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A 500,000 year environmental record from Chew Bahir, south Ethiopia: testing hypotheses of climate-driven human evolution, innovation, and dispersal

A 500,000 year environmental record from Chew Bahir, south Ethiopia: testing hypotheses of climate-driven human evolution, innovation, and dispersal

PI: Henry Lamb
Collaborators: Several collaborators on this project, including Christine Lane.

The Chew Bahir project aims to provide a long, continuous and highly-resolved palaeoenvironmental record from south Ethiopia that will facilitate tests of hypotheses linking human physical and cultural evolution to environmental variation, by reconstructing climatic and ecological change across critical intervals of the last half-million years of human evolutionary history. Chew Bahir palaeolake lies between the Ethiopian and Omo-Turkana Rifts, ideally placed to explore whether past periods of strong environmental variability, or sudden climatic changes, influenced biological and cultural transitions in East African hominin populations.

Far-travelled ashes preserved within the ~300 metre record are helping us to date and correlate the palaeolake sediments, aiming to provide direct connections to nearby archaeological records. The record is also generating one of the first stratified distal tephra records for southern Ethiopia, spanning ~ 500,000 years. Volcanic glass shards are being analysed using electron probe microanalysis and laser-ablation inductively coupled plasma mass spectrometry, to characterise the composition of each eruption. From this we are learning about when different volcanoes along the East African Rift were last active.

Chew Bahir is the youngest site within the wider Hominin Sites Palaeolake Drilling Project, which aims to improve the understanding of the palaeoenvironmental and paleoclimatic context of human evolution, through analysis of five palaeolake sediment records that together span the last 3.5 million years. In the Chew Bahir cores we are focussing on creating a high-resolution age model for the 135 ka - 125 ka interval, around the transition from MIS 6 to MIS 5, which will allow a test of the hypothesis that human population increase and range expansion from Africa to SW Asia at ca 130 ka took place at a time of stable, resource-rich conditions, following marked climate variability.

Cryptotephra

Cryptotephra: microscopic volcanic glass shards


Header image credit: Catherine Martin-Jones