Claim CB822:
According to the theory of evolution, life evolved with different forms
branching from a common ancestor. Recent scientific work contradicts
this expectation. Molecular data indicate that the tree of life should be
uprooted and discredits the homology concept.
Source:
Response:
- The claim refers to results that indicate that horizontal gene
transfer was common in the very earliest life. In other words, genetic
information was not inherited only from one's immediate ancestor; some
was obtained from entirely different organisms, too. As a result, the
tree of life does not stem from a single trunk but from a reticulated
collection of stems (Woese 2000). This does not invalidate the theory
of evolution, though. It says only that another mechanism of heredity
was once more common.
- Horizontal gene transfer does not invalidate phylogenetics. Horizontal
gene transfer is not a major factor affecting modern life, including
all macroscopic life: "Although HGT does occur with important
evolutionary consequences, classical Darwinian lineages seem to be the
dominant mode of evolution for modern organisms" (Kurland et al. 2003,
9658; see also Daubin et al. 2003). And it is still possible to compute
phylogenies while taking horizontal gene transfer into account (Kim and
Salisbury 2001).
Links:
Tamzek, Nic. 2002. Icon of obfuscation.
http://www.talkorigins.org/faqs/wells/iconob.html#Treeoflife
References:
- Daubin, V., N. A. Moran and H. Ochman. 2003. Phylogenetics and the
cohesion of bacterial genomes. Science 301: 829-832. See also:
Pennisi, E., 2003. Passages found through labyrinth of bacterial
evolution. Science 301: 745-746.
- Kim, Junhyong and Benjamin A. Salisbury. 2001. A tree obscured by
vines: Horizontal gene transfer and the median tree method of
estimating species phylogeny. Pacific Symposium on Biocomputing
6: 571-582.
- Kurland, C. G., B. Canback and Otto G. Berg. 2003. Horizontal gene
transfer: A critical view. Proceedings of the National Academy of
Science USA 100: 9658-9662.
http://www.pnas.org/cgi/content/abstract/1632870100v1
- Woese, Carl R. 2000. Interpreting the universal phylogenetic tree.
Proceedings of the National Academy of Science USA 97(15): 8392-8396
http://www.pnas.org/cgi/content/abstract/97/15/8392
Further Reading:
Doolittle, W. F. 2000. Uprooting the tree of life. Scientific American
282: 90-95.
Woese, Carl. 1998. The universal ancestor. Proceedings of the National
Academy of Science USA 95: 6854-6859,
http://www.pnas.org/cgi/content/full/95/12/6854
(technical).
created 2003-8-7, modified 2005-6-18