About the episode
The idea has long been that people will move mainly if the right weather conditions create so-called “green highways.” This means: when there was enough water and plenty of food, the population grew and spread in line with the flourishing of nature.
Well, there were several migrations out of Africa, but the largest, the one that generated almost the entire world's population, occurred less than 100,000 years ago. In a new study, scientists suggest that it is not just “green highways,” but also “blue highways” that are causing this mass spread. They followed the water.
In this research, they studied people who lived in what is now northwestern Ethiopia. This is the group that was still present after Toba's super-eruption, about 74,000 years ago.
She achieved this, among other things, by studying glass fragments from the volcano. Glass shards are thinner than a human hair. This requires a lot of patience and requires very precise work. Not many laboratories can do what is done now: detect the presence of fewer than 10 of those fragments in one gram of material.
This means they can now connect places up to 8,000 kilometers apart over weeks, rather than years.
By also looking at the animals' teeth and eggs found, they were eventually able to conclude that the group of people in Ethiopia lived through a long period of drought after the volcanic eruption. During those periods, people must have adapted by using the few remaining lakes. First by hunting the animals that came to it to drink, then by catching the fish that were trapped inside.
If the lake is empty or dried up, they leave. Thus they moved from lake to lake in a short time, and thus did not follow the path of green abundance. This may not have been the “group” that left Africa, but perhaps it was this flexibility that ultimately led to the great success of the migration.
Read more about the research here: Toba's super-eruption reveals new insights into early human migration
