During the glacial or ice age periods, the sea level was lowered because the ice sheets were formed upon the surface of the land. The huge ice sheets contained a considerable portion of the earth’s water. Much land was formed providing land bridges between continents for human and animal migrations permitting extensive interchange of faunas of North America and Eurasia.
The ice sheets made profound changes in the landscape and physical features of the regions it covered. The ice, which encroached gradually on regions previously warm, must have submitted all living things to new and unsettling conditions. In consequence some animals became extinct at this time, others moved southward.
When sea levels sank during the last Ice Age, a series of land bridges cut through the shallow waters connecting the Philippines with the rest of the Southeast Asia, one running through Palawan and Mindoro to Luzon, another through the Sulu Islands to Mindanao. Others linked Celebes with Mindanao. An even older land bridge connected northern Philippines with Taiwan at a time when that island was itself connected to the Asian mainland.
In between the time of glacial or ice age were periods of more moderate climatic conditions called the interglacials which were the times when the sea level rose due to the melting ice.
Human migration during the period 35,000 BC to 10,000 BC followed the migration of fauna and flora using these land bridges which connected the Philippines with the rest of Southeast Asia onto the new grassy plains until melting ice and rising sea levels submerged these land bridges 7,000 to 10,000 years ago. For thousands of years, bands of early hunters kept pushing farther and farther out into the new land.
In around 10,000 years BC, a change began to occur. Temperature began to rise and the ice sheets began to melt, gradually. Little by little rivers and lakes formed here and there. Decades past, centuries past and the ice slowly melt and the sea started to rise. With the flow and ebb of the water due to the melting ice caps, humans got isolated for scores of generations. Necessity dictated that they adapt to the new surroundings or they died. When the great ice sheets melted, the land bridges were submerged by rising waters, leaving the islands exposed.
After the Ice age, parts of the Asia mainland sank and the peaks remained surrounded by the waters of the China Sea.
Until next time. The story of the Philippines continues . . .