Natural history
The acquiring rof medical information for an individual.

Natural selection
Differential survival and reproduction of some mebers of a species due to genotypic differences.
2. The differential survival and reproduction of classes of organisms that differ from one another in on or more usually heritable characteristics. Through this process, the forms of organisms in a population that are best adapted to their local environment increase in frequency relative to less well-adapted forms over a number of generations. This difference in survival and reproduction is not due to chance.

Neo-Darwinism
The post-Darwinian concept that species evolve by the natural selection of adaptive phenotypes caused by mutant genes.

Neoplasm
An abnormal tissue that grows by cellular proliferation more rapidly than normal and continues to grow after the stimuli that initiated the new growth cease.

Nervous System
An organ system, composed of a network of cells called neurons, that allows an animal to monitor its internal and external environment, and to move voluntarily or in response to stimulation.

Neutral theory (and neutralism)
The theory that much evolution at the molecular level occurs by genetic drift.

New mutation
Mutation that occurs for the first time in that person and is not seen in any other related family members.

Newton, Isaac
An English physician and mathematician, considered the culminating figure of the scientific revolution of the 17th century. He is best known for his explanation of gravity and for laying the foundation for modern physical optics.