In recent weeks, on these pages, I have written some posts related to the end of evolutionary history and attacks on the views of Dr. Benjamin Carson, noted surgeon and commencement speaker at Emory University’s recent graduation. The posts have generated some thoughtful and animated discussion about what role, if any, God and supernatural forces have played in evolution, and whether the sources of morality and ethics are objectively external or self-actualized. But a new study, published in Nature on June 14, 2012, has concluded that all human beings (and not just attorneys-at-law) evolved from a prehistoric shark that lived more than 300 million years ago.

The article, entitled Acanthodes and shark-like conditions in the last common ancestor of modern gnathostomes, by Samuel P. Davis, John Finarelli and Michael Coates, concludes that the primitive shark, named Acanthodes bronni, was the common ancestor of all jawed vertebrates on Earth. (Who knew?) Acanthodes, which derives from the Greek word for “spiny,” was an early member of gnathostomes, which means “jaw-mouths,” whose descendants are believed to include thousands of species of vertebrates ranging from fish to birds, reptiles, mammals and yes, even human beings. Who knows what interesting creatures will be coming next in the evolutionary schema?

So, what was the reason that scientists have concluded that this primitive shark was our ancestor? According to Professor Michael Coates, one of the researchers and a biologist at the University of Chicago, it has to do with a study of braincases. In an interview in The Daily Mail, Dr. Coates is quoted as saying:

We want to explore braincases if possible, because they are exceptionally rich sources of anatomical information. They are much better than scales, teeth or fin spines, which, on their own, tend to deliver a confusing signal of evolutionary relationships. For the first time, we could look inside the head of Acanthodes, and describe it within this whole new context. The more we looked at it, the more similarities we found with sharks. It helps to answer the basic question of what is primitive about a shark. And, at last, we are getting a better handle on primitive conditions for jawed vertebrates as a whole.

So, there you go, and now, as our public service, you know why we descended from a primitive shark! Even though it is said that the acanthodians died out about 250 million years ago and generally left behind only tiny scales and elaborate suits of fin spines, Dr. Coates and his colleagues may be able to think about what is and is not primitive about shark skulls from a study of this ancient, distinct species of shark (hopefully not with too many taxpayer funds). But it might also be that studies of the ancient shark’s braincase merely show some common (and intelligent) design features, in the same way that all types of buildings use walls and roofs.