Answer
The Theory of Evolution meets Crow's criteria in that 1) it explains observations such as the many extinct species found in the fossil record and 2) it connects the very different looking limbs of different vertebrates (humans and bats, for example). 3) Evolutionary hypotheses can be tested by looking at more than one trait once a relationship is established to see if the relationship is confirmed, and 4) evolutionary theory leads to many new hypotheses about the evolution of larger and smaller groups than those worked on at a given moment. 5) The Theory of Evolution only requires a few things (heritable traits, variation, natural selection) to operate, and is thus elegant, and 6) it leads to some surprising connections, as when it links up with continental drift to explain the current distribution of organisms.
Work Step by Step
While most scientists would probably attack numbers 5 and 6 in anything but a scientific theory, these are useful criteria. 1) Evolution ties together many facts from fields like paleontology, genetics, developmental biology, physiology, and others, and 2) it helps us to see common relationships among what, at first glance, seem disparate structures and functions in Biology. 3) Evolution is difficult to test directly, except in bacteria, but it is tested using evidence such as the fossil record and what is recorded in genes, and 4) one evolutionary study leads to many others. 5) Scientific theories which are true are elegant, like Newton's Laws in Physics, and 6) true theories tend to surprise us just like turning up unimagined connection in our own families which, nevertheless, turn out to make sense once understood.
