New Scientific Evidence: Dead Fish Shook Hands!
"Every human handshake echoes the Devonian: the structures we shake with -- shoulder, elbow, wrist -- were first seen in fish living in streams 370 million years ago..."
Or so says Arts & Letters Daily for May 11, 2006 in the column labeled "Essays and Opinion" as the lead-in words linking to a website (Edge) featuring an excerpt from John Brockman's Intelligent Thought, an essay by Neil Shubin titled "The 'Great' Transition," which states:
The take-home message of this essay is a simple one: The transition of animals from water to land in the Devonian period, 370 million years ago, was profoundly important .... The effects of the transition are all around us .... We even see them when we shake hands. [.../..../...] The structures we shook with -- our shoulder, elbow, and wrist -- were first seen in fish living in streams over 370 million years ago. Our firm clasp is made with a modified fish fin.Huh? Talk about a bait-and-switch! I was really expecting to learn that those old dead fish shook hands. Or at least an explanation for the dead-fish handshake.
Setting aside the ridiculous for a moment, I should state that the article is actually very interesting, and for the following reason:
In 1987 my colleague, Jenny Clack, began new studies in East Greenland and found ... [an] important piece of evidence bearing on this water-land transition .... She discovered the skeleton of another truly extraordinary tetrapod .... [T]his creature has limbs with fingers and toes. It also has a very tetrapod-like hip, neck, and ear. What is remarkable is that this, the most primitive known tetrapod, is aquatic. It is not remotely specialized for life on land. It has fingers and toes but they are set within a limb that looks like a flipper. The limbs are delicate structures and seem unable to have supported the weight of the animal on land. It has a pair of hind limbs, but behind that is a tail that resembles that of a fish. Most important, this tetrapod has big gills.
The inescapable conclusion is that the most primitive tetrapod was an aquatic creature. The implications are profound: The fish-to-tetrapod transition likely happened not in creatures that were adapting to land but in creatures living in water. Moreover, everything special about tetrapods -- limbs, digits, ribs, neck, the lot -- might well have evolved in water, not on land.
Delicate limbs with fingers? Maybe this is the origin of the dead-fish handshake after all. Sorry, I'm supposed to have left the ridiculous behind.
So let me just add, in all seriousness, that the essay is fascinating and is part of a book intended to counter the arguments of those who advocate Intelligent Design (ID) by showing that complex structures could arise in one environment but come to be useful in an utterly different environment. That's an old argument, of course, and doesn't in itself answer Michael Behe's use of irreducible complexity to challenge evolutionary theory. I presume that the book does respond to that challenge as well, but I'll likely never get around to reading it, so if anybody else has read it, please fill us in on the details.