The term neo-Darwinism describes the modern theory of evolution based on Charles Darwin's idea of natural selection.
Neo-Darwinism extends the scope of the Darwinian idea of natural selection, specifically to include subsequent scientific discoveries and concepts unknown to Darwin such as DNA and genetics that allow rigorous, in many cases mathematical, analysis of phenomena such as kin selection, altruism, speciation.
A particular interpretation of neo-Darwinism most commonly associated with Richard Dawkins asserts that the gene is the only true unit of selection. Dawkins further extended the Darwinian idea to include non-biological systems exhibiting the same type of selective behavior of the 'fittest' such as memes in culture.