Symmetry refers to balance in dimensions. Symmetry has also been described as Exact correspondence on either side of a dividing line, plane, center or axis.
Human beings as well as most plant and animal species display a remarkable degree of symmetry where their left half is nearly identical to their right half. Since left and right halves are often identical, evolution would have need to evolve both left and right halves in the same way and do it repeatedly and never let one half evolve in one way when the other half doesn't evolve to match. Evolutionary theory has no mechanism to generate symmetrical pattern coordination between left and right halves of living beings.
Similarly, complementary Gender differences require coordinated evolutionary development to happen in two places at the same time.
In nature there are four kinds of symmetry:
- Bilateral Symmetry: has only one plane along the longitudinal axis that will produce identical halves. All vertebrates exhibit bilateral symmetry.
- Radial Symmetry: exhibits a circular body plan with a circular arrangement around a central axis. The animal can be cut through the central axis in more than one plane to produce identical halves. Jellyfish, Anemone, and starfish exhibit radial symmetry.
- Spherical Symmetry: exhibits a spherical body plan and can be divided into identical halves through any plane which passes through the center.
- Asymmetrical: has no pattern of symmetry. Sponges are asymmetrical.
- Symmetry by Greg Morgan
- http://en.wiktionary.org/wiki/symmetry [retrieved 2011.10.09]