Pittier: A Change in Sex-Ratio 
rule, the wives were taken from inside 
the tribe, according to a system which 
we might call semi-exogamic. The 
whole tribe was divided from the oldest 
times into two clans, each one of which 
was considered by the other as its 
conptiaty. «lune: men of, one. clan. 
could marry only in the opposite clan, 
to which the children would also be- 
long, the head of the family being not 
the husband, but the eldest brother of 
the mother. This custom was still 
rigidly enforced at the time of my 
exploration of Talamanca (1891-1898), 
when I succeeded in obtaining the 
complete list of the families forming each 
clan of the Bribri. 
Owing to this arrangement, the inner 
life of the tribe was not perhaps so 
deeply disturbed by the advent of 
Spaniards as was the case among the 
Tirub, and this is one of the explana- 
tions of the reason why the decadence 
of the Bribri has proceeded more 
slowly, as shown by the above tables. 
One of the first facts which draws the 
attention when studying these is the 
reversal of the ratio of sexes when we 
pass from the adult to the child genera- 
tion. Among the former the number of 
females is far above the normal in all 
cases, while among the children the 
male element is overwhelmingly pre- 
ponderant. It would seem, therefore, 
that the change has been a very sudden 
one, and this puts more difficulties in 
the way of a satisfactory explanation. 
That the adverse circumstances under 
which these natives live have been 
rapidly on the increase during the last 
years is an evident fact. The question 
is whether it would be sufficient argu-- 
ment to explain both the decrease in 
411 
natality and the great disturbance of 
the sex ratio. 
It has been suggested that certain 
native tribes limit the number of females 
by killing part of the baby girls at their 
birth. This, however, would not explain 
the present case and furthermore it 
certainly does not apply with regard to 
the Bribri Indians, among whom I 
lived for nearly three years and into 
whose more intimate life I pried almost 
at will. Not being an admissible ex- 
planation for the Bribri, this. could not 
be used as to the Tirub, whose case is 
more or less identical. 
On the other hand it is generally 
admitted that there is an automatic 
correlation between the birth rate and 
sex ratio on one side and the general 
vital conditions of the race on the other. 
The only apparent exception to that 
law is the presence of artificial condi- 
tions as produced by abuse of wealth 
and excessive physical refinement, as 
are known to exist in great cities and 
which lead so surely to race suicide. 
Under normal conditions, a_ strong, 
healthy stock tends to increase and with 
a higher rate of birth there is also a 
surplus in the number of females. 
Under adverse conditions, the facts 
become reversed. For instance, in a 
nation depleted of men and resources by 
war, natality is less and the proportion 
of males considerably larger. While 
statistical proof of these facts is in- 
adequate, there is some evidence to 
support them, and they formed the 
base of the explanation given in my 
former paper. 
Whatever this explanation, it is evi- 
dent that factors have been in operation 
among these Indians that have resulted 
in a definite and pronounced alteration 
of the sex ratio. 
Research Work at Sing Sing 
At the annual meeting of the National 
Committee on Prisons it was announced 
that a fund of $20,000 a year for five 
years has been guaranteed to provide 
medical and scientific treatment for 
the prisoners at Sing Sing. The Com- 
mittee on Eugenics has begun opera- 
tions in cooperation with the Police 
Department of New York City to 
arrive at the constitutional or hereditary 
factors in anti-social behavior with the 
aid of carefully compiled family his- 
tories.—Eugenical News (Cold Spring 
Harbor, Long Island, July, 1916.) 
