For the first time in history, scientists might be able to pinpoint the time when humans first arrived in Micronesia. And they use an unlikely source to determine it – soil sediments accumulated over millennia. A new study, recently published in The Proceedings of the National Academy of Sciences (PNAS), hints that humans might have arrived more than 5,000 years earlier than was initially thought.
First Migrations to Micronesia
The past few decades saw incredible advances in bio-anthropological and archaeological research in Oceania. Nevertheless, the precise pattern and timing of human activity (settlement) are still widely debated among scientists.
It’s believed that human activity in remote Oceania and Micronesia began some 3,300-3,500 years ago. To reach this destination, humans had to overcome challenges that were never seen in human history up to that time. Experts consider that, around that time, sea levels might have been over 6.5 feet higher than they are today. So, humans could have only passed thousands of miles through the ocean once its levels were lowered and stabilized.
Mangrove Trees Hold Clues
Across the Micronesia region, there are various high and low islands. Experts thought some of the higher islands would be more desirable than low-lying atolls, primarily due to their abundance of resources. Experts looked into settlements across the western part of Oceania. What they found was exactly what they expected – high islands showed evidence of earlier settlement compared to nearby atolls.
That pattern isn’t universal, though. In Micronesia, high islands like Kosrae show signs of human activity over 1,000 years later than nearby smaller islands.
Within the mangrove forests of Kosrae, scientists found sediments some 16 feet deep. Those trees, which grow at the coast, accumulate deep soils as sea levels rise. Researchers found that the oldest sediments in the mangroves were over 5,700 years old, meaning that over that time, the sea level rose by roughly 13 feet.
Scientists have proposed that land might be sinking relative to the sea surface. That would suggest evidence of earlier settlement in Micronesia’s Pohnpei and Kosrae might be submerged.