Scientists have an insatiable urge to understand "how" and "why."
How does gravity operate? Why is the sky blue?
How does a giant squid swim?
Why do atoms exist?
We are an intrinsically curious lot trying to pick apart the universe to get at the underlying principles. Show a scientist a problem or an anomaly and they set about trying to understand it. That is our nature.
Our explanations grow into theories - into testable hypotheses which we subject again and again to examination. Indeed, the vast majority of science ends up supporting the existing paradigm.
It is almost like scientists can't believe we actually understand something so we have to keep going back to it to make sure we really do. Occasionally, we do find something new.
As theories grow and mature, more and more evidence accumulates to the point where a theory becomes undeniable. Take the theory of atoms. Although the idea of an atom was first postulated by Demokritus of Abdera some 2,500 years ago, as an idea it lay dormant for a very long time.
In the early 1800s, John Dalton revitalized atomic theory because it could explain the observations being made in chemistry at the time. It tied them all together in a package but it was "just a theory."
One hundred years later, science had progressed enough that we could look inside atoms and see all the parts. Atomic theory had finally progressed to the point where it was accepted as fact.
It is still a theory, though, and if someone comes up with a better explanation for 200 years of scientific observations and experiments, we would be forced to consider the alternative as a competing theory. This is the beauty of science - it requires an open-minded view and a strict adherence to the evidence before us.
Atomic theory is a theory with a great deal of weight and evidence.
No one seriously questions the existence of atoms.
At the other extreme is string theory, which is the new synthesis or explanation of the world of the sub-subatomic where everything exists as multi-dimensional strings.
It is speculative theory - a possible explanation - with some interesting features and the ability to explain some of the unexplainable problems in physics. But it is not well tested nor well accepted yet. It is going to require a lot of evidence.
Further out on the scale of acceptable theories was the theory of phlogiston first stated in 1667 by Johann Joachim Becher, which held sway for well over a hundred years but ultimately was discarded as better explanations emerged.
Atomic theory relegated the theory of phlogiston to the role of a historical curiosity. This is another key aspect of science - theories evolve and disappear. Paradigms shift.
So, where is the theory of evolution in all of this? Is it grounded in 150 years of scientific experiments and solid observations?
Or is it mere speculation, as some would have it, on the nature of the world?
It is as solid as atomic theory.
Scientists would no more doubt the existence of evolution than they would doubt the existence of atoms. Indeed, Nature - one of the world's top two scientific journals - ran a feature recently asking why don't we just declare evolution a fact and get on with things?
They backed up this statement with 15 published papers which should have put the whole issue to rest. These articles range from the observations of the fossil record to experimental biology and provide a convincing array of evidence that not only has evolution happened but it continues to happen to this day.
The fossil record is sporadic because the vast majority of living organisms do not die in circumstances allowing them to become fossils. It takes a peculiar set of conditions for fossilization to occur.
This is why there are great tracts missing from the record of life.
However, in some modern species, the fossil record is very good with all of the intermediate species having been found. The development of whales from land-based organisms sharing a common ancestor with the hippopotamus is one such record and a recent article in Nature lays down the case quite convincingly.
The complaint that no one can do an experiment on evolution has been answered with various experiments on bacteria in which evolutionary challenges - changes in the environmental conditions - have resulted in the development of new species. Some of these experiments have been going for 25 years and involved 30,000 generations.
These 15 papers are a mere glimpse of the huge amount of evidence and experiments that has accumulated. Evolution is a theory but it is a theory tested and re-tested for 150 years. Maybe it is time to accept it is the right explanation for how complex life came to occupy this planet.
The evidence certainly says it is so.
