"It is hard to justify an "Origin of Species" unless one is clear what constitutes a species."

There is considerable debate amongst scientist concerned with any degree of phylogeny about what constitutes a species; there are various definitions. This is because (contrary to our christian friends misconceptions) every organism is in a state of transition; we know speciation occurs and we know some of the mechanisms of speciation, but when does one species become another? There are no absolutes. Some of the things that creepeth along the ground flyeth and swimeth also. God was ribbing everyone by making it all appear so simple in his big book..

This is one of the true delights of science; things refuse to be pigeon-holed and are invariably far more interesting than first meets the eye. And far more wonderful than the bible ever supposes.