Wednesday, April 05, 2006

Tik-taalik - Toe?

It looks like researchers have found a "missing link" between sea animals and those of the earliest ones on land. The newly discovered creature is similar to a fish, but has bones in its fin that are similar to the legs of early land animals.

Yet, while it's certainly an exciting find, I'm reluctant to call it a missing link. While I would certainly concede it is a link, there are many species that already bridge this gap. While anti-science propagandists frequently claim there are no transitionary fossils, this is far from the truth.

I think the most interesting way I've heard this put, is from a talk given by Kenneth Miller at Case Western University, in which he discusses this very topic starting at time marker 31:23.
He first presents a statement from the National Academy of Sciences in 1999 stating:
So many intermediate forms have been discovered between fish and amphibians, between amphibians and reptiles, between reptiles and mammals, and along the primate lines, of descent that it often is difficult to identify categorically when the transition occurs from one to another particular species.
He then goes on to tell of a colleague, Christine Janice of Brown University, who attended a conference in which there was heated debate over the discovery of 11-12 new fossils from the Powder River basin were having to be categorized and "almost fist fights broke out among the scientists arguing as to whether or not these fossils should be called mammal like reptiles or reptile like mammals."

However, the next point he brings up, and the one which leads me to believe that the new discovery is not especially monumental, is that it was well documented that whales and dolphins evolved from terrestrial mammals. For many years this was considered ridiculous and various drawings of strange half breeds were made in a sort of ridicule of this theory.

And then they discovered the fossils of just such creatures were discovered, such as the amublocetus natans (trans: walking whale that swims). So what does this show us? Evolution has made successful predictions which is one of the most compelling proofs a theory can offer.

But it didn't stop there. For this transition to occur, the structure of the inner ear would have to have changed significantly to make the transition from hearing in air, to hearing in water. And surely enough, more intermediate forms were discovered proving exactly this. So this leads to two successful predictions for a transition that seems more than a bit improbable. And all this from transitionary fossils that aren't supposed to exist.

However, I do note that this transition is in the wrong direction (ie, land to water instead of water to land), yet being able to successfuly go one way makes it all the more plausible that it can go the other.

And just in case you forget that there's numerous other transitionary fossils out there, be sure to check out a rather extensive list at talkorigins.

4 comments:

Tom said...

Thank you for this post. Are you writing your blog specifically to assist me in the writing of my film?

I should say, for the record, that the film is in development for a broadcast television network, which means that however committed they may be right now to controversy as a succesful promotional tool, when it comes right down to it, who knows whethey they will have the guts.

In fact, who knows whether they will have a good enough script? To that, end: back to work.

Jon Voisey said...

I just comment on whatever I see as important to the world of science, the religious right, and the interactions between the two.

Any assistance this give you for your film is purely coincidental, although it does give me a warm fuzzy feeling to know people are reading and interested.

Justin said...

Just started reading your stuff, and a couple minor points, one on spelling: Christine Janis.

The other one is about transitional forms in general. What I usually say is that anyone who says that there aren't any transitional forms obviously doesn't have a bloody clue how evolution actually works. Everything is a transitional form, in between its ancestor species and any descendant species that may arise (assuming it doesn't go extinct before giving rise to others).

Justin said...

Just started reading your stuff, and a couple minor points, one on spelling: Christine Janis.

The other one is about transitional forms in general. What I usually say is that anyone who says that there aren't any transitional forms obviously doesn't have a bloody clue how evolution actually works. Everything is a transitional form, in between its ancestor species and any descendant species that may arise (assuming it doesn't go extinct before giving rise to others).