Evolution
![](/Images/godic/202501/15/CollapsedtreeLabels-simplified.svg5048.png")
![LucretiusAlfred Russel WallaceThomas Robert MalthusBiologist and statistician Ronald FisherIn 1842, Charles Darwin penned his first sketch of what became On the Origin of Species.[28]](/Images/godic/202501/15/Lucretius_Rome5048.jpg")
![](/Images/godic/202501/15/Alfred-Russel-Wallace-c18955048.jpg")
![](/Images/godic/202501/15/Thomas_Robert_Malthus_Wellcome_L0069037_-crop5048.jpg")
Evolution is change in the heritable traits of biological populations over successive generations. Evolutionary processes give rise to diversity at every level of biological organisation, including the levels of species, individual organisms, and molecules.