Abnormal level of the Caspian Sea helped people to populate Asia

(ORDO NEWS) — The results of the study show that the dry steppe, semi-desert and desert zones of Central Asia were once a favorable environment for hominins and their settlement. Scientists even claim the key role of this region in the migrations of early people.

Central Asia is located at a crossroads connecting several zones important for the settlement of hominins in the middle Pleistocene, that is, 126-781 thousand years ago.

But the environment that we see there now does not seem particularly attractive: the arid plains do not look like a favorable corridor for the settlement of our ancestors.

Moreover, it is not so easy to understand exactly whether they have always been like this or whether it is only their current appearance.

This is partly due to the fact that in these areas erosion outpaces the accumulation of sedimentary rocks. This means that here we have few reliably dated archaeological finds and paleoclimatic data.

Nevertheless, based on rare finds of stone tools, we can confidently say that hominins appeared in Central Asia no later than 0.8 million years ago.

Abnormal level of the Caspian Sea helped people to populate Asia 2
From the stalagmites, one can understand how the humidity has changed over the course of one season or several millennia

The authors of the work collected and analyzed paleoclimatic and archaeological data from Central Asia during the Middle Pleistocene.

They studied both known examples of Paleolithic stone tools and mineral deposits (stalagmites) formed in a cave in southern Uzbekistan.

The growth rate of stalagmites depends on air humidity and temperature, which makes them fairly reliable “paleothermometers”.

To migrate to new places and overcome environmental difficulties, effective tools are needed. Ancient hominins carried their tools with them when they settled.

Unfortunately, the earliest finds (up to 0.8 million years ago) of this kind in Central Asia do not have a reliable context for dating, and it is difficult to reconstruct their environment.

Therefore, the researchers focused on finds dating back to about 400,000 years old. Dating is extremely important here: 374-424 thousand years ago, another interglacial was observed on the planet.

It was warm and – as a result – humid. How much has this ancient global warming affected Central Asia?

Cave deposits are a kind of archives of environmental conditions.

Using geochemical data from stalagmites, one can gain insight into seasonal and millennial changes in moisture availability and the climate dynamics that governed rain and snowfall.

Abnormal level of the Caspian Sea helped people to populate Asia 3
On the map, the black line outlines the study region, and the red line shows the Caspian catchment area

But not only stalagmites are interesting in terms of paleoclimatic data. The water level in the Caspian Sea is of great importance here.

The fact is that this inland sea is highly dependent on the full flow of the rivers flowing into it (as well as on the rains in the region).

And although we all remember that the largest of them has nothing to do with Central Asia, nevertheless, part of the rivers that supply the Caspian with water flow from the Asian side.

Stratigraphy shows that the level of the Caspian Sea during this period was consistently high. This means that full-flowing rivers flowed through the Asian plains.

And the climate there was warm and humid. That is, an environment that seemed to our ancestors quite suitable for life.

The latter conclusion confirms the combination of archaeological and paleoclimatic data.

The period for which a significant number of finds of stone tools is recorded coincides with a time when the Caspian Sea experienced a consistently high water level, which led to greater availability of moisture and more moderate conditions in usually (and today) arid regions.

The authors of the work believe that Central Asia was a key region through which the settlement of ancient people passed.

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