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Friday, March 28, 2008

cartoon contradictions

i have a post that is in no way related to bones, hominids, or science. if you were expecting that, then you shouldn't read the rest of this, and should instead go read science or nature or something else. but given it's a friday, i think it's okay to be a little irreverent.

so i pose a series of questions related to disney cartoon characters that don't sit well with me:

in a cartoon featuring donald duck, he is shown as wearing a towel when coming out of the shower around his waist. YET given the fact that he does not wear pants, i just don't get it.












and what's more...if donald wears no pants, you might think this is just a cartoon thing. but then what about mickey?







and even if you accept the fact that mickey wears pants and donald does not (but wears a towel when coming out of the shower so must have some sense of propriety), what is up with goofy and pluto?


Both goofy and pluto are dogs. so then why is goofy anthropomorphic, yet pluto is relegated to fetching the newspaper and carrying around bones? it just doesn't add up.









is it because of the location of goofy's foramen magnum? is that why he is bipedal?




it's funny because i never thought of these things when i was eight. but when i was eight, i also built a fort under my bed. when my sister was eight, she ate potpourri because she thought it was candy. so who knows?


Friday, March 21, 2008

Road Trip!

In an attempt to gather data for our osteology project (and my hominid origins project), Bernie and I left Ann Arbor at 6:20am this morning to visit the Cleveland Museum of Natural History. After an uneventful drive, we reached the museum early and stood around looking at a juvenile tyrannus saurus rex exhibit. We started measuring pelves around 10:30ish, having been shown around and learning how to articulate a pelvis with rubber bands (size matters). We took a break for lunch at the museum cafe (which had much better food than certain osteology profs led us to believe). After lunch we met Owen Lovejoy and Bruce Latimer, who were also doing work in the museum today. They're funny guys. Lyman Jellema (another guy with a great sense of humor) showed us his electronic bone board (which inputs the measurements into an Excel file with the press of a button). Overall, it was a great visit. Then, on the ride home.... SNOW ATTACK!!!! From Toledo to Ann Arbor, nothing but snow/slush/ice. Lots of people were in ditches. But I survived and the car made it and so did we... although it took about 4 and a half hours instead of the usual three due to having to drive 20 mph most of the way.

I got home to find out that my sister finally made it onto a plane that took off (and will hopefully land shortly in Kansas).

Overall, good day.

leaving the ivory tower

a major criticism of the field of anthropology has been that it lacks practicality and a use in the "real world." this, of course, has been countered by development of the field of applied anthropology, with anthropologists using their research for purposes other than getting published. i fully support this shift from the ivory tower, and have always felt the purpose of pursuing a higher degree - for myself - would be to use it in a practical way.

in the past weeks, i have attended several talks that have taken components of anthropological work and applied them to improving the quality of life for people in different parts of the world. today, i had the opportunity to hear Dr. Jacob Songsore, a professor from the University of Ghana, speak about health conditions in major residential areas in Ghana. the research done by Dr. Songsore and his colleagues was focused on the greater accra metroplitan area (GAMA) of Ghana, one of its most populous areas, with 2.7 million residents. basically, the research drew from three major sources: community-based/local clinic records, reports from local medical practitioners, but more commonly pharmacists about which diseases were most common, and a community survey of "female homemakers," women who were basically taking care of those who were sick at home. from all of this research, certain proxy indicators were identified, and nine environmental risk areas were identified. the largest risk appeared to be access to potable water, with other risks including contamination of food, indoor/outdoor air pollution, and hygiene behaviors/access to medical services, among others. additionally, there are underlying population trends which the researchers found, including correlates with age, sex, race, wealth, knowledge of risks, and possibly, predispositions to different medical conditions.

it may seem a little obvious to state that this research found that the poor were most affected by all of these risk factors most. but someone else at the talk brought up an important point that i had overlooked - the fact that research like this has quantified such statements is important. health reports such as this one, linking environmental risk and access to care with economic status are extremely important. additionally, such reports highlight the effects of seasonality on the impact of diseases such as malaria, and the key problems such as poor drainage in communities that lead to accumulation of solid wastes and pools of still water where mosquitoes, which are the vector for malaria, may breed.

Dr. Songsore mentioned in his introduction that he would discuss "environmental justice," a seemingly elusive and vague term that even after this talk, i am positive i do not fully understand. but he and his colleages quantified it in an interesting way. they measured environmental justice in terms of "excess environmental burdens," calculating preventable fraction of environmental burdens, which could have been avoided, and thus, i think, being able to determine which fraction of such burdens could not be avoided by reasonable means. they found that 67% of Accra, a low to medium class region of GAMA, lived in areas that had excess mortality rates. it seems tragically, that the poorest populations have the least enviromental justice - the most environmental burden. thus, as i have found, Dr. Songsore makes it clear that disease and health conditions do not derive outside of the social context of the individuals being considered. as he stated, it is true that, "The poor stay sick and die young."

maybe this all seems obvious to you, that poorer groups of people tend to have it worse in terms of many conditions, such as health status. but what i think this discussion has made clear to me is that there is a place for anthropologists in the sufferings of people in our world. throwing money at the problem is clearly no solution. towards the end of his talk, Dr. Songsore said, upon coming to the United States, he still cannot believe that there are homeless people on the streets, and sick people with no access to medical care in the richest country in the world. there is a real disconnect here between the institution of medicine and medical practice, and ensuring people are actually treated and cared for. additionally, it seems to me that many international, or large-scale, medical initiatives that have been attempted to combat horrible diseases such as HIV and AIDS, are largely unsuccessful. and i really think this is because there must be a true understanding between caregiver and the receiver of that care.

perceived cultural boundaries can not hold us back from putting an end to suffering. as anthropologists, we have a duty, a responsibility, to serve the people from whom we gain so much - the populations we research, the field guides that help us to excavate our field sites, or the people that tell us their life stories which we later write into ethnographies. i grasp the value of academic work in the pursuit of knowledge. but for myself - not just as an anthropologist, but a human being - i do not think it is tolerable to engage in such work unless we uphold that sacred responsibility to our fellow wo/man. and given the troubled history that anthropology has had, it is the least we can do. but honestly, the least we can do is not nearly enough.

Thursday, March 20, 2008

The Little Hominin That Could (Fuel Publications)

Two and a half months into 2008 and we already have three (if not more) papers out about (or with bearing on) the diminutive Flores hominin material. Indeed, interested paleoanthropologists are like the "first family" at AL 333, and the papers an interesting catastrophic event that is burying us all (not that they're terribly bad, or anything).

As mentioned in an earlier post ("Cretins and Omomyids"), the past four years have borne witness to a huge debate on whether the 'Homo floresiensis' is a new species of insular dwarfed hominin, pathological early human or what. There is no doubt about the fact that the material from Liang Bua cave, dating to as recent as 12 ka, is small. What has been most hotly debated is the etiology of the unique features of the LB-1 skull, such as (From Brown et al. 2004):
  • Cranial capacity estimated ~400 cc
  • Reduced parietal lobe development in the brain (relative to H. sapiens)
  • Long, low cranial vault
  • Maximum cranial breadth just above the mastoids
  • Prominent nasal pillars
  • Mesially rotated mandibular P4s
  • Posteriorly inclined mandibular symphysis (i.e. no chin)
Arguably these traits distinguish LB1 from modern humans (although one of my mandibular premolars is fairly mesially rotated), and more closely aligns it with earlier Homo taxa, e.g. H. habilis/erectus. Last year, Hershkovitz et al. made a pretty strong case for many of these 'distinguishing' characters being the result of Laron syndrome.

The first floresiensis-related paper this year was Obendorf et al.'s diagnosis of myxoedematous cretinism. According to them, thyroid malfunction resulted in the anamolous Liang Bua morphology. Their basis for this diagnosis was what they perceived to be an enlarged pituitary fossa, based on a picture of a CT scan. Though interesting, this hypothesis was nevertheless blown out of the water, as many parties--many of whom have seen the actual specimen--denied existence of an enlarged pituitary fossa. Bummer there.

A few days later, Berger et al. reported on diminutive humans (dating to 3-0.9 ka)from caves on the island of Palau. Authors noted some similarities to the Liang Bua material. They suggested that, since their material is undoubtedly human, but similarly tiny like floresiensis, many of the unique features of floresiensis might really be a function of their diminutive size, and that new species designation might not be appropriate. Of course, most of the LB 1 anomalies are cranial, and Palau crania are not yet observable, so Palau, at the moment, has little bearing on Liang Bua (viz. LB 1 and 6).

Finally, Gordon et al. today published a paper in which they used craniometric morphology of LB 1 to establish its taxonomic affinities. Their analysis shows that LB 1 falls outside their human sample, and clusters well with H. erectus, in a broad sense, and to a lesser extent with H. habilis. Thus, contra those who posit that LB 1 is human, but unique because of pathology or pleiotropic effects of small size, Gordon et al. support the idea that LB 1 (and therefore, all diminutive Liang Bua hominins) represents a new species, derived from H. erectus or habilis (cf. African or Dmanisi erectines). Their compartive sample included 2500 modern human crania from all over the globe and 30 hominin crania.

I suppose that I have to take issue with the sample. Comparing LB 1 to modern human crania from all over the globe is a bit like comparing a 15 ka Javanese apple to a modern, international fruit basket (I admit I'm embellishing). On the other hand, comparing it to a wide diversity of human crania might be generous, as it increases the range of variation, making it easier for LB 1 to fit in. But they did not address the issue of pathology very well. They write:
With regard to microcephaly, it should be noted that in the shape analysis performed here, LB1 cranial shape is shown to differ significantly from the modern human comparative sample (and from fossil H. sapiens and Neanderthals) and to be very close in morphological space to non-Asian H. erectus specimens (D2700 and KNM-ER 3733). And H. habilis specimens (KNM-ER 1813 and OH 24). LB1 and the non-Asian H. erectus specimens are much closer than the average pairwise distance between modern human crania, and standardized residuals of LB1 from the estimated non-Asian H. erectus and H. habilis scaling relationshps average 1.38 and 1.21 standard deviations away from expected shape, respectively . . . well within the range of population-level variation (Table 1). Thus, if microcephaly is responsible for the extremely small size of the LB1 cranium, of all possible ways that microcephaly could cause LB1 cranial shape to differ from that modern humans and for these six variables, it happens to differ in the same way that earlier Homo species differ from modern humans [p. 4654].
Ok, so here they sort of test the hypothesis that LB 1 is craniometrically like a microcephalic by comparing it to a large sample of non-microcephalics--now that's comparing ancient apples to a Harry and David exotic fruit basket! To my knowledge, Argue et al. (2006) are the only ones to compare craniometrics of Liang Bua to any microcephalics. Their findings (see their Figs. 3 and 4) show that, as in the Gordon et al. study, LB 1 is most close to ER 3733 and OH 24. But, this study looks at only two microcephalics (though they compare LB 1 to these in separate analyses...), and these two individuals are on the extreme margins of a wide range of human variation. Moreover, there are myriad ways to be microcephalic, and it is unclear how different ways might affect craniometric variation.

That Gordon et al. and Argue et al. agree that LB 1 is craniometrically very similar to ER 3733 and OH 24 might not be insignificant. But Gordon et al. make the assumption that modern human microcephalics are craniometrically no different from non-pathological humans. While the Argue study suggests microcephalics might not be too different, they do show they are nonetheless on the outskirts of human variation (when also compared to fossil hominins...); moreover their microcephalic sample is very small. In order for Gordon et al. to reject microcephaly, they need to satisfactorily establish that microcephalics are not too different from humans cranimetrically. And that requires a larger sample of microcephalics. Hey, there's a handful of microcephalic skulls (get it--"handful," cuz they're micro...) in my lab, maybe I'll undertake this endeavor, after I get done with my billion other projects....

Anyway, apparently Hershkovitz et al. didn't officially settle the Liang Bua issue. It'll be interesting to see what Falk et al. bring to the table in Columbus in a few weeks. A never-ending saga . . .
References
Argue D, Donlon D, Groves C, and Wright R. 2006. Homo floresiensis: Microcephalic, pygmoid, Australopithecus, or Homo? J Hum Evol 51: 360-374.

Berger L, Churchill S, de Klerk B, Quinn R. 2008. Small-bodied humans from Palau, Micronesia. PLoS ONE 3: e1780

Brown P, Sutikna T, Morwood M, Soejono R, Jatmiko, Wayhu Saptomo E, Awe Due R. 2004. A new small-bodied hominin from the Late Pleistocene of Flores, Indonesia. Nature 431: 1055-1061.

Gordon A, Nevell L, Wood B. 2008. The Homo floresiensis cranium (LB1): Size, scaling and early Homo affinities. Proc Nat Acad Sci 105: 4650-4655.

Hershkovitz I, Kornreich L, Laron Z. 2007. Comparative skeletal features between Homo floresiensis and patients with primary growth hormone insensitivity (Laron Syndrome). Am J Phys Anthropol 134: 198-208.

Obendorf PJ, Oxnard CE and Kefford BJ, in press. Are the small human-like found on Flores human endemic cretins? Proc R Soc B xx: 1-10.

Monday, March 17, 2008

Why won't those Neandertals SHUT UP?!

I know, lame title. And since I don't read articles on my own, I am once again linking us to a Hawk's blog post because his summaries seem to be all I'm willing to skim.

However, this is a neat paradigm shift, and one I know a little about having written an arch 1 paper on this topic. It is now concluded by A LOT of people, that Neandertals DID have human-like language. Hawks even goes so far as to say "I do not see how anyone can maintain the hypothesis that Neandertals ... did not have language."

I'm willing to bet Richard Klein (long-time supporter of the silent neandertals hypothesis) will continue to argue for language being a human development, but the evidence (summarized by Hawks) seems to be against him.

My own opinion is that it seems like Neandertals had language, but I'm still unsure if we can make the jump to "human-like language" - I mean, we talk a lot. It seems difficult to identify what good evidence for human-like language would look like. And (unlike Hawks) I don't think that having a throat capable of language, using pigment and making decorative ornaments necessarily constitutes proof they talked like we do now. That assumes a mind change that may not be present - we just don't know. We also don't know why they used pigment or made decorations. Hawks plans to post more on the pigment evidence, so perhaps he will sway me (I admit I have not read much on pigment usage as evidence for language). But for now, I'm surprised everyone is willing to jump so quickly from one extreme (Neandertals were dumb) to another (Neandertals talked like we do today), without even considering that maybe they had some sort of intermediate language ability.

OK, everyone I took arch 1 with, this is where you should chime in and correct me b/c I'm sure I've forgotten some of this stuff we talked about last semester.

Also, don't forget to comment on Kristen's post about summer-reading, below.

shameless misuse of the blog

hey everyone,

so one day, i'm going to blog about david buss (which ps he came on MARCH 6th...yeah i am a slacker), but for now i am using the blog for my own selfish purposes. i am going to be here for most of the summer, and i am planning to read alot. does anyone have good stuff i can add to my list of things to read for summer?

Wednesday, March 12, 2008

Coming soon: "3.5 million years BC"

Did anybody else read this review of 10,000 BC on Hawk's blog? I haven't seen the movie, but some of these so-called reviews he quotes are hilarious/sad/make me want to become a hermit.

P.S. The joke in the title is not mine, it is stolen from Dave Pappano, who is planning a trilogy movie-series poking-fun at the 10,000 BC movie. For more info, read his blog, "Musings From the Ivory Tower" (see sidebar for link) where he will shortly be detailing this filming-plan of his.

P.P.S. Folks (not including zach), we need to post on here more... did you know we got in a minor car accident road tripping to MSU TWO WEEKS AGO? What about the variety of lectures people have attended? (especially the ones I haven't gone to... somebody please post about those - Buss, Flannery...). If necessary, I can post about more TV shows, but most of them aren't as intelligent-ish as my last one. Come on, I know you aren't always taking notes in class!

P.P.P.S. Please note that the last postscript was directed at myself too, so please don't hate me.

Sunday, March 9, 2008

Spring forward, but don't touch your Molecular Clock

Today we switch out of Daylight Savings time, so don't forget to set your clocks ahead one hour (though most phones and computers do that automatically). But make sure the only clock you change is the one by your bed whose volume knob fell off and that wakes you up every morning to the classic "Kiss on My List," such that you wake up every morning to greet the new worst day of your life.


New dates have been published for TM 266, the Sahelanthropus tchadensis cranium (aka "Toumai"). The Sahelanthropus material was originally dated to 7 and 6 Ma, based on comparison of the TM 266 fauna to that of the Kenyan sites of Lothagam and Lukeino, respectively (1). The new dates are more "absolute," based on atmospheric beryllium-10 (10Be), and give a date of 7.2-6.8 Ma (2). I don't know the history or accuracy of cosmogenic beryllium dating (I'm more familiar with our friends Potassium and Argon), but the technique appears fairly widely used, and the fact that the radiometric date corroborates the faunal estimate suggests TM 266 is truly about 7 Ma.

Which is all well and good. I can accept that Sahelanthropus is about 7 Ma, but I'm less comfortable with the idea that 'the earliest hominind is 7 Ma' (cf. refs 1, 2). Here's the final paragraph of the new paper's discussion:
The radiochronological data concerning Sahelanthropus tchadensis . . . reported here is an important cornerstone both for establishing the earliest stages of hominid evolution and for new calibrations of the molecular clock. Thus, Sahelanthropus tchadensis testifies that the last divergence between chimps and humans is certainly not much more recent than 8 Ma, which is congruent with Chororapithecus abyssinicus, the new 10-Ma-old Ethiopian paleogorillid.... With its mosaic of plesiomorphic and apomorphic characters S[.] tchadensis, the earliest known hominid . . . is probably very close in time to this divergence contrary to the unlikely "provocative explanation," which recently suggested a "possible hybridization in the human-chimp lineage before finally separating less than 6.3 Ma [quoting ref 3]." (2, p. 3230-3231)
Is a recalibration of the molecular clock really necessary? The "molecular clock" is a way of figuring out when lineages (i.e. species) diverged. Assuming a constant rate of neutral mutation, the genetic differences between two lineages (say, humans and mice) can be compared to the fossil dates of their divergence. This allows one to determine the (again, assumed to be) constant rate of genetic change between lineages. Because fossils (arguably) don't give us a good picture of the human-chimp divergence, the molecular clock is used to determine when humans and chimps split, or when the hominins first emerged.

But these molecular estimates have a large range. Moreover, estimates haven't been as early as 7 Ma in a while. The most recent ones I've read put our divergence at about 6.3-5.4 Ma (3) and as late as 4.1 (4). I have no problem with these dates, although the latter date is a bit troubling, as we've got (arguably) unequivocal bipeds (read, "hominins") at 4.2 Ma with Australopithecus anamensis. But recalibration of the divergence date rests on the claim that Sahelanthropus was a biped (again, read "hominin"). Though apparently many in paleoanthropology accept TM 266 as a basal hominin, the case is not terribly strong that it's anything other than a Late Miocene ape (read "probably not a hominin") (5). So recalibrating the clock based on TM 266 at this point would be hasty, if not simply incorrect. Moreover, as John Hawks pointed out, pushing the human-chimp divergence back to 7 Ma would put the divergence of the human and orangutan lineages in the Oligocene (~33 Ma), which is absolutely unsupported by the fossil record (see ref. 4).

The point: Having current absolute dates for hominin fossils is always good. But recalibration of the molecular clock based on TM 266, at least at this juncture, is not only unnecessary but also is most probably incorrect.

Oh, the paper also dated the Au. bahrelgazali site (KT 12) to 3.5 Ma. But, then, we already know there's all sorts of crap running around--we've got bipedal hominins, after all--in Africa at 3.5 Ma.

References
1. Brunet M et al. 2002. A new hominid from the Upper Miocene of Chad, Central Africa. Nature 418: 145-151.
2. Lebatard et al. 2008. Cosmogenic nuclide dating of Sahelanthropus tchadensis and Australopithecus bahrelghazali: Mio-Pliocene hominids from Chad. Proc Nat Acad Sci 105: 3226-3231.
3. Patterson N et al. 2006. Genetic evidence for complex speciation of humans and chimpanzees. Nature 441: 1103-1108.
4. Hobolth A et al. 2007. Genomic relationships and speciation times of human, chimpanzee, and gorilla inferred from a coalescent hidden Markov model. PLoS Genet 3: 294-304.
5. Wolpoff M et al. 2006. An ape or the ape: Is the Toumai cranium TM 266 a hominid? Paleoanthropol 4: 36-50.

Wednesday, March 5, 2008

A Tale of Two Lineages

[Hey, I'll bet I'm the first person to make that allusion...]
In a paper published in JHE today, M. Schillaci posits that human facial anatomy suggests the existence of two human lineages in the late Pleistocene. Schillaci's analysis reveals that faces of early Australasian crania (40-8 ka) are very similar to those of Levantine specimens Skhul 5, Qafzeh 6 and Qafzeh (100-90 ka). The overall results of the study suggest that the Australasian and Levantine populations share an earlier common ancestor than modern humans, including Upper Paleolithic Europeans. Schillaci interprets this to mean that modern humans first dispersed from Africa around 100 ka, long before the supposed "revolution" of Paleolithic Europe, and made it as far as Australia; second dispersal then occurred some 50 ka later.

The article brings up the issue of Out-of-Africa (Replacement) vs. Multiregional models, but does not clearly come out directly in favor of either one. But by setting up a scenario in which two human lineages are present throughout the Old World in the last 100 ka, the possibility is opened up for these lineages to accrue genetic differences simply by drift or even by selection, then to come into contact again and admix, and for the "archaic" genes to be incorporated into the newer (and modern) genome (introgressive hybridization; cf Evans et al. 2006, Garrigan and Kingan 2007, Hawks and Cochran 2006).

Schillaci does note that the Levantine sample
exhibits a slightly closer genetic relationship to Neandertals (d=0.7318) than to Upper Paleolithic Europeans (d=0.7483). . . . This observed relationship is probably not the result of phenotypic convergence, and likely reflects a slightly more recent common ancestry and/or perhaps hybridization between early modern humans and Neandertals (Trinkaus, 2007). (p. 6)
However, he later notes,
In the present study, the relationship between early modern humans from the Levant and early Australasians (d=0.348) is more than 2.1 times closer than between early modern humans and Neandertals (d=0.7318), and Neandertals do not show a close relationship with early Australasians (d=1.2615). If the observed relationship between Neandertals and early modern humans is the product of hybridization, there is no craniometric evidence indicating that there was substantial introgression of Neandertal alleles into the dispersing modern human population... (p. 7)
Can Schillaci make these claims about "genetic relationship[s]" based on his data? Let's look at the opening line of the abstract: "This study examines the genetic affinities of various modern human groupings using a multivariate analysis of morphometric data." A rewording might be: This study examines the craniofacial affinities of various modern human groupings, and to thereby infer genetic relationships. Basically, Schillaci assumes that genetic relationships between populations are accurately reflected in facial anatomy, a bold statement to make. Indeed, he acknowledges the problems with this assumption, but also cites studies (which I haven't yet read) suggest that craniometric variation in humans throughout the world fits a neutral model of genetic variation. So, Schillaci talks about genetic relationships throughout the paper, but these aren't based on actual genetic data, but rather inferences from craniometric data--quite confusing. His aforementioned lack of evidence for introgression between neandertals and early modern humans does not preclude real genetic evidence for introgression (cf. what I cf-ed above.)

What I care about: the study allows for, and possibly corroborates, a Multiregional model of human evolution (of course, what I really care about is the possibility of such a model prior to, and in the early stages of, the genus Homo). Hey, I guess old-school craniometrics hasn't outlived its usefulness in physical anthropology.

References
Evans PD et al. 2006. Evidence that the adaptive allele of the brain size gene microcephalin introgressed into Homo sapiens from an archaic Homo lineage. Proc Nat Acad Sci 103(48): 18178-18183.

Garrigan D and SB Kingan. 2007. Archaic Human Admixture. Curr Anthropol 48(6): 895-902.

Hawks J and GM Cochran. 2006. Dynamics of adaptive introgression from archaic to modern humans. Paleoanthropol 4: 101-115.

Schillaci M, in press. Human cranial diversity and evidence for an ancient lineage of modern humans. J Hum Evol xx: 1-13.

Cretins and Omomyids

What's new in the world of Paleoanthropology?

The first bit of news is older than dirt: Christopher Beard reports in the 11 March issue of PNAS on new evidence of the earliest primates in North America around the time of the Paleocene, some 60-55 Ma. Fossil teeth discovered in Mississippi have been allocated to a new species, Teilhardina magnoliana, arguably the most primitive Teilhardina in North America or Europe. Beard argues this suggests that, contrary to current understanding of euprimate dispersal, early omomyids colonized North America around the Paleocene-Eocene Thermal Maximum via a Bering Strait land bridge. Possibly, these early critters thence colonized Europe. Pretty neat stuff: early primate forebears disperse from Asia to N. America, and some 55 Ma later modern humans follow their tiny footsteps. I don't know very much about primate origins (my interests like some 50 Ma after this event), but it's always nice to have a reason to say "omomyid" or "omomyiform."

Next, one of the most sensational paleoanthropological news bits, the famed hobbit, is back in the spotlight, in a paper in the Proceedings of the Royal Academy B. Recall that when the Flores hominin material was first reported about five years ago, it was argued to be a new species of an insular-dwarfed erectus-like hominin: Homo floresiensis. Others later argued that the Liang Bua material was pathological (i.e. microcephalic dwarf) H. sapiens. Most recently, Hershkovitz et al. made a pretty convincing case that the LB 1 was a modern human with Laron Syndrome, a pituitary disease. Their case is pretty strong, but the most troubling evidence, in my mind, against a pathological human is the fact that the diminutive Liang Bua specimens are very small and span a period of thousands of years. I look forward to Falk et al.'s presentation at the AAPAs in April ("LB1 did not have Laron Syndrome").

But the new Obendorf et al. paper gives the hobbit a new diagnosis: "myxoedematous cretinism." Thus, the diminutive stature and small brain of LB1, Obendorf and team hypothesize, is due to a non-functioning thyroid. Support for their hypothesis comes from, among other things, the enlarged pituitary fossa of the LB1 sphenoid and the morphology of the LB1 trapezoid. I must admit now that I have not yet read the entire paper (I have to teach in 10 minutes) but the paper looks interesting, and I am interested in how they propose to explain how only the "cretins" were preserved in Liang Bua cave, while non-pathological humans were not. The paper also reminds me of Dobson's (1998) paper that suggested that the thyroid and iodine deficiency were responsible for the anatomical differences between humans (as we generally know them today) and neandertals. I guess the evolutionary significance of the thyroid is really beginning to be appreciated by anthropologists...

Given this new diagnosis for LB1 and others, what might be interesting is a Bayesian approach to testing these hypotheses. Which hypothesis (diagnosis) is most likely given the data--new species, microcephalic or microcephalic dwarf H. sapiens, human with Laron Syndrome, or human cretin? Or, under which hypothesis(-es) are the observed data the most likely? The new diagnosis for the Liang Bua material is interesting and certainly provides good research questions. But, as is usually the case with fossil hominins, what would be really nice are more specimens against which to test our hypotheses.

References
Beard C. 2008. The oldest North American primate and mammalian biogeography during the Paleocene-Eocene Thermal Maximum. Proc Nat Acad Sci 105: 3815-3818.

Obendorf PJ, Oxnard CE and Kefford BJ, in press. Are the small human-like found on Flores human endemic cretins? Proc R Soc B xx: 1-10.

Tuesday, March 4, 2008

"Spring" Break TV

Spring break, even if it takes place in February, is not a time for being productive. I took this to heart last week as I caught up on zoning out in front of the TV. But it wasn't all Sabrina the Teenage Witch reruns for this girl: I also caught bits and pieces of two fairly interesting Nova episodes on PBS, "The Four-Winged Dinosaur" and "Ape Genius".

"The Four-Winged Dinosaur"
I'll admit, I'm not as fascinated by dinosaurs as some in this lab, so this episode did not hold my interest for the entire hour. However, I came in toward the end and was fascinated to discover that amidst scenes from "Jurassic Park", they were interviewing a real scientist who actually is trying to breed dinosaurs! The entire episode (or so I gathered) looked at how birds evolved from dinosaurs. They took a bird embryo, and injected it with a virus that would attack the DNA and turn on previously turned off genes, including one that apparently coded for the bird to grow teeth in its beak. But the bird embryo with a beak-full of teeth was not the coolest part. Next they tried to create an emu-asaurus! They didn't actually manage this, but the Nova voice-over talked us through the technique of how it could be possible to turn an emu egg into an emu-like dinosaur. To quote a friend, "haven't they seen Jurassic Park? Don't they know how that turns out??" All I know, is that if they ever manage to recreate dinosaurs, they should avoid breeding raptors - those guys in the movie are SCARY!

"Ape Genius"
This episode aired a while ago, but unfortunately I missed it the first time around. Thank god for reruns! This episode, which I actually watched most of, looked at what apes were and were not capable of doing in terms of communicating, learning, and working together (all those traits people try to describe as culture). I don't have any profound conclusions about this episode, but I found a number of the experiments they did interesting and will describe a few of them here.
  • Will two chimps work together to get and then share food? The animals had to both pull a string at the same time to get a long plate of food close enough to their cages to eat. Results: if the food was split already, the chimps would work together and each take their share. If the food was not split up, the chimps would usually start fighting and not get the food close enough to reach. If the apes were bonobos, they worked together and shared their food without problems.
  • Do chimps understand the value of an M&M? A trainer puts 7 M&Ms in one bowl and 2 in another, and whichever bowl the chimp points to, a second chimp gets those M&Ms. The first chimp gets the bowl he doesn't point to. Results: Even after multiple trials, the chimp still points first to the bowl with the most M&Ms, and thus does not get them.
  • Do human children understand the value of a gummy bear? Similar to the above test, in this one an adult explains to a 4-year-old that the one gummy bear in front of them is theirs to eat, but if they wait until the adult leaves and comes back, then they get the entire package of gummy bears. In most cases, the child ate the one gummy bear and did not get the package (these tapes were adorable to watch, by the way).
  • Do chimps understand numbers? A chimp is taught, using dots, the numbers 1-9. Then the previous chimp experiment (the one with the M&Ms) is repeated using numbers instead of M&Ms (introducing a symbolic element). In this case, the chimp learns to point to the lower number, and thus receives more M&Ms. However, the voice-over points out that chimps in the wild do not develop symbols on their own, they are just able to understand some of them when humans teach them.
  • Will bonobos protect or share outside of their own family group? A dead bonobo that is a stranger to a group of live bonobos is placed in the live bonobos' habitat. Humans with long poles use the sticks to "attack" the dead bonobo. Result: the live bonobos shriek and try to protect the dead bonobo from the offending poles, even though they did not know the bonobo in life.
These were just a few of the interesting experiments compiled in this episode. If you ever catch the rerun of either of these, they might be worth checking out! Next up, a post about all the crappy TV I also watched over break... or maybe I'll just keep that to myself.