An interview with Adam Van Arsdale
After my Q and A with paleoanthropologist Mica Glantz, I got a lot of great response -- people really liked reading about work in the field from somebody other than me!
So, I'm going to make these interviews a regular feature. When I was in Michigan last week, I got a chance to talk with Adam Van Arsdale, who graciously agreed to answer some questions about his work.
UPDATE(11/29/2007): After posting, I heard from a reader who reminded me that I omitted Adam's affiliation and info! Adam is a lecturer in anthropology at the University of Michigan. You can find out more about his interests on his webpage.
Hawks: You were lucky enough to work at one of today's most exciting paleoanthropological sites, Dmanisi. What can you tell us about your experience there?
Van Arsdale: Dmanisi is a wonderful place and I can't say enough positive things about the site and all the people I have worked with through the project. To begin, the site itself is just a nirvana for anyone with an interest in history or prehistory. The primary excavation area is in the middle of a ruined medieval citadel complex which rose to prominence as a trading town along the silk road; down from the promontory are the tombs of Mongols who sacked the city in the 12th century; further down are early Christian burials, and along the river are the remains of bath houses for travelers along the Silk Road. It is a literally a place where time seeps out of the ground.
Leaving the setting aside, the people associated with the project have been wonderful to work with. The size of the excavation team would vary but there would be times when, at the end of a long excavation day, I would find myself sitting at a long dinner table surrounded by 40 people speaking more than half a dozen languages. In the years I worked there as a graduate student I think we had students and researchers from 15 different countries (and I'm probably missing a few). Everyone who works at the site, including the local residents of Patara Dmanisi, adds their own character to the project. As a graduate student, my summers at Dmanisi served as something of a Paleoanthropology bootcamp, with regular discussions and debates between all of us with very different training and different theoretical perspectives on the issues of human evolution.
And then on top of all of this there are, of course, a remarkable set of fossils and archaeological materials.
Hawks: Do you want to give a shout-out to anybody in Georgia?
Van Arsdale: There are too many to name, but certainly David Lordkipanidze, who first invited me to Dmanisi in 2001, deserves recognition. I'll also add Gocha Kiladze, Teona Shelia and Dato Zhvania, who began working at Dmanisi in 1991 as students and who continue to play a significant role in the operation of the site today. One of the great things about the site is that it has served as a tremendous springboard for Georgian students interested in paleoanthropology. I think it is a safe bet we will be hearing a lot from our Georgian colleagues in the years ahead.
Hawks: Your dissertation work focused on the Dmanisi mandibles. I know that you still have publications coming out on these, so feel free to keep quiet about anything you're saving for print. What can you tell us about the sample?
Van Arsdale: The Dmanisi mandibles are a remarkable sample. They show a huge amount of morphological variation in a set of fossils derived from a temporally and geographically constrained set of deposits. One of the mandibles is in many characters the largest mandible assigned to the genus Homo. Two of the others are quite small, with variably large and small teeth. And the fourth specimen is one of the earliest edentulous mandibles in the hominid record. Given the current season, it is perhaps appropriate to describe the sample as a real cornucopia of variation. And the location and date of the site itself is surprising. Dated to 1.8 million years and about 2000 miles from the outlet of the rift valley in northeast Africa, the site is a long way from the contemporaneous and well-known deposits from the Turkana Basin in Kenya and Olduvai Gorge in Tanzania.
So how do we account for all this variation? That was basically the question of my dissertation. I sought to answer this question by testing a series of hypotheses focused first on sources of intraspecific variation, particularly age and sexual dimorphism, then secondarily on hypotheses of interspecific differentiation (i.e. multiple species). I then evaluated the results of these quantitative tests in the context of the comparative anatomy of the Dmanisi sample. Sparing you all the details, I think there are strong reasons to consider the Dmanisi hominid sample as that of a single species, but one displaying considerable amount of variation associated with age and possibly elevated levels of sexual dimorphism relative to what we observe in contemporary and recent human populations.
Hawks: Of course, your work required a lot of comparisons with other samples, and mandibles are among the most common skeletal elements represented in the fossil record. How did you handle your comparative work?
Van Arsdale: Paleoanthropology is at its root a comparative discipline. It is difficult to interpret any set of fossils outside of some comparative model. My work is no different. In asking questions about variation associated with age and sex, my dissertation is really asking how strange (or not strange) does the variation in the Dmanisi sample look if we treat it like a mixed age and sex sample of humans? Of chimpanzees? Of gorillas? Each of these species possess somewhat differing patterns of variation so that our final understanding of the Dmanisi specimens is based on a combination of similarities and differences with these different comparative models.
You can also try to understand the sample from the perspective of other fossils. These comparisons are more challenging because we have less certainty regarding the things we think we know about fossils. For example, in my dissertation I also make a series of comparisons between the Dmanisi mandibles and a sample of Australopithecus boisei mandibles from East Africa. It is much more difficult to say for certain whether any given fossil specimen is male or female, and in the absence of well preserved teeth, young or old. That uncertainty limits the power of the hypothesis tests we can bring to the question by limiting the amount of information we have to work with.
One of the exciting aspects of Paleoanthropology's comparative perspective is that new fossils give us new ways of looking at old fossils. Possibly the most exciting aspect of the Dmanisi fossils is that they provide us a tremendous platform from which to look back at these large samples from East and Southern Africa that we have known about for a long time and reexamine questions which had either previously been unanswerable or whose accepted answers no longer seem so clear.
Hawks: Any stories you can share about your travels?
Van Arsdale: One of the more unique experiences from my travels occurred while I was tagging along with a graduate student from Yale on her project involving 4.5 million year old fossil exposures in the Tugen Hills of the Central Rift Valley, Kenya. I was off on my own one day, walking along one of the exposures when I came across what appeared to be part of a fossilized crocodile skull just barely sticking out of the ground. I sat down and began very carefully exposing its boundaries so that it could be properly prepared and taken out. After about 20 minutes of this, a young Tugen boy came out of the bushes and sat down next me and began watching me work. I tried to say a few words of greeting in my very rudimentary Kiswahili, but either my pronunciation was too terrible to be understand (quite likely) or he was too young to have yet learned Kiswahili (he looked like he was between 8 and 10). After a few more minutes the boy, who had been carrying a small bow and set of arrows, took out one of his arrows and began using its steel tip as a mini-trowel. I would have discouraged him out of fear he might damage the fossil or go on trying to dig up other fossils in the area, but as I watched him he was exceedingly careful and seemed completely enraptured by the work. It was just one of those moments where, while the event was going on, I recognized how amazingly unique it was. Here we were, a graduate student from the University of Michigan with twenty plus years of formal education and a young Tugen boy with at most a few years of schooling, sitting side by side on a hillside in the middle of Kenya carefully exposing a 4.5 million year old fossil. The only common language between us was the action of my Marshalltown trowel and his handmade arrow point and a basic curiosity in this fossil.
Hawks: It's a story you hear from students a lot: teeth and mandibles are "bor-ing". But of course, they're the best representatives of variation we have through much of human evolution -- if you want to study evolution, you'll be studying jaws and teeth. What keeps these questions exciting for you?
Van Arsdale: One of the reasons I enjoy looking at mandibles and teeth are that they can potentially provide a window into numerous aspects of human evolution. As you point out, they are the most abundant element in the fossil record and therefore provide a large set of data with which to address questions of evolutionary relationships and evolutionary change. They can also tell you something about the ecology and diet of the individual specimen. Finally, they tell us something about how an organism develops throughout life and ages.
This also means that questions regarding variation in jaws and teeth can be difficult to answer because many different processes might account for the observed variations. When testing hypotheses about mandibular variation it is important to keep this in mind. It is always striking to me how many hominid type specimens are or have served at some time as type specimens for a new species. This is in part a reflection of their relative abundance, but I think it also reflects how difficult it is to adequately address all the potential sources of variation in mandibles. If you accept the conclusions of my research, the Dmanisi mandibles serve as a cautionary tale in this regard.
Hawks: Some readers may know that you and I share the same graduate advisor, Milford Wolpoff, who has certainly been a strong influence on the way I approach evolutionary questions. But I also find myself going back to other people who influenced my training. Who/what really got you interested in the field, or shaped the way you think about evolution?
Van Arsdale: I initially entered anthropology by happy circumstance. Entering college (Emory University) I was interested in majoring in both English Literature and Evolutionary Biology. My first year two things happened; I realized Emory's biology department was primarily focused on microbiology and full of pre-med students (something I was not interested in) and I took my first Anthropology course to fulfill a distribution requirement. I was immediately hooked. Here I could have the best of both worlds... an integrative approach towards understanding what it means to be human and a careful examination of the evolutionary processes which have shaped the pattern of human evolution. I owe a huge part of my perspective to Milford and the other faculty and students I worked with as a graduate student, but I don't think I fully realized the influence my undergraduate teachers had on my perspective till the AAA meetings last year when I was able to attend a session honoring the graduate advisor (Jack Kelso) of my undergraduate advisor (George Armelagos). I listened to talks by people I had never met, but with whom I share some of my academic phylogeny, and what I heard were familiar themes on the interaction of human biological and cultural processes. This bio-cultural perspective is something I carry with me from Emory and is evident in the approach I take towards questions of Pleistocene human evolution, where changes in human skeletal form cannot be understood outside of the context of our ever-expanding brains and the increasingly complex ways in which we interact with the people and environments around us. Now that I am teaching, it is something I am aware of when I am in front of the undergraduates in my own classes.
Hawks:Some of your current research involves a lot of genetic modeling. How did you get into this area? Can you tell us about some of your thoughts?
Van Arsdale: My interest in genetic modeling first began as an undergraduate. In part it reflects my status as an admitted math nerd. I like numbers, I like using computationally intense models and simulations to address specific hypotheses, and I like understanding how evolutionary and cultural processes interact in dynamic ways. But when I was an undergrad my interest in genetic models stemmed out of my interest in modern human origins and the belief that any really good model should be able to simultaneously explain the pattern of fossil, archaeological, and genetic evidence. At the time there was quite a bit of discussion not just about how the increasing amount of genetic data related to previously held understandings of the fossil and archaeological record, but also how compatible data from different genetic systems were with each other. In particular, data from non-recombinant genetic systems (mtDNA and parts of the Y-chromosome) seemed to provide a different picture of human evolution than data from recombinant genetic systems. My attempt to understand these differences is what really drew me into aspects of genetic modeling.
Since that time my interest genetic modeling has really developed out of what I consider an anthropological approach towards understanding genetic systems. I like to quote one of the take-away messages from the dissertation defense of another Michigan graduate, Keith Hunley, who modeled genetic aspects of South American population structure in his dissertation. As Keith said in his defense, what people do matters. Most genetic models are dependent on a variety of demographic parameters (population size, structure, etc.), all those things that people do. And yet most geneticists do not, or simply cannot directly address these demographic parameters with the data available to them. As a paleoanthropologist, one role my research serves is to provide better understandings of what people did and the ways in which they interacted in the past so as to better inform such genetic models.
On a more theoretical level I am very much interested in exploring how the unique ways in which humans shape and interact with our evolutionary landscape serves to structure genetic variation and the evolutionary forces which shape it.
Hawks: What's the next step for you? Where do you go from here with your research?
Van Arsdale: Most of the questions I am working on now reflect my current thinking that the basic pattern which characterizes Pleistocene human evolution; the complex interaction between increasing cultural complexity, expanding ecological niches, and basic anatomical changes (encephalization, dental reduction); establishes itself early in the Pleistocene if not prior than that. Essentially, that sometime around 2-2.5 million years ago a group of hominids stopped acting like bipedal apes (the Australopithecines) and started acting human. This basic human pattern then continued to develop and characterize Pleistocene hominids until about 10-20,000 years ago when we stopped acting like humans and started acting like domesticated humans.
By understanding how this pattern manifests itself early in the Pleistocene, for example, by considering how, why and with what changes human populations expanded into places like Southern Georgia as early as 1.8 million years ago, you can develop broader understandings of the Pleistocene as a whole. I am just finishing up two projects related to this broad topic, one examining the Habiline-Erectine transition in the Lower Pleistocene and another attempting to characterize broad demographic changes within the Pleistocene.
I also want to continue my involvement in paleoanthropological field work and would like to continue examining Plio-Pleistocene deposits in Western and Central Asia. Dmanisi is an incredible site and has provided a great amount of detailed evidence to address questions of human evolution from this time period. But the detailed picture it provides encompasses only a narrow range of time and space...the more we can expand that window the better we can understand the broad patterns of change which characterize humans in the Plio-Pleistocene.
An interview with Anne Weaver
I was surprised and delighted last week, when I got in the mail a copy of the new book, The Voyage of the Beetle.
It's what my daughter Sophie would call a "chapter book" -- a reimagining of Charles Darwin's Voyage of the Beagle as seen through the eyes of a beetle named Rosie. It starts with the real story of Darwin popping a beetle in his mouth, and proceeds along with his journeys and discoveries. Anyway, Sophie made off with it, so I guess Amazon's suggestion that the book's reading level is 9-12 years can extend to a bright 7-year-old.
The best treat is that the author, Anne Weaver, is an anthropologist! She's now working as a full-time writer in Santa Fe. She took her Ph.D. from the University of New Mexico and previously taught at Santa Fe Community College. Anne graciously agreed to answer some questions about her book and her earlier work on human brain evolution.
An interview with Mica Glantz
Last month, Johannes Krause and colleagues from the Max Planck Institute for Evolutionary Anthropology published mitochondrial DNA sequences from two Asian specimens. One, Teshik-Tash, is usually considered to be a Neandertal, based on its morphology. The other, a subadult individual from Okladnikov Cave in the Altai Mountains, is more fragmentary. The mtDNA sequences of both specimens cluster with European Neandertals.
I wrote to Michelle M. (Mica) Glantz to get a perspective on these finds, and to ask some broader questions about human evolution in central Asia. Mica is an associate professor in Anthropology at Colorado State University, where she researches human origins, specializing in Neandertals and culture-biology interactions. Her recent fieldwork has been in Central Asia, and she is right now on research leave in Kazakhstan.
Hawks: You're writing to us from Kazakhstan. What are you doing, and how's it going?
Glantz: I am writing you from an area that locals refer to as the "Texas" of Kazakhstan. The area is South Kazakhstan oblast, and we are in that province's capital city - Shymkent. It is the third largest city in terms of population in the country. Referred to as the Texas of Kazakhstan because of its similar geographic placement as that of our dear lone star state, but also because of the attitude of the people here. They are considered sort of 'cowboys'. It is also one of the most traditional areas of Kazakhstan, most folks speak Kazakh instead of Russian on the street -- this is very different from the rest of country, which is much more russified. What am I doing here? I applied for a Fulbright lecture/research grant last summer and received it. So, I am here teaching Human Origins and Variation at South Kazakhstan State University in the history/archaeology department. Next semester I will teach osteology and contemporary archaeological field methods. Kazakh universities really do not have anthropology as a discipline in the same way that it exists in the U.S. Archaeology is really culture history here and they consider anthropology to be what we think of as physical anthropology - but pre-Washburn anthropology. So, at first blush, most of my colleagues here believe I am interested in typology and straightforward categorization of human morphological features.
In terms of research, I am attempting to launch a new field project in the foothills of the Karatau mountains. These mountains run NW to SE and are a much older range than the Tien Shan, which you find directly to the south of the Karatau (they run east to west). From 1958-62, Alpisbaev, a Kazakh archaeologist, surveyed South Kazakhstan oblast for Paleolithic sites. He published a book on his findings in 1979. Only 2 of the 60-70 potential sites he identified were subsequently excavated and yielded Middle Paleolithic industries. It is my goal to relocate a handful of these sites and put some test trenches in and then from this initial work begin a new long-term project. My colleagues and I have identified two caves from Alpisbaev's map that look promising. I intend to survey and do preliminary excavations in April and May, and then do a more extensive exploration of one location from May to June with Kazakh students and handful from Colorado State. Those are the plans. I am working with my Uzbek colleague Rustam Suleimanov, who also teaches at South Kazakh State. We have many many challenges and obstacles to over come here before the research can really get off the ground.
The overarching theme of this work is to learn more about local hominin adaptations during the Middle Paleolithic. Of course, I am most interested in Neandertal paleobiology and whether this group existed in Central Asia in the same way that we know them from Europe (in terms of morphology and behavior). It has always been my position that it is rather simplistic to view Central Asia as the eastern outpost of the Neandertal range -- which has the unfortunate consequence of making the region peripheral to Europe and the Middle East and also diminishes the potential impact of hominin groups on the area who originated from the East.
Hawks: So, a couple of years ago you were presenting some work on Teshik-Tash. What is it? And ... What do you make of these new genetic results, connecting Teshik-Tash and another site (Okladnikov) to European Neandertals?
Glantz: For about four years now, I have been working on a reanalysis of Teshik-Tash. This project started as a Master's thesis (Terrence Ritzman, 2005). The idea to question the original taxonomic designation of Teshik-Tash was actually given to me by Milford Wolpoff, although other folks, like Weidenreich, also questioned whether Teshik-Tash was a Neandertal. Presently, Sheela Athreya, Terry and myself are working on what we hope is our final revision before publication in AJPA.
It has been a long road. The study is complicated by a number of factors that affect all of us that work with the record (incomplete specimens, too few specimens, on the specimens that exist -- the analogous morphological area is missing, etc.) but these problems are compounded by the fact that Teshik-Tash is a juvenile and we are not really conducting a growth study per se, but a comparison. One of our goals was to thoroughly examine the original Russian monograph (Gremyatskii, 1949) on the specimen to understand first-hand how the initial designation was made, and also to understand the ways in which Teshik-Tash has been reconstructed and if the reconstructions were sound. Another obstacle we have encountered is the entrenchment of the community of Paleolithic scholars that are interested in Neandertals, who are relatively wed to the idea of Teshik-Tash being a strong example of a European Neandertal -- this allows for easy support of the notion that Neandertals may have extended eastward to escape migrating modern humans as they moved into their core areas (Vishnyatsky, 1999) (I would be remiss to neglect mentioning that a number of other scenarios exist that explain the presence of Neandertals in Central Asia, but the one I mentioned above is the most irksome). Of course, this idea has been recently backed up by the Krause et al. (2007) study in Nature that compared mtDNA from Teshik-Tash and two specimens from Okladnikov Cave in southern Siberia to recent modern humans and the crew of Neandertals that have been sequenced. The major conclusion in this paper was that we can now move the Neandertal range 2000 miles farther east, because the Okladnikov juvenile sequenced as a Neandertal (although the adult did not -- but this is because it is geologically younger and could in fact be a modern human, according to the authors). Aside from the myriad of problems associated with mtDNA studies that you have outlined in your blog, I would like to make another observation related to Central Asia specifically. If we keep moving the Neandertal boundary eastward, then wouldn't Neandertals cease being a recognizable entity that is really separate from other archaic groups in the Old World during the Middle Paleolithic? In other words, who isn't a Neandertal in this case? Certainly we do not have enough similarly aged specimens from China and other points east to make thorough comparisons, but really the specimens we do have are usually not included in any of our analyses that are concerned with European Neandertals. Exceptions to this, like Rosenberg et al. (2006) study of Jinniushan, show that Asian specimens often look like they are part of the same cline as European Neandertals.
Our study of Teshik-Tash suggested that in a handful of linear measurements, Teshik-Tash more closely resembles Upper Paleolithic modern humans from Central Europe than European Neandertals. We do not use these results to exclaim therefore Teshik-Tash is a modern human, it certainly has enough discrete features that point to general archaic-ness to make that proposal seem unlikely. Instead, we wanted to emphasis that Central Asia and hominins that resided their during the Paleolithic, probably were part of a larger network of hominin groups that did not simply move in a west-east direction... I could go on and on here, but I have to stop myself.
Hawks: Of course, in historic times East and West were connected by the Silk Road. How far back can we trace connections across Central Asia?
Glantz: This is such an interesting question to me and one that I have thought about a lot. I think the answer can be gleaned from a good read of paleoclimatic studies of the region and how the Caspian and Aral Seas in the west and the Taklamakan desert and the high mountain zones of the east and south, respectively, have affected the exploitability of the region over time. In terms of topography, the mountain passes and valleys (Ferghana, etc.) that the ancient caravans traversed were viable options for Paleolithic migrations as well. Most of our evidence of Paleolithic occupation of the region comes from the foothills of the Tien Shan and Pamirs, close to all of the major Silk Road cities. Also, there is evidence of Middle Paleolithic folks in the areas that directly abut the Taklamakan in NW China. A potentially more significant area to examine for stratified sites, however, are the steppe/desert zones of Kazakhstan and Uzbekistan. We know very little about this vast area and sites there might be able to answer a number of questions about the region and its potential connections to the Russian Plains as well as southern Siberia. Also, from sites in this zone we might be able to get at why the foothills are relatively devoid of early UP sites.
Hawks: Was China its own story, or was it integrated in this network?
Glantz:I would argue that NW China, or Xianjiang province was definitely part of the Central Asian Middle Paleolithic, also probably Mongolia. But, I am not sure how to integrate the rest of China yet, because we have very different toolkits coming from those regions. I have no expertise studying the lithic record, but I have been told that there are some similarities between aspects of Early Pleistocene lithic assemblages from the Nihewan basin in China and those from the early Middle Pleistocene in Central Asia, namely Kul'dara from the Tajik depression. If these similarities are supportable, they may indicate that China was colonized by hominin moving out of Africa earlier than Central Asia and then these groups then moved into Central Asia after their initial expansion to north Asia. Interesting.
Hawks: I've been impressed by the recent archaeology coming out of Russia north of the Black Sea/Caspian Sea region. I'm thinking of Kostenki, Mamontovaya Kurya -- places that are geographically in between Central Asia and Europe. How does this region figure into the appearance of modern humans in Europe?
Glantz: I am also very interested in this area and the complexities of the lithic assemblages there. Certainly gives us a good window on Middle and Upper Paleolithic variability in this region. The lithic assemblages from Central Asia during the Middle Paleolithic appear to be less variable -- more homogenous across time.. and also Middle Paleolithic elements persist well into the Upper Paleolithic in the region. In fact no Upper Paleolithic traditions have been identified from the area that revival those from Kostenki. Don't know what to make of it, but OVERALL I am very hesitant to assume specific hominin group authorship for any assemblage, I just don't think biology and culture match up very clearly during this time.
Hawks: Any interesting stories you can relate?
Glantz: I have so many stories that are 'interesting', frustrating might be a better word. I am here with my family. My husband is actually Kazakh and was born here and we have two daughters (3 and 1). Even though I have enormous support from my husband's family and we have no problems with language, it still feels like we can spend three hours looking for a light bulb in the central market. Things just move at a different pace here.
Because the history/archaeology department here has no experience with biological anthropology, they made my course an elective (I have just recently come to understand this). What this means is that when I show up for my scheduled class (1 section on Tuesday and 1 section on Wednesday) I almost never have the same group of students. This is very disconcerting because I am never sure how to or what to teach. Recently I have been giving off the cuff lectures on things that I think are interesting, rather than try to teach in a linear framework. One time I gave a lecture in English without my Kazakh translator about primate discrete traits and wound up miming most of it, but it went over well and I found out the next week that they actually understood most of what I was trying to convey. Fieldwork presents another host of challenges, but I have been very lucky in the past and worked with very very good local scholars who are interested and committed to the project. So I am hoping for the best.
References:
Rosenberg KR, Zuné L, Ruff CB. 2006. Body size, proportions, and encephalization in a Middle Pleistocene archaic human from northern China. Proc Nat Acad Sci USA 103:3552-3556. doi:10.1073/pnas.0508681103
Krause J, Orlando L, Serre D, Viola B, Prüfer K, Ricards MP, Hublin J-J, Hänni C, Derevianko AP, Pääbo S. 2007. Neanderthals in central Asia and Siberia. Nature 449:902-904. doi:10.1038/nature06193
Vishnyatsky LB. 1999. The Paleolithic of Central Asia. J World Prehist 13:69-122. doi:10.1023/A:1022538427684
An interview with Michelle Drapeau
I've been trying to spread the interviews across the field in various directions. I (virtually) talked with Mica Glantz about Neandertals, Adam Van Arsdale about early Homo, and Anne Weaver about human brain evolution, all the australopithephiles in the readership are probably feeling neglected.
So I wrote to Michelle Drapeau, who was very generous in answering questions about her work on the anatomy of early hominids and her recent field work in Ethiopia. Michelle is on the faculty of the Université de Montréal, in the Department of Anthropology. She serves as co-director of field operations in the Bala Paleoanthropological Research Area of southern Ethiopia.
John Hawks Department of Anthropology
University of Wisconsin—Madison
Copyright © 2007 John Hawks