Insight into competitive advantage of modern humans over Neanderthals

Neanderthals and Homo sapiens coexisted in Europe for at least 5,000 years, before the latter population density became superior. However, it is still not clear why the  modern human populations could increase after migrating to Europe and successfully occupy new territories, while autochthonous Neanderthals disappeared ~40,000 years ago. For better understanding human evolution, it is of pivotal importance shedding more light on the competitive advantages that modern humans exerted over Neanderthals. 
The Uluzzian culture is the first Upper Paleolithic culture developed by modern humans in Europe, based on two deciduous teeth that were discovered at Grotta del Cavallo and attributed to Homo sapiens. Grotta del Cavallo (Nardò, Lecce, Italy) is a pivotal site for the Uluzzian because its stratigraphic sequence includes three main Uluzzian layers, namely from archaic to final Uluzzian, sandwiched between ~45,000 years ago to ~40,000 years ago.
The Uluzzian culture exhibits typical modern features characterized by the presence of ornaments, bone implements, coloring substances, and crescent-shaped backed pieces made on small blades or bladelets, also known as “lunates”, a distinguish trait of the Uluzzian culture (See Fig. 1a). 
In order to understand the differences in the Uluzzian from previous lithic traditions, a systematic use-wear analysis of total 146 excavated backed pieces was performed by combining macroscopic and microscopic analysis using a Hirox digital 3D microscope. They revealed that the major function of the Uluzzian lunates was hunting. To reconstruct the hafting modes, the frequency and type of the Diagnostic Impact Fractures (DIF) was compared with those obtained by projectile experiments with backed piece replicas. The projectile experiments indicated that DIFs on several lithic remains were comparable with when the pieces were hafted as tips onto wooden shafts. In addition, the extremely small dimensions of the Uluzzian backed pieces (on average 27.1 mm in length, 10.5 mm in width and 4.6 mm in thickness) suggest that they were suitable for neither thrusting nor throwing but they should behafted on the tip of small diameter wooden shafts. Moreover, the presence of multiple and large DIFs (the largest DIF measures 24.7 mm in length, and 9 DIFs are larger than 10 mm) indicate that they might have been delivered at high impact velocities. These results let us to suppose the use of a mechanical delivery system, such as a spear thrower or bow.
 

Figure 1.     a, Optical images at two different angles of a lunate. The area sampled by FTIR microscopy is highlighted by a black box and magnified in b and c. d, Representative FTIR spectra of the sampled residues from samples 34 and 75. Two selected reference spectra of beeswax and peach tree gum are also plotted, taken from the database of the Kimmel Center for Archaeological Science Infrared Standards Library (https://www.weizmann.ac.il/kimmel-arch/infrared-spectra-library). The orange shaded areas indicate the main absorption bands of beeswax organic fraction, while the green shadowed areas the ones of plant/tree gum. 


Certainly, high impact energies require stable hafting, for avoiding tip displacement during the impact. As in Fig. 1b, and highlighted in Fig. 1c most of the Uluzzian lunates have residues on the back, the chemical nature of which was assessed by FTIR microscopy at the Chemical and Life Sciences branch of the SISSI beamline (See Fig. 1d). FTIR microscopic analysis of few grains of the red deposits have revealed the presence of organic traces of beeswax and plant/tree gum, as proven by comparison with reference spectra. The organic fractions were present in different proportion in the diverse analyzed samples, as proven by the different ratio of the spectral bands associated to aliphatic chains (3,000–2,800 cm−1, and at ~1,460 and ~1,378 cm−1) and carbonyl groups (1,740 cm−1) of beeswax, and the ones of the carboxylate fraction of plant/tree gum (broad bands in the 1,650–1,550 cm−1 and 1,450–1,350 cm−1 spectral regions). Ochre was also identified as a constitutive part of the residues, supported by SEM/EDX analysis as well. Correlative FTIR and SEM/EDX analysis also allow excluding the presence of organic contaminants in the burial soil, as well as detecting a much higher percentage of ochre in the residues with respect to the soil.
Overall, the FTIR microscopy results have revealed that the residue stuck on the backed pieces is a mixture of plant/tree gum and beeswax intentionally mixed with ochre and applied as an adhesive, and therefore strengthened the use-trace analysis.
The present research allowed dating back the earliest evidence of projectile technology in Europe of about 20,000 years and to conclude that the spearthrower and bow-and-arrow technologies allowed modern humans to hunt more successfully than Neanderthals and may have been one of the factors depriving Neanderthals of a chance to recover their population.

 

This research was conducted by the following research team:

Katsuhiro Sano1, Simona Arrighi2,3, Chiaramaria Stani4, Daniele Aureli3, 5, Francesco Boschin3, Ivana Fiore6, Vincenzo Spagnolo3, Stefano Ricci3, Jacopo Crezzini3, Paolo Boscato3, Monica Gala6, Antonio Tagliacozzo6, Giovanni Birarda4, Lisa Vaccari4, Annamaria Ronchitelli3, Adriana Moroniand Stefano Benazzi2,7


Center for Northeast Asian Studies, Tohoku University, Sendai, Japan
Department of Cultural Heritage, University of Bologna, Ravenna, Italy
Dipartimento di ScienzeFisiche, della Terra e dell’Ambiente, UR Preistoria e Antropologia, Universitàdegli Studi di Siena, Siena, Italy
Elettra-Sincrotrone Trieste S.C.p.A., Trieste, Italy
UMR 7041, équipeAnTET, Université de Paris X-Nanterre, Paris, France
Bioarchaeological Service, Museo delleCiviltà. MuseoPreistoricoEtnografico “Luigi Pigorini”, Rome, Italy
Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany

Contact persons:

Katsuhiro Sano,  email: sano.k@tohoku.ac.jp
Stefano Benazzi,  email: stefano.benazzi@unibo.it
Adriana Moroni,  email: adriana.moroni@unisi.it


 

Reference

Katsuhiro Sano, Simona Arrighi, Chiaramaria Stani, Daniele Aureli Francesco Boschin, Ivana Fiore, Vincenzo Spagnolo, Stefano Ricci, Jacopo Crezzini, Paolo Boscato, Monica Gala, Antonio Tagliacozzo, Giovanni Birarda, Lisa Vaccari, Annamaria Ronchitelli, Adriana Moroni and Stefano Benazzi, "The earliest evidence for mechanically delivered projectile weapons in Europe", Nature Ecology & Evolution 3, 1409–1414 (2019); doi: 10.1038/s41559-019-0990-3

 
Last Updated on Friday, 25 October 2019 17:10