April 29, 1922 



NATURE 



553 



Evolutionary Faith and Modern Doubts.* 



By W. Bateson, F.R.S. 



I VISIT Canada for the first time in delightful 

 circumstances. After a period of dangerous 

 isolation, intercourse between the centres of scientific 

 development is once more beginning, and I am grate- 

 ful to the American Association for this splendid 

 opportunity of renewing friendship with my western 

 colleagues in genetics, and of coming into even a 

 temporary partnership in the great enterprise which 

 they have carried through with such extraordinary 

 success. 



In all that relates to the theme which I am about to 

 consider we have been passing through a period of 

 amazing activity and fruitful research. Coming here 

 after a week in close communion with the wonders of 

 Columbia University, I may seem behind the times in 

 asking you to devote an hour to the old topic of evolu- 

 tion. But though that subject is no longer in the 

 forefront of debate, I believe it is never very far from 

 the threshold of our minds, and it is with pleasure that 

 I find it appearing in conspicuous places in several 

 parts of the programme of this meeting. 



Standing before the American Association, it is not 

 unfit that I should begin with a personal reminiscence. 

 In 1883 I first came to the United States to study the 

 development of Balanoglossus at the Johns Hopkins 

 summer laboratory, then at Hampton, Virginia. This 

 creature had lately been found there in an easily 

 accessible place. With a magnanimity that on look- 

 ing back I realise was superb, Prof. W. K. Brooks had 

 -iven nxe permission to investigate it, thereby handing 

 over to a young stranger one of the prizes which in this 

 age of more highly developed patriotism, most teachers 

 would keep for themselves and their own students. At 

 that time one morphological laboratory was in purpose 

 md aim very much like another. Morphology was 

 studied because it was the material believed to be most 

 favourable for the elucidation of the problems of evolu- 

 tion, and we all thought that in embryology the quint- 

 essence of morphological truth was most palpably 

 presented. Therefore every aspiring zoologist was an 

 embryologist, and the one topic of professional conversa- 

 tion was evolution. It had been so in our Cambridge 

 school, and it was so at Hampton. 



I wonder if there is now a single place where the 

 academic problems of morphology which we discussed 

 with such avidity can now arouse a moment's concern. 

 There were of course men who saw a little further, 

 notably Brooks himself. He was at that time writing 

 a book on heredity, and, to me at least, the notion on 

 which he used to expatiate, that there was a special 

 physiology of heredity capable of independent study, 

 came as a new idea. But no organised attack on that 

 problem was begun, nor had any one an inkling of how 

 to set about it. So we went on talking about evolu- 

 tion. That is barely 40 years ago ; to-day we feel 

 silence to be the safer course. 



Systematists still discuss the limits of specific dis- 

 tinction in a spirit which I fear is often rather scholastic 

 than progressive, but in the other centres of biological 



> Address delivered before the American Association for the Advance- 

 ment of Science at Toronto on December 28, 1921. 



research a score of concrete and immediate problems 

 have replaced evolution. 



Discussions of evolution came to an end primarily 

 because it was obvious that no progress was being made. 

 Morphology having been explored in its minutest 

 corners, we turned elsewhere. Variation and heredity, 

 the two components of the evolutionary path, were 

 next tried. The geneticist is the successor of the 

 morphologist. We became geneticists in the conviction 

 that there at least must evolutionary wisdom be found. 

 We got on fast. So soon as a critical study of variation 

 was undertaken, evidence came in as to the way in 

 which varieties do actually arise in descent. The un- 

 acceptable doctrine of the secular transformation of 

 masses by the accumulation of impalpable changes 

 became not only unlikely but gratuitous. An examina- 

 tion in the field of the interrelations of pairs of well- 

 characterised but closely allied " species " next proved, 

 almost wherever such an inquiry could be instituted, 

 that neither could both have been gradually evolved by 

 natural selection from a common intermediate pro- 

 , genitor, nor either from the other by such a process. 

 Scarcely ever where such pairs co-exist in nature, or 

 occupy conterminous areas do we find an intermediate 

 normal population as the theory demands. The 

 ignorance of common facts bearing on this part of the 

 inquiry which prevailed among evolutionists was, as 

 one looks back, astonishing and inexplicable. It had 

 been decreed that when varieties of a species co-exist 

 in nature, they must be connected by all intergrada- 

 tions, and it was an article of faith of almost equal 

 validity that the intermediate form must be statistically 

 the majority, and the extremes comparatively rare. 

 The plant breeder might declare that he had varieties of 

 Primula or some other plant, lately constituted, uni- 

 form in every varietal character and breeding strictly 

 true in those respects, or the entomologist might state 

 that a polymorphic species of a beetle or of a moth fell 

 obviously into definite types, but the evolutionary 

 philosopher knew better. To him such statements 

 merely showed that the reporter was a bad observer, 

 and not improbably a destroyer of inconvenient 

 material. Systematists had sound information, but no 

 one consulted them on such matters or cared to hear 

 what they might have to say. The evolutionist of 

 the 'eighties was perfectly certain that species were a 

 figment of the systematist's mind, not worthy of 

 enlightened attention. 



Then came the Mendelian clue. We saw the varieties 

 arising. Segregation maintained their identity. The 

 discontinuity of variation was recognised in abundance. 

 Plenty of the Mendelian combinations would in nature 

 pass the scrutiny of even an exacting systematist and 

 be given " specific rank." In the light of such facts 

 the origin of species was no doubt a similar phen- 

 omenon. All was clear ahead. But soon, though know- 

 ledge advanced at a great rate, and though whole 

 ranges of phenomena which had seemed capricious and 

 disorderly fell rapidly into a co-ordinated system, less 

 and leSs was heard about evolution in genetical circles, 

 and now the topic is dropped. When students of other 



NO. 2739, VOL. 109] 



