Lagar Velho: a genuine Neanderthal-Modern Human hybrid?

Back in 1999 a juvenile skeleton was recovered from a limestone cliff site in central Portugal. The skeleton, which was the subject of intentional burial, was painted in red ochre and the grave was decorated with animal bones. Milk teeth found in the fossilised jaw [Photo 1] provided an age estimation of 4 years. Dated remains of charcoal, and bones of red deer and rabbit found in close proximity to the skeleton approximate the burial age at 24,500 years ago.

Dentition of the Lagar Velho skeleton. Note the unerupted molars and the prominent but reclining development of the chin. Source: Duarte et al., 1999.

 

Known as Lagar Velho 1 and/or Lapedo child, the skeleton was described as bearing a mixture of modern human and Neanderthal features – known as a morphological mosaic [Table 1]. In common with our species Homo sapiens, Lagar Velho child has a developed mental osseum (chin), which is a feature unique to our species. Tooth measurements and dimensions of the pubic (pelvic front) also align the child with our own species.

 

Table 1. Mixture of features displayed in Lagar Velho 1 skeleton
Modern Human	Neanderthal
Chin development Dental dimensions Mandibular features Radial features (curvature, tuberosity orientation) Pubic proportions	Chin orientation Femoral robusticity Femur:tibia length Muscle attachment sites (pectoralis major insertion) Tibial robusticity

 

However, the aforementioned chin slopes backwards as in archaic species like Neanderthals rather than the forward projection reminiscent of our own [Photo 1]. What’s more, Lagar Velho is similar to Neanderthals in measurements of the lower limb bones. Neanderthal leg bones are more sturdy and stocky than our own, possibly as an adaptation to a cold climate. Could Lagar Velho prove to be a bona fide example of a Neanderthal-modern human hybrid? 

Considerations

1) Modern humans equipped with their Upper Palaeolithic toolkit were invading Europe nearly 45,000 years ago, although the Iberian peninsula remained a Middle Palaeolithic landscape until much later. Evidence of Neanderthal occupation at Gorham’s Cave in Gibraltar, extends to 26,000 years ago. Therefore a potential overlap in population ranges can be implied.

2) Tattersall and Schwartz argue against the author’s (Duarte et al., 1999) conclusions in in the same edition of PNAS in which the original publication appeared. They account for In their view the Lagar Velho 1 skeleton was simply that of a “chunky Gravettian child” from a modern human population. All ambiguous Neanderthal-like morphological features are accounted for.

3) The Lagar Velho finds came to light 11 years before scientists announced the revelatory genetic signatures of Neanderthal-Modern Human interbreeding. However, new research suggests that conclusions of hybridisation based on genetic studies should be made with caution. Models need to instead account for population structure. Only the successful extraction and examination of ancient DNA from the Lapedo child will resolve the matter once and for all.

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Reference: Duarte, C. et al., 1999.  The early Upper Paleolithic human skeleton from the Abrigo do Lagar Velho (Portugal) and modern human emergence in Iberia. PNAS 96: 7604-760 9

 

Colourful picture emerges of Neanderthal fashion

When Robert Langdon (Tom Hanks) lectures on “symbology” in the Dan Brown novel The Da Vinci Code the implication is that symbols and art are an exclusively human feature. For many years the field of palaeoanthropology has clung to the concept that ornamental art is unique to modern man. The notion that Neanderthals were on a cognitive par with us has been stubbornly contested. Hints of decorated artefacts in association with Neanderthal toolkits have instead been attributed to mixings of archaeology or “imitation without understanding”.

Now, new finds from Spanish sites dating to the Middle Palaeolithic some 50 -45,000 years ago threaten to splodge paint all over the old theory which was until now set in stone. Naturally perforated marine shells containing remnant traces of colour pigments [below] were found alongside an assemblage of stone tools that apparently belonged to Neanderthals.

Neanderthal palettes? Left: external and internal views of a marine mollusc shell found at Cueva de los Aviones in Spain. Square section (maximised on right) indicates evidence of pigment residues. Source: Zilhao et al., 2010.

The most likely explanation is that the shells were used as personal ornaments or paint cups. A pointed and pigmented horse metatarsal found alongside the shells may even have been used as a prehistoric paintbrush or in the preparation of pigments. Tests performed by the scientists studying the artefacts rule out the random incidence of pigment in the shells. 

If genuine, our picture of the Neanderthals can once again be re-painted. Body art can be added to a list of their cultural aspects that includes burial of the dead. 

The finds were discovered at Cueva de los Aviones “cave of the birds/planes” which was located some 1.5-7km from the Mediterranean at the time. Like a bird or a plane, the new finds have come out of the blue to once again illuminate the argument of Neanderthal’s artistic abilities. Caution should be thrown to the wind however, for modern humans are now known to have invaded Europe close to 45,000 years ago. For all the world though, it seems Neanderthal life was as colourful as our own.

Reference: Zilhao, J. et al., 2010. Symbolic use of marine shells and mineral pigments by Iberian Neandertals. PNAS 107: 1023 -1028.

 

Collaring differences in Neanderthal & modern human clavicles

What exactly distinguishes Neanderthals and modern humans? Ok, Neanderthals had bulging brow ridges, flattened brain-cases and more robust bones overall – but these traits are still present in small frequencies of modern human individuals. Disregarding genetic information, only one feature that can be described as unique to our species: the humble chin! 

Clavicles are one of the poorest understood bones of the human body. These sturdy mechanical struts connect our scapulas (shoulder blades) to our sternum (breast bone). The bone is a constant feature shared by all primates but in terms of human evolution it has received very little attention.

French researcher Jean-Luc Voisin seized on this and performed an investigation looking for differences in clavicular curvature. By comparing modern human collarbones to those of Neanderthals and other archaic human species such as Homo habilis “handy man” and Homo erectus he found interesting results.

From above, the collarbones of humans, Neanderthals and apes both show a S-shape which enables us to climb, throw and carry heavy objects. From behind however a new picture emerges. Whereas the archaic human species and Western Neanderthals frequently display a double curvature as shown below, modern humans usually possess only a single curvature. The modern human condition positions the scapula lower on the posterior thorax (back of the ribcage).

Curvatures of the collarbone when looking from above (cranial view; top) and from behind (dorsal view; bottom). Diagram: Voisin, JL. 2006.

What’s more, Neanderthals from Western European sites typically have longer clavicles than their eastern counterparts, though this isn’t a result of their exceptionally broad ribcages. Both findings lend support to the idea that the classic features of Neanderthals evolved separately in Western Europe whilst the modern human condition evolved in isolation elsewhere when population sizes were small.

So although the single collarbone curvature is not apomorphic (entirely unique) to Homo sapiens, its high incidence is.

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Reference: Voisin, JL., et al. 2006. Krapina and Other Neanderthal Clavicles: A Peculiar Morphology? Periodicum Biologorum 108: 331-339

 

Rabbit appetite cause for modern human success?

Climate, competition or cultural means? Why the Neanderthals went extinct in Europe and why modern humans prevailed is a matter of constant debate in human evolution. New research (in Press) suggests that the utilisation of rabbits as a food source may have helped our species survive whilst the Neanderthals perished.

The authors examined animal bones found at excavation sites from Iberia to the south of France that date to between 70 and 10 thousand years ago. This period saw the earth plunge into a glacial maximum, commonly known as the last Ice Age. Whereas bones of large-bodied animals such as woolly mammoth declined dramatically during this period, smaller mammals like rabbits became superabundant. The hunting and consumption of fluffy bunnies may have contributed to the longevity of modern humans in the region.

Neanderthals on the other hand, classically viewed as big game hunters, may have been less versatile and remained reliant on the dwindling numbers of mammoths and the like for their main food source. This, coupled with an inability to switch their dietary preference or hunt small prey, was perhaps the death knoll for their species. 

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Reference: Fa, JE., et al. (in Press) Rabbits and hominin survival in Iberia. Journal of Human Evolution 

Link: Abstract

 

Wrist bones hand support to Hobbit species antiquity

The fossilised remains of a small-bodied human discovered on the island of Flores, Indonesia in 2003 created a rift in the scientific community. One camp of researchers posited that the bones belonged to an extinct ‘Hobbit‘ species called Homo floresiensis. Another set of researchers believed the remains constituted a pathological modern human of our own species Homo sapiens. Controversy and conjecture dwarved consensus in any case.

New evidence reported in the Journal of Human Evolution last month adds fuel to the former theory. Wrist bones from at least two new individuals display features in common with more ancient human ancestors and great apes. The lack of said features in modern human wrists suggests a more ancient evolutionary history for the Hobbit species than our own. 

Skull of Homo floresiensis, the famed Hobbit species from the Indonesian island of Flores. Photo: Ryan Willmore @ Flickr

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The shape of one of the wrist bones scrutinised, a capitate, suggests it articulated with a wedge-shaped rather than a block-shaped trapezoid, another wrist bone. Whereas chimpanzees, gorillas and Lucy’s kind Australopithecus (known from 3.9 – 2.9 million years ago) exhibit the former condition, modern humans and Neanderthals (present in the last 300 thousand years) exhibit the latter.

Another wrist bone studied by the American-Australian team, a hamate, shows less variation in shape over the timespan of human evolution during the last 5 – 7 million years. However, the Hobbit hamate’s hook (a projection of this bone) appears to lack an oval cross section as seen in modern humans and Neanderthals.

Both findings lend weight to the argument that the enigmatic Hobbits are biologically distinct from ourselves and are descendants of a more ancient lineage of human species that branched off earlier in our family tree. The discovery of more than one Hobbit individual with the original wrist condition further enhances the view that a population of Hobbits lived on Flores. 

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Paper: Orr, CM., et al. 2013. New wrist bones of Homo floresiensis from Liang Bua (Flores, Indonesia). Journal of Human Evolution 64: 109-129.

Links: Talk Origins, Nature

 

Stepping back in time

“You’ll never walk alone” – goes the famous Rodgers & Hammerstein show tune, sung vociferously by football fans. Now, it seems that the same message applies to Lucy, the famously upright Australopithecus afarensis type specimen, after the discovery of a new 3.4 million-year-old partial foot in Ethiopia. 

Reported in Nature yesterday, the partial foot appears to be evidence of a new extinct human species that lived and stood alongside Lucy. Lucy, the world’s first and foremost discovered bipedal species, was assumed to have roamed the Rift Valley landscape alone in her late Pliocene pursuits… until now.

Scientists have revealed that the newest ancient human foot had an opposable big toe, similar to chimpanzees and Ardi – the 4.4 million-year-old Ardipithecus ramidus species described in 2009. Lucy’s foot, on the other hand, was more anatomically akin to ours, with a domed big toe aligned with the other toes, making her better adapted to walking. 

Lead author and project leader Dr Yohannes Haile-Selassie said of Lucy, “Her species co-existed with close relatives who were more adept at climbing trees, like ‘Ardi’s’ species, Ardipithecus ramidus, which lived 4.4 million years ago.” Clearly then, two very contrasting modes of locomotion were being practised 3.4 million years ago. 

It is not such a gigantic step then to presume that the new foot bones belong to a descendant of Ardi?

For more information on this outstanding new matter, watch the video provided by Nature below.

 

Paper: Haile-Selassie, Y., et al., 2012. A new hominin foot from Ethiopia shows multiple Pliocene bipedal adaptations. Nature 483, 565-569. 

 

What of the Red Deer Cave people?

Reported in PLoS One on Wednesday were the astonishing remains of a potentially new human species whom scientists are labelling the Red Deer Cave people.

Bones of 5 individuals, dating from 11.5 – 14.3 thousand years ago, were described in the research paper written by Darren Curnoe, Ji Xueping and co. Crucially, the bones feature a remarkable array of modern and archaic human traits. Unlike our own species Homo sapiens, Red Deer Cave people possessed thick skull bones, prominent brow ridges, large molars and broad noses.

Note the fiercely jutting cheekbones [picture below], rivalled only in the human family perhaps by those of the Black Skull, a Paranthropus boisei individual.

Top left: The skull of a Red Deer Cave person whom lived around 11,500 years ago in what is today southern China. Source: Curnoe, D., et al. 2012.

The assortment of bones were discovered at two sites in southern China, one of which was excavated back in 1979 – five years after the unearthing of Lucy. Not until Xueping re-examined the bones in 2009 were the significance of the finds fully appreciated. As the bones share similar features, they are considered to belong to a shared population. 

Red Deer Cave people, named after an apparently favourite cervid dinner, lived at the dawn of agriculture in Asia; contemporaneous with the famed Hobbit, Homo floresiensis, and whilst modern humans in Europe were subjected to the final chills of the Ice Age.

Lead author Darren Curnoe from the University of New South Wales, Australia was typically coy in his assessment of the fossils. ”We’re trying to be very careful at this stage about definitely classifying them” he commented.

Could the Red Deer Cave people be relicts of an archaic population of modern humans that preceded the “Out of Africa” event? Are they hybrids: the result of interbreeding between modern humans and the Denisovans? Could they represent an inbred group of modern humans who experienced isolation and genetic drift? 

Chris Stringer, Head of Human Origins at the Natural History Museum, London plumps for the former explanation.

Whether the Red Deer Cave people constitute an anatomically and/or genetically distinct species will be deliberated vociferously but determined only by further examination. What seems likely either way is that a fascinating new piece has been added to the human origins jigsaw.

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Paper: Curnoe, D., et al., 2012. Human remains from the Pleistocene-Holocene transition of Southwest China suggest a complex evolutionary history for East Asians. PLoS One 7(3): e31918. doi:10.1371/journal.pone.0031918.