Birds flap their wings when they run up ramps. It takes less energy than flying. This is uncontroversial; it is observable, and science can measure the energy cost. But for at least eight years now, Ken Dial at the University of Montana has been claiming that this behavior explains the origin of flight in birds (01/16/2003, 12/22/2003). When he first came out with this hypothesis in 2003, Elisabeth Pennisi in the journal Science said, “I imagine people will continue to argue about the origin of bird flight for a long time.” There’s been very little argument in the media over the years, though (05/01/2006, 9/22/2007, 1/25/2008); in fact, the BBC News just gave another plug for Dial’s hypothesis with no criticism at all.
In her article “Flap-running in birds is key to flight evolution,” reporter Victoria Gill cheerfully quoted Dial’s colleague Brandon Jackson explaining the origin of flight:
"Flap running… lets young birds that cannot yet fly – because of small muscles, small wings, weak feathers, etc – get off the ground
and away from some predators," Dr Jackson told BBC Nature.
"And if baby birds can perform these behaviours, benefit from them, and transition gradually to flight in their life-time, we think it's probable that dinosaurs with (similarly small wings) could have performed these behaviours, benefited from them, and transitioned towards flight over evolutionary time."
So watching birds learn to fly could allow us a glimpse of the stages of flight's evolution.
On the surface, this hypothesis sounds Lamarckian. Presumably it could be incorporated into neo-Darwinism this way: a mutation occurred that made a young dinosaur hold out its forelegs as it ran up a hill escaping a predator. All the other siblings were eaten. This dinosaur one day found a mate with the same mutation, and the trait spread through the population. It’s a small start; were any other traits required after that to produce hummingbirds, eagles, ostriches, and great snipes flying 4,200 miles in 4 days?
Dr Jackson concluded: "Very small wings
powered by small muscles had aerodynamic function and survival benefits
when they were flapped.
"No more major steps were required after that, just gradual but beneficial steps. And we can actually observe [those steps] in developing birds today."
Now the explanation sounds Haeckelian. Jackson seems to be saying that chicks replay their evolutionary history. Not only that, he and Ken Dial overlooked a host of precision mechanisms needed to allow a dinosaur to become airborne with controlled flapping flight.
This just-so story is so lame, it should be a huge embarrassment to the Darwin Party. These guys don’t understand evolutionary theory at all. You can’t draw analogies
between chick development to adult bird in a year, and say a similar transition occurs in evolutionary time over millions of years. Chick development is encoded in DNA and in numerous epigenetic regulatory codes, and is observable in the present. Are they believers in some mystical meta-Gaia belief, that the history of the life on Earth develops from embryo to adult? This hypothesis is a cross between Lamarckism and recapitulation theory, both of which have been tossed into the dustbin of history. Two wrongs don't make a right.
We laughed this hypothesis off the stage when it first appeared (01/16/2003
), and even evolutionist Pennisi had her doubts. Now, eight years have gone by and Dial and Jackson are still promoting it. To make any progress toward sense in evolutionary circles, critics will have to at least get them to be consistent with their own belief system. Give us your suggestions for giving Jackson and Dial a much-needed red face. Reading them our 12/22/2003
commentary might be a start. If they are men of integrity, their faces will turn red with shame. If not, their faces will turn red with rage. (Note: federal funding, tenure, and media fame can have the unintended consequence of reducing integrity.)
(Visited 78 times, 1 visits today)