16 SEP 2011 by ideonexus
DNA as Evidence of Common Ancestry
By sequencing the DNA of various species and measuring how similar these sequences are, we can reconstruct their evolutionary relationships. This is done by making the entirely reasonable assumption that species having more similar DNA are more closely related—that is, their common ancestors lived more recently. These molecular methods have not produced much change in the pre-DNA-era trees of life: both the visible traits of organisms and their DNA sequences usually give the same informatio...The idea of common ancestry leads naturally to powerful and testable predictions about evolution.