Akar Nusa
A family gathers shellfish on a muddy shore at the edge of a wide river plain. Their grandmother remembers a coast a long walk away. Their grandchildren will see the water much closer. No one is in a hurry. The change is slow, but it never stops.
The story
During the last ice age, so much water was locked in ice that sea level was far lower than it is today. Maps made by the biologist Harold Voris estimate the exposed land using the depth of the sea floor today. He drew shorelines for sea levels up to 120 metres below the present. At those levels the shallow seabed between the Peninsula, Sumatra, Borneo and Java becomes land, crossed by large rivers that are now drowned. Scientists call this lost land Sundaland.
Then the ice melted. A sea-floor record from the Sunda Shelf, studied in 2000, covers the period from 21 to 14 thousand years ago. It shows that during one burst of melting, called meltwater pulse 1A, the sea rose by as much as 16 metres in about 300 years. That is about 5 centimetres a year. A person could notice it in a lifetime.
Voris also made a useful point. The very lowest sea levels lasted only a short time. For more than half of each long period he studied, the sea stood at middle depths, not at its lowest. So Sundaland was not one fixed continent. It shrank and grew many times.
By about 7,000 years ago the sea had mostly settled into the shape we know. The shelf had been broken into the Peninsula and the islands of the archipelago.
What happened to the people? Writing the full story is hard, because many camps lie underwater. What we can say is that the people who lived along these plains and shores had to keep moving as the water came in.
Where you can still see it today
- In the shallow seas. The Straits of Melaka and the waters around the Peninsula are shallow because they sit on the old shelf.
- In the rivers. Voris maps show big river systems running across the shelf, which today are drowned valleys under the sea.
- In coastal life. Fishing, boat building and shell collecting are old ways of living with the shore.
What DNA can tell, and what it cannot
A 2008 study of whole mother-line genomes found that one group, called E, grew up in island Southeast Asia over the last 35,000 years. It then spread widely around the beginning of the Holocene, just when rising seas were breaking Sundaland into islands. The authors suggest that warming and sea-level rise, from about 15,000 to 7,000 years ago, were the main forces shaping the diversity of people in the region.
If your result shows a mother line from this region, such as E, it can be a thread back to those times. Region estimates may also show shared roots across the archipelago.
DNA cannot tell you where your family stood when the sea rose. It also cannot decide race, religion or bumiputera status. It only shows that the people of this region share a very long, moving history.
