II. CAUSES OF DEAFNESS IN OHIO SCHOOL FROM 1829 TO 1872 AND FROM 1904 TO 1911.
PERIOD TOTAL NUMBER CONGENITAL SCARLET FEVER MENINGITIS TYPHOID FEVER MEASLES WHOOPING COUGH GENERAL FEVERS BRAIN FEVER PNEUMONIA DIPHTHERIA CATARRH UNKNOWN AND MIS.
---------+----+----+----+-----+---+---+---+---+---+---+---+---+-------- 1829-1872 1252 33.8 10.3 3.0 1.8 3.2 1.7 4.6 5.7 -- 0.3 -- 35.6 1904-1911 -- 38.9 5.0 9.2 1.4 2.8 1.7 1.1 5.3 0.5 0.5 3.5 30.1
III. CAUSES OF DEAFNESS IN IOWA SCHOOL FROM 1855 TO 1870 AND FROM 1855 TO 1912.
PERIOD TOTAL NUMBER CONGENITAL SCARLET FEVER MENINGITIS TYPHOID FEVER MEASLES WHOOPING COUGH GENERAL FEVERS BRAIN FEVER PNEUMONIA DIPHTHERIA CATARRH UNKNOWN AND MIS.
---------+----+----+----+-----+---+---+---+---+---+---+---+---+-------- 1855-1870 245 87.2 13.4 3.3 1.6 2.0 1.3 6.1 1.3 -- -- -- 33.8 1855-1912 1672 26.9 10.3 14.9 1.7 2.2 1.7 0.1 7.0 0.3 0.8 1.7 32.4
IV. CAUSES OF DEAFNESS IN NEW YORK INSTITUTION FROM 1818 TO 1853 AND FROM 1899 TO 1912.
PERIOD TOTAL NUMBER CONGENITAL SCARLET FEVER MENINGITIS TYPHOID FEVER MEASLES WHOOPING COUGH GENERAL FEVERS BRAIN FEVER PNEUMONIA DIPHTHERIA CATARRH UNKNOWN AND MIS.
---------+----+----+----+------+---+---+---+---+---+---+---+---+-------- 1818-1853 1148 42.9 7.2 --[39] -- 1.9 0.7 1.6 -- -- -- -- 45.7 1899-1912 -- 38.0 6.8 13.1 1.3 3.4 0.8 1.3 8.1 0.9 0.9 1.7 23.7
Taking these tables also collectively, we find in respect to scarlet fever a decline in all the schools, this being especially pronounced in the case of the Ohio. In meningitis, however, there is an increase so heavy as to call in question the accuracy of the earlier records; and it is possible that it failed to be entirely recognized then. In most of the other diseases, as in the previous case, no very great change is perceptible. In general fevers a decline is apparent in all, in most being considerable; and probably several diseases were formerly included which are now listed separately. In measles rather a decline is found in the American and Ohio schools, but a slight increase in the Iowa, and a somewhat larger one in the New York Institution. In typhoid fever there is a slight increase also in the Iowa School, but a decrease in the Ohio. In brain fever a considerable increase is observed in the Iowa School, but a slight decrease likewise in the Ohio. In whooping cough there is an increase in the New York Institution and the Iowa School, but a decrease in the American. Such diseases as pneumonia, diphtheria and catarrh seem not usually to have been separately classified in the past, though in the Ohio School we find diphtheria noted, and with somewhat smaller proportions than in later years; while in several of the schools we find "colds" given in former times, which may have been in part really catarrh.
Combining now the results of our two groups of tables, we may be able to reach some conclusions with respect to the increase or decrease of deafness from certain diseases, though on the whole far less definite than we could wish. In the first place, it seems safe to affirm that deafness from scarlet fever is becoming relatively less with the years; and it is possible that if it continues its present rate of decline, it will in time cease to be one of the main causes of deafness. On the other hand, meningitis, its great companion in evil, shows a striking increase in comparison with past years, as a cause of adventitious deafness; while its accretion may be traced as well in a series of recent years in certain schools, though not in others. But how far there is an absolute increase in meningitis over the past, and whether it is tending at present actually to increase, may be a matter for question.
In view of the possibility that the disease was not sufficiently accounted for in the past, and in the absence of any knowledge to indicate a reason for its less prevalence in earlier years, at least not to the extent indicated by the statistics, it may be that its increase is, after all, more apparent than real. The fact, moreover, that in the series of recent years a marked increase is found in some schools, but a marked decline in others, may perhaps be taken to mean that at present meningitis may be on the increase only in certain sections, depending possibly on local conditions. With the greater medical skill of to-day, and with a larger proportion of children in the schools, it may be open to considerable doubt if the movement of this disease is really one of increase, though it seems that we are on the whole making no great headway against it.
As to the minor diseases causing deafness, our statistics do not indicate just to what extent and in what direction deafness from them is being affected, and no precise conclusions can at present be set down.
It is probable, however, that with the increased attention to children's diseases, as we have noted, there is really less deafness from most of them than formerly.[40]
THE CONGENITALLY DEAF
When we come to consider the question of congenital deafness, which comprises a little over a third of the total amount of deafness, we have an even more difficult problem on our hands, for here we are to deal with some of the great questions of heredity--though hereditary deafness and congenital deafness are not altogether one and the same thing.[41]
For the purposes of our inquiry, let us think of the congenitally deaf as divided into three great classes in respect to their family relations: 1. the offspring of parents who were cousins; 2. the offspring of parents who were themselves deaf or members of families in which there are other deaf relatives; and 3. the product of families without either consanguinity or antecedent deafness. Of these three classes the first two only will engage our attention. Of the last, comprising, according to the census, nine-twentieths, or 44.4 per cent, of the congenitally deaf, there is not much that we can say. For a great part of it there no doubt exists in the parent, or perhaps in a more remote ancestor, some abnormal strain, physical or mental, in the nature of disease or other defect. But in respect to such deafness we have too little in the way of statistical data to help us arrive at any real determination; and for it as a whole we shall have to wait till we have greater knowledge of eugenics and the laws of heredity.[42]
THE OFFSPRING OF CONSANGUINEOUS MARRIAGES
Not all the deaf born of consanguineous marriages are congenitally deaf, but as the majority are so, and as the fact of the parents being blood relatives is assumed to have at least a contributing influence in the result, we may consider the matter in this place. It is in fact closely connected with the question of deaf relatives in general.
In the census investigations,[43] of the number who answered on this point, 2,525, or 7.4 per cent, have parents who were cousins. Of these cases, deafness occurred in 87 per cent before the fifth year of age, and in 60 per cent at birth. Of all the deaf born without hearing, 13.5 per cent are the offspring of consanguineous marriages. The proportion of those born deaf is thus nearly twice as great when the parents are cousins as it is among the whole class of the congenitally deaf; and the proportion is also nearly twice as great of the offspring of consanguineous marriages among the congenitally deaf as the proportion of the deaf from such marriages among the total number of the deaf.
Moreover, 55.0 per cent of the offspring of cousin-marriages have deaf relatives of some kind, and of the congenitally deaf from cousin-marriages, 65.6 per cent have deaf relatives; while the respective proportions when the parents are not cousins are 25.5 per cent and 40.7 per cent--in the one case less than half, and in the other two-thirds, as great.
Further statistics bear out the findings of the census. Dr. E. A. Fay in his "Marriages of the Deaf"[44]--a work we are soon to notice--finds that, though consanguineous marriages form only about one per cent of the total number considered, 30.0 per cent of the children of deaf parents who are cousins are deaf, and that 45.1 per cent of such marriages result in deaf offspring; but that when the parents are not cousins, the respective proportions are 8.3 per cent and 9.3 per cent--only about a fourth and a fifth as great. In the Colorado School, out of 567 pupils in attendance from the beginning to 1912, in 17, or 3 per cent, the parents were related before marriage. In the Kentucky School, out of 83 pupils admitted in 1910 and 1911, 18, or 19.3 per cent, and out of 42 admitted in 1912 and 1913, 8, or 19 per cent, were the offspring of parents who were cousins. In the Iowa School, out of 62 admissions in 1911 and 1912, 4, or 6.5 per cent, and in the Maryland School, out of a total attendance in 1911 of 135, 13, or 9.2 per cent, had parents who were cousins.[45]
Consanguineous marriages, so far as the effect on deafness is concerned, are not of relatively frequent occurrence. But where they do take place, there is found a decided connection between them and deafness, the increased tendency thus to transmit a physical abnormality being plain.
How far, however, if at all, such deafness is to be directly ascribed to consanguineous marriages, is a matter for question. The main consideration seems to be that in such marriages the chances are at least doubled of the offspring acquiring the characteristics of the parents; and that in them the liability is thus proportionately enhanced of transmitting deafness.[46]
THE DEAF HAVING DEAF RELATIVES
We are now to examine what traces there may be of deafness in a family by noting what proportion of the deaf have deaf relatives, and are to attempt to see what may be its bearings upon the question of heredity.
In the census investigations,[47] we find that out of 34,780 deaf persons who answered, there are 10,033, or 28.8 per cent, who have deaf relatives of some kind, direct or collateral, 8,170, or 23.5 per cent, having deaf brothers, sisters or ancestors. In all of these we can without difficulty discover the influence of heredity. In the congenitally deaf the trace of a physical defect is even more clearly indicated. Of these 40.1 per cent have deaf brothers, sisters or ancestors, and 46.2 per cent have also deaf uncles, cousins, etc.[48]
It is thus evident that there are certain families in society deeply tinged with deafness, that it sometimes passes from parent to child, from generation to generation, and that like a cloud it hangs over a section of the race.
THE OFFSPRING OF DEAF PARENTS
All this argument leads up to one most pertinent question: Are the statistics which we have indicative that this deafness which passes so remorselessly in certain families will be found all the stronger in the children of deaf parents? Have we ground to believe or fear that this deafness will crop out far more surely than in the children of parents not deaf? And can we determine to what extent possibilities are increased of the offspring of deaf parents being likewise deaf?
Let us now consider the statistics which we have in this matter, first examining the results of the census investigation.[49] Of the 8,022 married deaf persons for whom statements are made, we find that there are 190 who have deaf offspring, or 2.4 per cent. Of the 4,116 deaf persons who are married to deaf persons, 137 have deaf children, or 3.3 per cent; and of the 3,906 deaf persons married to hearing persons, 53 have deaf children, or 1.4 per cent. Of the married deaf having deaf children, 52.5 per cent have deaf relatives of some kind, and 54.7 per cent are congenitally deaf, the proportion of those having deaf relatives who are also congenitally deaf being 66.7 per cent. Of the deaf married to hearing partners, who have deaf children, 26.4 per cent are congenitally deaf, while 50.9 per cent of the partners in such marriages have deaf relatives of some kind.
From the census statistics, then, it appears that the married deaf as a class do not have a large proportion of deaf children, and that this proportion is only a little more than twice as great when the deaf are married to the deaf as when they are married to the hearing. It appears also, however, that when there are deaf relatives involved in either kind of marriages, or when there is congenital deafness in the deaf parent, the effect is quite marked in the offspring.
Besides the census returns, we have the statistics presented in the reports of certain schools, which are found to point, as far as they go, to the same conclusions. In the Kentucky School, out of 83 pupils admitted in 1910 and 1911, there were none the children of deaf parents, though 35, or 30.1 per cent, had deaf relatives; and out of 42 admitted in 1912 and 1913, there were 2, or 4.8 per cent, the children of deaf parents, and 12, or 28.8 per cent, with deaf relatives. In the Iowa School, out of 62 admissions in 1911 and 1912, 4, or 6.5 per cent, had deaf parents, and 21, or 33.9 per cent, "defective" relatives. In the Michigan School, with an annual enrollment of some three hundred, there were from 1903 to 1908 but three children of deaf parents.[50] In the Colorado School, out of a total attendance since its founding to 1912 of 567, 3, or 0.57 per cent, were the children of deaf parents, though 83, or 14.6 per cent, had deaf relatives. In the Missouri School, out of a similar attendance to 1912 of 2,174 there were 52, or 2.4 per cent, with deaf parents, though there were 235, or 10.8 per cent, with deaf relatives.[51]
The most exhaustive study of the question of the liability of the deaf to deaf offspring is that of Dr. E. A. Fay in his "Marriages of the Deaf"--covering the majority of the marriages of the deaf in America at the time it was made (1898).[52] Statistical information is presented for 7,227 deaf persons and for 3,078 marriages with either deaf or hearing partners.[53] In the following table are summarized the results of this investigation.[54]
MARRIAGES OF DEAF PERSONS
NUMBER OF NUMBER OF MARRIAGES CHILDREN ---------------------------------+------+---------+-----+------+----+----- Partners in Marriage Total Resulting Per Total Deaf Per in deaf cent cent children ---------------------------------+------+---------+-----+------+----+----- One or both deaf 3,078 300 9.7 6,782 588 8.6 Both deaf 2,377 220 9.2 5,072 429 8.4 One deaf, other hearing 599 75 12.5 1,532 151 9.8 One or both congenitally deaf 1,477 194 13.1 3,401 413 12.1 One or both adventitiously deaf 2,212 124 5.6 4,701 199 4.2 Both congenitally deaf 335 83 24.7 779 202 25.9 One congenitally, other adventitiously deaf 814 66 8.1 1,820 119 6.5 Both adventitiously deaf 845 30 3.5 1,720 40 2.3 One congenitally deaf, other hearing 191 28 14.6 528 63 11.9 One adventitiously deaf, other hearing 310 10 3.2 713 16 2.2 Both had deaf relatives 437 103 23.5 1,060 222 20.9 One had deaf relatives, other not 541 36 6.6 1,210 78 6.4 Neither had deaf relatives 471 11 2.3 1,044 13 1.2 _Both congenitally deaf_ Both had deaf relatives 172 49 28.4 429 130 30.3 One had deaf relatives, other not 49 8 16.3 105 21 20.0 Neither had deaf relatives 14 1 7.1 24 1 4.1 _Both adventitiously deaf_ Both had deaf relatives 57 10 17.5 114 11 9.6 One had deaf relatives, other not 167 7 4.1 357 10 2.8 Neither had deaf relatives 284 2 0.7 550 2 0.3 Partners consanguineous 31 14 45.1 100 30 30.0
It is thus seen that 9.7 per cent of the marriages of the deaf result in deaf offspring, and that 8.6 per cent of the children born of them are deaf--proportions far greater than for the the population generally.[55]
A striking fact to be noted, however, is that these proportions are greater when one parent is deaf and the other hearing than when both are deaf. The percentage of marriages resulting in deaf offspring when only one parent is deaf is 12.5, and when both are deaf, 9.2; while the percentage of deaf children born of them when only one parent is deaf is 9.8, and when both are deaf, 8.4. This is apparently a very strange result, though it probably may be accounted for in some part on the theory that it is not so much deafness itself that is inherited, but rather an abnormality of the auditory organs, or a tendency to disease, of which deafness is a result or symptom, and that with different pathological conditions in the parent there is less likelihood of deafness resulting.
The most significant part of the results seems to be found, as before, in respect to whether or not deaf parents are themselves congenitally deaf or have deaf relatives. On the one hand, when one or both of the parents are adventitiously deaf, the percentage of marriages resulting in deaf children is 5.6, and the percentage of deaf children is 4.2; when both parents are so, the percentages are lower: 3.5 and 2.3. The percentages rise when one parent is adventitiously deaf, and the other congenitally: 8.1 and 6.5. In respect to deaf relatives of parents, the percentages are very low when neither has such relatives: 2.3 and 1.2.
The lowest percentages of all are in the case where both parents are adventitiously deaf and neither has deaf relatives: 0.7 and 0.3.
On the other hand, we find the proportion of marriages resulting in deaf offspring and the proportion of deaf children much greater when there is congenital deafness in one or both parents, when one or both have deaf relatives, and greatest of all when these influences are combined. When one or both parents are congenitally deaf, the percentage of marriages resulting in deaf offspring is 13.1, and the percentage of deaf children is 12.1; when both parents are so, the percentages are doubled: 24.7 and 25.9. When one parent has deaf relatives and the other has not, the percentages are 6.6 and 6.4; when both have, the percentages are nearly four times as great: 23.5 and 20.9. When both parents are congenitally deaf but neither has deaf relatives, the percentages are 7.1 and 4.1.
When both are adventitiously deaf and both have deaf relatives, the percentages are 17.5 and 9.6. When both are congenitally deaf and one has deaf relatives, the percentages are 16.3 and 20.0; and when both have deaf relatives, the percentages are 28.4 and 30.3.
The evidence is very strong, then, with regard to the form of deafness and the presence or absence of deaf relatives. In cases where the parents are not congenitally deaf and have no deaf relatives, the proportion of deaf children is very low. When one or both parents are congenitally deaf or have deaf relatives--when the deafness is inherited or in the family--the likelihood becomes far greater, and greater still when the two influences are in conjunction. In general, in respect to the influences of heredity upon deafness, the main determinants seem to be found in the existence in the parties, whether hearing or deaf, of deaf relatives, and, to a less extent, in the existence in parties who are deaf of congenital deafness.
POSSIBLE ACTION FOR THE PREVENTION OF CONGENITAL DEAFNESS
We come now to the consideration of the question of possible action for the prevention of congenital deafness. This examination naturally centers about the matter of the regulation of marriage, with due attention to the extent that action on the part of the state is to be regarded as desirable or feasible.
We have seen that congenital deafness may, hypothetically, be divided into three distinguishable classes: that in which consanguineous marriages are concerned, that in which there is antecedent deafness in the family, and that in which neither of these conditions occurs; and in our inquiry it has seemed best to take up each of these separately.
It may be, however, that there is in fact no very radical difference between these several forms, and that with increased knowledge on the subject a more or less intimate relation will be found to exist.
Of that form of deafness in which neither consanguineous marriages nor antecedent deafness is involved, we are at present, as we have noted, able to say little definitely. In most cases we may be convinced that there exists in the parent some peculiar state of morbidity or other affection, latent or manifest, perhaps to some extent of hereditary influence, which has an effect on the organs of hearing of the offspring. A certain proportion is quite possibly due to recognizable defects both of physical and mental character. Our statistical evidence, however, in respect to this form of congenital deafness is too slight to warrant any positive deductions; and we will have to wait for further investigation to determine its nature fully. None the less, marriage of persons known to be liable to have ill effect on possible offspring is objectionable for not a few reasons, from the standpoint of the interests of society; and in their reduction there will probably be a greater or less diminution of congenital deafness.
With regard to consanguineous marriages and their effect on deafness we are on surer ground, so far as may be indicated by statistical data.
This question is found in very great measure to be connected with that of deaf relatives in general. The matter appears to be largely a part of a law of wide application, namely, that in the blood relationship of parents the possibilities are intensified of the perpetuation of a certain strain, which holds true no less with the transmission of deafness. Consanguineous marriages are perhaps not of sufficiently frequent occurrence, so far as concerns the effect on deafness, to require special action; but in the consideration of such marriages in general, their part in the causation of deafness should have due weight; and whatever may be said regarding them in other relations, they are to be avoided if we wish to remove all chances of this kind of deafness resulting.
The problem of deaf relatives and their connection with congenital deafness is a very large one. Attention however, has mostly been focused upon it in relation to the intermarriage of the deaf and its effect upon their offspring. Indeed, in such unions there has already been more or less concern, and there has even been question whether it is a wise or unwise policy to allow the deaf to marry other deaf persons. The deaf, as we shall discover, not only find their companions for social intercourse among similar deaf persons, but _a fortiori_ very often seek such persons for their partners in marriage--in fact, more often than they do hearing partners, nearly three-fourths of the married deaf being married to deaf partners.[56] Not only has it been feared that the offspring of such marriages might likewise be deaf, but there has also been apprehension lest in their encouragement there might result a deaf species of the race.[57]
From our discussion, however, we have found that in most of the marriages of the deaf we have but small reason for disquiet. If deafness in the parent is really adventitious, there is little possibility of its passing on to the offspring. When the deafness in the parent is itself congenital, the situation becomes more serious. If in such case there is no added risk from the existence of deaf relatives, the likelihood of transmitting deafness need not always be a matter of deep concern, though the hazard is materially larger than for adventitious deafness.
When there are deaf relatives involved, the peril, made stronger if coupled with congenital deafness, is most pronounced; and, indeed, the existence of collateral deafness seems a more certain sign of warning than direct heredity itself. Finally, even in the marriage of the deaf with the hearing, the dangers are not in fact lessened if conditions otherwise unchanged are attendant.
What action should be taken in respect to that part of the deaf who may marry under conditions favorable to the production of deaf offspring is not at present clear. Legislation would not appear on the whole to be advisable;[58] and the exertion of moral suasion, so far as possible, in the individual cases concerned would seem a more acceptable course. The matter, however, really belongs in the province of eugenics, and we will probably do best to await the authoritative pronouncement of its decrees before full procedure is resolved upon.