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A Heidelberg man of African originThe lower jaw of Homo heidelbergensis was an isolated find and has long been overshadowed byother spectacular early human finds. Homo heidelbergensis is regarded as the last commonancestor of Neanderthals and Homo sapiens, and so is a central part of the debate on modernhuman origins.

On the evening of 21st October 1907, Daniel Hartmann, a gravel pit worker known as ‘Sanddaniel’,walked into the Hochschwender pub in the village of Mauer near Heidelberg and announced that he

Lower jaw of Homo heidelbergensis. © Museum of Geology and Palaeontology, University of Heidelberg

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had found “Adam”. What he had found in the Grafenrain sand pit on the river Elsenz near Heidelbergwas an almost complete, fairly robust human jaw that appeared to be very old indeed. Thepalaeontologist Professor Otto Schoetensack from the University of Heidelberg who had previouslyvisited the Grafenrain pits in search of glacial fossils was contacted the following day. Schoetensackdescribed the find in a monograph entitled “Der Unterkiefer des Homo heidelbergensis aus denSanden von Mauer bei Heidelberg” (The lower jaw of the Homo heidelbergensis from the Mauer sandsnear Heidelberg”) published in 1908. Schoetensack realised almost immediately how important thediscovery was and believed the Mauer mandible to be older than the Neanderthals. Neanderthalswere classified as such based on a specimen discovered in the Neander Valley near Düsseldorf(Germany) in 1856. Following the discovery of this Neanderthal type specimen, other previouslydiscovered fossils were also (retrospectively) classified as Neanderthal.

The most famous lower jaw in the world

The jaw of the prehistoric man from Heidelberg, the valuable type specimen, has been dated toaround 600,000 years ago and is kept in a safe in the Institute of Earth Sciences (formerly, theInstitute of Geology and Palaeontology) at the University of Heidelberg. However, visitors can see adetailed replica of the fossil jaw in the institute’s museum as well as in the small primeval worldmuseum in Mauer town hall. No further remains of the “Heidelberg Man”, as Homo heidelbergensisis also known, have been discovered at the site despite intensive searches. However, huge quantitiesof single rhino, elephant, lion and hippo bones have been found in the Grafenrain sand pit and not so

The Grafenrain excavation site close to the village of Mauer, where the “Heidelberg Jaw” was discovered in 1907. © Institute of Earth Sciences, University of Heidelberg

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long ago human fossils were found in the village of Bilzingsleben near the Kyffhäuser mountains;these fossils are geologically more recent than the Mauer mandible, but have nevertheless beenassigned to the same species. Well-preserved hunting spears and animal skeletons have also beendiscovered in the village of Schöningen (close to Helmstedt), suggesting that their owners wereexcellent hunters. Illustrations of these finds are displayed in the primeval world museum in Mauer.

In the 1890s, Dutch geologist Eugène Dubois excavated the skull roof and thigh bone of a humanspecimen on Java, which he classified as a “species in between humans and apes”. He called itPithecanthropus erectus (originally Anthropopithecus), i.e. an “ape-human that stands upright”.However, many of his peers disagreed with Dubois’ interpretations, which is why the 1907“Heidelberg Jaw” was long seen as the earliest evidence of human evolution.

Palaeoanthropologists seem to be constantly embroiled in polemic, even according to the standardsof the scientific world. Could this be because their research objects cause a stir that spills over intothe non-scientific realm, often putting the researchers in the limelight? Could it also be becausepalaeoanthropologists are exposed to attacks from the church and from religious fundamentalists ofall creeds? In the first half of the 20th century, the passion of the disputes was often not only stokedby the vanity and vulnerability of the researchers, but also by nationalistic and racist prejudiceswhich seem odd to us today.

Homo britannicus

A few years after the discovery of the Mauer mandible, a spectacular discovery in a gravel pit near thevillage of Piltdown in the south of England hit headlines around the world. It consisted of fragmentsof a human skull with an ape-like lower jaw. Primitive stone tools as well as rhinoceros and elephantbone fragments were discovered alongside it. It seemed that the perfect missing link Darwin alludedto in his epochal oeuvre 40 years previously had finally been discovered. The outpouring of joy wastremendous because, at the height of Anglo-German rivalry in the period immediately precedingWWI, the British had outperformed the Germans, including in the field of human origin. The ironicterm “Homo britannicus” (the official name of the species was Eoanthropus dawsoni, after itscollector, Charles Dawson) suggested that at least one patriot truly believed that mankind was ofBritish origin.

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The Piltdown Man was “an audacious fake and a sophisticated scientific fraud” (quoted from thewebsite of the Natural History Museum in London). The skull fragments actually came from a modernhuman and had been artificially stained to match the surrounding gravel; the lower jawbone andcanine of an orang-utan were also found. From the outset, some scientists had expressed scepticismat the find, but it was not until 1952 – approximately 40 years after its alleged discovery – that theforgery was discovered by Kenneth Oakley, then a geoarchaeologist at the Natural History Museum,after he had carried out chemical analyses of the finds. He is credited with restoring the tarnishedimage of the world-famous museum. Now, a hundred years after the “discovery” of the skullfragments, this criminal case still occupies the minds of scientists around the world: what roles didthose involved in the fraud play, including famous figures like the Jesuit priest Teilhard de Chardin?What were the motives behind the fraud? In a recent publication, Professor Chris Stringer, head ofresearch of the “Human Origins” department at the Natural History Museum, presents the currentview of the scandal and a new research programme aimed at finally unravelling the mystery ofPiltdown Man using state-of-the-art DNA analysis, spectroscopy, radiocarbon- and isotope analysismethods (Nature 492, 177-179, 13th December 2012: “The 100-year mystery of Piltdown Man“).

Examination of the Piltdown skull in 1912. Charles Dawson (second from the right), fossil hunter who found Piltdown Manand prime suspect the fraud. © Natural History Museum, London

Out of Africa – again and again and again

Beyond a doubt, the scandal had damaged the reputation of science, but it did not succeed instopping the progress of research. In the decades after WW1, numerous discoveries “shed light on theorigin of man” (as Darwin once famously wrote). Racial prejudices nevertheless dominated humanthinking for quite some time. This led, for example, to an American anthropologist saying in 1962: “IfAfrica was the cradle of mankind, it was only an indifferent kindergarten. Europe and Asia were ourprincipal schools” (C. Stringer: The Observer, 19th June 2011). It was only modern DNA analyses thathelped the thesis that mankind actually originated in Africa to gain ground.

The first humans to leave Africa belonged to the species Homo erectus, named after the firstspecimen of Homo erectus discovered (and later confirmed as a true find) in Java by Eugène Duboisin 1891. The earliest Homo erectus fossils, dating to around 1.8 million years ago, were discovered inEast Africa. It is assumed that Homo erectus quickly migrated from Africa to West Asia (Dmanisi in

Homo heidelbergensis reconstruction. © Natural History Museum, London

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Georgia) and then moved on to China and Indonesia where Homo erectus descendants lived up untilat least 200,000 years ago. It is generally agreed that Homo erectus originates from more ancientAfrican hominids (Homo habilis or Australopithecus); however, the details of their phylogeneticrelationships remain highly controversial and are a central part of the debate on modern humanorigins.

For a long time, all hominids of the pre-Neanderthal era found in Eurasia were classified as Homoerectus. The Mauer mandible was therefore initially classified as Homo erectus heidelbergensis, aterm still used by the Heidelberg-based Museum of Geology and Palaeontology. Manyanthropologists are since using a new, broader nomenclature. The original H. erectus who livedapproximately 700,000 years ago evolved into a new human species with a much bigger brain whoused well-manufactured stone tools (known as the Acheulian culture) which, in a second propagationwave (out of Africa II theory), subsequently migrated to southern Europe, including Germany andEngland. All representatives of this more advanced human species are classified as Homoheidelbergensis based on the Mauer type specimen. Their robust build and excellent hunting toolsappeared to be well suited to dealing with the climate fluctuations in Europe. H. heidelbergensishominids evolved into the Neanderthals approximately 250,000 years ago.

The Homo heidelbergensis populations that remained in Africa (most probably the great majority)evolved into the ancestors of modern humans; however, little information is available about theirevolution. Humans classified as H. heidelbergensis lived in Ethiopia, Zambia and South Africa around600 – 500,000 years ago; around 200,000 years ago, anatomically modern humans lived in Ethiopiaand have therefore been recognised as Homo sapiens. These Homo sapiens specimens are part ofthe third propagation wave (out of Africa III or recent out of Africa theory), which occurred less than100,000 years ago. They colonised Europe around 45,000 years ago and eventually went on tocolonise the whole world.

The search continues

According to current scientific knowledge, the aforementioned scenario is plausible but notundisputed. New unexpected discoveries can change the picture tremendously, for example theHomo erectus fossil found in Dmanisi in Georgia, the dwarfish Flores Man (Homo floresiensis) datingto around 17,000 years ago and the Denisova Man from south Siberia identified from the DNAanalysis of a finger bone. Although multiple new human fossils have been discovered over the lastdecades, there are still big gaps in the fossil evidence regarding the alleged evolution of humans. Aneven bigger problem is that only fragments have been discovered: a few skull pieces here, and anarm bone, teeth, a cheekbone or a lower jawbone at a different site. This leaves room for differentinterpretations and controversy. Researchers are therefore diligently and patiently searching forfurther fragments at known discovery sites in the assumption that the sites harbour moreinformation about the fossils. The “Isotope Geochemistry” research group led by Dr. Bernd Kober atthe Institute of Earth Sciences at the University of Heidelberg, for example, is specifically focused onthe Mauer discovery site and is using a state-of-the-art thermion mass spectrometer to analyse theGrafenrain sand pit where Daniel Hartmann discovered his “Adam” in 1907.

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14-Jan-2013EJBioRN© BIOPRO Baden-Württemberg GmbH

The article is part of the following dossiers

Evolutionary research - from classical biology to molecular phylogeny

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