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IBS Discovers Climate-induced Migration of Early Homo Sapiens (Oct 29)

- Joint research team consisting of IBS, Australia and South Africa analyze DNA and climate data

- Published in Nature, identifying birthplace of modern humans and reason of migration

The research team of the Institute for Basic Science (IBS) Center for Climate Physics led by Professor Axel Timmermann (Pusan National University) identified the exact birthplace of modern humans* and the reason of migration for the first time in the world with research teams from Austrailia and South Africa.

*modern humans: earliest ancestors of anatomically modern humans (Homo sapiens sapiens)

The researchers found out that anatomically modern humans appeared in Africa’s Kalahari* region roughly 200 thousand years ago, and started migration due to climate change about 130 thousand years ago.

*Covering much of northern Botswana, as far as the borders of Namibia and Zimbabwe (southern part of the Greater Zambezi River Basin region)

The MSIT and IBS announced that the research was published in the online edition of the highly prestigious international journal Nature (IF 43.070, at 1 a.m. on October 29 (Korean time).

The joint research team tracked DNA of descendants living in South Africa to discover the exact location of where modern humans emerged.

It has already been known that modern humans emerged in Africa, but there has been controversy on the exact location of the birthplace. The oldest remains of modern humans were found in East Africa, but most descendants of the oldest lineage (L0) live in South Africa.

* L0: modern genetic technologies can track our ancestral mothers 200 thousand years ago, using mitochondrial DNA. L0 lineage is modern human’s earliest known population split from the first ancestral mother, and descendants of L0 lineage are still living in South Africa.

The researchers found 198 descendants of the L0 lineage and refined the evolutionary tree of the earliest ancestral branches to establish a new L0 timeline, which previously used 1,019 samples. The new samples helped the researchers to add rare and new sub-branches of this lineage.

The emergence of sub-branches is closely related to the time of migration. With the L0 timeline, the researchers aligned it with sub-lineages and subsequently, the culture, geography and language of those branches, and concluded the first migration route and the birthplace.

In particular, the IBS research team proved that early humans migrated due to climate change triggered by the earth’s axis wobble.

The research team analyzed climate computer model simulations and geological data and concluded that the slow wobble (precession*) of Earth's axis changes summer solar radiation in the Southern Hemisphere, leading to periodic shifts in rainfall across southern Africa.

*Precession: a change in the orientation of the rotational axis of the Earth, caused by the gravitational pull of the Sun and the Moon, every 21,000 years.

According to the research team, these shifts in climate would have opened green, vegetated corridors, first 130 thousand years ago to the northeast (Zambia and Tanzania), and then around 110 thousand years ago to the southwest (Namibia and South Africa), allowing our earliest ancestors to migrate away from the homeland for the first time. This is consistent with the timing and route of migration based on genetic analysis, leading us to conclude that modern humans migrated because of climate change.

This study carries significance by combining genetic evidence with climate physics and rewrote the history of early humans.

“Geneticists from Australia extracted and analyzed genome data and IBS’ climate physicists simulated old climate conditions to find the first evidence of the first migration,” said Professor Timmermann.

The research team will keep unraveling the mystery of early humans beyond the L0 lineage to find out how humans moved to other places of the world and how this is associated with climate change.

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