2014 Annual Science Report

Massachusetts Institute of Technology Reporting  |  SEP 2013 – DEC 2014

Early Animals: The Role of Biosignatures in Illuminating Homonin Diet

Project Summary

Work conducted by Ainara Sistiaga, a student visitor from the University of La Laguna, Tenerife, Spain, aimed to evaluate the biomarker methodologies we typically apply to modern and ancient sediments to the issues surrounding the evolution of homo sapiens. Gas chromatography-mass spectrometry data on samples from El Salt (Spain), a Middle Palaeolithic site dating to ca. 50,000 yr. BP, represents the oldest positive identification of human faecal matter. We showed that Neanderthals, like anatomically modern humans, have a high rate of conversion of cholesterol to coprostanol related to the presence of specific gut flora. Analysis of five sediment samples from different occupation floors suggests that Neanderthals predominantly consumed meat, as indicated by high coprostanol proportions, but also had significant plant intake, as shown by the presence of 5β-stigmastanol.

4 Institutions
3 Teams
1 Publication
1 Field Site
Field Sites

Project Progress

Sterols and human evolution

Work conducted by Ainara Sistiaga, a student visitor from the University of La Laguna, Tenerife, Spain, aimed to evaluate the biomarker methodologies we typically apply to modern and ancient sediments to the issues surrounding the evolution of homosapiens.

Many of the anatomical and physiological changes that shaped human evolution have been closely linked to our tendency to eat more meat, that is, increased intake of protein and fat. Hunting for meat, as well as its consumption, may have played a role in the development our contemporary physique, the development of large brains as well as our extended life spans.

We conducted a study of Neanderthal diet using faecal biomarkers. Gas chromatography-mass spectrometry data on samples from El Salt (Spain), a Middle Palaeolithic site dating to ca. 50,000 yr. BP, represents the oldest positive identification of human faecal matter. We show that Neanderthals, like anatomically modern humans, have a high rate of conversion of cholesterol to coprostanol related to the presence of specific gut flora.

Analysis of five sediment samples from different occupation floors suggests that Neanderthals predominantly consumed meat, as indicated by high coprostanol proportions, but also had significant plant intake, as shown by the presence of 5β-stigmastanol. This study highlights the applicability of the biomarker approach in Pleistocene contexts as a source of direct palaeodietary information and supports the opportunity for further research into cholesterol metabolism throughout human evolution.

A) El Salt site during excavation; B) Field photograph showing a detail of exposed combustion structure H44 (white sediment corresponds to the top ash layer). The black sediment to the left belongs to an overlying combustion structure (H32). C) Field photograph of sediment block showing the facies described in the text in microstratigraphic succession. D) Microphotographs of a slightly burned coprolite of putative human origin identified in El Salt Stratigraphic Unit X (sample SALT-08-13). The images under plane polarized light show the pale brown color and massive structure of the coprolite, as well as the common presence of inclusions, which are possibly parasitic nematode eggs or spores. Views under blue light fluorescence (black background) shows autofluorescence indicative of high phosphate content.

Partial chromatogram showing evidence for meat and plant intake. Partial chromatogram of summed GC-MS transition for C27+C28+C29 sterols and stanols from sample WL H44. Retention peaks matched those of reference samples of fresh faecal matter from primates and herbivores.