Biology Reference
In-Depth Information
aristocracy to read and even speak, he clearly demonstrated the fallacy of
the Aristotelian concept that the mutism that typically accompanied deaf-
ness was the result of a primary defect of the tongue.
2.1 Pre-Mendelian Era
Interest in the epidemiology of deafness began in the 19
th
century with
formal censuses of the deaf being conducted in many European centuries,
as well as in the United States. Although Mendel's seminal work on gen-
etics was not yet known by the scientific community, the familial aggrega-
tion of deafness was clearly recognized, and there was considerable
speculation about the significance of consanguinity as a cause of congeni-
tal abnormalities including deafness. For example, Mygind (1894) surveyed
the deaf in Denmark and reported the reduced reproductive fitness of the
deaf, as measured by the relative frequency of marriage in deaf males (41%)
and females (24%) compared with the hearing population. He also docu-
mented the high frequency of assortative mating (29%) among the deaf.
Towards the end of the century, as more schools for the deaf were
established and the social and economic prospects of the deaf improved,
the proportion of the deaf population who married and reproduced began
to increase. These trends prompted debate about the potential effects of
marriages among the deaf on the incidence of deafness in future genera-
tions. Thus, Mygind (1894) reported no cases of deaf-mutism among 183
children of marriages in which one or both parents were deaf. Similarly, in
1881 the commissioners of the Irish census reported that “it appears evident
that the question of deafness and dumbness in the parents has no influence
on the propagation of the defect” (Fay 1898).
In this country, however, Alexander Graham Bell expressed concern that
“if the laws of heredity that are known to hold in the case of animals also
apply to man, the intermarriage of congenital deaf mutes through a number
of successive generations should result in the formation of a deaf variety of
the human race” (Bell 1883). Bell collected data on more than 5,000 deaf
alumni of six schools for the deaf in the United States and showed that 29%
had deaf-mute relatives. Commenting on the data he collected in an article
in the
Memoirs of the National Academy of Science
(1883), Bell wrote:
“. . . but can it be accidental that there should have been admitted into one institu-
tion eleven deaf-mutes of the name 'Lovejoy' seven of the name 'Derby' and six of
the name 'Mayhew'. What interpretation shall we place upon the fact that groups
of deaf mutes are to be found having such names as 'Blizzard', 'Fahy', 'Hulett',
'Closson', 'Brasher', 'Coper', 'Gortschlag', etc.? Such names are by no means
common in the community at large, and the influence is irresistible that in many
cases the recurrences indicate blood relationships among the pupils.”
Prompted by Bell's concerns, E.A. Fay, a professor at Gallaudet College,
initiated the systematic collection of pedigree data on the occurrence of
