Select all of the following that are true regarding evolution. Although not all transitional organsisms have been preserved, scientists have unearthed many, including the tiktaalik. Evolution is a theory about how life originated Complex human structures did not evolves as a single functioning unit, but slowly over millions of years, piece by piece. Evolution is a theory or a well-established and accepted scientific model that is based on extensive experimentation and observation. Mutations that cause variation originate spontaneously by chance, but natural selections drives evolution and is not random. Evolution is both observable and testable; populations have been observed evolving in the laboratory and in the field. Evolution is a theory about how the diversity of life emerged after life originated. Human traits are too complex to have originated by random chance. Evolution is not observable or testable. Evolution is just a theory and therefore does not have much evidence to support it. There are no transitional fossils. Solution Following are the true statements regarding Evolution.