[cpleppert]

The same difficulties with identifying individual species today were faced by Darwin in the Origin of Species. That is in fact exactly what the title of the book refers to.

>>BTW: Earth does not orbit around sun. It orbits around center of gravity, which is not even inside Sun.

The center of gravity of the sun-earth system is most certainly inside the sun. If it wasn't, the sun would perceptively move as the earth orbited it.

[Ergomane]

The center of gravity of the entire solar system (the solar barycenter) wanders around and is currently located inside the star. It will be outside of the sun in 2017.

Jupiter, Neptune (edit: and Uranus) serve to create a giant spirograph.