The Climate in the Mediterranean Levant during the Younger Dryas: The micromammal evidence

indiana jones mouse

Hello Readers,

This summer I was invited to present my current research at an international conference called “Bones and Identity: Reconstructing Social and Cultural Landscapes in the Archaeozoology of Southwest Asia” or ASWA (Archaeozoology of South West Asia) in Haifa, Israel. Below you can view a summary of my work.

Enjoy and don’t forget to tell me what you think!

AmiraZara

INTRODUCTION

The Natufian culture represents a shift from a nomadic foraging lifestyle to a semi-sedentary farming community. One hypothesis for the origin of agriculture is that the climatic crisis of the YD resulted in environmental deterioration and a lack of resources and that this climatic event had a significant impact on the Natufian population, which is why paleoenvironmental reconstruction is important (fig.1). Others suggest it did not; that population growth was more important.

In the Mediterranean region, there are considerable local variations in environment due to differences in topography and microhabitats. Thus, there is not a consensus in the literature that the paleoenvironmental reconstruction of the Levant is indeed cold and arid. Others have suggested that it may be cold and wet with no resource stress.

Greenland Ice-core

Figure 1: Younger Dryas global climatic data from Greenland Interstadial (Johnsen et al. 1992).

Geographic distribution of cultural units and archaeological sites (modified from B. Weninger 2009)

Figure 2: Geographic distribution of cultural units and archaeological sites (modified from B. Weninger 2009).

BACKGROUND

In order to acquire a more robust reconstruction of a regional paleoenvironment, we used micromammal communities as a paleoecological proxy.  In this study, we reconstructed the paleoecology of the Mediterranean region of the Southern Levant, semi arid of the southern Levant and Northern Levant dating from 20 – 10 ka cal bp (pre and post dating the YD). Data was retrieved from the literature and augmented into a meta-analysis.

Micromammal fossils can be used to interpret and describe ecology and habitats that existed at the time the fossils were deposited. Micromammals that are distinctly related to certain habitats can be used to construct and define ecological zones.

Figure 3: Annual Isohyet levels of Israel

Figure 3: Annual Isohyet levels of Israe

Late Natufian Site distribution; isohyets (mm)

Late Natufian Site distribution; isohyets (mm)

METHODOLOGY

We applied a metadata analysis approach and retrieved micromammal data from sites within the literature. Data was grouped in the three regions based on annual rainfall levels (>600; 600-350 and >350 in the Northern Levant). In order to correct for small sample sizes we used the “range through method”. We also included modern taxa and Upper Paleolithic taxa from each region and upper and lower limit respectively.

RESULTS

The following species have been identified throughout the literature: Sciurus anomalus (Persian Squirrel; refer fig. 5), Crocidura leucodon (Bicolored White-toothed Shrew), Crocidura suaveolens (Lesser White-toothed Shrew), Microtus socialis (Social/Günter’s Vole), Apodemus sylvaticus (Wood Mouse), Mus musculus (House Mouse), Spalax ehrenbergi (Palestine Mole Rat), and Chiroptera (Bat).

Meta-analysis Data

Meta-analysis Data

Key to  data chart

Key to data chart

CONCLUSION

  1. The overall pattern is similar between all three regions although there are salient differences among them, which can be attributed to the differences in climate among the regions.

  2. Overall there is no change in the micromammal communities across the Younger Dryas (YD).

  3. There are indications of a shift toward aridification, but this occurs after the PPNC

  4. During the YD itself we have the presence of humid and cold loving species in both the Mediterranean, semi arid and Northern Levant; supporting a wide range climate for a cold and wet climate throughout the period which differs from today. This can be seen in the presence of Sciurus anomalus (squirrel).

  5. It does not appear that during a wet climate there would have been a climate stress as suggested by some. Specifically, there is no change between the Natufian period and the PPNA period, as suggested by those that espouse a strong climatic change during the YD.

  6. There are indications of a shift toward aridification at the end of the PPNC, which may be the 10.2 Ka event in Figure 1.

  7. These results confirm the importance of using such a model in order to create a site-sensitive paleoecological reconstruction as well as a revision of models that suggest the Natufian resulted from environmental pressure of the YD.

The presence of Sciurus anomalus (squirrel) suggests a wetter paleoenvironment during the Natufian and PPNA than previously believed. The presence of Spalax ehrenbergi (Palestine Mole Rat) in Northern Syria during the Natufian and PPNA  also do not support the proposed cold and dry conditions. These results indicate that climate may not have had as large of an impact on the origin of domestication and would also suggest the climatic event onset of the YD occurred after the PPNB period and into the PPNC. These results confirm the importance of using such a model in order to create a site-sensitive paleoecological reconstruction as well as a revision of models that suggest the Natufian resulted from environmental pressure of the YD.

REFERENCES

Andrews 1990, Bar-Yosef 1998, Henry 1989, B. Weninger  2009,  Johnsen 1992, Payne 1983, Tchernov 1998, Maher 2010

FUNDING

The Department of Anthropology, Tulsa Undergraduate Research Challange (TURC), and The Office of Student Research at The University of Tulsa, Oklahoma, USA

Author

Ashley Brown

ashley-brown@utulsa.edu

Department of Anthropology

The University of Tulsa

Tulsa, Oklahoma, USA

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One response to “The Climate in the Mediterranean Levant during the Younger Dryas: The micromammal evidence

  1. Pingback: Beisamoun Excavation 2013 | AmiraZara·

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