Osteology Everywhere: Aerial Ossicles

Last month I was flying down to New Orleans for the AAPA conference. I was excited to try authentic beignets & sazeracs, present new research, and catch up with colleagues. Midway through the flight I glanced out the window, not expecting to see much. But lo!

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Thankfully there wasn’t something on the wing. But there was something strange out there in the sparkle of sprawling city lights:

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What’s that I spy outside the city center?

A bit outside of the main jumble of street lamps appears to be a concentration of light superficially similar to an incus, one of the three auditory ossicles of the middle ear:

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Left: An osteologist’s nightmare at 20,000 feet. Right: Ear ossicles from White et al. (2012).

As a good mammal, there are three small bones inside your middle ear. These are fully formed at birth, and help transfer and amplify sound vibrations from your eardrum to your inner ear. It’s nuts. What’s even more nuts is that paleontologists and anatomists have figured out that the tiny, internal incus and malleus of mammals evolved from larger, external pieces of the jaws of our pre-mammalian ancestors. INSANITY!

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Cross section of a right ear, viewed from the front. Image credit.

Being so tiny, it’s not surprising that auditory ossicles are not often recovered from skeletal remains, and are pretty rare in the human fossil record. Nevertheless, some are known and their comparison with humans’ ossicles is pretty interesting. The oldest inci I know of are from SK 848 and SKW 18Australopithecus robustus fossils from Swartkrans in South Africa (Rak and Clarke, 1979; Quam et al., 2013). SK 848 is on the left in the set of images below:

Ossicles

Incus bones in three different views of SK 848, human chimpanzee, gorilla, sock puppet (left to right). Modified from Rak and Clarke, 1979.

SK 848 to differs from humans and African apes in looking more like a screaming sock puppet with a horn on the back of its head. Additional ossicles are known from South African australopithecines, including the older A. africanus from Sterkfontein (Quam et al., 2013). Interestingly, malleus of these hominins is very similar to that of humans, and Quam et al. (2013) think this ossicle may be one of the first bones in the entire skeleton to take on a human-like configuration during hominin evolution. Functionally, this may mean that the frequency range to which human ears are adapted may have appeared pretty early in our lineage as well (Quam et al., 2015).

Who’d’ve thunk we’d learn so much just from looking out an airplane window?

anthropology
ResearchBlogging.orgRead more!

Quam, R., de Ruiter, D., Masali, M., Arsuaga, J., Martinez, I., & Moggi-Cecchi, J. (2013). Early hominin auditory ossicles from South Africa Proceedings of the National Academy of Sciences, 110 (22), 8847-8851 DOI: 10.1073/pnas.1303375110

Quam, R., Martinez, I., Rosa, M., Bonmati, A., Lorenzo, C., de Ruiter, D., Moggi-Cecchi, J., Conde Valverde, M., Jarabo, P., Menter, C., Thackeray, J., & Arsuaga, J. (2015). Early hominin auditory capacities Science Advances, 1 (8) DOI: 10.1126/sciadv.1500355

Rak Y, & Clarke RJ (1979). Ear ossicle of australopithecus robustus. Nature, 279 (5708), 62-3 PMID: 377094

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Worst year in review

As we’re wrapping up what may be the worst year in recent global memory, especially geopolitically, let’s take a moment to review some more positive things that came up at Lawnchair in 2016.

Headed home

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Alternate subtitle: Go West
This was a quiet year on the blog, with only 18 posts compared with the roughly thirty per year in 2014-2015. The major reason for the silence was that I moved from Kazakhstan back to the US to join the Anthropology Department at Vassar College in New York. With all the movement there was  less time to blog. Much of the second half of 2016 was spent setting up the Biological Anthropology Lab at Vassar, which will focus on “virtual” anthropology, including 3D surface scanning…

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Cast of early Homo cranium KNM-ER 1470 and 3D surface scan made in the lab using an Artec Spider.

… and 3D printing.

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gibbon endocast, created from a CT scan using Avizo software and printed on a Zortrax M200.

This first semester stateside I reworked my ‘Intro to Bio Anthro’ and ‘Race’ courses, which I think went pretty well being presented to an American audience for the first time. The latter class examines human biological variation, situating empirical observations in modern and historical social contexts. This is an especially important class today as 2016 saw a rise in nationalist and racist movements across the globe. Just yesterday Sarah Zhang published an essay in The Atlantic titled, “Will the Alt-right peddle a new kind of racist genetics?” It’s a great read, and I’m pleased to say that in the Race class this semester, we addressed all of the various social and scientific issues that came up in that piece. Admittedly though, I’m dismayed that this scary question has to be raised at this point in time, but it’s important for scholars to address and publicize given our society’s tragically short and selective memory.

So the first semester went well, and next semester I’ll be teaching a seminar focused on Homo naledi and a mid-level course on the prehistory of Central Asia. The Homo naledi class will be lots of fun, as we’ll used 3D printouts of H. naledi and other hominin species to address questions in human evolution. The Central Asia class will be good prep for when I return to Kazakhstan next summer to continue the hunt for human fossils in the country.

Osteology is still everywhere

A recurring segment over the years has been “Osteology Everywhere,” in which I recount how something I’ve seen out and about reminds me of a certain bone or fossil. Five of the blog 18 posts this year were OAs, and four of these were fossiliferous: I saw …

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Anatomy terminology hidden in 3D block letters,

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Hominin canines in Kazakhstani baursaki cakes,

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The Ardipithecus ramidus ilium in Almaty,

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Homo naledi juvenile femur head in nutmeg,

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And a Homo erectus cranium on a Bangkok sidewalk. As I’m teaching a fossil-focused seminar next semester, OA will probably become increasingly about fossils, and I’ll probably get my students involved in the fun as well.

New discoveries and enduring questions

The most-read post on the blog this year was about the recovery of the oldest human Nuclear DNA, from the 450,000 year old Sima de los Huesos fossils. My 2013 prediction that nuclear DNA would conflict with mtDNA by showing these hominins to be closer to Neandertals than Denisovans was shown to be correct.

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These results are significant in part because they demonstrate one way that new insights can be gained from fossils that have been known for years. But more intriguingly, the ability of researchers to extract DNA from exceedingly old fossils suggests that this is only the tip of the iceberg.

The other major discoveries I covered this year were the capuchin monkeys who made stone tools and the possibility that living humans and extinct Neandertals share a common pattern of brain development.

Pride & Predator

An unrelated image from 2016 that makes me laugh.

The comparison between monkey-made and anthropogenic stone tools drives home the now dated fact that humans aren’t the only rock-modifiers. But the significance for the evolution of human tool use is less clear cut – what are the parallels (if any) in the motivation and modification of rocks between hominins and capuchins, who haven’t shared a common ancestor for tens of millions of years? I’m sure we’ll hear more on that in the coming years.

In the case of whether Neandertal brain development is like that of humans, I pointed out that new study’s results differ from previous research probably because of differences samples and methods. The only way to reconcile this issue is for the two teams of researchers, one based in Zurich and the other in Leipzig, to come together or for a third party to try their hand at the analysis. Maybe we’ll see this in 2017, maybe not.

There were other cool things in 2016 that I just didn’t get around to writing about, such as the publication of new Laetoli footprints with accompanying free 3D scans, new papers on Homo naledi that are in press in the Journal of Human Evolution, and new analysis of old Lucy (Australopithecus afarensis) fossils suggesting that she spent a lifetime climbing trees but may have sucked at it. But here’s hoping that 2017 tops 2016, on the blog, in the fossil record, and basically on Earth in general.

Osteology Everywhere: Skull in the Stone #FossilFriday edition

It’s that time of year again.

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It’s the end of the year and I’ve got Homo erectus on the brain somethin fierce. Our precedent-erect first popped up in Africa around 1.9 million years ago, quickly spread throughout much of the Old World, and persisted until perhaps as late as ~ 100,000 years ago in Java, Indonesia. This was a very successful species by all accounts, and as a result of its great range and duration, you can imagine it was also pretty variable.

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Hominin brain sizes. Boxes and whiskers represent sample tendencies and points are individual specimens. 1 = Australopithecus, 2 = Early Homo (cf. habilisrudolfensis), 3 = Dmanisi H. erectus, 4 = Early African H. erectus, 5 = Early Indonesian H. erectus, 6 = Chinese H. erectus, 7 = Later Indonesian H. erectus, 8 = modern humans.

Despite this great variation, H. erectus skulls generally share a common visage: long and low cranial vault, low forehead, protruding brow ridges, fun tuberosities and tori in the back. You’d recognize them anywhere. Including the sidewalk!

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Homo erectus in front of Ploenchit Tower, Bangkok (lateral view, front is to the right).

The relief in this sidewalk slat superficially looks like a trace fossil of partial H. erectus cranium, the face either missing (from the lower right) or taphonomically displaced toward the left side of the tile (see here for actual H. erectus trace fossils). This looks really similar to H. erectus from Indonesia, not surprising given its discovery in Thailand. Why, it could have come straight out of Figure 6 from a 2006 paper by Yousuke Kaifu and colleagues:

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Left lateral views of Javanese H. erectus crania, modestly modified from Kaifu et al. (2006: Fig. 6). Front is to the left this time.

Using my insane photo editing skills, I’ve inserted the Ploenchit Tower trace fossil (reversed) within the horde of heads presented by Kaifu et al., above. Like many of the real fossils, the Ploenchit specimen is missing the face (due to taphonomy), the supraorbital torus or brow ridge juts out from a low-rising forehead, and the occipital bone also projects out about from the otherwise rounded contour of the cranium. Note that there is a good deal of variation in each of these features among the real fossils.

What a happy holiday accident to find a Homo erectus cranium on the street!

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ResearchBlogging.org Reference
Kaifu Y, Aziz F, Indriati E, Jacob T, Kurniawan I, & Baba H (2008). Cranial morphology of Javanese Homo erectus: new evidence for continuous evolution, specialization, and terminal extinction. Journal of human evolution, 55 (4), 551-80 PMID: 18635247

The strange days of yore

Today is not like the good ol’ days. In many ways things have changed for the better. For instance, in the good ol’ days, many paleontologists would find fossils but let nary a soul examine them; today, you can download high quality 3D models of many important fossils from both East and South Africa, completely for free!

Robert Broom’s (1938) account of the discovery of the first Paranthropus (or Australopithecus) robustus is also a reminder of the strangeness of the bygone days of yore:

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Wait for it …

In June of this year a most important discovery was made. A schoolboy, Gert Terblanche, found in an outcrop of bone breccia near the top of a hill, a couple of miles from the Sterkfontein caves, much of the skull and lower jaw of a new type of anthropoid. Not realizing the value of the find, he damaged the specimen considerably in hammering it out of the rock. The palate with one molar tooth he gave to Mr. Barlow at Sterkfontein, from whom I obtained it. Recognizing that some of the teeth had recently been broken off, and that there must be other parts of the skull where the palate was found, I had to hunt up the schoolboy. I went to his home two miles off and found that he was at the school another two miles away, and his mother told me that he had four beautiful teeth with him. I naturally went to the school, and found the boy with four of what are perhaps the most valuable teeth in the world in his trouser pocket. He told me that there were more bits of the skull on the hillside. After school he took me to the place and I gathered every scrap I could find; and when these were later examined and cleaned and joined up, I found I had not only the nearly perfect palate with most of the teeth, but also practically the whole of the left side of the lower half of the skull and the nearly complete right lower jaw.

What a wild time – Broom hunts down poor Gert, barges into the school, then makes the kid show him where he hacked the skull out of the rock. Poor, poor Gertie.

Maybe it was a different Gertie, but surely the reaction was the same.

Maybe it was a different Gertie, but surely the reaction was the same.

Of course, there was a lot at stake. I mean, brazen Gert harbored not just “beautiful teeth,” but “the most valuable teeth in the world.” IN HIS TROUSERS! And of course Gert was also the soul possessor of priceless intel – the source of the fossils. So maybe Broom was justified in this zealous abduction. And O! such prose in a Nature paper! WAS IT WORTH IT, DR. BROOM?

At Sterkfontein, a bronzed Broom considers the weight of his actions.

At Sterkfontein, a bronzed Broom considers the weight of his actions.

Of course, Gert wasn’t the last kid to discover an important human fossil. The game-changing Australopithecus sediba  was discovered when Matthew Berger, son of famed Lee Berger and only 9 years old at the time, saw a piece of a clavicle sticking out of a block of breccia. Both Gert and Matthew show that you don’t have to be a doctor to make amazing discoveries. What future fossil discoveries will be made by kids, and making my adult accomplishments pale in comparison?!

Homo naledi in a lawn chair

It is a great relief that Homo naledi, a most curious critter, was announced to the world on Thursday. I’ve been working on these fossils since May 2014, and it was really hard to keep my trap shut about it for over a year.

Homo naledi on my mind, and phone, all year.

Homo naledi on my mind, and the lock screen on my phone, all year. CT rendering of cranium DH3, top is to the left and front is to the top.

I was in London for the ESHE conference last week when **it hit the fan, and so I got to attend a small press conference from the paper’s publisher, eLife, for the announcement.

eLife press conference last Thursday. From left to right: Will Harcourt-Smith, Matthew Skinner, Noel Cameron, Alia Gurtov and Tracy Kivell.

eLife press conference last Thursday. From left to right: friends and colleagues Will Harcourt-Smith, Matthew Skinner, Noel Cameron, Alia Gurtov and Tracy Kivell.

I had just flown in from Kazakhstan, and was presenting some recent work on the evolution of brain growth (I’ll write a post about it soon, promise), so it was a bit hard to appreciate the gravity of the announcement. Although the awesome spread in National Geographic did help it sink in a bit.

Really blurry photo of Markus Bastir holding up the heaviest copy of National Geographic ever.

I’m wending my way back to Kazakhstan now, but in the coming weeks I will try to post more about these fossils, the project, and specifically what I’m working on.

Until then, I’d like to point out how much information is freely and easily available to the entire world about these fossils. The paper, full-length and filled with excellent images of many of the specimens and reconstructions, is available for free online here. In addition, you can download 3D surface scans of over 80 of the original fossils on MorphoSource, also totally free. Everything about this scientific discovery and its dissemination is unprecedented – the sheer number of fossils and the ease of access with which literally everyone (well, with an internet connection) can access this information has never occurred before. This is the way paleoanthropology should be. Hats off to Lee Berger and the other senior scientists on the project for making such a monumental resource available to all.

ResearchBlogging.orgBerger LR, Hawks J, de Ruiter DJ, Churchill SE, Schmid P, Delezene LK, Kivell TL, Garvin HM, Williams SA, DeSilva JM, Skinner MM, Musiba CM, Cameron N, Holliday TW, Harcourt-Smith W, Ackermann RR, Bastir M, Bogin B, Bolter D, Brophy J, Cofran ZD, Congdon KA, Deane AS, Dembo M, Drapeau M, Elliott MC, Feuerriegel EM, Garcia-Martinez D, Green DJ, Gurtov A, Irish JD, Kruger A, Laird MF, Marchi D, Meyer MR, Nalla S, Negash EW, Orr CM, Radovcic D, Schroeder L, Scott JE, Throckmorton Z, Tocheri MW, VanSickle C, Walker CS, Wei P, & Zipfel B (2015). Homo naledi, a new species of the genus Homo from the Dinaledi Chamber, South Africa. eLife, 4 PMID: 26354291