FOOTNOTES
[2] “Franklin’s Miscellany,” p. 9.
[3] “Darwin and after Darwin,” vol. i., p. 257.
[4] Chapter xxvii., vol. ii., 1875.
[5] “Life and Letters,” vol. ii., p. 14.
[6] “Journal of the Anthropological Institute,” vol. v., pp. 344–7.
[7] “Natural Inheritance” (1889), p. 14.
[8] “Studies in the Theory of Descent,” translated by Raphael Meldola, p. 692.
[9] “Essays upon Heredity,” translated by Poulton, Schönland and Shipley; vol. i. published in 1889, vol. ii. in 1892.
[10] Translated by W. Newton Parker (1893).
[11] D’Orbigny’s “Dictionary.”
[CHAPTER III.
CAUSES AND SIGNS OF PHYSICAL DETERIORATION.]
[Modern Care for the Individual.]
In the last chapter we saw that while selection is an evident and powerful factor in the production of racial change, there is but slight and in many cases questionable evidence that acquired characters are ever transmitted. During their lifetime a man or woman may be subject to the most varied conditions, and yet the quality of his or her offspring will not be affected by these conditions except in cases where impoverishment or poisoning of the blood has ensued, thereby enfeebling his or her reproductive cells. These facts have not been gained by a study of the lower animals alone, for most researchers have kept man in view, while others, like Malthus and Galton, have confined their observations almost exclusively to the human kind. In this chapter we shall see how these generalisations are borne out by the study of disease, and we shall see what effect the modern methods for the treatment of the sickly and feeble are having upon the race. We moderns as individuals have many advantages over those who have gone before us; we owe to the untiring energy of our ancestors the facilities for travel, the pleasures of accumulated music and literature, etc., but among these hundreds of advantages we possess none are more marked than those we owe to the scientific followers of the profession of medicine, the application of whose learning gives in our day to the less robust a possibility of life and happiness they never had before.
[Preventive Medicine.]
The words “mederi,” to heal, “medicus,” the healer, and “medicina,” the remedy, indicate pretty clearly the almost superstitious feeling current in early times regarding the attributes of the medical man; but physicians have in more recent years begun to doubt in some measure of their power to cure disease when once established. With increased knowledge, and with growth of professional acumen, the limits of this power are more clearly seen, and the solution of a metallic salt, or decoction of a herb is now withheld when at one time it would have been administered with the fullest confidence. With this healthy scepticism as to their power to cure has come very certain and exact knowledge of how to prevent, and preventive medicine has recently exercised an influence upon disease and upon mortality which is unique in the history of humanity. But while the benefit of our changed and more healthy surroundings are to the advantage of us all individually, we shall have to consider whether as a people we shall in the long run be the better for this change, or, on the other hand, whether in obtaining this individual advantage we are not imperilling the vigour of the race.
[Micro-organisms of Diseases and their Extermination.]
Nowhere has preventive medicine achieved greater triumph than in the extermination of certain micro-organisms which gain access to the body and cause the febrile class of diseases, such as small-pox, measles, typhoid fever, and very many others. At present none of these micro-organisms can be said to be extinct, but they have in some cases been banished to distant parts of the globe, and in other cases the conditions suitable to their existence, and the means of their propagation are so well understood that their banishment is being systematically and successfully carried out, so much so that a disease such as small-pox, which at one time headed the list of fatal diseases, does not come in the category of anxieties of the mother of to-day; and pyæmia and puerperal fever, which twenty years ago were at times dreaded scourgers in most hospitals, now occur only from culpable and punishable neglect.
[The Reproductive Cells are as a Rule unaffected by them.]
A short study of these diseases should well repay us, showing as it will do that in by far the greater number of cases these severe constitutional derangements produce no effect upon the reproductive cells; that they are in fact incapable of producing a change that will be hereditarily transmitted. We shall learn, moreover, the part that they have played, and can play, in producing racial change by selection. The micro-organisms of disease are of many varieties, and each variety is capable of setting up its own peculiar disturbance. The disturbance set up by one kind we call small-pox, that arising from another kind, cholera, and so on. Now, the very curious point comes out that in most of these diseases, although the composition of the blood is profoundly altered, and many of the tissues undergo marked change, this change, fortunately for us, is quite of a temporary character, and when the attack is over there is only one test which will enable us to say that the body is not just in the same condition as it was before. This test is that it cannot be infected again for a long time, if at all, by the same micro-organism.
This induced immunity from further attacks has received in the hands of Metschnikoff a curious and very interesting explanation. He has shown that an army of small cells, called phagocytes, which wander through the blood and tissues, are able to attack the microbes of disease, and that after a struggle they are able in many cases to kill these voracious invaders. In so doing, however, the weaker phagocytes succumb to the struggle, while those which are left alive within the body of the convalescent patient possess the power of resisting and destroying the particular microbe which had undertaken the invasion. These resisting phagocytes, selected from the rest, together with their descendants, who share their resisting qualities, are able to prevent fresh inroads of the same enemy. We need not, therefore, assume that this acquired immunity, the sole relic of the attack, indicates any change in the ordinary muscle or brain cells of the body, or that the reproductive cells are in any way altered, for the immunity is due only to a change in the phagocytic army.
The germ cells in almost every case get off scot-free, and there is nothing in the organisation of a child to indicate whether or not his father or mother suffered from measles, or scarlet fever. It might at first sight be urged, in opposition to this fact, that, although we cannot recognise the child of a man who suffered from measles or scarlet fever by any visible sign, yet the child is in some way different, inasmuch as he is to some extent immune to those diseases. In favour of this belief, the many instances in which a fever has been brought to a country never before accessible to the germ (for instance, the introduction of measles and small-pox to newly discovered America, where fearful ravages were caused thereby), may be brought up as evidence to prove that those habitually living among the germs must have become immune and have transmitted this immunity to their progeny. Again, the black population of Sierra Leone have only a mortality of 24 per cent. from malaria, while the mortality of the white settlers is 47 per cent.;[12] and, in this case, it may be urged that the black race has become by transmission of immunity partially immune. But these cases which appear to be examples of transmitted immunity may receive another, and a much more simple, explanation. No two children of the same parents are alike in colour of hair, shape of limb, temperament, etc., and they also differ widely in their capacity to receive and combat infection. An epidemic of fever, therefore, will always select to kill those organically most liable to fall a prey to it, while the remnant, having by nature greater power of resistance, not only survive, but may also be calculated upon to produce progeny, on the whole, as resistant as they are themselves.
[Man has been selected by the Action of the Microbes of Fever.]
Races, therefore, subject to epidemics of a particular fever, suffer selections in the hands of the microbe of that particular fever, and those living are survivals cast in the most resisting mould. It may not be flattering to our national vanity to look upon Englishmen as the product of the selection of the micro-organisms of measles, scarlet fever, small-pox, etc., but the reasonableness of the conclusion seems to be forced upon us when we consider his immunity from these diseases as compared with that of natives of the interior of Africa, or of the wilds of America, whose races have never been so selected, and who, when attacked for the first time by these diseases, are ravaged almost to extermination. We find, then, that an ordinary attack of measles, scarlet fever, whooping cough, erysipelas, typhoid, or typhus fever, when it has passed away, leaves the tissues of the body in as sound and healthy a condition as before; and, indeed, were it not for this fact, the human race could hardly have existed at all, continually exposed as it has been, for countless ages, to the aggressions of these microbes. By exterminating these diseases, we shall, no doubt, preserve countless lives to the community, who will in their turn become race producers, but, inasmuch as the individuals thus preserved will in many cases belong to the feebler and less resisting of the community, the race will not become more robust. In fact, it is probable that, as a race, we shall thereby suffer, for the banishment of the disease will enable the feebler members of the community to live, and in larger proportion contribute to the progeny of the future. That this is actually the case will shortly be pointed out.
[Leprosy an Exterminator of the Unhealthy.]
But there are other microbes which, in addition to the production of blood changes, have a profound and lasting effect upon many of the tissues of the body. Such are the microbes of leprosy and syphilis.
The terrible ravages that the microbe of leprosy is capable of effecting are appreciated only by those who in Norway or elsewhere have visited those death-houses now fortunately to be found in but one or two parts of Europe. Yet, even in this case, strange to say, the germ cells do not seem to be reached by this loathsome disease, and it is not transmitted from parent to child.[13] A disease of mediæval, not of modern, Europe, we need not discuss its action on racial change more than to say that, hideous as are its aspects, it must be looked upon as a friend to humanity; for, while the microbe of typhoid fever will attack a man who is healthy and living in healthy surroundings—excepting for the microbe that lurks in his well—the microbe of leprosy feeds upon those who are debilitated by conditions under which healthy and strong racial development is impossible. It is a depopulator of starved, ill-nourished districts, and the race recruits to its advantage from those more favourably placed.
In the case of syphilis, serious and often permanent tissue change is produced as a result of the action of the microbe, and in this disease, to an absolute certainty, an effect may be produced upon the offspring. Many suppose that this is due to the transmission of the specific microbe itself from the body of one or both of the parents to the developing egg. That such a thing is not impossible is shown in the case of silk-worm disease, in which the spores are to be found within the egg of the silk-worm moth. These spores subsequently develop and attack the tissues of the grub of the next generation. In syphilis the same kind of thing no doubt occurs; for a syphilitic child may subsequently infect the mother or nurse during the period of suckling. But there are other cases in this disease which appear hardly to be explained so easily, and we have to assume that the germinal cells are themselves changed in some way during their sojourn in the parental body, for after a certain time the disease is no longer capable of transmission by the parent, and the children born after this period, though themselves diseased, are incapable of infecting those who tend them. We have every reason to believe, therefore, that there are no specific germs or microbes left in the body of the parent, and that we have to do solely with the more or less permanent change in the reproductive cells, produced by the microbes during their residence in the body of the parent. The children born during this period are frequently ill-nourished, possess recognisable indications of disease, and are subject to nervous and other affections.
We have here, therefore, for the first time, distinct evidence that an obviously acquired constitutional disease is transmitted, and that that transmission is in some cases due to a direct effect of the action of the microbe upon the germinal cells. The microbe of syphilis, unlike the microbe of leprosy, but like that of measles, feeds on healthy blood and tissue. It attacks the strong as well as the weak, and, if the weak more readily succumb, yet the strong and vigorous are more apt to acquire it. It is not, therefore, selective, like leprosy, and this fact, added to that of its capacity of transmission, ranks it as a disease distinctly inimical to race progress.
[Germs of Phthisis and Scrofula, our Racial Friends.]
During recent years it has been discovered that the symptoms of phthisis and scrofula are due to a microbe, the tubercle bacillus. It appears, however, that this bacillus cannot gain access to, or multiply in, the tissues of a healthy and vigorous man or woman; most of us probably have often carried this micro-organism within the mouth or stomach, and though our gastric juice has not been able to destroy it, as is the case with so many of our invisible foes, it has been unable to pass into our blood or lacteals. Dr. Woodhead puts this fact strongly.[14] He says: “A perfectly healthy individual, placed under favourable conditions as regards food, fresh air, and exercise, is never attacked successfully by tubercle bacilli, the active, vigorous tissue cells being perfectly able to destroy any bacilli that make their way into the lungs, the pharynx, or the intestine.”
It appears, too, that a certain type of individual is readily attacked by this microbe, while the normal individual, debilitated though he may be by unfavourable external conditions, falls far less readily a victim. As Prof. Sir Lauder Brunton[15] remarks: “We are constantly meeting with persons belonging to very consumptive families who escape the disease by living under conditions where the bacillus tuberculosus is likely to be absent. On the other hand, persons such as nurses are in all probability frequently inhaling the microbe, and yet are not attacked by the disease. In the first case immunity is probably due to the absence of the seed, notwithstanding the favourable condition of the soil; in the second it is due to the barrenness of the soil, notwithstanding the presence of the seed.”
Inasmuch as phthisis is markedly hereditary, we may look upon the type, not the disease, as being transmitted. A phthisical type of person is one who comes of a family liable to fall a prey to this microbe, and he is recognisable by many distinctive characteristics of hair and complexion, and by qualities of temperament, feature, and figure.
Sufferers from phthisis are prone to other diseases, such as pulmonary and bronchial attacks, so that over and above the vulnerability to this one form of microbe they are to be looked upon as unsuited not only for the battle of life, but especially for parentage and for the multiplication of the conditions from which they themselves suffer.
The phthisical are attractive in personal appearance on account of their rich skin and hair colouring and their frequent brightness and vivacity, and their obvious delicacy also elicits a feeling of pity and wish to protect them. In consequence of this they easily marry, and they are as a rule very fertile. Galton[16] says: “There is fair doubt whether a group of young persons destined to die of consumption contribute considerably less to the future population than an equally large group who are destined to die of other diseases.” Now this phthisical type is very common with us indeed, and it appears to be an innate variation to which our race is liable. It is evident, therefore, that those people with the tuberculous variation who, even under the present circumstances, manage to contribute their quota to the population, would, were the bacillus tuberculosus altogether exterminated, contribute more than their share, and the type would become more common. And let it be remembered that this type, apart from the action of the bacillus, is a delicate and fragile one and liable to other affections, and the effect of giving the type any advantage in the struggle for life would surely imperil the well-being of the future of the race. When, some years ago, it was thought that a cure for phthisis had at last been obtained, great tribute was naturally and rightly paid to its discoverer; but had this cure proved as efficient as the more sanguine were led to expect, it would be terrible to contemplate the eventual suffering that would have resulted from the constantly increasing numbers of the phthisical type that would have been born with each generation.
[If we stamp out Infectious Diseases we perpetuate Poor Types.]
It is a hard saying, but none the less a true one, that the bacillus tuberculosus is a friend of the race, for it attacks no healthy man or woman, but only the feeble. It is like the bacillus of leprosy in this respect, but in this respect only, for leprosy attacks anyone living under certain unhygienic conditions. Remove these conditions—as we have done long ago—and the bacillus of leprosy disappears; its duties are over, like those of the extinct plants and fishes in the rocks.
The tubercle bacillus on the other hand attacks a type to be found not only in the poor, ill-fed, and ill-conditioned, but also those who live well. It is a disease of all classes, and those who live in well-ventilated rooms, and who conform to every sanitary regulation, may still belong to the type who fall a prey to it. It is certain, therefore, that, improve the external conditions of life how you will, this type will remain. It is also as certain that in giving the type a better chance than it has already, by preventing infection or by delaying the disease, the type will be more and more prevalent as each generation comes to life.
It comes out pretty clearly from our short study of the infective diseases that some of the microbes that cause these, such as the bacillus of tubercle, only feed on unhealthy human tissue, while the greater number of them kill, if anything, the weak rather than the strong. They are, therefore, on the whole, and as a natural consequence, our race friends rather than our foes, and if we attempt seriously to do away with their selective influence—viz., the elimination of the weak and the preservation of the strong—we must supply this selective influence by one equally potent, or the race will tend to deteriorate. What can be done in the future, and what it is expedient for us to do at the present time, will be more fully discussed in a subsequent chapter; but I may state at once that pari passu with our endeavour to prevent these diseases must be our efforts to enlist the co-operation of the human charity that would avert suffering in such selection as shall necessitate the birth of future generations from the healthiest and best of those amongst us. As selection is the race-changer, we must replace the selection of the microbe by the selection of human forethought.
A number of diseases, which are due probably to innate family predispositions, are known to us. Of these diabetes, hæmophilia, and some others are of comparative rarity, and may be left on one side in this necessarily contracted sketch. Others, such as cancer and constitutional weakness of the respiratory and other organs, as well as insanity, are frequent enough to merit our close attention. Of cancer we at present know too little, and I propose to leave it on one side. Of inherited weakness of special systems we have many examples, such as a delicate respiratory or digestive mucous membrane, inherited variations in the mechanism of assimilation, and also gout and obesity—in fact, innate delicacy of all kinds, which renders their possessor less able to cope with his natural surroundings, let these be what they may.
There is hardly a family that can boast of the complete want of hereditary weakness, and among the children of particular families, where these weaknesses exist, some show the taint more than others. In times of hardship, cold, exposure, coarse food, etc., these weaker ones perish, and the race is consequently propagated from the stronger ones. Within certain limits cold, exposure and coarse food are compatible with great physical excellence, for the cold and exposure, hurtful to the sickly, braces and hardens the more robust, and coarse but nutritive food supplies him with energy and strengthens the powers of digestion. The finest races have been bred by hardship. It is proverbial to speak of “the hardy mountaineer,” and one cannot look at a lowland Scot without feeling that his stock had, in days gone by and for many centuries, run the gauntlet of oatmeal porridge and cold east wind.
But we are rapidly diminishing those selective agencies which in the past have developed race vigour. As we shall presently see, skill in nurturing the sickly has, in modern times, wonderfully reduced the mortality amongst infants; improvements in methods of nursing, the replacement of cotton by flannel and wool, and the use of many foods, some of them artificially digested, gives a sickly infant a chance of living, and it survives its first most dangerous years. Then its chances are again improved, for the infective diseases are being held in check, and it has comparatively little to fear from them. Thus it survives and lives to adult age, when, like the hothouse plant, it is still protected from hardships to which the race had formerly been freely exposed. It lives to lower the average physique of the mothers or fathers who produce the next generation of children.
This increased preservation of the sickly has had the effect of increasing the life period of an average child, and this increase in the life probability is often and very rightly cited as an indication of the improved sanitary conditions of the people. Improved sanitary surroundings, as we have seen, are taken advantage of chiefly by the sickly, and thus with our increased probability of life we have diminished the average robustness of constitution, or innate healthiness of the race, for a larger proportion of sickly ones are living amongst us. In our day a greater number of parents suffer from phthisical, scrofulous and other taints than in days gone by, and these and other taints are passed on to their children.
So far we have seen what of necessity follows from our biological premises, but it is also possible, I think, to show by statistics that already very observable deterioration has taken place.
[Births, Deaths, and Marriages.]
If we examine one of the reports of the Registrar General for births, deaths and marriages, we shall gain pretty full information concerning the deaths from disease, accident, old age, etc., that have occurred during the last thirty or forty years.
[Increase of Constitutional Weakness.]
In Report 54, Table 17, the annual death-rates from various causes per million of population are given, and arranged in groups of five years from 1858 to 1890. We have there a history of thirty years, and even in that time a notable change in this history is to be observed. I have arranged the greater number of facts given in Table 17 in the following table, so as best to bring out those points which we are discussing. In the first group of disease are those due to micro-organisms, and a diminution of these diseases to a marked extent is to be observed of late years. Phthisis and scrofula placed by themselves in this group share in this decrease. In the second group are diseases that are due in great measure to carelessness, want of management, neglect and ignorance, such as convulsions, diseases of dentition, parturition and registered accidents. These, too, as one would expect, diminish yearly in a country where surrounding comforts and a sense of responsibility are on the increase. When we turn to the third group, that of constitutional disease, where the hereditary tendency comes in, we find an increase in almost all the hereditary diseases. A tendency to an increase of neurotic affections is shown by an increase in the deaths from nervous diseases, suicide and intemperance. A large increase in the diseases of the respiratory system is due in part to the increasing number of tuberculous patients who, kept from inroads of microbes, nevertheless readily fall a prey to other affections: there is, too, an increase in diseases of the circulatory system, in cancer, diabetes and other constitutional diseases.
Annual death-rates in England from various causes, per million persons living, in groups of years 1858–1890—
[[Version of the table for narrower screens]]
| CAUSE OF DEATH. | 1858–60. | 1861–65. | 1866–70. | 1871–75. | 1876–80. | 1881–85. | 1886–90. |
|---|---|---|---|---|---|---|---|
| GROUP I. | |||||||
| Phthisis and scrofula | 3304·0 | 3311·0 | 3300·2 | 2940·6 | 2816·8 | 2540·8 | 2322·2 |
| Other diseases of micro-organisms[17] | 4403·9 | 4498·6 | 4677·2 | 4055·8 | 3233·6 | 2708·8 | 2417·0 |
| GROUP II. | |||||||
| Diseases of dentition, parturition, convulsions, accident and negligence | 2257·0 | 2262·0 | 2191·0 | 2077·2 | 1860·4 | 1678·6 | 1538·0 |
| GROUP III. | |||||||
| Some constitutional diseases[18] | 6056·3 | 6311·4 | 6594·6 | 7199 | 7536·4 | 7531·2 | 7929·4 |
[17] These include small-pox, measles, scarlet fever, simple and ill defined fever, whooping cough, diphtheria, miasmatic diseases, cholera, diarrhœa, dysentery, erysipelas, puerperal fever and thrush.
[18] Diseases of the nervous, circulatory and respiratory systems, cancer, diabetes and other constitutional diseases.
This table demonstrates, therefore, in a most marked manner, the action of modern civilisation and of preventive medicine, which, by removing the microbe and diminishing the dangers of child-rearing, has diminished the rate of mortality to a very notable extent in the early years of life. The increase in the number of deaths from constitutional diseases, occurring as they do in middle or advanced age, are probably due to the survival of an increased number of individuals into the period of maturity. From this table it is difficult to say whether or no these individuals are below the mean average type. We have to die at one period of life or at another, and if men and women are preserved from the dangers of childhood and youth, there will be more to fall victims to the lung and chest complaints of more advanced life.
But it is possible by other sets of figures, obtainable from the Registrar General’s reports, to arrive at some sort of decision as to the healthiness of the middle-aged and elderly people living to-day, and to compare these results with similar ones drawn from the statistics of twenty or thirty years ago.
[Death-rate for Advanced Years on the Increase.]
In table 13 (Report of the Registrar General for 1891) the death-rates per 1,000 are given for different age periods, and these results date from 1841 to 1890, and are arranged in groups of ten years.
The table was prepared in the following way. At each period given, say from 1841–50, the number of persons living at a certain age was calculated from the census returns. The numbers dying at that age being known, these are given in the table per 1,000 persons of that age. In order to reduce the number of figures, I have shown the death-rates of two groups only, the first group of persons (males) younger, and the second group of persons older than 35 years.
| GROUP I. 0–35 years. | GROUP II. 35 and upwards. | |
|---|---|---|
| 1841–50 | 112·0 | 591·0 |
| 1851–60 | 111·2 | 581·9 |
| 1861–70 | 110·8 | 595·1 |
| 1871–80 | 101·0 | 616·7 |
| 1881–90 | 87·8 | 589·3 |
Group I. shows the very steady diminution in the death-rate of the earlier years of life, and similar results are also brought out by a corresponding table showing the death-rates among females.
Group II. showing the death-rates of individuals above 35 years of age, at first sight seems to give no very satisfactory predications of either increase or decrease of mortality, indeed the last period indicates a very decided fall in the mortality. We have, however, to remember that climatic influences are variable, and that certain groups of years are especially healthy and others inimical to well-being. That the last period is a very healthy one is indicated by the excessive fall seen in Group I., and by a corresponding fall in the number of deaths of females. These climatic variations may be assumed to influence the numbers of Group II. more than those of Group I.; indeed, on reference to the details given in the full report, I see that the fall in that period is in large measure due to the decreased mortality of those over 75, a time of life very susceptible to climatic influences.
On the whole, Group II. indicates that the death-rate above 35 is increasing, for if we add together any two consecutive periods, say 1841–50 and 1851–60, we shall find that the mortality of the last twenty years is greater than that of the first. By taking in this way longer periods of time, we can eliminate factors other than the time factor, and we can, at any rate, feel strongly suspicious that the mortality of middle and advanced life is on the increase.
The same results can, perhaps, even more conclusively be demonstrated by a study of tables showing the expectancy of life.
[Life Tables compared.]
The late Dr. Farr constructed tables showing the expectancy of life calculated upon the death-rates of the years 1838–54, and similar tables have more recently been constructed by Dr. Ogle, from the death-rates of the years 1871–80. In the case of male children newly-born, a child born in the first period could expect to live 39·91 years if he lived to an average age; a child born in the second period had a longer expectancy of life, namely, 41·35 years. While, however, the expectancy at birth during childhood and youth has been increased, the following table (extracted from their tables) will show that the expectancy during manhood has diminished; that is to say, men are either not so strong, or their surrounding conditions are less favourable than they were, and they cannot expect to live for so long a period. The details of this table are as follows:—
| Ages. | GROUP I. 1838–1854. | GROUP II. 1871–1880. |
|---|---|---|
| 0 | 39·91 | 41·35 |
| 5 | 49·71 | 50·87 |
| 10 | 47·05 | 47·60 |
| 15 | 43·18 | 43·41 |
| 20 | 39·48 | 39·40 |
| 25 | 36·12 | 35·68 |
| 30 | 32·76 | 32·10 |
| 35 | 29·40 | 28·64 |
| 40 | 26·06 | 25·30 |
| 45 | 22·76 | 22·07 |
| 50 | 19·54 | 18·93 |
| 55 | 16·45 | 15·95 |
| 60 | 13·53 | 13·14 |
| 65 | 10·82 | 10·55 |
| 70 | 8·45 | 8·27 |
| 75 | 6·49 | 6·34 |
| 80 | 4·93 | 4·79 |
| 85 | 3·73 | 3·56 |
| 90 | 2·84 | 2·06 |
| 95 | 2·17 | 2·01 |
| 100 | 1·68 | 1·61 |
[Physical Degeneration of the Race already indicated.]
It seems improbable that the short expectancy of middle age can be due to modern overstrain, for external conditions are on the whole improving, and the same fact may be observed in the expectancy of women, who certainly have not been placed under more unfavourable external conditions. Calculations from other periods of years would be here of great value, in order further to eliminate the effects of climatic changes, etc., and it must be remembered that the figures which are the basis of all statistics are only approximate to, and never exactly represent, the true condition of things. For these reasons, it seems important to pursue statistical investigations still further, and to examine the returns of other nations in order to determine whether or no their facts are similar to ours.
In the meantime, we may view, and not without inquietude, the probability that our statistics, as far as they go, indicate that racial deterioration has already begun as a sequence to that care for the individual which has characterised the efforts of modern society. The biologist, from quite another group of facts, has independently arrived at conclusions which render this view in the highest degree probable.