The latest on Homo naledi

Relatively complete skeletons from early human ancestors typically generate a ton of buzz in the popular media. None, however, has generated as much in the last 10 years as the finds of Homo naledi. The remains of at least 15 individuals have been unearthed within the Rising Star Cave System in South Africa since its discovery by cavers in 2013. In 2017, an additional three individuals were announced from a separate chamber in the cave. The finds show an interesting, and perplexing, mixture of traits that recall everything from Homo habilis to H. erectus and even Australopithecus.

Last fall, the President of our Student Anthropological Society here at UNCG, Cory Henderson (who was recently accepted to graduate school at Penn State), asked me if I could get in touch with a friend of mine, Dr. Zach Throckmorton, who is a member of the Rising Star team, to talk about Homo naledi. Zach generously agreed, and on Friday, April 7th the Department of Anthropology and Student Anthropological Society at UNCG hosted Zach and another Rising Star researcher, Dr. Chris Walker. The background to the Rising Star discovery and the rapid fire, open-access approach to research dissemination are well documented and controversial, and I'll leave it to the reader to delve into those issues. Here, I'll just summarize what I found to be particularly intriguing. First up was Zach, who is an expert on feet and discussed the post-cranial anatomy:

• H. naledi has long thumbs, just like modern humans (this is one of the features that gives us the ability to precisely manipulate objects with our hands). However, the fingers are somewhat curved.
• The torsion, or twisting, of the humeral shaft relative to the humeral head is odd in that it falls within a range of modern monkeys. 
• The lower limb, including the foot, appears to be more-or-less modern human-like. However, H. naledi was small--Zach estimates that the complete foot would have fit into a size 3 shoe. 
• So, overall, the upper limbs retain some features that may be adaptations for climbing, while the lower limbs share many similarities to modern humans. 

Chris followed with a discussion of growth and development in H. naledi:

• A majority (eight out of thirteen, to be exact) of the individuals from the cave for which age can be determined are juveniles. Most of the complete long bones are also from juveniles. 
• Based on the dental data, it seems that H. naledi followed a modern-human like growth trajectory. 
• The legs are very long relative to body size (which was pretty small, perhaps 147 cm and around 45 kg), but the intermembral index is human-like. This means that H. naledi had longer legs than would be expected for a hominin of its body size but they are not longer relative to their arm length than would be expected for a modern human. Such long legs may be an adaptation for efficient terrestrial bipedalism. 

The anatomy of H. naledi, and the provocative interpretation put forward by the Rising Star team for the assemblage's origin (the intentional disposal of the cadavers within the cave by other hominins), was even more puzzling because no one knew how old the fossils were. Based on their morphology, some estimated the fossils to be early Pleistocene in age (perhaps one or two million years old). A colleague who has seen the bones first hand told me that they didn't appear to be fossilized, which is difficult to accommodate with such an ancient date. Earlier this year the Rising Star team announced a much younger date of ~300,000 years. While deliberate placement of the bodies in the cave is perhaps more easily reconciled with a younger age, the brain size (less than half the size of a modern human) and the complexities of cave geology make this hypothesis far from demonstrated. Either way, this is extremely interesting, and I am looking forward to seeing where it goes...

Patricia Wright, girl power, and lemur conservation

Phi Beta Kappa is the oldest honor society for liberal arts and sciences in the U.S., and their Visiting Scholars Program helps fund visits by leading scholars to institutions across the country. Our department head, Bob Anemone, applied for one of these awards in order to bring Patricia Wright to UNCG. Dr. Wright is a world expert on lemurs and has dedicated her incredible career to conserving this unique group of primates.

Dr. Wright spent a couple days in Greensboro. On Monday, April 10th she had lunch with our anthropology undergraduates and, later that evening, gave a public lecture on her conservation work in Madagascar entitled "Back from the Brink of Extinction: Saving the Lemurs of Madagascar." I couldn't attend this presentation, but those who did said it was incredibly inspiring. The Greensboro Science Center then hosted a showing of her film Island of Lemurs: Madagascar on Tuesday evening. Unfortunately, I couldn't fit this in either, but sandwiched in between was a RISE sponsored lunch with Dr. Wright that I did attend. It was an intimate event in which she discussed her early years in primatology and her recent research with lemurs.

Her early years in primatology are documented in High Moon over the Amazon: My Quest to Understand the Monkeys of the Night, so I'll just touch on a couple of events. Her first encounter with a primate occurred in 1968 when she and her husband Jaime ran into a pet shop during a New York rainstorm. Within, they saw, and fell in love with, an owl monkey. They bought it for $40 and quickly learned that almost nothing was known about this species. (Dr. Wright was very aware of the irony of purchasing a primate as a pet given her later career choices). They learned, too, that monkeys do not make great pets and that perhaps their owl monkey needed a companion. So, they eventually traveled down to Colombia in 1971 to do just that.

Dr. Wright continued to study the owl monkey and discovered that males are heavily involved in infant care, a finding that was very different from what was known among other primates. This led her to wonder: how did parental care evolve? She was determined to study owl monkeys in the wild, and after a great deal of persistence and some encounters with several individuals both within and outside of academia (including one with Mrs. Nancy Mulligan, a wildlife enthusiast whose husband was an early investor in George Eastman's Kodak company--we all know how that turned out), she eventually received funding and an affiliation as an adjunct researcher at the New School for Social Research to work in Peru. The rest, as they say, is history: Dr. Wright completed ground-breaking work with owl monkeys and eventually began studying lemurs.

Among her most intriguing findings is that females rule the roost in lemur societies, and they enforce this dominance over males with violence. Dr. Wright related several rather humorous anecdotes of female lemurs walking up to males and literally beating them away from prime feeding locations. Given that females feed and carry the offspring, it makes sense that they would make every effort to secure priority when it comes to food. Why, then, Dr. Wright asked, keep the males around at all when females are not sexually receptive? After all, they don't help with infant care and compete with females for food. She doesn't know for sure, but one suggestion is that males provide a useful predator alarm and deterrence system. Another interesting issue is the ability of females to exert dominance over males in the absence of strong sexual dimorphism (females are no larger or stronger than males).

A couple of other observations that Dr. Wright and her colleagues have made over the years include "day cares" among black and white ruffed lemurs (females will leave their offspring in communal nests and go off, sometimes for hours at a time, to feed) and the formation of brain plaque among lemurs with heavily processed diets and a sedentary lifestyle (sound familiar?).

I did get a chance during her busy schedule to speak one-on-one with Dr. Wright. As the father of a four-year-old, I was particularly interested to hear that she had brought her then-young daughter into the field. I have begun to think seriously about bringing my son to Armenia or Tanzania in the next year or so, and Dr. Wright reported that the experience with her daughter in the field was wonderful.

Society for American Archaeology meetings 2017

This year's Society for American Archaeology meetings were held in Vancouver, British Columbia from March 29th to April 2nd. I flew into town on Thursday night (the 30th) and had to run out on Saturday night. It was a whirlwind trip for me, as I presented a paper, co-chaired a special session, and supervised two undergraduate researchers who also presented at the meetings. As always, there was too much going on to see everything that was of interest, but I'll present my highlights:

• Way back in June 2016 I was invited by Karen Ruebens to contribute a paper to a symposium entitled "Connecting Middle Paleolithic Datasets: the Interplay of Zooarchaeological and Lithic Data for Unraveling Neanderthal Behavior," which was co-organized by Geoff Smith, Theresa Steele, and Tamara Dogandzic. Around that time I was reading an interesting paper by Marie-Cécile Soulier and Eugène Morin about the use of cutmark orientation to reconstruct planning depth in the Paleolithic, and this sparked my interest because, in 2014, we published a paper suggesting that cutmark orientation might be used to identify the skill level of prehistoric butchers. So, I thought the symposium would be a great venue to explore this issue further and I happily agreed to participate. The paper I presented with my colleagues Chris Nicholson, Kevin Covell, Robert Sanderford, Kristen Welch, and Metin Eren "Cutmarks, Lithics, and the Identification of Skill and Tool Utility in Experimental and Middle Paleolithic Contexts," turned out to be slightly different than what I had originally submitted in our abstract (a not unusual situation given that abstracts are due a full seven months, yes SEVEN MONTHS, before the meetings), but our major findings were (1) that inexperienced butchers tend to create more cutmarks and more variation in cutmark orientation than do more experienced butchers and (2) that Levallois flakes (which were produced by Metin, who is a world-class knapper and lithic technologist) are ideally suited to butchery because of their versatility. 

The preparation of cores for the removal of Levallois flakes.
From Eren and Lycett (2012: Figure 1).

While both conclusions are interesting, the latter was of particular note in the context of the symposium, since the creation of Levallois flakes is a labor intensive, not to mention difficult to learn, process (see figure above). Our results suggest that Levallois flakes' utility and durability as butchery implements may partially offset the energy expended to create them. In other words, it might make sense to spend an hour or two preparing cores (and wasting a lot of raw material in the process) if it results in the production of three or four Levallois flakes that can butcher a couple of carcasses without being replaced. I slipped out briefly after our talk to visit the poster session down the hall since my student, Liat Lebovich, was presenting on some landscape taphonomy we've conducted on the savanna just north of Olduvai Gorge, but returned for the symposium's first question break and the remainder of the session. Several questions were thrown my way, relating mainly to the application of our cutmark data to archaeofaunal assemblages (we have not yet taken that step). One interesting query, I believe from Eugène Morin, involved cutmark frequencies: we found that novice butchers produce more cutmarks within each "cluster" (defined by us as a group of cutmarks separated from other groups of cutmarks by at least one centimeter) than do experienced butchers. He asked if I thought that novice butchers would create more, or fewer, cutmark clusters. After thinking about it for second, I responded that while novice butchers create more cutmarks per cluster, they probably produce fewer clusters since the marks they create tend to be scattered across relatively expansive portions of the bone surface rather than the few discrete clusters (that make anatomical sense) created by more experienced butchers. I hadn't thought to examine this variable, and I certainly will do so as we move forward with our study. The rest of the papers were interesting, and the integration of faunal and lithic data is obviously critical to understanding Neandertal lifeways. Very honored to have been invited to participate in the symposium.


• On Saturday morning, I co-chaired a session with my friends and colleagues Tori Johnson and Ryan Byerly entitled "Ecological Perspectives on Hominin Landuse Use during the Early Stone Age of Africa." Included in the session were papers presented by Julio Mercader, Cynthia Fadem, David Braun, Briana Pobiner, and another of my students, Cory Henderson. The session was well-attended (it wasn't a massive room, but most of the seats we did have, perhaps 75 or so, were full). As I stated in my short introductory remarks, the impetus for the symposium stemmed from Rick Potts's "Variables Versus Models of Early Pleistocene Hominid Land Use" manuscript published in Journal of Human Evolution in 1994. In that paper, Potts argued (correctly, I believe) that paleoanthropologists should resist the urge to force early Pleistocene archaeological sites into specific "types," or, using Potts's terminology, models (e.g., Home Base vs. Refuge vs. Central Place). A more productive approach involves the identification of the ecological variables (e.g., the distribution of raw material outcrops, plant and animal foods, competitors, etc.) that influenced where and when early hominins accumulated stones and bones on the landscape. I also made it clear that our purpose in convening the symposium was not to chastise paleoanthropologists for not taking this approach--it is, in fact, relatively common among researchers investigating Early Stone Age archaeology--but, rather, to highlight the latest work being done from this perspective. UNCG undergrad (and recently accepted graduate student to the biology program at Penn State) Cory Henderson summarized the analyses we've been conducting on raw material outcrops in the Olduvai Basin over the past couple of years. Quartzite dominants a majority of the Bed I and Bed II sites at Olduvai, and it has always been assumed that the source of this raw material is Naibor Soit, a set of three closely spaced inselbergs just north of the gorge.

View looking south at one of the inselbergs (foreground) that makes up the
Naibor Soit quartzite outcrop. Photo by C.P. Egeland.

This is not an unreasonable assumption: Naibor Soit is very close to most of the archaeological sites and would certainly have been a conspicuous feature on the landscape, just as it is today. However, Naibor Soit may not have been continuously accessible, especially when a fully transgressed lake Olduvai likely transformed the inselbergs into islands. There are at least two additional sources of quartzite in the basin, Shifting Sand and Naisiusiu Hill, and we wanted to know if hominins were traveling to other parts of the basin to access this type of toolstone. This is not a straightforward exercise, though, because the quartzite from all the sources is macroscopically very similar. We decided to use X-ray fluorescence to determine if the outcrops could be distinguished based on their elemental composition. It turns out that there is considerable overlap, but samples of known origin can be correctly classified with between 36% and 76% accuracy, which is better than random chance (which would be 33%). When we threw some archaeological artifacts from Bed I into the analysis, most (64%) were inferred to have derived from Naibor Soit. However, a couple were a better match for one of the other quartzite outcrops. So, while hominins appear to have used Naibor Soit a majority of the time, they also visited other parts of the basin to acquire quartzite (from Shifting Sand, Naisiusiu or, perhaps, other sources that are currently buried or otherwise unobservable). The ability to tie artifacts to individual outcrops could potentially reveal very nuanced patterns of movement, which is required to rigorously test various models of hominin land-use at Olduvai. The most interesting paper, at least for me, was presented by Dave Braun on behalf of his co-authors Jonathan Reeves and Matthew Douglass and entitled "Behavioral Inferences from Early Stone Age Sites: A View from the Koobi Fora Formation." Every so often archaeologists, particularly those working in the Paleolithic, need to be reminded of the importance of scale: that is, the scale at which we would like to reconstruct behavior and ecological affordances (months, years or, ideally, days) and the scale at which our proxies of these variables actually permit (months, years, decades, and millennia--rarely, if ever, days). Dave provided exactly that reminder within the context of their on-going work at Koobi Fora, Kenya. They point out that archaeologists continue (wishfully, perhaps?) to apply behavioral models suited for temporal scales that are in most cases simply not reflected in the scatters of bones and stones that litter early Pleistocene paleolandscapes. Cynthia presented the latest geoarchaeological data from our ongoing excavations at DK East (Bed I) and BK East (Bed II). Perhaps most important is her identification of several unnamed tuffs within the DK East sequence. Dating these sediments should allow us to increase greatly the chronological precision in the area and, thus, derive narrower age ranges for the numerous fossiliferous deposits and more accurate estimates of sedimentation rates.    

• The session I most enjoyed, and learned the most from, was chaired by Erick Robinson, Robert Kelly, and Nicolas Naudinot and was organized around "The Future of 'Big Data' in Archaeology." An archaeologist's idea of big data (thousands to hundreds of thousands of records) differs substantially from what is typical in computer science (millions and millions of records), but increased computing power and more sophisticated statistical techniques now permit the aggregation and analysis of huge archaeological databases. I recently received a Digital Partners Grant from the UNCG libraries to collaborate on a database for Paleolithic sites, so I was particularly interested to hear about the latest from folks that have been thinking deeply about data and databases. There are a number of open-access databases, some of which I am familiar with and others with which which I am not, including:
• Canadian Archaeological Radiocarbon Database (CARD): a global compilation of 14C dates.
• Ancient Cacao Map: an interactive database for samples of ancient cacao in the Americas.
• ARIADNE: this is a database of archaeological databases spanning many periods and regions.
• The Paleoindian Database of the Americas (PIDBA): a repository of artifact distribution maps and images. 
• The Digital Index of North American Archaeology (DINAA): this site creates interoperability among archaeological site databases in North America. A good friend with whom I attended graduate school, Josh Wells, is one of the senior investigators on this project.  


Some of the major lessons that I drew from this symposium are:
• The longevity of databases is a real issue, since the people who run them retire and the funding that supports them expires.
• There was a lot of discussion about 14C databases. Many people are using them to model demography, for example (the basic idea: more 14C dates for a particular time period = higher population sizes), but the quality of dates remains very difficult to assess. This same issue of data quality applies to many large databases.

• I recently developed an interest in the use of social network analysis in archaeology. In fact, I've begun a collaboration with a colleague of mine at UNCG, Jing Deng, who is a computer scientist that specializes in online networks. We've joined forces to use his technical know-how and my background in archaeology to apply network analysis to the Paleolithic. Our Undergraduate Research, Scholarship and Creativity Office here at UNCG just funded a proposal we put together to build a social network database for the Magdalenian of western Europe with the aid of Amanda Chase (an anthropology major) and Nathaniel Arnold (a computer science major). The Magdalenian is an ideal test case since there are hundreds of well-dated sites with thousands of artifacts suited to the construction of social networks: portable art. The idea is that stylistic similarities reflect some sort of shared social identity, so if we can identify sites with high frequencies of shared artifacts with shared stylistic variants, we may be able to reconstruct social networks. Jing is adept at using social network software to identify important nodes and relationships between nodes. I do not know much about Paleolithic art and how it is categorized, so I sat in on a "Not Just Good to See: Global Perspectives on Scenes in Rock Art" session. While the focus was on rock, and not portable, art, I gained some perspective on how we might organize art into an analysis. Elizabeth Culley, who is a PhD candidate at Arizona State University, outlined an ontology of parietal art from France between 40,000 and 11,000 years ago. I listened closely as she discussed her use of the number of distinct scenes, the number of narrative scenes, the theme of the scenes (e.g., fighting animals), and the number of animals as important features that distinguish various sites. The other paper I was able to listen to, from Melanie Chang of Portland State University and April Nowell of the University of Victoria, discussed the (mis)use of gender binaries in interpretations of Paleolithic art. They show convincingly that many images that are traditionally identified as either male or female are, in fact, quite ambiguous when it comes to biological sex. Much of this "forcing" of images into male or female reflects modern western gender biases. This was pertinent to me, too, because I need to be careful about past interpretations of some of these images, since biological sex would be an important trait to use in the classification of images for social network analysis. The last presentation that I visited related to social network analysis was a poster by William Ridge (University of Illinois at Chicago) on social networks in the Early Bronze Age of the Aegean. What I thought was interesting was his use of geographic distance between sites ("nodes" in social network terminology) as the null hypothesis for further analysis. In other words, all else being equal, one would expect sites that are closer to each other in an absolute geographic sense to have stronger social ties than sites further apart. If the network analysis does not show strong ties between closely spaced sites, then other hypotheses (trade routes, etc.) can be explored. I will certainly use this approach with our own work in the Magdalenian.  

Well, that's it from my notes, great meeting!