An international research team’s latest study, which was just published in the journal Science, reveals that early human species were able to adapt to a variety of food sources and mosaic landscapes, which would have made them more resilient to past climatic changes.
Over the last 3 million years, at a time of escalating warm/cold climate fluctuations, our genus Homo underwent evolution. It is still unclear how early human species have adjusted to the worsening of climate extremes, ice ages, and significant changes in the landscape and vegetation.
Did our ancestors adjust to local environmental changes over time, or did they seek out more stable environments with diverse food resources? Was our human evolution influenced more by temporal changes in climate, or by the spatial character of the environment?
The research team combined a collection of more than 3,000 precisely dated human fossil specimens and archeological sites, representing six different human species, with simulations of a realistic climate and vegetation covering the last 3 million years to test these fundamental hypotheses about human evolution and adaptation quantitatively.
Our analysis shows the crucial importance of landscape and plant diversity as a selective element for humans and as a potential driver for socio-cultural developments.Elke Zeller
The scientists focused their analysis on biomes geographic regions which are characterized by similar climates, plants, and animal communities (e.g., savannah, rainforest, or tundra).
“For the archeological and anthropological sites and corresponding ages, we extracted the local biome types from our climate-driven vegetation model. This revealed which biomes were favored by the extinct hominin species H. ergaster, H. habilis, H. erectus, H. heidelbergensis, and H. neanderthalensis andbyour direct ancestors H. sapiens.,” said Elke Zeller, Ph.D. student from the IBS Center for Climate Physics at Pusan National University, South Korea, and lead author of the study.
According to their analysis, the scientists found that earlier African groups preferred to live in open environments, such as grassland and dry shrubland. Migrating into Eurasia around 1.8 million years ago, hominins, such as H. erectus and later H. heidelbergensis and H. neanderthalensis developed higher tolerances to other biomes over time, including temperate and boreal forests.
“To survive as forest-dwellers, these groups developed more advanced stone tools and likely also social skills,” said Prof. Pasquale Raia, from the Università di Napoli Federico II, Italy, co-author of the study.
Eventually, H. sapiens emerged around 200,000 years ago in Africa, quickly becoming the master of all trades. Mobile, flexible, and competitive, our direct ancestors, unlike any other species before, survived in harsh environments such as deserts and tundra.
The scientists discovered a large grouping of early human habitation sites in areas with enhanced biome diversity after delving further into the favored landscape features.
“What that means is that our human ancestors had a liking for mosaic landscapes, with a great variety of plant and animal resources in close proximity,” said Prof. Axel Timmermann, co-author of the study and Director of the IBS Center for Climate Physics in South Korea. The results indicate that ecosystem diversity played a key role in human evolution.
The authors demonstrated this preference for mosaic landscapes for the first time on continental scales and propose a new Diversity Selection Hypothesis: Homo species, and H. sapiens, in particular, were uniquely equipped to exploit heterogeneous biomes.
“Our analysis shows the crucial importance of landscape and plant diversity as a selective element for humans and as a potential driver for socio-cultural developments,” adds Elke Zeller. Elucidating how vegetation shifts have shaped human sustenance, the new Science study provides an unprecedented view into human prehistory and survival strategies.
On Aleph, one of South Korea’s fastest research supercomputers, climate, and vegetation models were simulated over the course of the past 3 million years of Earth history.
“Supercomputing is now emerging as a key tool in evolutionary biology and anthropology,” said Axel Timmermann.