Claim CB810:
Homology is defined as similarity due to common ancestry. The claim then
that it is evidence for common ancestry is a circular argument.
Source:
Wells, Jonathan, 2000. Icons of Evolution, Washington DC: Regnery
Publishing Inc., pp. 63-65.
Response:
- Homology is not defined as similarity due to common ancestry and then
used as evidence for common ancestry. Rather, the evidence for common
ancestry comes from the patterns of similarity of many traits. These
similarities show that organisms group naturally into a nested
hierarchy. For example, that ladybugs and scarabs are both types of
beetle is based on various common traits such as hardened front wings;
beetles, flies, and grasshoppers are types of insect; insects,
scorpions, and centipedes are types of arthropod. Such grouping does
not depend on any assumptions about origins and in fact was first
codified by Linnaeus, a creationist. A grouping suggested by many
common traits is evidence of common ancestry. This is true no matter
what you choose to call the traits. The homology label gets added
after the evidence for common ancestry is already in.
Further Reading:
Mindell, David P. and Axel Meyer. 2001. Homology evolving. Trends in
ecology and evolution 16: 434-440.
created 2001-1-27, modified 2005-2-11
