Biology Reference
In-Depth Information
they no longer encode proteins, many of them are still transcribed into RNA, A
recent discovery is that some pseudogenes that do not encode proteins still produce
functional products, in the form of RNA molecules that regulate the activity of the
original gene from which they are derived. So some pseudogenes may not dead-
end products of mutation, but form a potential source of new functions if natural
selection happens to favour the effects of further mutations in these genes.
The widespread occurrence of vestigial structures is predicted by evolutionary
theory. If it is correct that all organisms are descended from a common ances-
tor, then both structures and functions necessarily will have been gained and lost
as new species arise. In the section entitled “Facts, Theories and Hypotheses” in
Chapter 2, I pointed out that to be considered scientific, a hypothesis must be capa-
ble of being falsified. This requirement is admirably met by vestigial structures.
According to evolutionary theory, no organism can have a vestigial structure that
was not previously functional in its ancestors. It follows that if evolution is an
incorrect description of the living world, we could find vestigial structures that
lack an evolutionary explanation. For example, evolution would be falsified if we
found vestigial feathers or wings in mammals, apes with vestigial gizzards, vesti-
gial spinal columns in crustacea, or pseudogenes encoding the enzymes of cellulose
biosynthesis in mammals. So far, evolutionary theory has withstood such potential
falsification.
Further Reading
1.
Evolution:
Nicholas H. Barton, Derek E.G. Briggs, Jonathan A. Eisen, David B. Goldstein and
Nipam H. Patel. Published by Cold Spring Harbor Laboratory Press, 2007. ISBN 978-0-87969-
684-9.
2.
Evolutionary Analysis:
Scott Freeman and Jon C. Herron. Published by Pearson Education,
Inc. 2007. 4th edition. ISBN 0-13-239789-7.
3.
Evolution:
Mark Ridley. Published by Blackwell Publishing, 2004, 3rd edition. ISBN 1-4051-
0345-0.
4.
Understanding Evolution: History, Theory, Evidence and Implications
. Geoff Price, 2006.
www rationalrevolution.net/articles
/ - scroll down to 'Understanding Evolution: History,
Theory, Evidence, Implications'. This is a comprehensive account of the historical relations
between science and religion in the context of evolution.
5.
The Making of The Fittest: DNA and the Ultimate Forensic Record of Evolution
. Sean B.
Carroll. Published by Quercus, 2006. ISBN 978 1 84724 4765. This topic is a very readable
account for the non-specialist of the evidence for evolution that resides in the sequences of
DNA molecules.
6.
Your Inner Fish.
Neil Shubin. Published by Allen Lane, 2008. ISBN 978-0-713-99935-8. A
very readable account of the evidence that many features of the human body evolved from
those of animals that once swam in the oceans.
7.
The Real life of Pseudogenes.
Mark Gerstein and Deyou Zheng. Scientific American, 295:22
49-55, August 2006. A recent account of research on pseudogenes that emphasises that some
have acquired new functions.
