Early hominin meat-eating and expensive tissues

I actually was not aware of its publication until I came across it on John Hawks's weblog, but Joseph Ferraro and his coworkers have come out with a detailed taphonomic analysis of the faunal remains from Kanjera South, an important Oldowan site from Kenya that dates to about 2 million years ago. Their abstract does a nice job of summarizing the significance of the site and the study's findings (I guess this is what abstracts are supposed to do, after all; Ferraro et al., 2013: 1):

The emergence of lithic technology by ~2.6 million years ago (Ma) is often interpreted as a correlate of increasingly recurrent hominin acquisition and consumption of animal remains. Associated faunal evidence, however, is poorly preserved prior to ~1.8 Ma, limiting our understanding of early archaeological (Oldowan) hominin carnivory. Here, we detail three large well-preserved zooarchaeological assemblages from Kanjera South, Kenya. The assemblages date to ~2.0 Ma, pre-dating all previously published archaeofaunas of appreciable size. At Kanjera, there is clear evidence that Oldowan hominins acquired and processed numerous, relatively complete, small ungulate carcasses. Moreover, they had at least occasional access to the fleshed remains of larger, wildebeest-sized animals. The overall record of hominin activities is consistent throughout the stratified sequence - spanning hundreds to thousands of years - and provides the earliest archaeological evidence of sustained hominin involvement with fleshed animal remains (i.e., persistent carnivory), a foraging adaptation central to many models of hominin evolution.

This research team has been working hard out a Kanjera for many years now, and its really nice to see a comprehensive analysis of the faunal material from the site (we'd been getting tantalizing hints in various publications and presentations for some time).

Before we proceed, let me summarize the state of affairs just prior to these latest data. The 1.8 Ma time marker that Ferraro et al. mentions refers to the burst of evidence for meat-eating that emerges almost exclusively from Olduvai Gorge in Tanzania. One site in particular, the very well-known Level 22 at the gorge's FLK locality (also known as the Zinjanthropus Floor), dates to about 1.84 Ma and preserves thousands of fossils, many of which bear clear indications of hominin butchery. Now, up until a few years ago, it was thought that the animal bones from many of the other sites from Beds I and II of the gorge (ca. 1.9-1.2 Ma) were also largely the result of hominin activity. However, my colleagues and I showed that there are really only two sites, the previously mentioned FLK 22 from Bed I, and the site of BK, in upper Bed II (about 1.3 Ma), that are largely the result of hominin butchery (Domínguez-Rodrigo et al., 2007, 2009; Egeland, 2008; Egeland and Domínguez-Rodrigo, 2008). Now, we're not saying that hominins weren't at the sites; they certainly made, used, and left stone tools at these locations, but they were not doing a lot of meat-eating. There are a couple of other Oldowan sites here and there with some evidence for butchery, but if we ignore FLK 22 for the moment, good evidence for lots of meat-eating (or, to use Ferraro et al.'s term, "persistent carnivory") really doesn't pick up until much later, perhaps about 1.5 Ma.

What does all of this have to do with expensive tissues? Well, researchers have come up with several well reasoned, and very popular, human evolutionary models based ultimately on the shift to meat-eating. To start, brains and guts are very expensive tissues: one does a lot of thinking and the other does a lot of digesting, both of which take up good amounts of energy. If you start eating more meat, which is nutrient dense and easy to digest, you can divert energy from the guts to develop bigger noggins. Other possible correlates of a diet based increasingly on meat would be increased range size (carnivores, and other animal that eat high quality, easy to digest foods, tend to have larger ranges) and unique life histories (extracting nutrients using technology, and hunting with technology in particular, are difficult things to learn, and you don't want to die before you learn how to do them well, so perhaps we've evolved extended life spans to fit this need). People have traditionally seen the evolution of Homo erectus, with its bigger brain, long, lanky legs, and ability to leave Africa to colonize parts of Eurasia, around 1.8 Ma as great evidence for these shifts. Ok, all well and good, but, to use an old phrase: where's the beef? In other words, where is the evidence for sustained meat-eating just before and as H. erectus was evolving? Other than a single site, FLK 22, there really wasn't much...until now.

This is what makes the Kanjera evidence so important. I'm not sure it completely quashes my reservations (after all, we still only have two sites with good evidence for regular meat-eating between 2.6 Ma, when stone tools were first invented and used to butcher carcasses, and 1.5 Ma), but it is a good start.

References:

Domínguez-Rodrigo, M, Barba, R, Egeland, CP (2007). Deconstructing Olduvai: A taphonomic study of the Bed I sites. Springer, New York.

Domínguez-Rodrigo, M, Mabulla, AZ, Bunn, HT, Barba, R, Diez-Martín, F, Egeland, CP, Egeland, AG, Yravedra, J, Sánchez, P (2009). Unraveling hominin behavior at another anthropogenic site from Olduvai Gorge (Tanzania): New archaeological and taphonomic research at BK, Upper Bed II. Journal of Human Evolution 57, 260-283.

Egeland, CP, Domínguez-Rodrigo, M (2008). Taphonomic perspectives on hominid site use and foraging strategies during Bed II times at Olduvai Gorge, Tanzania. Journal of Human Evolution 55, 1031-1052.

Ferraro, JV, Plummer, TW, Pobiner, BL, Oliver, JS, Bishop, LC, Braun, DR, Ditchfield, PW, Seaman III, JW, Binetti, KM, Seaman Jr, JW, Hertel, F, Potts, R (2013). Earliest archaeological evidence of persistent hominin carnivory. PLoS ONE 8, e62174.

Archaic humans versus giant hyenas in Pleistocene Europe

María Patrocinio-Espigares and her colleagues have published an interesting study claiming to have identified evidence for competition between archaic humans and giant hyenas for access to a mammoth carcass from a site in Spain dated to over one million years ago. The site, Fuente Nueva-3, is found near the southern Spanish village of Orce, which is an extremely rich area for early Pleistocene fossils, including those of hominins. In fact, Fuente Nueva-3 and a nearby site, Barranco León, dated to 1.3 and 1.4 million years ago, respectively, currently preserve the oldest well accepted evidence for hominin occupation in all of Europe.

The excavations at Fuente Nueva-3 have been ongoing for well over a decade, but this paper reports on a partial skeleton of Mammuthus meridionalis, a species of mammoth, found in association with a few stone tools and, intriguingly, some coprolites (that is, fossilized poop). The materials were deposited near the edge of an ancient lake, and the authors argue that the mammoth (an old female) probably died of natural causes. The skeleton is relatively complete; only the legs and the head are missing.

Photo (A) and map (B) showing the distribution of mammoth bones, stone tools, and coprolites from Fuenta Nueva-3 . From Espigares et al. (2013: Figure 4).

Butchery marks (cutmarks from stone knives and percussion marks and notches from breaking open bones for marrow; although, some of the so-called percussion notches look a lot like the carnivore-created notches I've seen from modern assemblages) and tooth marks are pretty common on many bones from levels above and below the mammoth skeleton, but none whatsoever have been discovered on the mammoth bones in question. Nevertheless, the authors contend that the carcass was butchered by hominins, who removed the legs for consumption elsewhere, and later partly consumed by giant short-faced hyenas (Pachycrocuta brevirostris; they do not, however, tell us how they know the coprolites are those of a hyena).

I suppose this is possible. The authors correctly note that proboscideans are so big, and are covered by so much tough soft tissue, that butchery and tooth marks are unlikely to be inflicted. Pachycrocuta, though, as a recent paper by many of the same authors tells us, was about one-and-a-half times bigger than modern spotted hyenas and probably better adapted to bone-cracking than any other mammal that ever existed (Palmqvist et al., 2011) so, if anything would have left tooth marks on a mammoth-sized carcass, you would think it would be Pachycrocuta. I'll let the authors summarize their thoughts (Patrocinio-Espigares et al., 2013: 122; see the drawing by the very talented Mauricio Antón below for a reconstruction):

The Upper Archaeological Level of Fuente Nueva-3, dated around 1.3 Ma, provides the oldest evidence of a probable competition between Homo and Pachycrocuta, the two major bone-modifying and accumulating agents during early Pleistocene times in Europe. The evidence lies in the finding of an incomplete skeleton of M. meridionalis surrounded by 34 coprolites and 17 lithic artifacts. The skewed spatial distribution of these elements, the physical characteristics of the coprolites and the absence of the elephant limbs and cranium suggest that both hominins and hyenas scavenged the carcass of this megaherbivore, following a sequence of consumption in which the hominins arrived first, dismembered and transported the limbs, and probably also the cranium, and later the hyenas consumed the rest of the elephant carcass.

Original caption: Reconstruction of the possible sequence of interaction between hominins (A) and hyenas (B) during the exploitation of the carcass of M. meridionalis. From Patrocinio-Espigares et al. (2013: Figure 7). 

These conclusions are all based on indirect evidence (stone tools that may or may not have been used to butcher the animal, coprolites that may belong to hyenas that may have fed on the carcass). Either way, this does bring up the interesting issue of how hominins and carnivores interacted: were they competitors on the landscape for carcasses? Was this competition direct (i.e., fighting over access to carcasses) or indirect (one removing edible carcasses from the environment that the other in turn could not exploit)? Researchers have in fact suggested that competition from large carnivores went a long way towards preventing hominin populations from permanently colonizing Eurasia until after 600,000 years ago or so.

References:

Palmqvist, P, Martínez-Navarro, B, Pérez-Claros, JA, Torregrosa, V, Figueirido, B, Jiménez-Arenas, JM, Patrocinio-Espigares, M, Ros-Montoya, S, De Renzi, M (2011). The giant hyena Pachycrocuta brevirostris: modelling the bone-cracking behavior of an extinct carnivore. Quaternary International 243, 61-79.

Patrocinio-Espigares, M, Martínez-Navarro, B, Palmqvist, P, Ros-Montoya, S, Toro, I, Agustí, J, Sala, R (2013). Homo vs. Pachycrocuta: earliest evidence of competition for an elephant carcass between scavengers at Fuente Nueva-3 (Orce, Spain). Quaternary International 295, 113-125.

Bead-making in the early Upper Paleolithic

Mary Stiner and her colleagues (2013) recently published a really fun analysis of shell beads from the Paleolithic site of Üçağızlı Cave I in Turkey. The levels at the site date to the early Upper Paleolithic, between about 41,000 and 29,000 radiocarbon years ago (calibrated dates place the occupations between about 45,000 and 35,000 years ago).

Examples of perforated shells from Üçağızlı Cave I. From Stiner et al. (2013: Figure 5). 

After demonstrating (convincingly) that the modified shells are, in fact, artificially punctured beads, Stiner et al. (2013) show that the types of shells brought back to the cave, and the types that were chosen as beads, change over time. They provide four hypotheses to explain the change in shell type frequencies: (1) environmental changes determined what sorts of shelled animals were living near the cave, and thus what was available for bead exploitation; (2) the distance from raw materials (mediated by sea level fluctuation) changed over time, in which case people would accumulate more "junk" when raw materials were close and/or convenient and be very selective (i.e., only take the best stuff) when raw materials were distant and/or inconvenient; (3) the diversity of shell types is a function of the number and heterogeneity of shell collectors and users (that is, the more folks, and the more types of folks, exploiting shells will result in greater shell diversity); (4) cultural "conformism," where norms determine the types of shells used during any one time period.

The first hypothesis was not supported, as habitats don't appear to have changed significantly over time. The second hypothesis found some support in the fact that the diversity of ornament shells increased in those levels with evidence of frequent shellfish consumption. The latter would, theoretically, signal that the coast, and thus the raw materials for beads, were relatively close by and people became less picky about what they brought back to the cave for ornamental use. However, Stiner et al. (2013) question whether the distances to, and the weight of, the shells would have played much of a role in mediating what was, or was not, transported to the cave.

In the end, they feel that group size and composition and conformist behavior best explain the patterning in shell usage at the site. This is based on two observations. First, an inverse relationship exists between the diversity of species brought back to the site and the frequency of shells that were actually perforated for use as beads. That is, during time periods where many different types of shell were collected, only a few of those types appear to have been utilized for bead use. In the earliest levels, on the other hand, people transported only a few types of shells back to the cave, but most of them were subsequently perforated. Second, the size and shape of perforated specimens is relatively consistent regardless of time period. Stiner et al. (2013: 396) therefore conclude that:

Several factors contributed to the variation in the UcI ornament assemblages. Sample size effects were addressed early in the analysis and do not explain the patterns that concern us. The taxonomic diversity of the assemblages as a whole stems first from the natural biotic diversity of the marine environment. However, changes in littoral habitats to not seem to account for the differences between assemblages or changes over time. Many other aspects of the variation developed as the material was filtered by human choices. The narrow range of shapes and shell sizes is clearly attributable to human preferences, as are the bias toward whole specimens and the methods of modifying the shells for suspension. The extent of 'noise' or variance in the ornament assemblages is a product of the relationship between raw material collection activities and ornament manufacture and use. 

The fact that the taxonomic diversity of the UcI shell ornaments increased with time while the percentage of holed specimens decreased demonstrates that variation in the assemblages must be considered according to two distinct technological stages: raw material collection and artifact manufacture. The more playful and less constrained stage of artifact life history is raw material collection. Variation in overall raw material diversity among the assemblages related in part to how convenient access was to the shoreline and/or the overall importance of marine foraging from UcI. Variation in raw material also correlates with increasing occupation intensity and dietary breadth; the least variable assemblages formed during the lightest occupations. Changes in the size and complexity of the social groups that occupied UcI therefore may have played a role in shaping variation in the ornament assemblages. Unfortunately, the predictions for neutral social effects (more people on site or present for longer periods) and high-grading effects (raw material access) are difficult to distinguish in this particular case. What we can be certain about is that more 'junk' found its way into the shell raw material brought to the site at some intervals and that very different criteria took over at the manufacture stage. As the times collected were streamed into more formal uses, their characteristics narrowed, and many of the shells initially collected were rejected before further modification. It is for these reasons that we conclude that post-manufacture characteristics of the ornament assemblages most clearly reflect the influence of shared esthetic and visual norms. 

I actually ran into this article while I was mining the latest publications on modern human origins, which we are currently covering in my Paleolithic Archaeology class. One of the traits that many archaeologists associate with "modern" behavior is the use of personal adornment, since it is extremely likely that these items were used by ancient people as symbols to transmit information about themselves (just as jewelry does today). Stiner and her colleagues do not involve themselves in the modern human origins debate (as they note, the beads are not among the oldest in the world, or even in the Levant), but there analysis got me thinking about the importance of group size and complexity in the production of symbols. There is, in fact, quite a bit of recent work in Paleolithic archaeology that invokes the importance of demographic factors (mainly population size and density), rather than cognitive factors, to explain the appearance (and disappearance) of symbolic objects among pre-Upper Paleolithic cultures. Think about it: if you interacted with other groups only very rarely, or you ran into the same groups over and over again, there is very little incentive, even if you were cognitively able, to create a ton information transmitters (i.e., symbols) of any kind, much less those that would preserve in the archaeological record.

References:

Stiner, MC, Kuhn, SL, Güleç, E (2013). Early Upper Paleolithic shell beads at Üçağızlı Cave I (Turkey): Technology and the socioeconomic context of ornament life-histories. Journal of Human Evolution 64, 380-398.

Reconstructing subsistence during the Plio-Pleistocene

I just finished going through an interesting analysis by Michael Pante of the large mammal faunal assemblage from the site of JK2, which is in Bed III of Olduvai Gorge and dates to approximately 1.0 million years ago. The study in important for a number of reasons, not the least of which is the fact that we have so few decently preserved faunal assemblages that date to this time period. What is more, JK2 preserves butchery marks, another rarity among sites of this age, which show definitely that hominins (in this case, probably Homo erectus) were cutting flesh from carcasses and breaking open bones for marrow.

Ultimately, Pante uses the frequency and anatomical placement of the butchery marks and the carnivore tooth marks to argue that Homo erectus was gaining early access to carcasses (that is, before other carnivores had a chance to consume the carcass). This is potentially important, because there has been a lot of discussion about the importance of meat in the diets of early hominins. If meat was a staple of the diet, it is possible that it partly drove other evolutionary changes such as increased brain size (meat is easy to digest, so if you could free up energy that is usually channeled to the guts to process food, it can be diverted to other important organs, namely the brain). Pante compares the frequencies of butchery and tooth marks in the fossil assemblage to experimental assemblages of bones exposed to various processes:

• Hammerstone-only, in which humans cut the flesh from bones and then broke them open with stones to access the marrow
• Carnivore-only, in which carnivores (mainly hyenas) consumed carcasses
• Hammerstone-to-carnivore, in which humans cut the flesh from bones, broke them open for the marrow and, afterwards, carnivores scavenged the remains
• Whole bone-to-carnivore, in which humans cut the flesh from the bones but left everything else (flesh scraps and marrow) for carnivores to scavenge
• Vulture-to-hominin-to-carnivore, in which vultures ate some of the flesh, humans broke open the bones for marrow, and then carnivores scavenged the leftovers

The important observation here is that each of these experimental scenarios results in different frequencies and locations of butchery and tooth marks. For example, when humans remove the flesh and the marrow, there are very few tooth marks, since carnivores have little reason to gnaw on bones that are devoid of edible tissue.

While I agree that Homo erectus probably gained early access to carcasses, what struck me is the fact that the JK2 assemblage really does not match up very well with any of the experiments. I have run across this myself in analyses of other assemblages, and I can't help but wonder that the experimental scenarios that we've come up with so far, while extremely useful, simply are not comprehensive enough to model the complexities we're seeing at these Plio-Pleistocene sites, a point that Pante concedes in the paper. Regardless, this paper provides additional data on a critical, and currently poorly sampled, time period.

In my mind, two of the most important things that Plio-Pleistocene taphonomists need to work out are (1) reaching consensus on exactly how we identify marks on bones and (2) producing experimental bone assemblages that can test a wider variety of potential behavioral scenarios.

References:

Pante, MC (2013). The larger mammal fossil assemblage from JK2, Bed III, Olduvai Gorge, Tanzania: implications for the feeding behavior of Homo erectus. Journal of Human Evolution 64, 68-82.

Neandertals in Denmark? Maybe not...

There has been quite a bit of discussion about the range and, thus, the colonization abilities of Neandertals. Traditionally, the Neandertal world was thought to be limited to western, central, and eastern Europe, north Africa, and western Asia, with Uzbekistan representing the group's easternmost outpost. However, more recent mitochondrial DNA analyses of human fossils from Siberia effectively extended the known Neandertal range some 2,000 km to the northeast, and excavations at other sites now show that they inhabited a wide variety of habitats, including coastal areas and relatively rugged mid-altitude zones. Basically, Neandertals appear to have been much more adaptable that we've historically given them credit for.

My colleagues and I just published a study, which was funded by Aarhus University, on some ~120,000-year-old fallow deer skeletons from Denmark that were thought for many years to have been butchered. Butchered animals bones, of course, mean that humans were around and, given the age of the finds, Neandertals were considered the most likely culprit. If the remains were indeed butchered, this would have been the earliest and best evidence for a human presence in the region before the end of the last Ice Age (about 18,000 years ago).

After having looked the bones over, however, we were forced to conclude that there is no definitive evidence that Neandertals, or anyone else for that matter, butchered these animals. The bones are indeed broken, and one of them does show marks that could be interpreted as originating from a stone knife. The reason we're so cautious is that no compelling reason exists to attribute the breakage or the mark to anything other than natural processes.

Reconstruction of a rather sunburned Neandertal (courtesy of Berlingske Tidende)

Although this isn't huge, international news, it did make quite a splash in the Danish media. You can check out some of these stories (if you don't speak Danish, I suggest Google Translate, it does a fair job):

• Here's the Aarhus University press release
• Stories from the larger national newspapers Berlingske Tidende and Politiken, and the smaller, regional newspaper Jyske Vestkysten

One of the main problems here is that Danish archaeology has traditionally been dominated by later prehistoric and Medieval research. So, no one has really take the time to look for well-preserved Paleolithic sites. Luckily, Trine Kellberg Nielsen, a Ph.D. student at Aarhus and one of the co-authors on our fallow deer study, has recently received support to systematically examine the issue of a Neandertal occupation of Denmark. Hopefully her work will help turn up definitive evidence...

UPDATE 3.28.13

Here is a poster that Trine recently presented highlighting her plans for future work in Denmark. The most interesting aspect will involve paleoenvironmental reconstructions that will attempt to highlight areas most likely to have been occupied by Neandertal groups.