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.

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.

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

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

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

Range_of_Homo_neanderthalensis
Range of Homo neanderthalensis

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

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

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

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

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

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

Large Adult: SD-1699 (Right)

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

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

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

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

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