Characterization of ancient lipids in prehistoric organic residues: Chemical evidence of livestock-pens in rock-shelters since early neolithic to bronze age.

The characterization of ancient lipids from prehistoric sediments (fumiers) located in a rock-selter has been possible after the optimization of an analytical method based on the microwave-assisted extraction and solid-phase extraction clean-up step and a final derivatization step followed by gas chromatography with mass spectrometry. Eight sterols and two bile acids were detected just in the partially burned and unburned layers of the fumiers (animal organic residues deriving from manure/dung). The relationship between some of these compounds can be used to distinguish the biogenic origin of the samples, concluding that these strata (from Early Neolithic to Late Chalcolithic/Early Bronze Age) can be classified as ruminant residues. Three main periods of activity are observed over a period of 2000 years: one from 3990 +/- 40 before present (4530-4410 calibrated before present) to 4100 +/- 40 before present (4820-4750/4730-4510/4470-4450 calibrated before present), the second from 4470 +/- 40 before present (5300-4970 calibrated before present) to 5490 +/- 30 before present (6310-6275/6230-6220 calibrated before present) and the third from 5880 +/- 30 before present (6775-6765/6750-6645 calibrated before present) to 6010 +/- 30 before present (6940-6780/6765-6755 calibrated before present). Chemical data obtained are in concordance with the previous results obtained in the area.