Can Fossils Indicate Ancestry?
by Bill Pratt
In most cases, fossils cannot give us ancestry, according to paleontologist Donald Prothero. This statement, coming from Prothero, shocked me when I first read it, because it seems like fossil news headlines always make claims about ancestry, but here is Prothero, a staunch supporter of evolution, disagreeing.
Let me explain, lest I be accused of quote mining. In his book Evolution, Prothero dedicates an entire chapter to explaining how scientists classify plant and animal life. According to Prothero, the dominant method used today is cladistics, where the relationships among animals and plants are determined by the comparison of shared derived characters. This theory has only taken hold in the last few decades, replacing older systems of classification.
|‘Like’ The Poached Egg on Facebook!||Follow @ThePoachedEgg||Donate to TPE!|
A cladogram (cladistic diagram) comparing an assortment of vertebrates (e.g., lamprey, shark, frog, cow, monkey, human) might look at shared derived characters such as jaws, vertebrae, lungs, four legs, hair, mammary glands, opposable thumb, and stereovision. Cladograms are powerful tools for classifying life because they are using directly observable evidence taken from living animals and from fossils. But do cladograms indicate fossil ancestry? Only minimally. Here is Prothero:
Some aspects of cladistic theory have proven more difficult for many scientists to accept. For example, a cladogram is simply a branching diagram of relationships between three or more taxa. It does not specify whether one taxon is ancestral to another; it only shows the topology of their relationships as established by shared derived characters. In its simplicity and lack of additional assumptions, it is beautifully testable and falsifiable.
Prothero explains that cladistics frustrate some evolutionists who want to say more about ancestry from the cladograms, but Prothero urges caution…
RECOMMENDED APOLOGETICS RESOURCES FOR FURTHER READING: