The marvelous evolution of whales

Our understanding of how animals evolved (developed) is based on the theory of evolution that Charles Darwin came up with 150 years ago. New research on the evolution of whales may change that understanding.

Darwin’s theory

Charles Darwin’s ideas compared evolution to a tree with each species as a branch.  Each species grew differently based on the different habitats they occupied and they changed as they came up against climate change, change of diet or arrival of new predators. The sheer distances between the different habitats kept each species unique and different. Thus Darwin’s vision was of an ever-branching tree. Central to his theory is the idea that once a species starts changing from the original, it stays on its unique path, with no connections to other species that may have also branched out from the original.

The new research on whales

Researchers from Germany have been studying the genetic connections between certain kinds of whales. Genes are part of the cells of all living animals and they contain instructions based on which the body grows and develops. Genes also connect us to our family and the human species as all members of a species share common genes.

The whales studied were the baleen whales including Humpback, Fin, Sei, Minke and Blue Whales. These whales are part of a family known as rorquals-they’re the baleen whales with pleated throats, allowing them to gulp huge mouthfuls of seawater that they strain for food using baleen plates. The researchers also studied Gray Whales that belong to another family of whales.

Baleen = flexible, fibrous plates made of keratin and hangs from upper jaws. Whale intakes a mouthful of water, raises tongue and squeezes water out through bristles. Food is then licked off the baleen.
Baleen = flexible, fibrous plates made of keratin and hangs from upper jaws. Whale intakes a mouthful of water, raises tongue and squeezes water out through bristles. Food is then licked off the baleen.

When they studied the genes of these whales, they found that Gray Whales were in fact also rorquals, and were in fact closely related to Fin and Humpback whales. In fact Grays are more closely related to Fin and Humpback Whales compared to the connections between Fins, Humpbacks and other rorquals.

Web, not tree

This new information on the connections between different whale species may push us towards thinking of evolution not as a tree of life but as web. Unlike a tree where branches don’t meet once they’ve separated from the main trunk, a web allows for multiple connections in different directions.

This kind of family connections seen between species we thought weren’t connected at all may have to do with the habitats whales occupy. They live in vast oceans that are interconnected-thus it is more difficult to isolate (keep alone) a species. There inter-breeding (when whales of two different species make a new family) and hybrids (formed by such inter-breeding) may be more common than we think.

Genetic analysis of species is quite a new science, and it is quite likely that we will discover many more such interesting connections between species.

A sketch from one of Darwin’s notebooks. Information we now have shows that instead of a tree of life, the map of species in the world looks more like a densely connected web.
A sketch from one of Darwin’s notebooks. Information we now have shows that instead of a tree of life, the map of species in the world looks more like a densely connected web.