We've been shaped by the same forces that shaped all life on earth. To understand how we fit in, we need to look back to long before our origins, to see how other living things evolved.
Mammals first appeared on earth around 200 million years ago, on land. Mammals are warm blooded, they give birth to living young, and they breathe air. These are all adaptations to living on land.
But whales and dolphins are mammals too. Whales are the largest living animals. Like us, whales and dolphins took on their present forms relatively recently. For a long time, the origin of these marine mammals was a scientific mystery.
Whales and dolphins are mammals that live in the water, but we know that mammals evolved on land so its a real puzzle how whales originally evolved. By understanding how that happened, we'll begin to understand how the big transformations happened generally.
All images and extracts from NOVA, WGBH Boston, PBS Television |