Figure 3. Stratigraphic section (left) shown with the image (right) of the outcrop highlighting the positions of the three major tuffs. All hominin fossils were found on the surface or in secondarily deposited sediment below the Ileret Tuff (1.52 ± 0.01 Ma). Some of the remains were found above the Lower Ileret Tuff (1.53 ± 0.01 Ma) indicating that the bones must have been buried above it. The large excavation area is visible on the right side of the outcrop and gully; the lower footprint level (Bennett et al., 2009, Dingwall et al., 2013, Hatala et al., 2017) is exposed on the left side of the image. All fragments of KNM-ER 47000 were located on the surface of the lower portion of the outcrop or secondarily buried in sediment eroded from the drainage that extends up the slope from the excavation site toward the right margin of the picture.
Paranthropus boisei was first described in 1959 based on fossils from the Olduvai Gorge and now includes many fossils from Ethiopia to Malawi. Knowledge about its postcranial anatomy has remained elusive because, until recently, no postcranial remains could be reliably attributed to this taxon. Here, we report the first associated hand and upper limb skeleton (KNM-ER 47000) of P. boisei from 1.51 to 1.53 Ma sediments at Ileret, Kenya. While the fossils show a combination of primitive and derived traits, the overall anatomy is characterised by primitive traits that resemble those found in Australopithecus, including an oblique scapular spine, relatively long and curved ulna, lack of third metacarpal styloid process, gracile thumb metacarpal, and curved manual phalanges. Very thick cortical bone throughout the upper limb shows that P. boisei had great upper limb strength, supporting hypotheses that this species spent time climbing trees, although probably to a lesser extent than earlier australopiths. Hand anatomy shows that P. boisei, like earlier australopiths, was capable of the manual dexterity needed to create and use stone tools, but lacked the robust thumb of Homo erectus, which arguably reflects adaptations to the intensification of precision grips and tool use. KNM-ER 47000 provides conclusive evidence that early Pleistocene hominins diverged in postcranial and craniodental anatomy, supporting hypotheses of competitive displacement among these contemporaneous hominins.
Figure 1. Right upper limbs of a modern human (left), chimpanzee (center), and KNM-ER 47000 (right), which preserves lateral portions of the scapula, the distal portion of the humerus, most of the ulna, and most of metacarpals (MCs) 1-3 and proximal phalanges 2-4. KNM-ER 47000 has primitive traits including a gracile thumb MC, lack of MC 3 styloid process, curved phalanges with prominent flexor sheaths, a long and curved ulna, a humerus with thick cortical bone and a prominent brachioradialis flange, and obliquely oriented scapular spine. Derived traits include a relatively long thumb, short manual phalanges, and a lateral scapular glenoid orientation. Scale bar at right is 10 cm.
The ecology of Neanderthals is a pressing question in the study of hominin evolution. Diet appears to have played a prominent role in their adaptation to Eurasia. Based on isotope and zooarchaeological studies, Neanderthal diet has been reconstructed as heavily meat-based and generally similar across different environments. This image persists, despite recent studies suggesting more plant use and more variation. However, we have only a fragmentary picture of their dietary ecology, and how it may have varied among habitats, because we lack broad and environmentally representative information about their use of plants and other foods. To address the problem, we examined the plant microremains in Neanderthal dental calculus from five archaeological sites representing a variety of environments from the northern Balkans, and the western, central and eastern Mediterranean. The recovered microremains revealed the consumption of a variety of non-animal foods, including starchy plants. Using a modeling approach, we explored the relationships among microremains and environment, while controlling for chronology. In the process, we compared the effectiveness of various diversity metrics and their shortcomings for studying microbotanical remains, which are often morphologically redundant for identification. We developed Minimum Botanical Units as a new way of estimating how many plant types or parts are present in a microbotanical sample. In contrast to some previous work, we found no evidence that plant use is confined to the southern-most areas of Neanderthal distribution. Although interpreting the eco-geographic variation is limited by the incomplete preservation of dietary micro remains, it is clear that plant exploitation was a widespread and deeply rooted Neanderthal subsistence strategy, even if they were predominately game hunters. Given the limited dietary variation across Neanderthal range in time and space in both plant and animal food exploitation, we argue that vegetal consumption was a feature of a generally static dietary niche.
Dental calculus indicates widespread plant use within the stable Neanderthal dietary niche
Robert C. Power, Domingo C. Salazar-García, Mauro Rubini, Andrea Darlas, Katerina Harvati, Michael Walker, Jean-Jacques Hublin, Amanda G.Henry
It has been a while since I posted on my blog and so out of guilt I’m back again to give you all a new post. This time I want to review a book published in 1987 on the political history of Palaeoanthropology. Written by biochemist Roger Lewin (1944 – Present) it charts the history of the science of Palaeoanthropology and is a must read for anyone interested in the origins of the genus Homo. In 1989, Lewin won the Royal Society Prizes for Science Books, for this very work. Many palaeoanthropologists at the top today could use with reading this book, to help them reflect on their own interaction with other workers in the field. The book was later revised in 1997, which at the time of posting was 21 years ago. There is no question that the field in need of an update to see if the field has changed or remained the same. I hope we will see this 3rd edition in the near future. Among other topics there is no doubt that the recent sexual misconduct of some scientists will need to be discussed in that new book. Let’s talk about the book. The title is very appropriate but when I first heard of it many years ago, I couldn’t help but bring out the immature side in me and snigger at the close similarity of the title with “Boners of Contentions”. I pondered on the potential look of the T-shirt, I could have printed. Anyway, the book covers a number of important moments in palaeoanthropological history.
In no particular order, Lewin discusses the storm surrounding the Taung Child, Ramapithecus, the KBS Tuff, the famous Australopithecus afarensis A.L. 288-1 and finally the work of the Leakey, specifically the father and the son. Here we see human nature at its worst usually, particularly when we get emotionally invested in a fossil or hypothesis or even flawed radiometric dating. Human evolutionary research, whether the workers in the field, like it or not, is storytelling. Storytelling based on evidence, I might add, but it possesses shades of science fiction. The hominin fossil record is extremely fragmentary and the stories told by these fossils are also extremely fragmentary. They are necessarily weak and this is not particularly useful in a field, where the scientists develop emotional attachment to their pet hypotheses. Even in the light of new evidence many still ignore due to the embarrassment of admitting you are wrong, based on the new evidence. In Palaeoanthropology, admitting you were wrong has been virtually impossible. There is really only one recorded case of a straight up “I was wrong and someone else was right”, that honour goes to Arthur Keith and his review of Raymond Darts Taung Child.
The book allows me to reflect on my own strongly held convictions that Homo heidelbergensis is a valid taxon, at a time when palaeoanthropologists generally shy away from using it. I have imbued it with my own emotional attachment and will remain unconvinced that it should be invalidated. But equally, those who argue the latter, are blinded by their own biases. They do forget that the fossil record of the species is incredibly sparse, with only a handful of skulls representing it. Admittedly, they have a point regarding the Mauer Mandible as the holotype of the species. Ideally, the holotype should be a complete skeleton, but the early science of palaeoanthroplogy was not rigorous in how it proposed new species. So, we are stuck with a mandible in a hypodigm entirely of crania, you read right one mandible and a handful of crania. This, I would argue is no grounds to invalidate a species. In debates, the emotional investment, gets in the way of objective thought and they can get quite heated. Thankfully, I’m not the only palaeoanthropology student indulging in Pro-Heidelbergensis camp. In 2017, Roksandic et al., conducted a revision of the representatives of Homo heidelbergensis. Bones of Contention has allowed me to at the very least be aware of my flaws when it comes to interpreting the fossil record, but with the above paragraph, I’ve really only scratched the surface and it will require a separate essay on the topic for the future.
Bones of Contention is a well written book and while it loosely follows event chronologically, Lewin does compare and contrast most of the events, concluding with a theme that binds these momentous events together. The reminder that we are telling stories is the key thought all palaeoanthropologists should be aware of. I’m aware that the latter is quite a risky statement, but in order for the palaeoanthropology student to be as objective as possible, we need to keep reminding ourselves of that. Many at the top, I suspect, will laugh at this as obsurd. One could argue that the science is far more rigorous in every way today than the time Eoanthropus dawsonii was first unveiled to the world. The Humans that study the fossils, well they have not changed. We are still flawed scientists, whether we like to admit it or not. This is uncomfortable for me to say, but it is true. In the early 1900’s, scientists saw hominin evolution as a variation of the chain of being, a line from ancient apes to human’s, today a variation of multiregional evolutionism is the hip new hypothesis with the “river delta” as its logo.
One topic that the book does not cover is the nature of public engagement of palaeoanthropology contrasted with scientific process associated with palaeoanthropology. For me, these are two different worlds, incredibly incompatible and one scoffs at the other in righteous indignation. There will be no way to bridge the gap between the two. Yes, some seem to be bridging this gap, but if you really dig deeper, the reality is very different. Science is an ever shifting process of evidence evaluation, something that is incompatible with the requirement of certainty in the press. I often cringe at the often used phrase that “textbooks will have to be re-written on palaeoanthropology”. This comes as no surprise to any palaeoanthropology student, but this statement implies that palaeoanthropologists had figured out the evolutionary steps hominins took over the past seven million years to get to where we are today. Far from it and this is what angers a lot of palaeoanthropology students and lecturers. The media need a hook and unfortunately the most effective hook to draw the public in is the above statement. You can’t blame them for reaching as wide an audience as possible. But this has meant that palaeoanthropologists in particular are cautious when they engage with the media. The seemingly innocuous move to record conference talks on new scientific findings is very risky from the point of view of the speaker. Choice of words at a presentation on record and the choice of words on the academic paper may be subtly different but they have the potential to ruin the academic standing of the speaker. Additionally, journals have strict embargo rules on when engagement with the media can begin. Break these rules and the paper will never be published. There will remain a tension between these two worlds for many centuries to come. I hope that the 3rd edition of Bones of Contention will cover this in more detail than I have here.
The only criticism I have of the book is the placement of the black and white photographs in the book. It would be more beneficial to have them scattered throughout the book, associated with their appropriate chapters, instead of combining them together in two groups in the centre of the book. This is not much of a criticism, but it does demonstrate the difficulty I had in my attempt to find one. It is an excellent book. To use a quote from Leonard to Sheldon in the Big Bang Theory, reading this book “is like looking into an obnoxious little mirror”. It help us re-examine ourselves and re-focuses our thoughts on a very controversial science.
Alan Cyril Walker (born August 23, 1938) died on November 20, 2017, of pancreatic cancer. He was a world-renowned paleoanthropologist and the recipient of numerous awards for his extraordinary scientific achievements, including a “genius” award from the John D. and Catherine T. MacArthur Foundation, and lifetime awards such as the Charles R. Darwin Lifetime Achievement Award from the American Association of Physical Anthropologists and the Leighton Wilkie prize of the Center for Research into the Anthropological Foundations of Technology (CRAFT) and the Stone Age Institute, Indiana University, and the International Fondation Fyssen Prize in Paris. He was one of the only scholars in the world elected to the Royal Academy (U.K.) as well as the United States National Academy of Sciences and the American Academy of Arts and Sciences.
Dr. Walker was born in Leicester, England, the second of four sons of Cyril Walker, a carpenter, and Edith Tidd Walker, a housewife. He was preceded in death by his parents, his first wife Patricia Nicholson, and a younger brother, Gerald Walker. He is survived and mourned by his elder brother, J. Trevor Walker and his younger brother Michael D. Walker, both of whom livie in England, his loving second wife of 42 years, anthropologist and author Pat Shipman, of Moncure, N.C. , his son Simon B. Walker, and his son’s wife Shellene Wellnitz Walker, and his granddaughters Bryn and Meghan Walker of Morrisville, N. C. In addition, he is remembered fondly by many of his former students and colleagues in several countries.
Alan Walker earned an undergraduate degree with honors in the Natural Sciences (Geology, Zoology, Mineralogy, Petrology, and Palaeontology). Following his childhood fascination with animals and fossils, Walker obtained a grant to attend the University of London, earning a Ph.D. in Anatomy and Palaeontology under the mentorship of John Napier. His thesis topic was a study of the functional anatomy and behavior of living and fossil lemurs of Madagascar. His work had a major influence on the field, emphasizing deducing the behaviors of extinct species from living ones to paleontology. He later received an honorary D.Sc. from the University of Chicago.
For much of his career, Dr. Walker was a brilliant teacher of human gross anatomy, training thousands of future physicians. Institutions where he worked included the Royal Free Hospital, School of Medicine, London (19165), Makerere University College, Kampala, Uganda (1965-1969), the University of Nairobi Medical School, Kenya (1969-1974), Harvard Medical School (1973-1978), and The Johns Hopkins University School of Medicine (1978-1995). In 1995 he moved to The Pennsylvania State University to teach anatomy and biology to undergraduate and graduate students, retiring in 2010 as an Evan Pugh Professor of Anthropology & Biology.
Throughout his academic career, Alan Walker was known for his kindness and generosity to students, for the tremendous breadth of his interests and knowledge, and for pioneering new approaches to evolutionary problems. He was instrumental in developing the field of dental microwear to deduce diets of extinct species and was among the first to the study of the structure of the inner ear of fossils to understand their patterns of locomotion and movement of extinct animals.
He was also known for his collaborations in finding fossils with Richard and Meave Leakey in Kenya. One of their most important discoveries was the finding, excavation, and analysis of the most complete ever skeleton of Homo erectus from Nariokotome, Kenya. This skeleton revealed the startlingly tall and lanky stature of a youngster of the species that first migrated out of the African continent. His research also had a major impact on the study of fossil apes, following his discovery of thousands of bones of several extinct apelike creatures on Rusinga and Mfwangano Islands in Lake Victoria, Kenya.
In accordance with his wishes, there will be no funeral or memorial services. Condolences may be sent to his wife, Dr. Pat Shipman, at 3140 Chatham Church Road., Moncure NC 27559 or (email@example.com). In lieu of flowers, friends and family in the U.S. may send donations to St John’s College, Cambridge, at www.cantab.org/giveonline or, in the U.K., to https://johnian.joh.cam.ac.uk/giving/donate.
John Hawks discusses the latest news on the Rising Star Project:
Africa’s richest fossil hominin site has revealed more of its treasure. It’s been a year and a half since scientists announced that a new hominin species, which they called Homo naledi, had been discovered in the Rising Star Cave outside Johannesburg.
Now they say they have established and published the age of the original naledi fossils that garnered global headlines in 2015. Homo naledi lived sometime between 335 and 236 thousand years ago, making it relatively young.
They’ve also announced the discovery of a second chamber in the Rising Star cave system, which contained additional Homo naledi specimens. These include a child and the partial skeleton of an adult male with a well-preserved skull. They have named the skeleton “Neo” – a Sesotho word meaning “a gift”.
The Conversation Africa’s Science Editor Natasha Joseph asked Professor John Hawks, a member of the team, to explain the story behind these finds.
To an ordinary person, 236 000 years is a very long time ago. Why does the team suggest that in fact, Homo naledi is a “young” species?
The course of human evolution has taken the last seven million years since our ancestors diverged from those of chimpanzees and bonobos. The first two-thirds of that long history, called australopiths, were apelike creatures who developed the trick of walking upright on two legs.
Around two million years ago some varieties of hominins took the first real steps in a human direction. They’re the earliest clear members of our genus, Homo, and belong to species like Homo habilis, Homo erectus and Homo rudolfensis.
Homo naledi looks in many ways like these first members of Homo. It’s even more primitive than these species in many ways, and has a smaller brain than any of them. People outside our team who have studied the fossils mostly thought they should be around the same age. A few had the radical idea that H. naledi might have lived more recently, maybe around 900,000 years ago.
Nobody thought that these fossils could actually have come from the same recent time interval when modern humans were evolving, a mere 236 to 335 thousand years ago.
How do you figure out a fossil’s age?
We applied six different methods. The most valuable of these were electron spin resonance (ESR) dating, and uranium-thorium (U-Th) dating. ESR relies on the fact that teeth contain tiny crystals, and the electron energy in these crystals is affected by natural radiation in the ground over long periods of time after fossils are buried.
U-Th relies on the fact that water drips into caves and forms layers of calcite, which contain traces of uranium. The radioactive fraction of uranium decays into thorium slowly over time. So the proportion of thorium compared to uranium gives an estimate of the time since the calcite layers formed. One of these calcite deposits, called a flowstone, formed above the H. naledi fossils in the Dinaledi Chamber. That flowstone helps to establish the minimum age: the fossils must be older than the flowstone above them.
For these two methods, our team engaged two separate labs and asked them to process and analyse samples without talking to each other. Their processes produced the same results. This gives us great confidence that the results are reliable.
What does the discovery of Homo naledi’s age mean for our understanding of human history and evolution?
For at least the past 100 years, anthropologists have assumed that most of the evolution of Homo was a story of progress: brains got bigger over time, technology became more sophisticated and teeth got smaller as people relied more upon cleverness to get better food and prepare it by cooking.
We thought that once culture really got started, our evolution was driven by a feedback loop – better food allowed bigger brains, more clever adaptations, more sophisticated communication. That enabled better technology, which yielded more food, and so on like a snowball rolling downhill.
No other hominin species could compete with this human juggernaut. You would never see more than one form of human in a single part of the world, because the competition would be too intense. Other forms, like Neanderthals, existed within regions of the world apart from the mainstream leading to modern humans in Africa. But even they were basically human with large brains.
That thinking was wrong.
Africa south of the equator is the core of human evolutionary history. That’s where today’s human populations were most genetically diverse, and that diversity is just a small part of what once existed there. Different lineages of archaic humans once lived in this region. Anthropologists have found a few fossil remnants of these archaic populations. They’ve tried to connect those remnants in a straight line. But the genetic evidence suggests that they were much more complex, with deep divisions that occasionally intertwined.
H. naledi shows a lineage that existed for probably more than a million years, maybe two million years, from the time it branched from our family tree up to the last 300,000 years. During all this time, it lived in Africa with archaic lineages of humans, with the ancestors of modern humans, maybe with early modern humans themselves. It’s strikingly different from any of these other human forms, so primitive in many aspects. It represents a lost hominin community within which our species evolved.
I think we have to reexamine much of what we thought we knew about our shared evolutionary past in Africa. We know a lot of information from a few very tiny geographic areas. But the largest parts of the continent are unknown – they have no fossil record at all.
We’re working to change that, and as our team and others make new discoveries, I’m pretty sure we are going to find more lineages that have been hidden to us. H. naledi will not be the last.
The first Homo naledi discoveries were made in the Dinaledi Chamber. What led researchers to the second chamber? And what did you find there?
The Dinaledi Chamber is one of the most significant fossil finds in history. After excavating only a very tiny part of this chamber, the sample of hominin specimens is already larger than any other single assemblage in Africa.
The explorers who first found these bones, Rick Hunter and Steven Tucker, saw what the team was doing when they were excavating in the chamber. The pair realised that they might have seen a similar occurrence in another part of the cave system. The Rising Star system has more than two kilometres of mapped passages underground. In another deep chamber, accessed again through very tight underground squeezes, there were hominin bones exposed on the surface.
Our team first began systematic survey of this chamber, which we named the Lesedi Chamber, in 2014. For two years Marina Elliott led excavations, joined at times by most of the team’s other experienced underground excavators. They were working in a situation where bones are jammed into a tight blind tunnel. Only one excavator can fit at a time, belly-down, feet sticking out. It is an incredibly challenging excavation circumstance.
The most significant discovery is a partial skeleton of H. naledi, with parts of the arms, legs, a lot of the spine and many other pieces, as well as a beautifully complete skull and jaw. We named this skeleton “Neo”. We also recovered fragments of at least one other adult individual, and one child, although we suspect these bones may come from one or two more individuals.
Is there a way for people to view these discoveries in person?
On May 25 – Africa Day – Maropeng at the Cradle of Humankind World Heritage Site outside Johannesburg will open a new exhibit with the discoveries from the Lesedi Chamber and the Dinaledi Chamber together for the first time.
For people outside South Africa, the data from our three-dimensional scans of the new Lesedi fossils are available online.
Anyone can download the 3D models, and people with access to a 3D printer can print their own physical copies of the new fossils, as well as the fossils from the Dinaledi Chamber. It’s a great way for people to see the evidence for themselves.
A team of scientists recently announced an extraordinary claim that the 130,000 Cerutti Mastodon was manipulated by hominins.
“I have read that paper and I was astonished by it,” archaeologist Donald Grayson of the University of Washington. “I was astonished not because it is so good, but because it is so bad. Cracked bones and chipped stones at a fossil site might mean anything”, said Grayson. “It is quite another thing to show that people, and people alone, could have produced those modifications. The study doesn’t take that step, he said, “making this a very easy claim to dismiss.”
Gary Haynes of the University of Nevada Reno had this to say, “The paper states that the bones were being exposed by a backhoe. These pieces of heavy equipment weigh seven to fifteen tons or more, and their weight on the sediments would have crushed bones and rocks against each other.” When asked, Holen, the study leader, said that it “was very easy to tell the difference” between fractures made by stone hammers and those seen in bones crushed by bulldozers. He did not elaborate on how the differences manifest. “He’s pretty much dead wrong — there’s no definable difference,” Haynes said. A similar fossil dispute broke out in 2015 over a 24,000 year old mammoth in Maryland, he noted, shown to be fractured by heavy equipment. Also troubling, the “hammer” and “anvil” stones described in the paper don’t unequivocally look like tools, said Michael Waters of Texas A&M’s Center for the Study of the First Americans.
Michael Waters of Texas A&M’s Center for the Study of the First Americans noted that the “hammer” and “anvil” stones described in the paper don’t unequivocally look like tools. The study also runs afoul of the mounting genetic evidence, which indicates that the first people to reach the Americas and eventually give rise to modern Native Americans arrived no earlier than 25,000 years ago.”
Everybody has heard of the Elgin Marbles and the debate surrounding the right’s of countries to those artefacts. These marbles are famous the world over but this story is repeated many more times not just in archaeology, but palaeoanthropology also. Zambia was once a colony of the British Empire and it was during that time that a certain hominin skull E 686 was uncovered. This skull is now lies in the vaults of the South Kensington Museum, London. In Zambia, Deputy Minister Susan Kawandami (pictured) recently reported before the Zambian Parliament that years of talks failed to secure the return of E 686 to Zambia with the Natural History Museum, London prepared to make copies of the skull instead. Kawandami will now establish new discussions through UNESCO, while Minister of Chiefs and Traditional Affairs, Nkandu Luo will visit London to establish a dialogue with the Trustees of the Museum.
If the Natural History Museum is ever to return the fossil, one thing is for sure, Zambia will have to convince the London Museum, that it is proactive in heritage (particularly palaeoanthropological) promotion and will ensure great care for the priceless skull. Which is currently not the case. The famed locality has no interpretative centre, no sign, no indication that two pivotal hominin bones – E 686 (Skull) and E 691 (tibia), were uncovered there. On the 17th of June 1921, A. S. Armstrong and A. W. Whittington uncovered those remains at Mutwe wa Nsofu, Mulungushi Road, Kabwe, Zambia. That same year, the fossils were given a new human species name – Homo rhodesiensis. This species has, thus far, only ever been found in Africa and it is a species that is seldom used by palaeoanthropologists. Most consider it a variation of Homo heidelbergensis. A key species that diverged into Homo sapiens (in Africa)and Homo neanderthalensis (in Europe). From about 1.5 million to 500,000 years ago, is a time that palaeoanthropologists have difficulty understanding due to the particularly patchy fossil record. So, what I have described is quite simplistic and many would argue over the exact details. The two fossils represent two adults males, that lived around 1 million years ago. Sadly, given they were found in the 1920’s, excavations in the field of human evolution were in their infancy and so, grossly inaccurate. The only way to date the site was through biostratigraphy. By looking at the animals that were found in the layers in which the fossils were found, later palaeoanthropologists compared those assemblages to strata at other sites which were radiometrically dated. The Kabwe stratigraphy was quite similar to Bed IV at the Oldupai Gorge which was dated to between 780,000 years to 1.3 million years.
Zambia’s National Heritage and Conservation Commission (NHCC) is now in the process of rehabilitating the site. Chief executive officer of the commission, Collins Chipote warned that though the site was intact, it needs to be secured and developed. A Kabwe Mining museum was commissioned by Minster Nkandu Luo (pictured), which will be run by the Lead-Zinc Mining company Enviro-Processing Ltd. a subsidary of the giant Berkeley Mineral Resources PLC. More effort is required on the part of Zambia to show that they have the determination to celebrate their priceless heritage and right now, there seems to be no action, but plenty of talking.
Efforts to return the cranium have remained futile. Minister for Tourism Charles Banda visited London’s Natural History Museum to engage in talks over the issue. Learn more here.
On the 23rd of January 1995, a team of palaeontologists discovered a fragment of fossil jaw lying on the gravel desert of northern Chad. The fossil could not be accurately dated, nevertheless stratigraphic layers nearby suggested it could be around 3.5 million years of age. Back then, the site of Koro Toro was on the edge of a 3 million square kilometre Lake called Megachad. The fossil, now codenamed KT 12/H1 consisted of the front portion of the jaw with a number of teeth still in place. By using Isotopic analysis the diet of the hominin shortly before it died, can be determined. The fossil showed a preference for C4 plants, including sedges and grasses, suggesting that the area around Koro Toro was predominantly grassland. Comparing the fossil to other hominins, the features were considered very different compared to Australopithecus afarensis, 2,500 km away in Ethiopia and Kenya. The French team, led by Michel Brunet, concluded the fossil was part of a new species of Australopithecus – Australopithecus bahrelghazali. This caused a bit of a stir in the palaeoanthropological community, but progressively began to die down. The lack of fossil finds in Chad thereafter contributed to the rate at which the palaeoanthropological community forgot about the fossil, that was, until 2001. Given the same variety of animals can be found in both Ethiopia and Chad, it is not a stretch to imagine australopithecines travelling between the two regions three million years ago and many palaeoanthropologists now consider the fossil, a variant of Australopithecus afarensis.
How did the fossil make palaeoanthropologists rethink their understanding human evolution? “Abel” as the fossil became to be known reminded palaeoanthropologists that human evolution could have been more complex than previously accepted. Though once you considered the features of an Australopithecus afarensis jaw and compare that to “Abel”, it is acceptable to attach it to the Ethiopian hominin. The differences are subtle. It is worth reminding here however that the use of species names don’t tell us much about the hominins palaeobiology, are primarily to put, order to our understanding of evolution and are a useful means of scientific communication. Palaeoanthropology has had a long history of naming new species, when later we realize we were too optimistic. In the sense, that we forget how useless this venture is. More is learned from the fossils, about a hominins diet, locomotion patterns and physical characteristics than what species it belongs too. Thankfully, science is less focused on this and we are now learning much more about the hominin and the ecosystem it was once a part of. The second way in which “Abel” got us thinking, was via the surprise geographic location. Up until that time, any fossil finds made on the continent of Africa were made exclusively in eastern and southern Africa. “Abel”, reminded us that hominins were not just restricted to those regions and likely could be found all over Africa. Exciting though this prospect was, it could not solve the problem of preservation in areas where fossils cannot survive, in the hostile environments of the Sahel.
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.
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.
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.
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!