Which of the following is not an observation that was made by darwin a. different animals living in similar environments often had similar characteristics b. closely related animals living in different environments often had different features c. fossilized, ancient creatures sometimes had similar features to living creatures d. all livings things share a universal genetic code what is the principle of common descent a. the principle of common descent is the idea that all living and extinct organisms shared a common ancestor at some point in their evolutionary history b. the principle of common descent is the idea that organisms that evolve in the same environment will have the same characteristics c. the principle of common descent is the idea that the fittest members of a population will survive and produce more offspring d. the principle of common descent is the idea that organisms evolve at a slow and steady rate