A TOOTHLESS TYPE OF MAN" 



The "Bhudas" of India — A Case of Sex-linked Inheritance 



K. I. Thadani, B. Ag. 



Agricultural Department, Bombay, India 

 (Graduate Student in the A. 6° M. College of Texas, College Station, Texas) 



THERE occurs in the Hindu Amil 

 community of Hyderabad Sind, a 

 town in India, a type of men who 

 have no teeth. These men are further 

 characterized by a bald head and an 

 extreme sensitiveness to heat. They 

 are known as "Bhudas," which Hteraliy 

 means "toothless." The following 

 facts are known about them : 



(1) When such a man (a Bhuda) 

 marries a normal girl having both 

 parents free from these defects, all the 

 children, both males and females, are 

 apparently normal — that is to say, 

 apparently free from the defect. 



(2) When the Fi males marry normal 

 females having both parents normal, 

 their children, both males and females, 

 are apparently normal. 



(3) When the Fi females marry 

 normal males, their female children are 

 apparently normal, while the male 

 children are "Bhudas." 



(4) No case is known in which a 

 toothless man has married the daughter 

 of a "Bhuda." 



(5) No females have been found 

 showing the anodont condition. 



BIOLOGICAL EXPLANATION OF THE 

 PHENOMENON 



This is, apparently, a case of sex- 

 linked inheritance in man. The in- 

 heritance of this toothless condition, as 

 well as the associated defects of 

 sensitivity and hairlessness, is a case in 

 point, and the causative character 

 seems to be carried by the sex chromo- 

 somes. The factors involved are: 

 B for the normal condition, and its 

 recessive allelomorph "b" for the tooth- 

 less condition. 



(a) When a female of the genetic 

 constitution (BX) (BX) is mated to 

 a male (bX) Y, we get: 



Genotypes Phenotypes 



Fi (BX) (bX) Normal females. 



(BX) Y Normal males. 



That is to say all the children are nor- 

 mal in appearance. This explains fact 

 No. 1, stated above. 



(b) Fact No. 2 is self-explanatory 

 when we consider the genetic constitu- 

 tion of the Fi male. 



(c) Fact No. 3 carries us to the F2 

 generation. When an Fi female (BX) 

 (bX) marries a normal male (BX) Y, 

 who has the same genetic constitution 

 as her Fi brother, then we shall get: 



Genotypes Phenotypes 



F2 (BX) (BX) Normal female. 



(BX) (bX) Normal female. 



(BX) Y Normal male. 



(bX) Y Toothless male. 



The following points are worth noting: 



(1) We expect all females to appear 

 normal; this is what acutally happens 

 in practice. So the theoretical expecta- 

 tions coincide with the practical results. 



(2) Of the males we expect some 

 toothless, some normal, strictly speak- 

 ing one to one. Now let us see what 

 actually occurs in practice. The gen- 

 eral belief is that all males are tooth- 

 less, but this is a matter for further 

 investigation. At the same time, the 

 absence of normal males in the F2 gen- 

 eration in actual practice can be 

 explained by taking into consideration 

 the fact that only one individual is 

 produced at a time, therefore the 

 chances of one of the phenotypes not 

 appearing at all, or another appearing 

 repeatedly, are as great as the chances 

 of all the phenotypes (comprising 4 

 genotypes in the present case) being 

 represented in a single generation. In 

 order that all of the phenotypes may 

 appear, we must have a sufficient 

 number of individuals under observa- 



' A preliminary report. 



87 



