Thursday, January 08, 2009

Evolutionary gems

Nature is running a little online feature 15 Evolutionary Gems that have been published on its pages over the past 10 years.

One of the interesting things you'll note is the amount of molecular biology appearing in the section on the fossil record. Nevertheless, fossils have given us next to zero molecular data (even what is known is a infinitesimally small proportion of fossils in the fossil record). The reason this is possible is because of the way in which fossils fit into the tree of life: they intercalate into the branches between living branches. Thus, they act as a sort of "control" on how we propose hypotheses of morphological change -- in fact they often tell us all we can know about morphological change.

But there's more to this than just fossils: stories from population-level studies show us how the mechanisms of evolution act. Fossils and gene expression data tell us about patterns, but population studies tell us about evolution at the level of process. How natural selection and other forces act to shape the morphology, physiology, and behaviour of organisms can only be studied in real time, using population-based analyses. The work highlighted by Nature tackles important topics such as the role of natural selection in speciation, co-evolution, and the contingent nature of evolution -- the necessary consideration of phylogenetic history in studying adaptation.

Finally, we marry these two through the study of molecular processes. Mutation, gene regulation, epigenetics, these are all forces that influence the possibilities of evolution. These are the driving forces of diversification, but also the conservative nature of descent with modification. It is a slow and stumbling processes. Nature illuminates these issues by covering gene regulation studies in Galapagos finches, insects, among other worthwhile reads.

My main problem with this piece, however, is the way in which item #13 suggests that there is a fundamentally different macroevolution and microevolution. It attributes perceived large steps in evolution as real and refers to them as "macroevolutionary". This reads to me like saltationism, which seems to be bore strictly out of the argument from ignorance or the assumption that gaps in the fossil record are real. Nevertheless, it's a nice summary and worth checking out.

8 comments:

catch22 said...

After listening to your talk with Kent Hovind in YouTube about common ancestry, I must say I was impressed and googled your name. I think you did better than Michael Shermer on his debate with Hovind. Your arguments were direct and clear. It really helped me clarify some fundamental questions on evolution. Keep up the good work and I hope that you have a great career!

SFU-FHS said...

I've just listened to your debate with Kent Hovind and was completely blown away at the sheer knowledge you possess about the field of biology and evolution.

Thank you for inspiring me (a fellow Canuck pursuing his bachelors)

Sam Harris said...

What evidence is there showing that we descended from rocks? The answer is very simple. Some people still have them in their head.

mark said...

Dude, do you hate your blog? You're the guy who humiliated Hovind on his own show, write some more. I'm sure you have some interesting things to say.

merdarius said...

hey Martin,

enjoyed the read but I have an objection.

ok, I don't know how these concepts are usually used in current paleontological debate, but I get the feeling you are mixing things up a bit when arguing against macroevolution because it is saltationist.

For me, the major argument against macroevolution is that it postulates two entirely different ways of evolution, which is methodologically unattractive and goes against the "uniformitarianism" which has been a cornerstone of evolutionary theory ever since Darwin picked it up from Lyell's in turn revolutionising geology (thereby also going against the parsimony principle, Occam's razor, at heart of the scientific method itself), and also typically fails to demonstrate a realistic explanation of the mechanisms by which this second type of evolution actually works (thereby again leaving the revolutionary scientific force of darwinism behind).

Saltationism I understand as a mere model of uneven rate in evolution (back from Gould et al), as opposed to a model of a very slow pace of very smooth accumulation of very tiny changes which is called gradualism (symmetrically popularised by Dawkins). Both are useful models, and both are absurd if considered to be the law or ultimate truth of evolution - as such both are indeed falsified by available empirical evidence; there are examples of almost perfect longterm transformation series as well as examples of no visual changes for long eras and sudden changes brought about by geological or ecological events. Those working in genetics and molecular biology sometimes favor gradualism because it emphasises the genetic level as a driving force in evolution, those who work with organisms (systematists and ecologists) often favor saltationism because it emphasises historical and population-level drama. Perhaps one could also say that aspergerians and logicians favor gradualist explanations because they enjoy the simplicity of linear models, while poets & hegelians like myself, psychedelics and even poststructuralists favor saltationist explanations because they enjoy the dynamism of non-linear models. But evolution itself doesn't conform to one of the models.

Saul L said...

Good morning Dr. Martin I'd appreciate very much your opinion about this videos:
http://www.youtube.com/watch?v=9EZyFzkUC4c
http://video.google.com/videoplay?docid=-1622091589404607061&ei=gEy_SaHzJZ7OqwK9icDcCw&q=+Myth+of+the+Organic+Soup+
http://www.youtube.com/watch?v=Wj4Q1hPRoDs
http://www.youtube.com/watch?v=ByUod2VmBQY

They explain the appearance of species without evolution, but with predefined genetic profiles but with environment influence. I'm an Electronics student, I like science but I'm just a layman on genetics, biology or biochemistry, so your enlightenment would be crucial to me on this matter: Evolution. Those videos got me convinced so, I'm being hoaxed by them?

Regards, Saul L.atencid

Chris said...

Hello, Dr. Brazeau, congratulations on completing your studies.
I would just like to say I'm another YouTube wanderer who googled my way here after witnessing your merciless torture of Kent Hovind.
I realise with the knowledge you have in evolutionary biology, taking on Hovind was a little like knocking on a door with a hydrogen bomb, but I enjoyed it immensely anyway.
When he finally returns from his well deserved, enforced vacation, will you be gracing us with round two?
I realise it is a bit of a drag for an educated person to converse with such oxygen wasters, but it's just so damn entertaining.

Good luck with your career, Dr. Brazeau, I hope to read more of your fascinating blogs, and hear more of your irreverent, intellectual pruning of our misinformed Creationist brethren.

Macque77

Random Comment Generator said...

Hi there sir. Are you ready for this?! I doubt it, lol. Yer not a human. By the way you talk, I would say you've never been a human and if you were at one time, you have surely lost all of yer humanity. You are a vampire.

So, Mr. I like to drink blood - where do vampires fit into evolution, because I think I missed that chapter.

Science says you don't exist, how does that feel?! Yer not a real person. How does that feel?!

Shapeshifting... a product of evolution, right?! The power to manipulate atoms, and turn into anything... all came from random mutations right, lol.

You are a pitiful excuse for a person. I heard yer debate with Hovind, and the sound of yer voice made me want to puke.

You have no idea what it even means to be a human. You are a product of the devil, not of evolution.

Nested hierarchy doesn't mean shit... it's a dynamic, conceptual framework... that can be changed when need be - by simply creating a new branch anytime you find an organism that doesn't fit anywhere else.

Which means - there is no way to falsify common ancestor except with the fossil record... WHICH CLEARLY DOES FALSIFY THE UCD HYPOTHESIS, because the predictions (fine, gradated, intermediate forms) made by Darwin's theory are not present in the fossil record.

Cambrian Explosion, game over. It disproves Darwinian Evolution and common ancestor... the type of diversity of life we see today, just appeared all at the same time without a gradual branching from a common ancestor. FAIL!