Evidence for Biological Evolution

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What is the best evidence for biological evolution?

There are two kinds of biological evolution: micro- and macro-. Macro-evolution is the idea that one kind of organism can change into another kind over time and that the potential for change is essentially unlimited. Reptiles, for example, would be able to change into birds over time. This supposes the emergence of new genetic information somewhere along the way. Reptiles donít currently have the genetic information necessary to grow wings for example, so in order for reptiles to evolve into birds, they need to acquire new genetics. Macro-evolution is the foundational premise behind Darwinian evolution, the idea that all life has evolved and descended from a common ancestor which in turn evolved from non-living material. Whenever someone asks for the best evidence for biological evolution, they are usually referring to macro-evolution.

Micro-evolution is different. Micro-evolution says that animals can change over time but that these changes are limited. A bird can adapt to its environment but it remains a bird. No new genetic information is required. The ability to adapt or change is preprogrammed into the organismís genetic code. This is why we see so much variety in life. There are tall people, short people, black people, white people, etc. There are different shades of skin, eye color, hair texture, etc., but people are still people. Human DNA allows for this variation. In the same way, plant and animal DNA allow for great diversity.

Micro-evolution is an observed, established phenomenon and as such is the best evidence for biological evolution in terms of macro-evolution. However, macro-evolution remains an extrapolation of micro-evolution. The question is, are there limits to biological change? Can micro-evolution lead to macro-evolution over long periods of time? The debate rages on.

When an insect or bacterium develops a resistance to a pesticide or an antibiotic, this is micro-evolution. The insect or bacterium does not gain any new genetic information. In fact, it actually loses genetic information (the information needed to produce the enzyme). It loses the ability to produce the enzyme which interacts with the poison to produce a lethal effect. The organism is actually worse off everywhere except in the environment which contains the pesticide or antibiotic. Biophysicist Dr. Lee Spetner explains, ďAll of the mutations that have been examined on a molecular level show that the organism has lost information and not gained itĒ (From a Frog to a Prince, documentary by Keziah Films, 1998). This is not in a direction towards macro-evolution, which would require new genetic information. So should micro-evolution be considered as evidence for biological evolution in terms of macro-evolution? The debate rages on. . .



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