Natural radiations, such as cosmic rays, undoubtedly cause a fraction of them, but it has been estimated that the intensity of natural radiations is not sufficient to account for all the mutations that occur in plant and animal populations. While the genetic hazards of radiation are of most immediate concern, there are more positive implications of the new knowledge of genetics and evolution for the future of humanity. 27). Darwin's theory of natural selection lacked an adequate account of inheritance, making it logically incomplete. His observations of the wildlife of the Galapagos (alongside his observations of wildlife elsewhere), led to his theory of evolution, which was published in his book ‘On the Origin of Species by Means of Natural Selection ‘.