The Explosive Appearance of Whales

It happens so often in the current scientific literature that it is almost cliché, but scientists have once again found that contrary to evolutionary expectation, a pervasive type of organism appeared and diversified rapidly in earth’s history.

Whales inhabit a wide variety of the ocean’s habitats – they can be found almost anywhere in the ocean, even in some rivers, and come in a dazzling variety of shapes and sizes. One would suspect if one adhered to Darwinian notions of evolution that this variety was the product of the slow accumulations of modifications over time, the result of the selection process which presumably gave us the variety of species we see on earth today. If you believed that, in the case of whales you would be wrong.

Instead researchers have found through molecular and computational methods that whales diversified rapidly and completely early in their history, fulfilling all the niches they occupy today, and then stabilizing into those forms. As the Science Daily article reports:

“Biologists have debated whether some key evolutionary feature early in their history allowed whales to rapidly expand in number and form,” Alfaro said. “Sonar, large brains, baleen (a structure found in the largest species for filtering small animals from sea water) and complex sociality have all been suggested as triggers for a diversification, or radiation, of this group that has been assumed to be rapid. However, the tempo — the actual rate of the unfolding of the cetacean radiation — has never been critically examined before. Our study is the first to test the idea that evolution in early whales was explosively fast.”

One explanation for whale diversity is simply that they have been accumulating species and evolving differences in shape as a function of time. The more time that goes by, the more cetacean species one would expect, and the more variation in body size one would expect to see in them.

“Instead, what we found is that very early in their history, whales went their separate ways from the standpoint of size, and probably ecology,” Alfaro said. “This pattern provides some support for the explosive radiation hypothesis. It is consistent with the idea that some key traits opened up new ways of being ‘whale-like’ to the earliest ancestors of modern cetaceans, and that these ancestors evolved to fill them. Once these forms became established, they remained.”

This of course is just one more finding that completely contradicts evolutionary prediction and expectation, but will have little effect on the beliefs of adherents to Darwin, given that their devotion is rarely the product of evidence to begin with.


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