208 



NATURE 



[October 31, 1912 



limits the range of the space waves seriously but does 

 not so limit the surface waves. 



One ditliculty in reading Sommerfeld's paper is that 

 he does not sufficiently translate his mathematical 

 analysis into physical concepts. Hence it is desirable 

 to consider a little in general terms how these surface 

 waves arise. 



(To he continuei.) 



MODERN PROBLEMS RELATING TO THE 



ANTIQUITY OF M.4A'.i 

 /~\N my bookshelves there is placed a series of old 

 ^^ volumes containing past reports of this Associa- 

 tion,^ which fortune sent my way many vears ago on 

 a Whitechapel bookstall. .'Vmong them 'there is one 

 volume I prize— that which contains the history of 

 the meeting at Aberdeen in 1859. In that volume 

 you will find an early phase of the subject of my 

 discourse for this evening— the antiquitv of man". 

 Sir Chas. Lyell presided over the section of Geology; 

 in his opening address he announced that "a work 

 will very shortly appear by Mr. Charles Darwin— the 

 result of twenty years' observation and experiment," 

 and that the evidence which had accumulated in 

 recent years "made it probable that man was old 

 enough to have co-e.xisted at least with the Siberian 

 mammoth." From other statements made in his 

 address it is clear that Lyell was then convinced that 

 man's appearance on earth was infinitelv older than 

 thf- limits fixed by Biblical record. I do' not suppose 

 I have a single listener who heard that address in 

 Aberdeen sixtv-three years ago, but even those who 

 are not yet old will concede that the new doctrine, 

 preached so moderately by Sir Charles Lvell, was not 

 likely to be acceptable to' the general membership of 

 the Geological Section in the year 1S59. You will find 

 an exact record of what happened at the meeting— 

 not in the official report of the vear, but in the letters 

 of Mr. William Pengelly, the explorer of Kent's 

 Cavern. Orthodoxy was represented at the meeting 

 by the Rev. Dr. Anderson, who, in Mr. Pengellv's 

 words, "attempted to castigate Lyell for his openins" 

 address. There was a considerable amount of 

 orthodoxy in the room, and Dr. .'\nderson srot a verv 

 undue_ share of applause." The doctrine which Lvell 

 and his companions championed in the face of public 

 opprobrium in 1859 is the accepted and orthodox 

 opinion of the vast majority of thoughtful people in 

 the vear 1912. 



That splendid movement of the nineteenth century 

 which knocked the shackles of tradition from the 

 problenis of man's origin was led by men of couraee, 

 conviction, and sound judgment. It was a progressive 

 and victorious movement they initiated, but in every 

 movement of that kind there comes a time when 

 those who cleared the way turn circumspect, cautious, 

 and more critical than constructive. Opinion tends 

 to become fixed and conventionalisec^. and then a 

 new heterodoxy raises its head. That is the phase 

 which we, who make a special study of the facts 

 relating to man's origin, seem to have reached now. 

 I cannot cite a more stalwart or distinguished repre- 

 sentative of the orthodox opinion of to-dav than Prof. 

 Boyd Dawkins, of Manchester. In his Huxley lec- 

 ture in 10 10 he gives very clearlv his opinions on 

 the antiquity of man — rine convictions which are 

 founded on a lifetime of active investigation and 

 study. Tn his opinion the historv of man does not 

 extend beyond the Pleistocene period — the phase of 

 the earth's history which immediately precedes the 



* Discourse delivered before the British .Association at Dundee on 

 September q by Prof, .\rthur Keith. 



NO. 2244, VOL. 90] 



one in which we live. He accepts the fossil man of 

 Java — Pithecanthropus — a being with a brain a little 

 more than half the size of a modern man's, as repre- 

 sentative of mankind at the beginning of the PIei_sto- 

 cene ; before the end of that period men of the modern 

 type appeared. In Prof. Boyd Dawkins's opinion, 

 then, man was evolved during the Pleistocene period, 

 and, therefore, from a geologist's point of view, is 

 a recent addition to the earth's fauna. If we ask 

 how long ago it is since man appeared, Prof. Bovd 

 Dawkins replies : " It cannot be measured in years — 

 only by the sequence of geological events and by the 

 changes in animal life." Yet we are certain that 

 years came cycling round in the Pleistocene period 

 just as they do now, and that every cycle wrought 

 some degree of change on the face of the earth and 

 on the form of living things — a degree of change 

 which may be imperceptible in the period of a man's 

 life, and vet cumulative and apparent in the course 

 of time. Men who have studied the transformations 

 effected during the Pleistocene period have formed 

 varying estimates of its duration, but we may safely 

 adopt as a moderate figure the 400,000 years given 

 by Prof. .SoUas at a meeting of this .'\ssociation in 

 1900. We may accept, then, as the orthodox opinion 

 of to-day that the dawn of the very earliest form of 

 humanity lies 400,000 years behind us ; in that space 

 of time man as we know him now was evolved from 

 a crude, almost prehuman form. 



For a representativ-e of modern heterodoxy — as far 

 as relates to the antiquity of man — we cannot do 

 better than visit the Royal Natural History Museum 

 in Brussels and follow the guidance of M. Rutot, who 

 has devoted himself to the study of the stone imple- 

 ments of ancient man, and of recent geological forma- 

 tions. One civilisation succeeded another in Pleisto- 

 cene as in historical times. You will admit, when 

 you examine the handiwork of the men of the Mag- 

 dalenian age — at the close of the Pleistocene — that 

 our ancestors were then artistic and skilled workmen ; 

 as we pass backwards in time from the Magdalenian 

 to the Solutrean, and from the Solutrcan to the Mous- 

 terian, Mousterian to .'Xcheulean, and .-Xcheulean to 

 the Chellean — thus passing well beyond the mid-point 

 of the Pleistocene — that although the handiwork of 

 man changes in form and in design, it does not lose 

 in skill of execution ; those flints of the remote 

 Chellean period assure us that man had then a 

 capable brain and a skilled hand. When, however, 

 M. Rutot proceeds to show us the implements which 

 were fashioned by men in the earlier parts of the 

 Pleistocene, it is very probable that our orthodox 

 companions will pull out their watches and find they 

 have pressing engagements elsewhere. Human 

 workmanship becomes cruder as we approach the 

 commencement of t'ne Pleistocene. The stones which 

 have been wrought by man's hand (eoliths) become 

 then more diftlcult to distinguish from those which 

 have been shaped by natural forces. M. Rutot, how- 

 ever, is convinced that he has traced man, by means 

 of his Eolithir culture, not only to the commencement 

 of the Pleistocene, but into and through the two long 

 geological periods which preceded the Pleistocene — the 

 pliocene and Miocene — and even well into the forma- 

 tions of the still older period, the Oligocene. In 

 M. Rutot's opinion the origin of mankind must be 

 assigned to a time as early as the Oligocene period. 

 Prof. Sollas has made a provisional estimate of 

 qoo,ooo j'ears for the Pliocene and i, 800,000 for the 

 Miocene. On this crude estimate the heterodox 

 opinion as to the antiquity of man must be placed 

 at more than 3,000,000 years. It is only just to 

 M. Rutot to state that he would by no means agree 

 with the estimates given by Prof. Sollas. In his opinion 



