Ready When Made

I wish to offer arguments in support of mike the wiz. He does have a very good point here. Let's look at it in a simple manner.Say any species suddenly is faced with a challenge to survival that will require some new trait to keep it alive. Suppose we have some bears on an island. The climate gets colder. Natural selection kicks in, and soon we have only the bears with genetic information for long hair surviving to pass on their chromosomes. So the gene pool has narrowed down to long hair only. But then temperatures reverse to very hot. However, since natural selection has thinned the gene pool down to longhaired bears, there are no shorthaired bears to breed with to regain genetic information for short hair.
Obviously, these bears are going to need some macroevolution by random mutation to gain short hair again in order to remain cool. But before the long time periods required by evolution pass, the bears have all perished in the heat. Natural selection should have tipped the scales back to shorthaired bears again, only there weren't any after they all died out in the preceding ice age.
This illustration shows how species diversify, losing genetic information through natural selection, and may become extinct because they don't have time to develop a survival trait. Life on earth is clearly therefore deteriorating.

Doesn't macroevolution take many tens of thousands of years on average? Well, the climate can reverse pretty fast. In several centuries you can get vast climatic variation such as the small ice ages we've had - I believe in the nineteenth century the Thames froze thick enough to hold a fair thereon - and the incredibly sweltering weather going on in Europe. But climatic variation is not the point of the argument. It was an example, referring to any change that takes place quickly (from a few seconds to a few hundred years) and requires new survival traits.

Whoops. We're at crosspurposes here. I completely agree with everything balyons said, except that no mutation can be beneficial. Mutations can be beneficial - depending on what criteria you're using - but they can't add information. This ties in nicely with Loudmouth's argument concerning nylon-digesting bacteria. Although that may have looked like new genetic information, or macroevolution, at first, it's more likely to have been a loss of information in that the enzyme catalysis processes became less specific. By a loss of information, the enzymes would be less effective but more general in what they digested, allowing the enzymes to remove any inbuilt inhibition they may have had against chewing up nylon. Proteins and nylon are digested in a very similar manner (which is why nylon is the first substance you'd notice being catalysed if these mutations began). Degeneration again - beneficial for the moment, mind you, depending on whether nylon is good for bacteria, but such losses of information would eventually create an enzyme that is permitted to digest a wide range of substances but is not good at it. Such bacteria would not survive when pitted against bacteria with substrate-specific very efficient enzymes.
But new evidence actually suggests plasmids may be responsible for the nylon digestion. Other bacteria have the same property and could have passed this information to the flavobacteria. See e.g. K. Kato, et al., ‘A plasmid encoding enzymes for nylon oligomer degradation: Nucleotide sequence analysis of pOAD2’, Microbiology (Reading) 141(10):2585—2590, 1995.

Nylon may not have existed until modern times, but remember it's a man-made compound composed of natural substances which did exist a long time ago. Enzymes, as far as my limited knowledge tells me, are specific in what they digest. As I said above, a degeneration in the gene pool could have reduced their inhibition towards digesting the particular composition of natural materials that makes up the polymers of nylon. Nylon and protein digestion processes are very similar.
Before this mutation, the enzyme has a precise design of what it will digest. Afterwards, its plan is incomplete and it will digest a similar substrate that is also composed of organic substances and also involves destroying amide linkages. This is a loss in information, and since it also involves the enzyme becoming less specific, is probably not in the long run beneficial.

Dear schrafinator:If, say, the bears can't survive without a coat length of at least 10 cm, all bears with anything less than that will die. Thus the genes for anything longer than 10 cm will survive, and above that number there will be variation. Genes will be unlikely to survive for hair beneath 10 cm. If the following heat wave kills bears with a coat length of more than 8 cm, since all genetic information for such hair is gone - the DNA has lost the ability to create it - the bears will become extinct. Variation can only occur if the information for hair less than 8 cm exists.
To gain such hair by a gain in mutation would be macroevolution. Such gains have not been observed, but even if they did happen the bears could not afford to wait until one came along.