I see it now: U.S. scientist shows evolution of flatfish

William Atkins
Thursday, 10 July 2008 21:12

Science - Biology

The conclusions of the Friedman study shows that the evolution of the flatfish was gradual, not quick as earlier studies explained.

Friedman states, "The important thing about this study is it delivers evidence of those intermediates.” [Reuters: “Fish fossils plug hole in evolutionary theory”]

For a long time evolutionary biologists could not explain how these flatfish came to have both eyes on one side of their heads. They already knew from fossil records that very early on in their development these flatfish had one eye on each side of their head.

Some studies in the past even suggested that the change from symmetry to asymmetry was done very quickly. This, “macromutation” type of evolution (fast acting change) was thought to occur all at once with a quick type of mutation.

Friedman stated, "There was no macromutation that all of a sudden gave them both eyes on the same side of the head.” [Reuters]

The point that the theory of natural selection (evolution) was missing was “transitional species.” Scientists had yet to find transitional fossils that showed the intermediate step in the evolution of a particular characteristic.

Until now, that is.

In the case of the flatfish, scientists had fossils of primitive flatfish species that showed one eye on each side of the body. And, they also have modern specimens living today on Earth.

 However, they could not find the “transitional species” for the flatfish that showed the transition in the trait.

Until now, however.

Plus, many scientists contended that such “transitional species” could not exist because it would be a detriment to them, and they would not likely survive.

The research by Friedman disproves this contention. It also helps to provide the evidence for "transitional species" in the process of evolution, and that transitional species did exist and survive to evolve even further.

The article “The evolutionary origin of flatfish asymmetry” summarizes the conclusions of this study. It is found in the July 10, 2008 issue of the journal Nature. (Nature 454, 209-212)