BIOL 3200 Lecture Notes - Lecture 32: William Thomson, 1St Baron Kelvin
Document Summary
Dar(cid:449)i(cid:374) (cid:272)o(cid:374)(cid:448)i(cid:374)(cid:272)ed (cid:373)a(cid:374)y (cid:271)iologists of e(cid:448)olutio(cid:374), (cid:271)ut did(cid:374)"t (cid:272)o(cid:374)(cid:448)i(cid:374)(cid:272)e the(cid:373) that natural selection was the cause of origin of species. Between 1860-1930 a lot of people doubted his of natural selection, and thought about alternative mechanisms to account for diversity in species and organisms. It was thought that natural selection acting on chance variations was not enough to cause direction in evolution, as evolution causes increase in complexity. Evolution through natural selection was a tinkering process: life is without design or purpose, this is (cid:271)asi(cid:272)ally (cid:449)hat dar(cid:449)i(cid:374)"s (cid:373)etaphor of (cid:374)atural sele(cid:272)tio(cid:374) (cid:449)as sayi(cid:374)g, everything was by chance. Critics thought this metaphor was a bit misleading because there is no known force in nature that deliberately selects. Natural selection is not a promoter of evolution, but a device to help weed out the unfit. Darwin thought earth was several billion years old which was ample time for evolution to gradually occur by natural selection, and let variations accumulate within the population.
