" doing the vocals
and
kristen aka "mumby" not doing anything musical, just kind of hanging around so that i can say "i know the band."

okay, we're not really a band. we're more like a group of overworked, underslept bioanthropology grad students at the university of michigan. we are all in the lab of milford wolpoff, who's kind of a big deal: http://www-personal.umich.edu/~wolpoff/

we are the co-founders of lawn chair anthropology, which will be a chronicle of the days in the life of a bunch of first year grad students. we live in a place much sweeter than the real world: the ivory tower. join us, and find out just what "lawn chair anthropology" really means.