Possible Interbreeding in Late Italian Neanderthals? New Data from the Mezzena Jaw (Monti Lessini, Verona, Italy)

Silvana Condemi,Martina Lari,Paolo Giunti,David Caramelli,Aurélien Mounier,Laura Longo,David Frayer

doi:10.1371/journal.pone.0059781

Abstract

In this article we examine the mandible of Riparo Mezzena a Middle Paleolithic rockshelter in the Monti Lessini (NE Italy, Verona) found in 1957 in association with Charentian Mousterian lithic assemblages. Mitochondrial DNA analysis performed on this jaw and on other cranial fragments found at the same stratigraphic level has led to the identification of the only genetically typed Neanderthal of the Italian peninsula and has confirmed through direct dating that it belongs to a late Neanderthal. Our aim here is to re-evaluate the taxonomic affinities of the Mezzena mandible in a wide comparative framework using both comparative morphology and geometric morphometrics. The comparative sample includes mid-Pleistocene fossils, Neanderthals and anatomically modern humans. This study of the Mezzena jaw shows that the chin region is similar to that of other late Neanderthals which display a much more modern morphology with an incipient mental trigone (e.g. Spy 1, La Ferrassie, Saint-Césaire). In our view, this change in morphology among late Neanderthals supports the hypothesis of anatomical change of late Neanderthals and the hypothesis of a certain degree of interbreeding with AMHs that, as the dating shows, was already present in the European territory. Our observations on the chin of the Mezzena mandible lead us to support a non abrupt phylogenetic transition for this period in Europe.

Highlights

One of the most frequently debated questions in paleoanthropology concerns the arrival in Europe of our species, Homo sapiens, anatomically modern humans (AMHs), and the fate of the humans who lived in this territory prior to their arrival, the Neanderthals.For many decades there were two different responses to this question: according to one point of view the Neanderthals did not really disappear, but were incorporated into the new incoming modern humans
The genetic analysis of the small fragment of hypervariable region 1 of the mtDNA with the well-known diagnostic Neanderthal substitutions presents a classic Neanderthal motif (16234 T, 16244 A, 16256 A, 16258 G) with the diagnostic transversion 16256 C/A which classifies the Mezzena mandible as a Neanderthal. These results are further supported by the comparative morphology analysis which shows similarities between the Mezzena mandible and Neanderthals
The symphysis of the Mezzena mandible is very close to the European classic Neanderthals (i.e. Regourdou and Guattari III) and late Neanderthals (Spy, La Ferrassie 1, Saint-Cesaire, Vindija and Las Palomas) showing an incipient mental trigone and more vertical symphyses than earlier Neanderthals [5,36,40]

Summary

Introduction

For many decades there were two different responses to this question: according to one point of view the Neanderthals did not really disappear, but were incorporated into the new incoming modern humans. Authors who support this hypothesis have argued that there was a change in morphology of late Neanderthals [1,2,3] and have interpreted certain anatomic features observed among early AMHs in Europe as a result of a continuity with Neanderthals [4,5]. European Neanderthals have been considered to be the producers of Mousterian assemblages and the makers of the later so-called "transitional assemblages" (Chatelperronian, Uluzzian, Bohunician, Szeletian) [8,9], either by internal modification [7,9,10] or through acculturation by AMHs [11,12].

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