Judging from orthodox Darwinian theory, we should expect to see fossils appearing in larger and larger sizes, at a steady rate of progression between 2 billion years ago and 100 million years ago. But the fossil record shows no such thing. Instead, we see very little fossil evidence of life prior to the Cambrian era about 540 million years ago. But during the Cambrian era (between about 540 million years ago and 485 million years ago), there is a sudden surge of fossils in the fossil record. This sudden blossoming of life during the Cambrian era is known as the Cambrian explosion. This sudden surge is quite a problem for orthodox biological theory.
The largest categories of life are called phyla. Most of the major phyla first appear in the fossil record during this relatively short Cambrian era. The Cambrian explosion may be described as an information explosion or a body plan explosion. The Earth seems to have suddenly got implementations of all these body plans there was no sign of before. How could that have happened?
An article on February 16th in the journal Nature seems to suggest that a solution to this great puzzle may be near. The article headline says the following:
An evolutionary burst 540 million years ago filled the seas with an astonishing diversity of animals. The trigger behind that revolution is finally coming into focus.
But when we read the article we are disappointed. The only “trigger” described is a rather slight increase in oxygen. That's hardly an explanation for this astonishing information explanation. The article covers up the difficulty by completely failing to even mention that the sudden appearance of such a large variety of highly developed animals in the fossil record is a difficulty for the prevailing account of evolution.
Imagine if you and your spouse go out to a movie. You come back and see on your dining room table there are several freshly typed books describing the US and its cities. You are puzzled: where did this come from? But suppose your spouse suggests this answer: the explanation is that the books are written on paper that she only bought this morning; so the reason they appeared is that only today was there the paper the books needed. That would be a ridiculously inadequate explanation for the appearance of the books. Generally you don't explain the appearance of something merely by mentioning that one of its prerequisites was met at some particular time. Similarly, we cannot explain the sudden appearance of highly developed animal forms by just mentioning that at some particular point one of the prerequisites for such things was met.
The Nature article also seems to have advanced a dubious factual claim, that there wasn't enough oxygen prior to the Cambrian period beginning 540 million years ago. A recent scientific paper authored by ten scientists is entitled, “Sufficient oxygen for animal respiration 1,400 million years ago.” The paper states: “We suggest that there was sufficient atmospheric oxygen for animals long before the evolution of animals themselves, and that rising levels of Neoproterozoic oxygen did not contribute to the relatively late appearance of animal life on Earth. ”
The Nature article is an example of a type of science journalism we see again and again: what I may call the “Explanation is coming” story or the “We're on the brink of explaining this” story. It is as if such articles were written according to the lesson plan shown below.
Various versions of these “We're on the brink of explaining this” stories have been appearing for more than 50 years. For more than 45 years I've been reading occasional stories suggesting that scientists are on the brink of solving the mystery of the origin of life. They actually seem to be ages away from solving such a problem. For more than 45 years I've been reading occasional stories suggesting that scientists are on the brink of solving the mystery of consciousness. Our scientists actually seem to be ages away from solving such a problem. If you checked the last 40 years of stories on the protein folding problem, you'd probably read a continual stream of assertions that the solution is right around the corner. But scientists still are stumped by the problem.
You might get the impression from reading these stories that scientists are getting ever-more-triumphant at explaining things. But it may well be that something like the opposite is true. There were many triumphs in explaining things between the year 1850 and the year 1975 (although not all the things that you might list). But in the past 40 years the explanatory triumphs of science seem to have been few and far between. Can you name one big thing that science has explained in the past 40 years, something that was not explained by earlier research? The average person probably can't think of anything. Applied science (pretty much the same as technology) is doing very well, but explanatory science may be sputtering.
It could be that the predominant “bottom-up” approach toward scientific explanation is running out of gas. There is only so far you can go at trying to explain things by trying to describe how little things can add up to big things or by trying to explain a whole just by mentioning the action of its parts. We need to think of more “top-down” explanations in which deep and grand principles cause the things that we are trying to explain. Something like consciousness will not be explained by some little bottom-up explanation involving some nerdy detail of neurons. Our scientists keep looking for some leverage effect by which piddling little things can produce magnificent outputs, failing to suspect that behind the magnificent outputs they are trying to explain may be some equally magnificent cause.