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

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.”

Returning Kabwe Man To Zambia: Renewed Efforts for 2015

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 Mr-Kabimba-with-Hon.-Susan-Kawandami-in-Kaoma-for-the-Kazanga-ceremony-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.

E 686

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.

homo_heidel_655_fs
E 686 (Kabwe 1) fleshed out in this hyper-realistic reconstruction by John Gurche (http://www.gurche.com)

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 Nkandu-LuoMinster 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.

Meganthropus palaeojavanicus – The Early Years of Palaeoanthropological Research (1942 – 1955)

Meganthropus palaeojavanicus (from the Ancient Greek, meaning Ancient Java’s Great Human) is a redundant genus and species that was first formally introduced by Gustav vonKoenigswald (1902 – 1982) in 1950. The genus once referred to a set of fossils found on the island of Java in the 1930’s, 1940’s, 1950’s and 1980’s. The Javan fossils are now attributed to the hominin Homo erectus that lived from 1.9 million years ago to 300,000 years ago and had a range from Africa to Eurasia.

vonKoenigswald’s Meganthropus palaeojavanicus

von_Koenigswald
Gustav Heinrich Ralph vonKoenigswald (1902 – 1982)

On the 15th of January 1942, the Director of the Geological Survey of the Netherlands Indies, W. C. B. Koolhoven wrote a letter to anatomist and palaeoanthropologist, Franz Weidenreich informing him that vonKoenigswald wishes the 1939 and 1941 to be attributed to a new genus and species of ape called M. palaeojavanicus. In 1945, Weidenreich referred to it as “vonKoenigswald’s Meganthropus palaeojavanicus”. Held in the Senckenberg Forschungsinstitute und Naturmuseum, an unpublished 1949 scientific paper written by vonKoenigswald proposes that Sangiran 1a,  It was not until 1950, the vonKoenigswald committed his new genus and species to print in a formal introduction. As the sixth decade of the 20th century developed, consensus shifted towards H. erectus as the taxonomic appellation of the Javan fossils.

“Meganthropus” Fossils

The following are a list of fossils that were taxonomically assigned to Meganthropus, but have now been officially assigned to H. erectus

Franz Weidenreich
Franz Weidenreich (1873 – 1948)

Sangiran 6a

Kromopawiro (a team member) discovered the fossil adult mandible fragment “near Glagahombo, north of Sangiran” not far from where another cranium was uncovered in 1939 and south of Sangiran 4’s location. Weidenreich described the 1.6 million year old fossil in 1945, in which he pointed out the size of the mandible and the primitive premolar morphology as evidence to support the application of a new genus and species – M. palaeojavanicus. This conclusion was revised in 1989, when Kramer concluded that the size was within the size range of H. erectus.

Sangiran 7

Dating to between 1.51 and 1.6 million years of age, Sangiran 7 (comprising 54 teeth) was recovered from 1937 to 1941. Fred Grine analysed some of the teeth in 1984, but it would be a decade later before he revised his earlier conclusion that they were hominin. As a result, three teeth FS 67, 72 and 83 were re-attributed to Pongo sp.

Wilfrid Le Gros Clark (1895 – 1971)

Sangiran 8

Uncovered in 1952, Sangiran 8 comprises fragment of mandible, with some teeth roots intact and a complete third molar crown. This individual is interpreted to have died in the jaws of a crocodile, based upon the scare marks on the fossil. The fossil was first described in 1953 by P. Marks concluding it lay outside the size range of H. erectus. In 1955, Le Gros Clark concluded that the fossil was within the range of H. erectus and that has remained the official attribution for Sangiran 8 ever since.

Sangiran 27

This partial adult cranium was first found in 1978 near Sangiran village, north of the River Chemoro and it was found as construction was underway on a new dam. The skull was found in the upper levels of the Sangiran Formation dating to between 1.66 and 1.58 million years of age. The fossil was described by Teuku Jacob in 1980, in which he attributed it to Meganthropus but was taxonomically revised in 2008 for reasons similar to the taxonomic revision of Sangiran 8. Indriati and Anton (2008) also noted that hyper-robust features of the fossil reflects earlier representatives of H. erectus.

Modern Uses of Meganthropus

Though taxonomically and scientifically redundant, Meganthropus is used by pseudoscientific Creationists as evidence for the Nephilim, giants that lived before Noah’s flood, referenced from an Iron Age manuscript called the “Book of Enoch”.

Norandino and Lucina Discovered by the Ogre (1624) – Giovanni Lanfranco (1582 – 1647)

A trickle of scientific papers and posters have been published and presented over the decades, claiming evidence for Meganthropus. Authors have suggest that Sangiran 5 is evidence of the existence of an older, “more robust morph”, with pongo-like characteristics. Suggesting that a Gigantopithecus-like counterpart lived in island South-East Asia. The most recent appearance of support for Meganthropus was at the 83rd annual meeting of the American Association of Physical Anthropologists in 2014, a team of scientists led by Clement Zanolli presented a poster on their analysis of a fossil mandible fragment code named Arjuna 9. They suggested that teeth had enamel thickness and dental tissue proportions that differed from those seen in H. erectus. The statistical analysis of the enamel-dentine junction also seemed to support an attribution to Pongo sp. The fact remains, no evidence exists to support classifying the Javan fossils as Meganthropus.

17 Palaeoanthropological Terms in Irish / 17 Téarmaí Pailéantraipeolaíochta as Gaeilge

Here are just some of the words, that you are likely to use in discussion of human evolutionary research. For more information regarding how to pronounce the words check out the video below.
Gaeilge To English
Pailéantraipeolaíocht – Palaeoanthropology

Anailís Lithic – Lithic Analysis

Seandálaíocht – Archaeology

Astrálaipiticín – Australopithecine

Scaipeadh – Dispersal

Bhreismheascadh – Admixture

Antrapóideach – Anthropoid

Pléisticéineach – Pleistocene

Geomoirfeolaíocht – Geomorphology

Bunús Daonna – Human Origins

Daoine anatamaíoch Nua-aimseartha – Anatomically Modern
Human

Ilchríoch – Continent

An Afraic – Africa

An Eoráise – Eurasia

Anailís Timpeallachta – Environmental Analysis

Dátú Argón-Argón – Argon/Argon Dating

Anailís Ghéiniteach – Genetic Analysis

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