from Koinonia House
Most of modern scientists assume that all life today evolved from single-celled organisms over the past several billion years. Since that assumption is pretty settled for the majority, biologists don’t bother questioning it. Instead, they assume it to be true, and spend time trying to figure out the evolutionary relationships of animals. What is the nearest common ancestor of both the frog and the newt? What are the ancestors of modern birds and how did they gain the ability to fly? How is this animal related to that animal, and where do they both fit in the evolutionary family tree? Enter cladograms. A cladogram is simply a branched, tree-like diagram that is used to put evolutionary relationships in order. Plants or animals are arranged along the branches according to the order in which they evolved from common ancestors. Cladograms can be useful in sorting out closely related creatures….provided there actually is a relationship. The study of cladistics is based on the concept that animals with similar structures and body parts are related. All vertebrates have a backbone, therefore evolutionists assume they all descended from a common ancestor with a backbone. Organisms are placed onto different branches based on similar characteristics, called "characters." Characters might include number of toes or number of sacral vertebrae. They might be, "has a jaw" or "chisel-like teeth". Characters can get very specific, like "Bifurcated neural spine in cervical vertebrae." The more similar characteristics different organisms have, the more closely they are considered related. It would be nice for evolutionary theory if the taxa being placed on a cladogram lined up nice and neatly, step-by-step. But, that’s often not the case. Let’s say organisms A B and C are being ordered on the cladogram based on four different characters. If A had characters #1 and #2, B had characters #1, #2, and #3, and Organism C had characters #1, #2, #3, and, #4, it would be reasonable to say that C evolved from B, and B evolved from A in neat and tidy single-transition steps.
| Organism | Character 1 | Character 2 | Character 3 | Character 4 |
| A | Yes | Yes | No | No |
| B | Yes | Yes | Yes | No |
| C | Yes | Yes | Yes | Yes |
In real life, cladograms are not so simple. What if organism A has characters #1, #2, and #3, B has characters #1, #3, and #4, and C has #2 and #4? Which organism came first? Which came second?
| Organism | Character 1 | Character 2 | Character 3 | Character 4 |
| A | Yes | Yes | Yes | No |
| B | Yes | No | Yes | Yes |
| C | No | Yes | No | Yes |
