Related Experiment Video
Updated: Jun 12, 2026

Adaptation at the Extremes of Life: Experimental Evolution with the Extremophile Archaeon Sulfolobus acidocaldarius
Published on: June 14, 2024
High-temperature environments of human evolution in East Africa based on bond ordering in paleosol carbonates
Benjamin H Passey1, Naomi E Levin, Thure E Cerling
1Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA. bhpassey@jhu.edu
Abstract:
Many important hominid-bearing fossil localities in East Africa are in regions that are extremely hot and dry. Although humans are well adapted to such conditions, it has been inferred that East African environments were cooler or more wooded during the Pliocene and Pleistocene when this region was a central stage of human evolution. Here we show that the Turkana Basin, Kenya--today one of the hottest places on Earth--has been continually hot during the past 4 million years. The distribution of (13)C-(18)O bonds in paleosol carbonates indicates that soil temperatures during periods of carbonate formation were typically above 30 degrees C and often in excess of 35 degrees C. Similar soil temperatures are observed today in the Turkana Basin and reflect high air temperatures combined with solar heating of the soil surface. These results are specific to periods of soil carbonate formation, and we suggest that such periods composed a large fraction of integrated time in the Turkana Basin. If correct, this interpretation has implications for human thermophysiology and implies a long-standing human association with marginal environments.
Related Concept Videos
Diversity of Archaea IV
Diversity of Archaea I
Diversity of Archaea III
Hyperthermophilic Bacteria
Global Climate Change
Factors Influencing Microbial Growth: Temperature

