NATURE 



[November 21, 1912 



The Making of a Rostro-carinate Flint Implement. 



Bv the courtesy of Sir Hercules Read, K.C.13., I 

 have now been able to exhibit in the (-ase at the 

 British Museum containing the sub-Red Crag rostro- 

 carinate implements a specimen which I have myself 

 flaked, using an ordinary flint pebble as a hammer- 

 stone, into this definite and peculiar form. 



It was only after a very careful and prolonged 

 studv of one of the sub-Crag implements that I was 

 able to recognise the plan upon which the ancient 

 men had worked, and, after many failures, to produce 

 a true rostro-carinate type. 



I found it to be necessary to select a potato-shaped 

 nodule of flint, and to detach a flake from one end 

 of it, and in such a manner as to produce the ventral 

 plane (Fig. i). Then, having by this means got a 

 flaking surface, I was able to remove flakes on either 

 side of this surface and to produce the typical " keel " 

 or carina (Fig. 2). 



I may say that unless the nodule of flint is held in 

 a particular manner when being struck the flakes 

 detacKed will not be fallen off at the required angle, 

 and no "keel " will be formed. 



When this " keel " is produced the flint must be 

 undercut or cleared at the point X (Fig. 3) to form 

 the actual overhanging "beak." 



This is a verv difficult task, as if a careless blow- 

 is given the end of the implement is broken off, and 

 it is useless, a fact continually impressed upon one 

 when making these rostro-carinate specimens. The 

 only means of avoiding the necessitv for undercutting 

 js to detach the primary flake of such a concave 

 shape that the neccssarv overhang is produced 

 fpig. 4). 



Careful flaking will then give the "keel," and the 

 rostro-carinate implement be complete. 



I find it is sometimes necessary to detach flakes 

 from the dorsal as well as the ventral surface to get 

 the required form, and an examination of the sub- 

 Crag specimens shows that their makers were occa- 

 sionallv compelled to adopt this method. 



It was also noticed that some of the sub-Crag pieces 

 when held with the "beak" towards one exhibited 

 a curious one-sided appearance, which puzzled me 

 greatly for some time. 



I was also very surprised to find the specimens of 

 my own manufacture also showed this same pecu- 

 liarity. I have now found that this is due to the fact 

 that 'flakes of unequal size and thickness are taken 

 off from the two sides respectively when forming the 

 "keel," which causes one side to get more hollowed 

 out than the other, and the asymmetrical appearance 

 to be produced. 



I hope this description of the rostro-carinate 

 flints will convince archajologists that we are dealing 

 with a very complex type of implement, and that 

 such a highly specialised tool cannot very well have 

 been produced by unguided, haphazard natural forces. 



J. Reid Moir. 



12 St. Edmund's Road, Ipswich, November S. 



On an Apparent Fallacy in the Statistical Treatment 



of "Antedating" in the Inheritance of Pathological 



Conditions. 



The problem of the "antedating" of family diseases 

 IS one of very great interest, and is likely to be more 

 studied in the near future than ever it has been in 



NO. 2247, VOL. 90] 



the past. The idea of antedating, i.e. the appearance 

 of an hereditary disease at an earlier age in the off- 

 spring than in the parent has been referred to by 

 Darwin, and has no doubt been considered by others 

 before him. Quite recently, studying the subject on 

 insanity. Dr. F. W. Mott speaks of antedating or 

 anticipation as "nature's method of eliminating un- 

 sound elements in a stock" ("Problems in Eugenics," 

 papers communicated to the First International 

 Eugenics Congress, 1912, p. 426). 



I am unable to follow Dr. Mott's proof of the case 

 for antedating in insanity. It appears to me to depend 

 upon a statistical fallacy, but this apparent fallacy 

 may not be real, and I should like more light on the 

 matter. This is peculiarly desirable, because I under- 

 stand further evidence in favour of antedating is soon 

 forthcoming for other diseases, and will follow much 

 the same lines of reasoning. Let us consider the whole 

 of one generation of affected persons at any time in 

 the community, and let n, represent the number who 

 develop the disease at age s, then the generation is 

 represented by — 



^•VkiiS «.). »i, II., . . . n, . . . iti„„ say. 



Possibly some of these groups will not appear at all, 

 but that is of little importance for our present purpose. 



Let us make the assumptions (i) that there is no 

 antedating at all ; (2) that there is no inheritance of 

 age of onset ; thus each individual reproduces the popu- 

 lation of the affected reduced in the ratio of p to i. 

 Then the family of any affected person, whatever 

 the age at which he developed the disease, would 

 represent on the average the distribution — 

 pii„, p?iy, /«._, . . . pil, . . . piiim- 

 The sum o'f such families would give precisely the age 

 distribution at onset of the preceding generation. 



Now let us suppose that for any reason certain of 

 the groups of the first generation do not produce 

 offspring at all, or only in reduced numbers. Say 

 that y, only of the lu are able to reproduce their 

 kind; then of the older generation, limited to parents, 

 the distribution will be — 



but the younger generation will be — 



/('Ai + '/i+ • • • +V'+ ■ ■ ■ +?ioo)i"o + "i+ • • • 

 + n,+ ... -f«ioo), 



i.e. the relative proportions will remain absolutely the 

 same. 



The average age at onset and the frequency dis- 

 tribution of the older generation, that of the parents, 

 will be entirely different from that of the offspring, and 

 will depend wholly on what values we give to the 5's. 

 If frequency curves be formed of the two generations 

 they will differ substantially from each other. This 

 difference is not a result or a demonstration of any 

 physiological principle of antedating, but is solely due 

 to ' the fact that those who develop the disease at 

 different ages are not equally likely to marry and 

 become parents. 



A quite striking instance of the fallacy, if it be such, 

 would be to consider the antedating of "violent 

 deaths." Fully a quarter such deaths in males, nearly 

 a half in females, occur before the age of twenty 

 years. Consider now the parents and offspring who 

 die from violent deaths ; clearly there would be no 

 representative of death from violence under twenty 

 in the parent generation, and we should have a most 

 marked case of antedating, because the offspring 

 generation would contain all the infantile deaths from 

 violence. 



In the case of insanity, is the man or woman who 

 develops insanity at an early age as likely to become- 



