Now, the findings of an international team of biologists demonstrate that evolution is not a random process, but rather occurs through the natural selection of successful traits. The collaborative study by researchers at the Technion-Israel Institute of Technology in Israel, the U.S, France and Germany is published in the November 2007 issue of Current Biology (vol. 17, pp. 1925-1937).

To settle the question about whether evolution is deterministic or random, the researchers used various tools -- including DNA strand analysis and electronic microscopy -- to study female sexual organ development in 51 species of nematode, a type of worm commonly used to better understand evolutionary processes.

When the researchers measured changes in 40 defined characteristics of the nematodes' sexual organs (including cell division patterns and the formation of specific cells), they found that most were uniform in direction, with the main mechanism for the development favoring a natural selection of successful traits, the researchers said.