New Dating Upsets Neanderthal Theory

Discussion in 'Science and Nature' started by MelT, Nov 15, 2011.

  1. Members of our species (Homo sapiens) arrived in Europe several millennia earlier than previously thought. This was the conclusion by a team of researchers, after carrying out a re-analyses of two ancient deciduous teeth.
    These teeth were discovered in 1964 in the “Grotta del Cavallo”, a cave in southern Italy. Since their discovery they have been attributed to Neanderthals, but this new study suggests they belong to anatomically modern humans. Chronometric analysis, carried out by the Oxford Radiocarbon Accelerator Unit at the University of Oxford, shows that the layers within which the teeth were found date to ~43,000-45,000 cal BP. This means that the human remains are older than any other known European modern humans. The research work was published in the renowned science journal Nature.
    [​IMG]Grotta del Cavallo (red arrow) opens on the bay of Uluzzo, which is located in the Regional Natural Park of Portoselvaggio, Apulia, southern Italy. Image: Annamaria Ronchitelli

    Grotta del Cavallo, in Apulia, was discovered in 1960. It contained about 7 m of archaeological deposits spanning the period during which Neanderthals were replaced by modern humans. Two milk teeth were unearthed in 1964 by Arturo Palma di Cesnola (emeritus of the University of Siena) from the so-called Uluzzian archaeological layers. The Uluzzian culture has been described from more than 20 separate sites across Italy, and is characterised by personal ornaments, bone tools and colourants; items typically associated with modern human symbolic behaviour. But the teeth from Cavallo were identified in the 1960′s as Neanderthals who lived around 200,000 to 40,000 years ago. This attribution has been at the heart of a widely held consensus that the Uluzzian and the complex ornaments and tools within it were also produced by Neanderthals.

    Comparison of micro-computed-tomography scans of teeth


    [​IMG]Mesial view of the specimen Cavallo-B (deciduous left upper first molar), the first European anatomically modern human. The white bar in the figure is equivalent to 1 cm. Image: Stefano Benazzi

    Stefano Benazzi, post-doc at the Department of Anthropology at University of Vienna, and his colleagues were able to compare digital models derived from micro-computed tomography scans of the human remains from Grotta del Cavallo with those of a large modern human and Neanderthal dental sample: “We worked with two independent methods: for the one, we measured the thickness of the tooth enamel, and for the other, the general outline of the crown. By means of micro-computed tomography it was possible to compare the internal and external features of the dental crown. The results clearly show that the specimens from Grotta del Cavallo were modern humans, not Neanderthals as originally thought.”

    New chronometric analyses of the Oxford Radiocarbon Accelerator Unit

    Katerina Douka, post-doc at the Research Laboratory for Archaeology and History of Art at the University of Oxford, undertook a comprehensive programme of radiocarbon dating to establish a firm chronology for the finds. Previous dates for the Uluzzian were problematic and affected by contamination. Since the teeth were too small to date directly, Douka developed a new approach that focused on the dating of marine shells found in the same archaeological levels as the teeth. This approach showed that the modern human teeth must date to between ~43,000-45,000 years ago. Douka said, “Radiocarbon dating of Palaeolithic material is difficult because the levels of remaining radiocarbon are very low and contamination can be problematic. Shell beads are important objects of body ornamentation and have allowed us directly and reliably radiocarbon date items associated with these early Homo sapiens settlers of Europe.”
    [​IMG]Uluzzian artefacts from Grotta del Cavallo, Apulia, southern Italy. Credit: Annamaria Ronchitelli and Katerina Douka

    Uluzzian culture was made by modern humans


    “What the new dates mean“, Benazzi summarised, “is that these two teeth from Grotta del Cavallo represent the oldest European modern human fossils currently known. This find confirms that the arrival of our species on the continent – and thus the period of coexistence with Neanderthals – was several thousand years longer than previously thought. Based on this fossil evidence, we have confirmed that modern humans and not Neanderthals are the makers of the Uluzzian culture. This has important implications to our understanding of the development of ‘fully modern' human behaviour. Whether the colonisation of the continent occurred in one or more waves of expansion and which routes were followed is still to be established.”
    Based on this fossil evidence, we have confirmed that modern humans and not Neanderthals are the makers of the Uluzzian culture

    Read more >> New dating of cave site upsets Neanderthal theory | Past Horizons
    Read the Archaeology News - then buy the Trowel at Past Horizons Tools
     
  2. Aren't present day neanderthals gingers?

    And that we all have a little ginger in us? Except africans.
     
  3. From the thread title I thought Neanderthals were pissed about some sort of dating service.
     
  4. Modern humans have red hair because of the expression of a particular gene, but the same gene in neanderthals was expressed in a different way with a similar result.

    \t\t\t\t \t\t\t\t\tNeanderthals 'were flame-haired' \t\t\t\t
    \t\t\t
    \t\t \t\t \t\t \t\t \t \t\t \t \t\t \t\t\t By Paul Rincon
    Science reporter, Murcia, Spain
    [​IMG]
    \t
    \t \t\t
    \t\t\t \t\t\t \t\t\t\t[​IMG] \t\t\t\tNeanderthal genetics is revealing surprises
    \t\t\t
    \t\t\t \t\t \t\t \t \t Some Neanderthals were probably redheads, a DNA study has shown. A team reports in the journal Science that it extracted DNA from the remains of two Neanderthals and retrieved part of an important gene called MC1R.



    In modern people, a change - or mutation - in this gene causes red hair, but, until now, no one knew what hair colour our extinct relatives had.



    By analysing a version of the gene in Neanderthals, the scientists found that they also have sported fiery locks.
    "We found a variant of MC1R in Neanderthals which is not present in modern humans, but which causes an effect on the hair similar to that seen in modern redheads," said lead author Carles Lalueza-Fox, assistant professor in genetics at the University of Barcelona, Spain.
    Though once thought to have been our ancestors, the Neanderthals are now considered by many to be an evolutionary dead end.
    They appear in the fossil record about 400,000 years ago and, at their peak, these squat, physically powerful hunters dominated a wide range spanning Britain and Iberia in the west, Israel in the south and Siberia in the east.
    Our own species, Homo sapiens, evolved in Africa, and displaced the Neanderthals ( Homo neanderthalensis) after entering Europe about 40,000 years ago. The last known evidence of Neanderthals comes from Gibraltar and is dated to between 28,000 and 24,000 years ago.



    Selective pressure
    Until relatively recently, scientists could turn only to fossils in order to learn what Neanderthals were like. But recent pioneering work has allowed scientists to study DNA from their bones.
    \t
    \t [​IMG] \t\t \t \t\t[​IMG] \t\tIn Neanderthals, there was probably the whole range of hair colour we see today in modern European populations, from dark to blond right through to red \t\t[​IMG]
    \t

    \tDr Carles Lalueza-Fox

    \t \t Genetics could shed light on aspects of Neanderthal biology that are not preserved in fossils. These include external appearance - such as hair, skin and eye colour - cell chemistry and perhaps even cognitive ability.
    This will help scientists address key questions, such as why we and not they inherited the Earth.
    Genes for skin colour and hair colour are obvious early targets for scientists engaged in these efforts.
    In modern people from equatorial areas, dark skin and hair is needed to guard against skin cancer caused by strong UV radiation from the Sun.
    By contrast, pale skin - along with red or blond hair - appears to be the product of lower levels of sunlight present in areas further from the equator such as Europe.
    "Once you go out of Africa, the selective pressure from UV radiation disappears. So any mutation that falls into the MC1R gene is allowed to survive and spread through a population," said Dr Lalueza-Fox, speaking at the Climate and Humans conference in Murcia, Spain.
    But people with fair skin are able to generate more vitamin D, which may have given them an evolutionary advantage in northern regions.



    Altered chemistry
    The latest research suggests that similar adaptations were evolved independently by Neanderthals and modern Europeans in response to similar environmental circumstances.
    \t \t\t
    \t\t\t \t\t\t \t\t\t\t[​IMG] \t\t\t\tDNA was taken from Neanderthal bones found in northern Spain
    \t\t\t
    \t\t\t \t\t \t\t \t \t All humans carry the MC1R gene, but modern redheads possess an altered, or mutated, version of it. This rare variant does not work as effectively as more common forms of the gene. This loss of function alters the chemistry of the cell, producing red hair and pale skin.
    In the latest study, the authors retrieved fragments of the MC1R sequence from Neanderthal bones found at Monte Lessini in Italy and from remains unearthed at El Sidron cave in northern Spain. DNA is notoriously difficult to obtain from very old specimens such as these.
    "This was a bit like finding a needle in a genomic haystack. I couldn't believe we found it the first time. I asked my friends to repeat the results. Eventually the variant was found in two separate Neanderthals in three different labs," said Dr Lalueza-Fox.
    Unique variant
    The researchers found that Neanderthals carried a unique variant of the gene not present in modern humans.
    \t \t\t
    \t\t\t \t\t\t \t\t\t\t[​IMG] \t\t\t\tUntil now, information on hair colour has been sparse
    \t\t\t
    \t\t\t \t\t \t\t \t \t In order to test what effect it had on hair and skin colour, the researchers inserted the Neanderthal variant into a human cell called a melanocyte.
    Melanocytes produce the dark pigment called melanin which gives skin, hair and eyes their colour.
    The researchers saw the same loss of function in the Neanderthal form of MC1R as they did in modern variants of the gene which produce red hair.
    "In Neanderthals, there was probably the whole range of hair colour we see today in modern European populations, from dark to blond right through to red," Dr Lalueza-Fox told the BBC News website.
    To Dr Lalueza-Fox, the observation that the Neanderthal version of the gene is not found in modern humans suggests they did not interbreed with each other, as some scientists have proposed.



    Primitive speech
    Dr Clive Finlayson, director of the Gibraltar Museum, commented: "It's extremely interesting - it makes us understand a bit more about who the Neanderthals were.
    "It suggests there may be a propensity towards the reduction of melanin in populations away from the tropics. If the Neanderthal and modern variants are different, it may be a good example of parallel, or convergent evolution - a similar evolutionary response to the same situation."
    "Neanderthal genetics is going to give us a lot more information. This is the tip of the iceberg."
    In a separate study, published in the journal Current Biology, Dr Lalueza-Fox and colleagues extracted the DNA sequence for a gene called FoxP2 from Neanderthals.
    Modern people have several changes in this gene that are absent in our relatives the chimpanzees. This suggests that FoxP2 may have been an important gene in the evolution of language, something which separates us from the great apes.
    The researchers found that Neanderthals shared these key mutations in FoxP2 with modern humans, suggesting they had some of the prerequisites for language and speech.
    An ongoing project to sequence the entire Neanderthal genome was recently hit by claims by a group of researchers that samples could be contaminated with modern human DNA.
    Paul.Rincon-INTERNET@bbc.co.uk \t\t \t
     

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