Evolution

Evolution refers to systematic change over time. During the nineteenth century, growing evi-dence about extinct species such as dinosaurs compelled scientists to explain such findings. Although speculations about evolution had been offered for over two millennia, Charles Darwin, in the mid-nineteenth century, pro-posed for the first time a coherent theory and mechanism for evolution and amassed sup-portive empirical evidence. Darwin’s theory of evolution by natural selection offers a natural-istic explanation for the existence and diversity of life. Since its presentation in On the Origin of Species in 1859, the core of Darwin’s theory has survived thousands of empirical tests. Over more than 150 years, scientists have added to, elaborated, and modified details of the theory. Yet, no empirical work has contradicted the core of the theory, and all empirical evidence supports the main tenets: populations change over time; this change is gradual; speciation occurs; all species share common ancestry; and the primary cause of evolution is natural selection. The evidence for evolution includes empir-ical results generated within, for example, zoology, biochemistry, morphology, genetics, geography, and paleontology. To reject the evidence for evolution requires also rejecting well-supported results in these and other sci-entific fields. There is now as much evidence for evolution by natural selection as there is for the theory of gravity and the germ theory of disease (see Coyne, 2009). Furthermore, there is currently no empirically supported alterna-tive theory. Evolution by natural selection is the only known process capable of producing complex biological systems. It is the unifying theory of the life and social sciences