Palaeoanthropologist Alan Cyril Walker (1938 – 2017)

CaptureAlan 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 ( In lieu of flowers, friends and family in the U.S. may send donations to St John’s College, Cambridge, at or, in the U.K., to


Lessons of Homo naledi

New discoveries of fossilised hominin remains have to varying degrees helped to shape our ever-morphing interpretation of hominin evolution. Homo naledi is a case in point.

Though many worker in the field of palaeoanthropology were disappointed with the confirmed Middle Pleistocene age of the Dinaledi remains, this news nevertheless fills a void in our understanding of Middle Pleistocene evolution.

H. naledi confirms what we have known since the astonishing discovery of Homo floresiensis, namely that small brained hominins continued to thrive in some part of the planet right up to recent times. H. naledi can now join Homo floresiensis in the small brain Middle to Late Pleistocene club.

Palaeoanthropologist can now exercise a high level of skepticism on dating hominin fossilised remains using morphological stucture and statistics. In 2015, palaeoanthropologist John Francis Thackeray concluded Homo naledi to be over 1.5 Ma, while Mana Dembo and her colleagues concluded an age of 930,000 years of age for the Rising Star remains. Though Dembo et al were closer to actual age of the remains, they were still nearly 600,000 years off.

Finally, H. naledi continues to confirm what we have known since the announcement of Australopithecus sediba that hominin evolution features an ever changing mosasicism. With Australopithecine-like shoulders and cranium, while the lower limbs and foot appears more derived.

Middle Pleistocene Homo naledi

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.

Explorers Mathabela Tsikoane, Maropeng Ramalepa, Dirk van Rooyen, Steven Tucker (seated), and Rick Hunter (seated) inside the Rising Star cave system. Wits University/Marina Elliott

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.

Geologist Dr Hannah Hilbert-Wolf studying difficult to reach flowstones in a small side passage in the Dinaledi Chamber. Wits University

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 DayMaropeng 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.

Reprint from The Conversation

Doctoral student addresses critics of the Cerutti Mastodon Controversary

An anonymous doctoral student associated with the Cerutti Mastodon research addresses critics on Reddit as follows:

First off, my qualifications: My current advisor is the third author on this paper and I worked under (and collaborated with) the second author when I worked at the San Diego Natural History Museum (in fact, I re-prepared some of the material in this paper about 6 years ago). Furthermore, I am a doctoral student in the final months (hopefully) of my PhD. My dissertation work has been on proboscideans (elephants and their relatives), but I have also done a fair amount of work on cetaceans (whales) and other vertebrates.

As far as the dating methods go, this site was dated using multiple types of absolute dating methods, which all resulted in a very similar age. However, the Uranium-series dating (not to be confused with radiocarbon dating, which could not give you an accurate age this old) that was used here got results with a very high confidence. In fact there is essentially no evidence of alteration that might lead to an older date (which really would not be common anyways). The dates recovered are almost unimpeachable (and I don’t say that lightly). I would be very surprised if a geochronologist or any other expert had a major problems with the dates themselves (in fact a geochronologist was a reviewer for this paper for just this reason). Also, to the people that are saying that it is perhaps time to reassess our methods of isotopic dating in general, I strongly suggest you spend more time researching and trying to understand these methods before you make a claim like this…

One other misconception that I keep seeing here are peoples’ interpretation of what is meant by “human” in this paper. “Human” is meant here in the sense of a species of the genus Homo, not necessarily Homo sapiens specifically. In fact, because of the old age it seems fairly unlikely that this would be the modern species of human rather than some other [unknown] species.

I’m sure there will be other questions or comments here throughout the next day or so, and I will try to check in from time to time and update this post. I’m also happy to answer any questions that I can (to the best of my knowledge).

Edit 1: To the folks wondering if this site could have been scavenged by humans (as opposed to hunted), I would say that, that is absolutely possible. In fact there is really no evidence one way or another to argue for hunting over scavenging at this site, and I don’t believe that this paper takes a stance on this either. In fact, I would say that the argument of hunting vs scavenging in association with this mastodon is somewhat irrelevant. What is important is that this extremely old site (relatively speaking, anyways) has fairly clear association with ancient human activity.

Edit 2: Several people have pointed out that the article discusses a lack of evidence of meat stripping on the specimen. This does suggest scavenging, as it likely means the soft tissue was at least somewhat rotted and not usable.

Edit 3: Many people are suggesting that this animal could have been scavenged or had its bones modified many thousands of years after its death (i.e., implying the tools are much younger than the mastodon). To that point 1) the type of breakage seen on these bones is indicative of damage while the bone was still fresh. Fresh bone (sometimes called “green bone”) breaks in a very different “spiral pattern” than older dried out bone; and 2) you have to remember that the sediments that the tools and mastodon are found in represent the context in which they were buried. Therefore since these materials were all found within the same layer they must have been buried at the same time. It is possible that ancient humans exhumed old bones (though I know of no actual evidence of this), but we would see telltale signs of disturbance to the sediment (which was not observed here).
In other words, I don’t think that arguments about this site will come down to whether the material is associated and coeval, but whether folks think that these artifacts are indeed stone tools. Those people who do not agree with this identification will then have to reconcile the crazy taphonomy at this site and attribute it to some other natural process (which will be no small feat, IMHO).

Edit 4: For the people asking why we don’t have any evidence of humans (or human remains) in North America in the time between the age of this site and more generally accepted dates:

First off, I would just like to note that we are almost certainly not talking about a direct lineage of humans between the time of this site and those of Clovis times (in fact, as I’ve stated above, we are likely not even talking about the same species). This was likely a very small population of humans that made it to North America that probably died out long before the modern species of human ever made it over. In that sense, there isn’t necessarily a gap of time to “bridge”.

As for why potential sites might not be preserved: There are a couple of reasons that you might not have evidence of humans found from this time. First off, you may not have rocks of the right age readily exposed in the region where the individuals were living (which is somewhat the case on the west coast, as far as I am aware). Second, the individuals could be living in an environment that is not conducive to preserving fossils (e.g., organisms that live in montane environments tend to not preserve in the fossil record because sediments are not being deposited in those regions). Third, getting preserved in the fossil record (in general) is very rare, and if your study organism has a very small population size or is short lived (as we would expect in the case here) then you have a very very low probability of being preserved (let alone found and collected). Finally, even if these scenarios aren’t the case, there is the possibility that scientists have just been looking in the wrong strata, region, or age.

Three reasons the Cerutti Mastodon was not manipulated by hominins

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.”

The 1,000,000 year old child of Ngrejeng, Indonesia

NG 8503
Date Found: March 1985
Found By: Ngrejeng Villager
Locality: Near Ngrejeng Village, Indonesia
Announced: 1994
Fossil: Partial mandible (Right side), with M1 and M2. The latter had not yet erupted at time of death.
Age: 1.02 – 1.51 million years of age

Papers to check out:

1994 – Aziz et al – Preliminary report on recent
discoveries of fossil hominids from the Sangiran area, Java.

2005 – Kaifu et al – Hominid mandibular remains from Sangiran (1952-1986) Collection

2006 – Kaifu – Advanced dental reduction in Javanese Homo erectus

2011 – Wood – Encyclopedia of Human Evolution