Blocked Evolution

Startling Scientists, Plant Fixes Its Flawed Gene

(Excerpts)

In a startling discovery, geneticists at PurdueUniversity say they have found plants that possess a corrected version of a defective gene inherited from both their parents, as if some handy backup copy with the right version had been made in the grandparents' generation or earlier.

The finding implies that some organisms may contain a cryptic backup copy of their genome that bypasses the usual mechanisms of heredity. If confirmed, it would represent an unprecedented exception to the laws of inheritance discovered by Gregor Mendel in the 19th century. Equally surprising, the cryptic genome appears not to be made of DNA, the standard hereditary material.

The discovery also raises interesting biological questions - including whether it gets in the way of evolution, which depends on mutations changing an organism rather than being put right by a backup system.

"It looks like a marvelous discovery," said Dr. Elliott Meyerowitz, a plant geneticist at the California Institute of Technology. Dr. David Haig, an evolutionary biologist at Harvard, described the finding as "a really strange and unexpected result," which would be important if the observation holds up and applies widely in nature.

A mutated gene can be put right by various mechanisms that are already known, but all require a correct copy of the gene to be available to serve as the template. The Purdue team scanned the DNA of the entire arabidopsis genome for a second, cryptic copy of the hothead gene but could find none (Nicholas Wade, New York Times, March 23, 2005).

[TBC: The theory of evolution continually faces questions which necessitates that researchers "make it up" as they go along.]