New evidence on the diet of the Homo antecessor from Atapuerca

Human Evolution

A team led by experts of the University of Barcelona, the Catalan Institute of Human Paleoecology and Social Evolution (IPHES) and the University of Alicante, analyzes for the first time the diet of the Homo antecessor with the study of the microscopic traces left by abrasive particles of food on dental enamel surfaces 

According to the new study, published in the scientific journal Scientific Reports, the Homo antecessor processed and consumed food differently from Lower Pleistocene hominins
The dietary pattern of the Homo antecessor could be related to an environment with significant fluctuations in climate and food availability

The Homo antecessor, a hominin species that inhabited the Iberian Peninsula around 800,000 years ago, would have a mechanically more demanding diet than other hominin species in Europe and the African continent. This unique pattern, which would be characterised by the consumption of hard and abrasive foods, may be explained by the differences in food processing in a very demanding environment with fluctuations in climate and food resources, according to a study published in the journal Scientific Reports and led by a team from the University of Alicante, the Faculty of Biology of the University of Barcelona and the Catalan Institute of Human Palaeoecology and Social Evolution (IPHES).

This new research, which reveals for the first time the evidence on the diet of these hominines with the study of the microscopic traces left by food in the dental enamel, counts with the participation of the researchers Alejandro Pérez-Pérez and his team, formed by the doctors Laura Martínez, Ferrán Estebaranz, and Beatriz Pinilla (UB), Marina Lozano (Catalan Institute of Human Paleoecology and Social Evolution, IPHES), Alejandro Romero (University of Alicante), Jordi Galbany (George Washington University, United States) and the co-directors of Atapuerca, José María Bermúdez de Castro (National Research Centre on Human Evolution, CENIEH), Eudald Carbonell (IPHES) and Juan Luís Arsuaga (Universidad Complutense de Madrid).

Before /Prior to this research, the diet of the hominines of the Lower Pleistocene of Atapuerca (Burgos, Spain), our most remote European ancestors, had been inferred from animal remains –a great variety of large mammals and even turtles– found in the same levels in which the human remains were found. Evidence of cannibalism has also been suggested in some of these fossils.

Foods that leave a mark on the enamel

The study is based on the analysis of the buccal microwear pattern of the fossils from Trinchera  Elefante and Gran Dolina in the Atapuerca site. The examined microwear features are small marks on the buccal teeth enamel surface , whose density and length depend on the types of chewed food. “The usefulness of this methodology has been proved by the study of the microwear patterns of present populations, both hunter-gatherer and agricultural, showing that different feeding patterns correlate with specific microwear patterns in the vestibular surface of the dental crown”, explains Professor Alejandro Pérez-Pérez, professor at the Zoology and Biological Anthropology Unit of theof the Department of Evolutionary Biology, Ecology and Environmental Sciences at the University of Barcelona.

In the new study, the Atapuerca fossils have been compared with samples from other Lower Pleistocene populations: with fossils of the African Homo ergaster, ancestors of all Europeans dated from 1.8 million years ago; and also with Homo heidelbergensis, which appeared more than 500,000 years ago in Europe and lasted until at least 200,000 years ago, and finally with Homo neanderthalensis, specimens from the Iberian Peninsula that lived between 200,000 and 40,000 years ago.

Higher striation densities in Homo antecessor

The results of the study show that the teeth of H. antecessor show higher striation densities than the rest of the analyzed species. “Our findings do not allow us to say exactly what foods they ate, since the abrasive materials that cause the marks on the teeth may have different origins, but they do allow us to point out that H. antecessor would have had a diet largely based on hard and abrasive foods, such as plants containing phytoliths (which are silica particles produced by plants that are as hard as enamel), tubers with traces of soil particles, collagen or connective tissue and bone or raw meat”, says the researcher.

The researchers suggest that differences in the Gran Dolina microwear patterns among the compared samples could reflect cultural differences in the way food was processed. “Hunting and gathering activities are consistent with the highly-abrasive wear pattern we have encountered, but it is very difficult to think that the available food in the Atapuerca area was very different from that available to other hunter-gatherer hominins. Therefore, it would be the different ways of processing the food that would give rise to these differences in the dental microwear patterns. That is to say, they obtained, processed and consumed the food in different ways”, explains Alejandro Pérez-Pérez, who leads a team that has also applied this methodology in the study of feeding behaviors of the hominins of the Pleistocene of East Africa, including the species Paranthropus boiseiand Homo habilis.

A more primitive lithic industry

This pattern of great abrasiveness, observed on the enamel teeth surfaces in Gran Dolina contrasts with what has been observed in the compared species in the study. “UnlikeH. neanderthalensis, which had a more advanced lithic industry (called Mode 3 or Mousterian), the tools that have been found related to Homo antecessor are primitive (Mode 1). These industries would not facilitate food processing, as also suggested by evidence that they used teeth to chew bones. In addition, the lack of evidence of the use of fire in Atapuerca suggests that they would surely eat everything raw, causing more dental wear, including plant foods, meat, tendons or skin.

For the researchers, a diet with a high meat consumption could have evolutionary implications. “Meat in the diet could have contributed to the necessary energy gain to sustain a large brain like that of H. antecessor, with a brain volume of approximately 1,000 cubic centimeters, compared to the 764 of H. ergaster, but it would also represent a significant source of food in a highly demanding environment where preferred foods, such as ripe fruits and tender vegetables, would vary seasonally”.

The research contributes significantly to the better understanding of the dietary adaptations of our ancestors and highlights the importance of the ecological and cultural factors that have conditioned our biological evolution.

Paper reference:

A. Pérez-Pérez, M. Lozano, A. Romero, L. M. Martínez, J. Galbany, B. Pinilla, F. Estebaranz-Sánchez, J. M.  Bermúdez de Castro, E. Carbonell y J. L. Arsuaga. «The diet of the first Europeans from Atapuerca». Scientific Reports, February, 2017.

IN THE MICROSCOPE, Aliejandro Romero, the researcher of the University of Alicante qu eha participated in the project

Reprint from University of Alicante

Gorjanović-Kramberger Hypothesis: Took 99 Years, But We Finally Tested It

Anatomy, Human Evolution, Palaeoanthropology, Palaeobiology, Paleoanthropology, Paleobiology, Science, Statistics

You meet Homo neanderthalensis in a dark alley……………….What do you do?

Homo neanderthalensis is one of the best understood species of hominin today. One that lasted many hundreds of thousands of years throughout Europe. Despite what we know through the lens of science, there is still much that we want to know about this species of human. Interrogating the subtle pieces of evidence is the task of palaeoanthropologists, archaeologists, palaeoenvironmental scientists throughout the world. Contrary to what you may see on your average human evolution documentary, the kind of research conducted can be much more subtle. Here I will draw your attention to a difficult question. If we could fill the Great Hall of the South Kensington Museum with a few hundred individuals of our extinct cousin, what differences would we see in the upper chest and neck. The answer to that, at the beginning of 2015: We are not happy that we really know enough to give an answer.

Range_of_Homo_neanderthalensis
Range of Homo neanderthalensis

H. neanderthalensis is a well represented species of human in the fossil record, but the post-cranial anatomy is less well accounted for than the skulls. Not ideal for an investigation into the chest and abdominal regions of the human body. Nevertheless, it is vital we exhaustively examine what we have, to reveal potential clues to the kind of morphology these populations once exhibited. To that end, ten palaeobiologists from various Spanish academic institutions presented evidence that may be useful here. The mechanics of the breathing system, constrained by the rib cage and not the evolution of the species, is the focus here. Research continues to be a work in progress, new technologies arrive and they help further our understanding of the past. This research is no exception. Two year into the new millennium a new form of analysis that gauged quantity within a structure was applied to a collection of isolated ribs from an individual codenamed Shanidar 3. This individual had a more splayed lower rib cage compared to the more barrel-like form of our lower rib cage. Thus started a series of papers that suggested the lower rib cage of Homo neanderthalensis was generally less like ours. Comparatively less investigative research has been given to the upper end of the rib cage. This latest academic paper sets out to help understand just that.

Title and Authors of the Paper in Question
Title and Authors of the Paper in Question
640px-Krapina_-_Dragutin_Gorjanovic_Kramberger
Dragutin Gorjanović-Kramberger (1856 – 1936)

In 1906 and a time when ancient humans were Anti or Post Diluvian Era (Noah’s Great Flood), Dragutin Gorjanović-Kramberger suggested that the superior ribs are an important facet of an upper thoracic orchestra of components, that together control upper thoracic breathing, separate from diaphragmatic breathing. It was not until 2015 that this hypothesis was put to the test on six hominin first-ribs from the cave site of El Sidrón, Asturias, northern Spain. The six first-rib fragments may represent, at most, four individuals. The first step was to identify the bone fragments and place them in their correct anatomical position. Below is a re-organisation of the information given about the sample itself. The first-rib of Kebara 2 was found to be similar in shape space and form space (both terms used in a statistical analysis of shape, known as Procrustes Least Squares (PLS)) to SD-1767 and SD-1699, indeed H. neanderthalensis exhibits straighter first-ribs than modern day Homo sapiens. What could this mean? The scalene muscles are the ones that give your neck, its shape. They run from the Rib 1 and Rib 2 up the side of your neck attaching to the vertebrae. Alteration in shape of the first ribs, and the attached muscles will have to operate differently, but may help explain the differences we see between H. sapiens and H. neanderthalensis. The principle component analysis (PCA) reveals some overlap in the linearity of the rib shaft. Such results are reflected in analysis of the specimens of Krapina Cave, Croatia and ATD6-108 representing Homo antecessor, from Gran Dolina Cave, Atapuerca, Spain. So, the straightness of the first-ribs may affect the movement of the upper torso during breathing.

Juvenile 1: SD-2148 (Right) and SD-2172 (Left)

Juvenile 2: SD-417 (Left) and SD-1225 (Right)

Large Adolescent / Small Adult: SD-1767 (Left)

Large Adult: SD-1699 (Right)

Looking at the juveniles, it is important to understand costal cartilage development. Understanding adult H. neanderthalensis individuals is easier, as there are more post-cranial fossils, but the El Sidrón hominins will be useful in understanding the ontogeny of costal cartilage in future fossil ribs of  juveniles. The El Sidrón juveniles confirm a tighter upper chest for H. neanderthalensis. The first-ribs are smaller, but feature larger attachments at the rib heads, whereas the lower ribs have smaller attachment points. Therefore, a H. neanderthalensis individual, exhibited a smaller upper torso, which was further from the cranium thanks to the slightly longer neck vertebrae. First-ribs that are straighter would have to project out from the skeleton more and Gorjanović-Kramberger proposed that the rest of the rib-cage would project outward, just as much. The scientific team added to this, that a change in the first ribs would in turn affect the rest of the rib-cage, because the ribs are latched together with intercostal muscle, preventing individual ribs from varying in shape, that ultimately allows coordination of muscle, chest wall and breathing action. Upper ribs connect directly with the sternum and so, result in distinctive rib shape compared with the lower thorax.

Association of Intercostal Muscle and Rib Bone
Association of Intercostal Muscle and Rib Bone

To summarise, the first ribs appear to determine the shape of the upper thorax ribs, but straightness of the first rib is linked with the straightness of the upper ribs. Together, this suggests the existence of different rib shape and functions between the upper and lower thorax. When you look at a particular fossil specimen, it is important you are aware of what bones, muscles, cartilage was associated with it. They all interact in subtle ways which we are piecing together in hominins, with the variety in body forms available going back 7 million years. In examination of the monophyly of Paranthropus, cladistical statistics showed us that the skeletal points used, should not be linked with eachother. An example of that, would be the masticatory system in Paranthropus comprising numerous points, all interacting with one another. This is a shame because the crania and mandibles are predominantly all we have of that genus. Currently, most are happy that Paranthropus boisei, Paranthropus aethiopicus and Paranthropus robustus are part of the same family – they are monophyletic. The rib cage, is similar to the masticatory system but it is a single unit with two functions, one  is upper thoracic respiration and the other is diaphragmatic respiration. H. neanderthalensis evolved a more restrictive respiratory system and highly developed arm muscles, evolutionarily more important for the condition in which it lived. So, if you were to meet our ancient ancestor in a dark alley, what should you do? It would have been prone to breathlessness, but could rearrange your face easier. Moral of the story, RUN!

The costal remains of the El Sidrón Neanderthal site (Asturias, northern Spain) and their importance for understanding Neanderthal thorax morphology