born and reared were recorded. From this astonishing number of observations it is proved that local influences of some kind act directly on stature; and we further learn that "the State "where the physical growth has in great measure taken place, "and the State of birth, which indicates the ancestry, seem to "exert a marked influence on the stature." For instance, it is established," that residence in the Western States, during the years of growth, tends to produce increase of stature." On the other hand, it is certain that with sailors, their life delays growth, as shewn "by the great difference between the statures of soldiers “ and sailors at the ages of seventeen and eighteen years." Mr. B. A. Gould endeavoured to ascertain the nature of the influences which thus act on stature; but he arrived only at negative results, namely, that they did not relate to climate, the elevation of the land, soil, nor even "in any controlling degree" to the abundance or the need of the comforts of life. This latter conclusion is directly opposed to that arrived at by Villermé, from the statistics of the height of the conscripts in different parts of France. When we compare the differences in stature between the Polynesian chiefs and the lower orders within the same islands, or between the inhabitants of the fertile volcanic and low barren coral islands of the same ocean,18 or again between the r'uegians on the eastern and western shores of their country, where the means of subsis-tence are very different, it is scarcely possible to avoid the conclusion that better food and greater comfort do influence stature. But the preceding statements shew how difficult it is to arrive at any precise result. Dr. Beddoe has lately proved that, with the inhabitants of Britain, residence in towns and certain occupations have a deteriorating influence on height; and he infers that the result is to a certain extent inherited, as is likewise the case in the United States. Dr. Beddoe further believes that wherever & "race attains its maximum of physical development, it rises highest in energy and moral vigour." Whether external conditions produce any other direct effect on man is not known. It might have been expected that differences of climate would have had a marked influence, in as much as the lungs and kidneys are brought into activity under a low 17 'Investigations in Military and Anthrop. Statistics,' &c. 1869, by B. A, Gould, p. 93, 107, 126, 131, 134. 18 For the Polynesians, see Prichard's Physical Hist. of Mankind,' vol. v. 1847, p. 145, 283. Also Godron, De l'Espèce,' tom. ii. p. 289. There is also a remarkable difference in appearance between the closely-allied Hindoos inhabiting the Upper Ganges and Bengal; see Elphinstone's History of India,' vol. i. p. 324. 19 Memoirs, Anthropolog. Soc. vol. iii. 1867–69, pp. 561, 565, 567, temperature, and the liver and skin under a high one. It was formerly thought that the colour of the skin and the character of the hair were determined by light or heat; and although it can hardly be denied that some effect is thus produced, almost all observers now agree that the effect has been very small, even after exposure during many ages. But this subject will be more properly discussed when we treat of the different races of mankind. With our domestic animals there are grounds for believing that cold and damp directly affect the growth of the hair; but I have not met with any evidence on this head in the case of man. Effects of the increased Use and Disuse of Parts.-It is well known that use strengthens the muscles in the individual, and complete disuse, or the destruction of the proper nerve, weakens them. When the eye is destroyed, the optic nerve often becomes atrophied. When an artery is tied, the lateral channels increase not only in diameter, but in the thickness and strength of their coats. When one kidney ceases to act from disease, the other increases in size, and does double work. Bones increase not only in thickness, but in length, from carrying a greater weight.21 Different occupations, habitually followed, lead to changed. proportions in various parts of the body. Thus it was ascertained by the United States Commission 22 that the legs of the sailors employed in the late war were longer by 0-217 of an inch, than those of the soldiers, though the sailors were on an average shorter men; whilst their arms were shorter by 1·09 of an inch, and therefore, out of proportion, shorter in relation to their lesser height. This shortness of the arms is apparently due to their greater use, and is an unexpected result: but sailors chiefly use their arms in pulling, and not in supporting weights. With sailors, the girth of the neck and the depth of the instep are greater, whilst the circumference of the chest, waist, and hips is less, than in soldiers. Whether the several foregoing modifications would become hereditary, if the same habits of life were followed during many generations, is not known, but it is probable. Rengger 23 attributes the thin legs and thick arms of the Payaguas Indians to 20 Dr. Brakenridge, Theory of Diathesis,' 'Medical Times,' June 19 and July 17, 1869. 21 I have given authorities for these several statements in my • Variation of Animals under Domestication,' vol. ii. pp. 297–300. Dr. Jaeger, "Ueber das Längenwachsthum der Knochen," Jenaischen Zeitschrift,' B. v. Heft i. 22 Investigations,' &c. By B. A Gould, 1869, p. 288. 23 Säugethiere von Paraguay, 1830, s. 4. successive generations having passed nearly their whole lives in canoes, with their lower extremities motionless. Other writers have come to a similar conclusion in analogous cases. According to Cranz," who lived for a long time with the Esquimaux, “ the "natives believe that ingenuity and dexterity in seal-catching (their highest art and virtue) is hereditary; there is really something in it, for the son of a celebrated seal-catcher will distinguish himself, though he lost his father in childhood." But in this case it is mental aptitude, quite as much as bodily structure, which appears to be inherited. It is asserted that the hands of English labourers are at birth larger than those of the gentry.25 From the correlation which exists, at least in some cases,26 between the development of the extremities and of the jaws, it is possible that in those classes which do not labour much with their hands and feet, the jaws would be reduced in size from this cause. That they are generally smaller in refined and civilised men than in hard-working men or savages, is certain. But with savages, as Mr. Herbert Spencer has remarked, the greater use of the jaws in chewing coarse, uncooked food, would act in a direct manner on the masticatory muscles, and on the bones to which they are attached. In infants, long before birth, the skin on the soles of the feet is thicker than on any other part of the body; 28 and it can hardly be doubted that this is due to the inherited effects of pressure during a long series of generations. 27 It is familiar to every one that watchmakers and engravers are liable to be short-sighted, whilst men living much out of doors, and especially savages, are generally long-sighted.29 Shortsight and long-sight certainly tend to be inherited.30 The inferiority of Europeans, in comparison with savages, in eyesight and in the other senses, is no doubt the accumulated and transmitted effect of lessened use during many generations; for Rengger 31 states that he has repeatedly observed Europeans, who had been brought up and spent their whole lives with the wild Indians, who nevertheless did not equal them in the sharpness of their senses. The same naturalist observes that the cavities in the skull for the reception of the several sense-organs are larger in the American aborigines than in Europeans; and this probably indicates a corresponding difference in the dimensions of the organs themselves. Blumenbach has also remarked on the large size of the nasal cavities in the skulls of the American aborigines, and connects this fact with their remarkably acute power of smell. The Mongolians of the plains of Northern Asia, according to Pallas, have wonderfully perfect senses; and Prichard believes that the great breadth of their skulls across the zygomas follows from their highly-developed sense-organs." The Quechua Indians inhabit the lofty plateaux of Peru; and Alcide d'Orbigny states that, from continually breathing a highly rarefied atmosphere, they have acquired chests and lungs of extraordinary dimensions. The cells, also, of the lungs are larger and more numerous than in Europeans. These observations have been doubted; but Mr. D. Forbes carefully measured many Aymaras, an allied race, living at the height of between 10,000 and 15,000 feet; and he informs me 4 that they differ conspicuously from the men of all other races seen by him in the circumference and length of their bodies. In his table of measurements, the stature of each man is taken at 1000, and the other measurements are reduced to this standard. It is here seen that the extended arms of the Aymaras are shorter than those of Europeans, and much shorter than those of Negroes. The legs are likewise shorter; and they present this remarkable peculiarity, that in every Aymara measured, the femur is actually shorter than the tibia. On an average, the length of the femur to that of the tibia is as 211 to 252; whilst in two Europeans, measured at the same time, the femora to the tibia were as 244 to 230; and in three Negroes as 258 to 241. The humerus is likewise shorter relatively to the forearm. This shortening of that part of the limb which is nearest to the body, appears to be, as suggested to me by Mr. Forbes, a case of compensation in Physiology,' &c., 1822, p. 404) on this same subject. M. Giraud-Teulon has recently collected (Revue des Cours Scientifiques,' 1870, p. 625) a large and valuable body of evidence proving that the cause of shortsight, "C'est le travail assidu, de près." ** Prichard, Phys. Hist. of Mankind,' on the authority of Blumen bach, vol. i. 1851, p. 311; for the statement by Pallas, vol. iv. 1844, p. 407. 33 Quoted by Prichard, 'Researches into the Phys. Hist. of Mankind,' vol. v. p. 463. 34 Mr. Forbes' valuable paper is now published in the Journal of the Ethnological Sec. of London, new series, vol. ii 1870, p. 133. relation with the greatly increased length of the trunk. The Aymaras present some other singular points of structure, for instance, the very small projection of the heel. These men are so thoroughly acclimatised to their cold and lofty abode, that when formerly carried down by the Spaniards to the low eastern plains, and when now tempted down by high wages to the gold-washings, they suffer a frightful rate of mortality. Nevertheless Mr. Forbes found a few pure families which had survived during two generations: and he observed that they still inherited their characteristic peculiarities. But it was manifest, even without measurement, that these peculiarities had all decreased; and on measurement, their bodies were found not to be so much elongated as those of the men on the high plateau; whilst their femora had become somewhat lengthened, as had their tibiæ, although in a less degree. The actual measurements may be seen by consulting Mr. Forbes's memoir. From these observations, there can, I think, be no doubt that residence during many generations at a great elevation tends, both directly and indirectly, to induce inherited modifications in the proportions of the body.35 Although man may not have been much modified during the latter stages of his existence through the increased or decreased use of parts, the facts now given shew that his liability in this respect has not been lost; and we positively know that the same law holds good with the lower animals. Consequently we may infer that when at a remote epoch the progenitors of man were in a transitional state, and were changing from quadrupeds. into bipeds, natural selection would probably have been greatly aided by the inherited effects of the increased or diminished use of the different parts of the body. Arrests of Development.-There is a difference between arrested development and arrested growth, for parts in the former state continue to grow whilst still retaining their early condition. Various monstrosities come under this head; and some, as a cleft-palate, are known to be occasionally inherited. It will suffice for our purpose to refer to the arrested brain-development of microcephalous idiots, as described in Vogt's memoir.86 Their skulls are smaller, and the convolutions of the brain are less complex than in normal men. The frontal sinus, or the 35 Dr. Wilckens (Landwirthschaft. Wochenblatt,' No. 10, 1869) has lately published an interesting Essay shewing how domestic ani mals, which live in mountainous regions, have their frames modified. 36 Mémoire sur les Microcé. phales,' 1867, pp. 50, 125, 169, 171, 184-193. |