Tuesday, May 03, 2005

Evolution is a Scientific Theory

In my previous post, I argue why Creationism and Intelligent Design are not scientific theories because there is no test or observations that provide physical evidence for the underlying foundation of those models, which is a Creator or supernatural intelligent entity. Why, then, is evolution the dominant and overwhelmingly favored scientific theory that tries to account for the development and variety of life?

Science uses physical evidence as the cornerstone of many conclusions it reaches. This may be direct evidence as well as indirect evidence, where patterns emerge that support a particular conclusion. My background, for example, is in high energy particle physics. As a member of the team at Fermilab that discovered the top quark, I can state from firsthand knowledge that I, or anyone else, have never seen a top quark! And yet we claimed discovery. To many, this may seem odd and contradictory. The way it worked in the case of the top quark was that a theory, called the Standard Model (SM), predicted that a top quark should exist (for a variety of reasons). The SM makes a series of predictions about the properties of a top quark such as what other sets of particles it can decay into (the top quark is radioactive, and spontaneously ‘dies’ and turns into other types of particles). The SM can even predict probabilities for decaying into each set of particles. The top quark lives for an incredibly short period of time before it decays, and we simply do not have the means to observe something directly for such a short period of time. What we looked for were the second and third generation particles from the original decay. Like a puzzle, those pieces were put together in various ways to see where they came from. When this was done, one has a consistent and conclusive result, along with specific mass and measurement of other properties of a particle that is unique and fits into the theory, so we were confident that it was a top quark. This result was published and scrutinized by the rest of the scientific world, and the results were confirmed at another independent experiment at Fermilab. The study of evolution, as well as many other areas of science, works in similar ways.

Over the past century and a half, literally thousands of scientists have independently studied the theory of Darwin. The main premise of evolution is that all life forms evolved from common ancestors. Billions of years ago single-celled organisms developed naturally, and over time genetic mutations transformed those organisms into new species. Evolution does not address how the first organisms formed, but rather describes a process where new species form from older species. Those that are best suited to survive in the environment survive, those who are disadvantaged perish…the ‘survival of the fittest’ concept, or natural selection. How does one test this theory? One way is to look for evidence that supports the idea of new species that resemble earlier species (ancestors), as well as evidence for an increasing variety of species over time. This evidence has been found in fossil records, and more recently in genetic patterns that suggest links between related species.

Evolution suggests that a great period of time is required for speciation to take place, and ample evidence exists that the Earth is multiple billions of years old. While some like to argue there are holes in the fossil record (but it is worth mentioning that these holes tend to fill in more and more each year as new fossils are routinely discovered around the world), the case for evolutionary principles becomes more convincing when evolution can be observed directly with modern, living organisms. No, I am not talking about seeing a man develop from apes. Instead, within relatively short periods of time one can observe many generations of shorter lived organisms such as bacteria. It is becoming apparent that antibacterial soaps lose their effectiveness over time. Why? Because the types of bacteria the soaps initially killed mutate relatively frequently and sometimes the offspring have a new genetic makeup that allows them to resist the effects of the soap. Those offspring are better fit to survive the environment, and they prosper. Before long the original species of bacteria is terminated but a new strain persists and flourishes. Think about new strains of flu and cold viruses, and so on. We are observing evolution in real time.

Of all the thousands of scientists who have done experiments and studied the stacks of evidence related to an evolutionary hypothesis, the overwhelming majority has reached the same conclusion: the principles of evolution are supported by multiple streams of data, observations, and experiments. This is the scientific process, and evolution is a grand example of a scientific theory. Creationism and intelligent design have not been supported in a similar scientific manner, and remain in the realms of religion and philosophy.

1 comment:

mark said...


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