Mutation in Evolution

Abstract

The concept of intrinsic mutagenesis is no more than a formal expression for the opinion that the commonly accepted environmental causes of mutation are in normal circumstances quantitatively unimportant and for the most part effective only through their influence on the errors in DNA replication of intrinsic origin. Under these circumstances it is inevitable that discussion should centre first on the most readily measured mutagen and the one with the strongest emotional impact: ionizing radiation. The whole world is conscious of the danger associated with military and peaceful uses of atomic energy, and, like most senior biologists with some interest in public affairs, I have taken some part in official or semi-official discussion in this field. Always the controversy has centred on the question of the level of exposure that is safe, in the sense of producing no medically significant mutations or other genetic anomalies and no leukaemia or other form of neoplastic disease. In 1973 there was strong opposition to the expansion of the nuclear power industry in North America, and in Australia and the rest of the southern hemisphere equally fervent resentment at the atmospheric tests of nuclear devices in French territories in the Pacific. The problem is in principle highly relevant to the present theme and calls for a fairly detailed discussion.