A Transitional Turtle

Horniman turtle carapace skeletonTurtles: how did they evolve?

Turtles (a group which includes within it tortoises) are most famous for their shells, which are made of their fused ribs. No other animal has a shell constructed in this manner, and it is a feature that all turtles share. The turtle evolution question, therefore, is somewhat synonymous with how turtle shells evolved. It’s also a case where creationists might reasonably ask “where are the transitional forms” – how do you get to shell from no shell? Unfortunately for them, fossils that fit the bill do exist. In 2009, for example, fossils of Odontochelys were discovered in China. This turtle had a complete plastron, the bottom of the shell, but instead of the upper part (the carapace) it merely had broadened rib bones. That sounds like a transitional form to me. Continue reading

Zebrafish Limbs

Zebrafish embryosFor Monday Jeff Tomkins writes “Did Scientists Make Fish Grow Hands?” The subject is a recent Developmental Cell paper called Hoxd13 Contribution to the Evolution of Vertebrate Appendages, which describes and experiment on zebrafish that induced them to grow what look more like limbs than fins, by promoting the expression of the Hoxd gene. This plugs a gap in our knowledge of how land animals evolved from fish – though, obviously, Tomkins disagrees.

A recent news story featured a variety of science writers repeating the meme “Fish grow ‘hands’ in genetic experiment.” These sensationalized stories attempted to describe a new genetics research study published in the journal Developmental Cell. The primary results of the study actually produced data that refuted the accompanying evolutionary hype.

Reference to memetics from a creationist cracks me up, but I suppose it’s now part of the general lexicon. Continue reading

Variation Within the Human Kind

Well that was fast: in the form of New African Fossil Confirms Early Human Variations Brian Thomas already has an article on the new Homo rudolfensis fossils. The standard creationist strategy when it comes to hominin fossils is to obfuscate, claim that all fossils can be neatly divided into ‘human’ and ‘ape,’ and then obfuscate again for good measure. Insinuating the possibility of fraud by bringing up past examples, claiming deceit or other bad practise in the fossil discovery and excavation, and arguing that this or that trait cannot be determined from the evidence are all tactics that play a role in the obfuscation. Thomas’ new article is textbook, except that he doesn’t seem to want to be completely pinned down over which side of the divide the new fossils lie on.

The cover of the August 9, 2012 issue of the journal Nature featured the reconstructed face of newly-discovered human-like fossil bones described by Meave Leakey and colleagues in their report.

Indeed it did, or close enough anyway: Continue reading

Limits to Evolution and an Out of Place Fossil – Quick DpSU 14 June

Our first DpSU is entitled “The Cost of Adaptations Limits Evolution“. This seems to be a classic Micro/Macro Evolution story, and by my reckoning a Type AE DpSU (Misrepresented Study).

Or in this case, studies. Mr Thomas is talking about two studies from a recent issue of the journal Science in which bacteria (Methylobacterium and E. coli) were experimented upon, with the researches investigating the effects of multiple mutations on Epistasis. Epistasis, btw, is (to quote WP) “the phenomenon where the effects of one gene are modified by one or several other genes, which are sometimes called modifier genes.” Interestingly, the ICR article does not mention the word Epistasis anywhere outside of it’s references.

The problem I have with this article is that I don’t have access to any part of the studies beyond the abstract, so I’m a bit limited about what I can say.

To distil the ICR article down somewhat, what the studies seem to show is that, as beneficial mutations accumulate, their benefits decrease, causing a diminishing returns situation. And this disproves evolution how? Mr Thomas extrapolates this to say that animals only have a limited ability to evolve. So Baraminology is out the door then? Definiately an AE, though I don’t have the time to deconstruct the article.

As for the second, “Out of Place Marine Fossil Disrupts Evolutionary Index“.

The science behind this is that a group of animals from the Cambrian period, the Anomalocaridids, have been shown to have survived significantly longer. It might be added that we already knew that to a certain degree, but that wont stop Mr Thomas.

No, a new discovery shows (according to him) that the whole ‘Evolutionary Index’ is unreliable, as Anomalocaridids are a defining feature of Cambrian rocks, indeed make Cambrian rocks Cambrian. There is, however, no reference to that claim, which would help. He also claims that Noah’s flood predicts that fossils should be disorganised, and that this is a prime example of that. I’ll cover this kind of thing in my Noah’s Ark series shortly, but I’ll add here that the Flood would disorganise fossils a whole lot more than is observed.

Thomas also throws in a declaration that the fossils found are already perfect, and therefore could not evolve further and could not have been evolved either — therefore God (spot the logical fallacy anyone?). Also, he says that “no anomalocaridid looks like an evolutionary transition”. *sigh*. What is an evolutionary transition by Mr Thomas’ unknown definition anyway. A ‘transition’ looks no different from any other fossil, and is defined only by the prior discovery of fossils that have the potential to be ancestors/aunts and descendants/nieces of the new discovery. If you find fossils in a different order, different fossils are classified as ‘transitional’.

And that’s all I have time for tonight…