No, this is not another post about the sexual habits of female apes. This is about enzymes, and their ability to catalyze different reactions with different substrates, even those that aren’t found in nature. It’s a property known as “promiscuity”, one that’s being increasingly recognized as important in enzymology and enzyme evolution.
The usefulness of enzymes derives in part from their specificity, in that they don’t just catalyze any old reaction with any old substrate. It would be hard for cells to maintain homeostasis if enzymes were highly nonspecific; helpful reactions would be coupled with harmful side reactions, regulation would be impossible, and things would get messy real quick. So it’s useful for enzymes to specialize in certain functions so that they can be applied for specific tasks at specific times. But because nature is a bit sloppy, enzymes are often able to catalyze many reactions weakly in addition to the “native” functions that they specialize in. These additional weak activities are referred to as promiscuous activities, and they’re potentially very important in enzyme evolution. Now a recent study (subscription required) published in Nature Genetics by Amir Aharoni and coworkers sheds some light on why enzymes are promiscuous, and what it means for their evolvability. (There is some good non-technical commentary on the paper here and here.) It also badly knocks down some bold claims made by leading ID proponents.
11 Comments
Great White Wonder · 27 January 2005
frank schmidt · 27 January 2005
Mark Perakh · 27 January 2005
Scientists usually shy away from making predictions. Recall that false prophets were to be stoned to death as Dembski and Co's favored book tells us, and the risk of becoming a false prophet calls for a caution in making predictions. Martin Gardner had defined a crank (in a book first published about 50 years ago). There are a number of features typical of a crank. A crank often has a penchant for introducing new terms (like Dembski's "unsimplifiability"), claiming to have discovered new important scientific laws (like Dembski's "law of conservation of information"), suggesting new, allegedly powerful methods of research (like Dembski's explanatory filter) etc. Behind this impressive facade there is in fact nothing of value. A crank may display enormous erudition, ingenuity in coming up with seemingly sophisticated arguments, and typically is absolutely convinced that his critics are stupid and either do not understand his great breakthroughs or willfully try to suppress his discoveries because of some non-kosher reasons. Gardner should have added one more feature typical of cranks - a penchant for dabbling in prophecies. In this contribution Steve Reuland gives a fine example of the abismal failure of one such bold prediction made by Dembski with his typical unbounded self-confidence. I doubt that the failure of Dembski's prediction will teach him a lesson. We can expect more such predictions from Isaac Newton of information theory. Perhaps there will be all kinds of arguments attempting to justify Dembski's uncautious wrong prediction, but no spin can deny the obvious.
Wedgie World · 27 January 2005
Another gap is closed for ID to hide in. While science uncovers more and more evidence and mechanisms, ID is doomed to remain ignorant.
While some people try to portray ID as scientific the reality is that there is NO scientific theory of ID. All there is, is a belief that science cannot explain all features and that this is evidence of 'design'. While admitting that ID was formulated to avoid addressing issues of 'who/what designed', the ID movement has made it clear that its designer is God.
Often ID can be observed claiming that it adds to science by providing means to detect design, something lacking in science while at the same time arguing that design detection has been applied succesfully in science. So in other words, the design ID is referring to cannot be about science since science already can detect design and thus this addition to science is, as expected, supernatural.
Not only is ID scientifically flawed and meaningless but it proposes that science can falsify God, who is forced to hide in gaps of our ignorance. A theologically risky and flawed position which may cause much damage to Christian faith.
Here we have a good example where ID is found to be wrong in its claims. Does this mean that ID has been falsified?
Jeff Low · 27 January 2005
Steve Reuland · 27 January 2005
I have a hard time believing anyone could buy such an illogical argument. The researchers did not "design" the proteins. They simply applied a selection criterion without any knowledge of the actual mutations involved. The results are proof of principle that mutation plus selection can create new proteins, the very thing that IDists have said couldn't happen. There is nothing stopping this from happening in the wild so long as there is selective pressure to encourage it to happen (which is precisely the case with PCP degradation, for example.)
By your reasoning, there is no such thing as a laboratory experiment that is not "intelligent design". Any variables that the researchers control means that they're using "intelligence", so therefore it's impossible to study any natural process whatsoever.
Great White Wonder · 27 January 2005
Steve Reuland · 27 January 2005
I can only assume they mean mice with brains that consist entirely of human neurons.
Great White Wonder · 27 January 2005
What "traces" of "human" cognitive behavior does he expect to observe in his little mouse dude?
I'll be frank, here: the remote possibility of benefits flowing from this research don't outweigh the sickening feeling.
From my perspective, that sort of experiment is no different from creating a human embryo and allowing the embryo to develop "traces" of "human" cognitive behavior so Dr. Weissman can experiment on it.
Steve Reuland · 27 January 2005
I don't really know, but my guess is that they'd like to see if the neurons form the same kinds of connections that human neurons do, or if the brain specializes the way human brains do, or if they act more "mouse-like". That would tell us if the factors responsible for human cognition (or at least human brain structure) are contained within the neurons themselves, or are influenced by other factors within the organism.
But this stuff isn't really my field. I prefer enzymes. (Hint.)
Great White Wonder · 27 January 2005
I put my follow-up thoughts on the "Little Mouse Dude" sub-thread up on the Bathroom Wall, in case anyone is remotely interested. ;)