Sediment cores retrieved from the Pleistocene Olduvai Basin by the Olduvai Gorge Coring Project (OGCP) provide a high resolution record of tuffs and other volcaniclastic deposits, together with a lacustrine sedimentary record full of paleoenvironmental indicators. Correlating tuffs between the cores and outcrops at Olduvai, where these tuffs are identified at paleoanthropologically important sites, is critical for applying the new paleoenvironmental data to the conditions under which hominins lived. Tuffs and other volcaniclastic deposits from three cores were analyzed for mineral assemblages and glass and mineral major element compositions (feldspar, augite, hornblende, titanomagnetite, and glass where possible) to compare to published geochemical fingerprint data, based on marker tuffs from outcrop equivalents at Olduvai Gorge. In combination with stratigraphic position, these mineralogical and geochemical data were used to correlate between the cores and outcrops, providing direct temporal tie-lines between the cores and sites of paleoanthropological interest. Direct correlations are most certain for Olduvai Bed I, where all major tuff markers from outcrop are identified for one or more of the three core sites, and for the upper part of the underlying Ngorongoro Formation, which includes the Coarse Feldspar Crystal Tuff (CFCT) and Naabi ignimbrites exposed in the oldest Pleistocene exposures of the Western Gorge. Also characterized were the mineral and glass compositions of tuffs and ignimbrites pre-dating the oldest exposed outcrop units, extending our record of explosive events from the Ngorongoro Volcano. While no specific correlations can be confirmed between individual Bed II tuffs in the cores and in outcrops, correlations are possible between the cores themselves (using newly identified tuff compositions), and some potential correlations (non-unique, based on individual mineral phases) between core and outcrop can be used in conjunction with other stratigraphic tools to help constrain the intervals in question.
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.
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.”
Deinotherium. The Terrible Beast. A Proboscidean. The video below was one of my first introductions to the world of palaeoanthropology and 3D reconstructions of prehistoric life. It inspired me to learn more about the remote prehistory. This creature, a relative of the famed African Elephant, would have been between 4.5 to 5 metres in height at the shoulder, with a set of short downward-facing tusks and would have had a similar behavioural characteristics to modern day elephants. Nobody knows how long the trunk was, though the muscle attachments regions on the front of the skull can give some clues, its length remains conjectural. The set of downward-facing tusks have been the subject of much debate, ranging from sexual display to digging for roots and tubers to tree bark scraping. Again explanations vary. The Deinotheres has, thus far, been broken up into three species – D. giganteum, D. bozasi and D. indicum. The earliest examples of this group have been dated to about 23 million years ago (Early Miocene), while their extinction took place some time in the Middle Pleistocene, about 700,000 years ago. This was probably caused by the knock-on effects of climate change on the habitats in which they lived. The Deinotheres have a history that extends back into the Oligocene Epoch and this will be the subject of this discussion. As a side note, it is really sad that documentaries on human evolution and prehistoric beasts, do not explain the following. This is documentary material, in my opinion.
As Gondwana began to rupture apart 184 million years ago in the Early Jurassic. Africa was the first isolated baby continent of Gonwana. It remained as such, quite literally up until about 25 million years ago, 159 million years of isolaton for evolution to work its magic on a limited diversity of placental mammals that called Africa, home. But given that elephant-like creatures existed in Late Oligocene (34 – 28 Million Year ago) Pakistan, land bridges must have developed between Africa and Arabia / Eurasia as the continent made the relentless push north. With such unimaginable tectonic forces at work, it is inevitable that volcanism increases in activity. The tectonic dynamics were such in eastern Africa million of years ago that a unique type of volcanic eruption occurred. Everybody is familiar with the power of water, in the form of slow development floods and the devastating flash-flood. Lava is equally capable of flooding the landscape, not as we all know it today, but on a scale that we cannot comprehend. Everybody is familiar with the Cretaceous – Paleogene Extinction Event, but few are aware of the most devastating mass extinction event in the prehistory of the planet – The Permian – Triassic Extinction Event. It was brought on by a truly massive flood basalt eruption. This is what quite literally created Siberia, that’s right Siberia. Today, 252 million years on, the remains of that basalt eruption covers an area of over 2 million sq km² and may, back then, have covered over 7 million sq km². Eleven flood basalt eruption events have taken place within the last 250 million years. The Eritrean Intertrappean Beds is a much smaller events and featured episodes of volcanic activity followed by laying down of fluvial sediment, hence the “Inter-Trappean”. These beds can be up to 100 metres in depth and cover many square kilometres. This intermittent event has been dated from 29 to 23.6 million years of age.
Mendefera, is the town capital of the Debub Region of Eritrea and it sits atop the Eritrean Intertrappean Beds. It was at a number of outcrops of fluvial mudstones and siltstones that fossils of the early ancestors of Deinotherium were uncovered recently, called Prodeinotherium. Numerous other sites have revealed early Proboscideans such as Gomphotherium, which is likely to be the earliest representative of this intriguing family. During the Oligocene, Arabia and north-eastern Africa flirted with the Tethys Ocean promiscuously. So the sight you might have seen from the Eritean highlands, back then was swamp, river and lake populated landscapes, perfect for tropical wet forests, especially when the basaltic volcanism of the area was on hiatus. As Africa edged closer to Arabia and Eurasia, the lack of diverse fauna, may have allowed a large influx of Eurasian fauna to call Africa, home for the first time. There are an estimated six Trans-Tethyan Paleogene mammalian dispersals all of which were limited by the availability of land bridges. So large herbivores could not cross into or out of Africa without substantial land bridge crossing points. By the beginning of the Miocene, there was a massive faunal turnover in the form of African endemic species dying out and the movement of Eurasia fauna south into the continent. This dynamic change in faunal movements also included the northward movement of Prodeinotherium into Eurasia, evolving into the Deinotherium we all know and love.