A CHANGE IN SEX-RATIO 
Overwhelming Preponderance of Male Births Among Certain Tribes of Costa 
Rican Indians—Females in Great Majority Among Adults—Tribes 
Rapidly Disappearing 
HENRY PITTIER 
Bureau of Plant Industry, Washington, D. C. 
Zeitschrift fir Ethnologie a short 
note on the Tirub, or on what is left 
of that once powerful tribe, dominat- 
ing the plains and mountains bordering 
on the present boundary line of Costa 
Rica and Panama. ‘The abode of these 
remnants is now restricted to the upper 
reaches of the Tararia or Changuinola 
River, included in the territory of the 
latter republic. 
In the above mentioned contribution, 
there were given some statistical data 
showing the rapid decrease of the 
Tirub and the unusual numerical dis- 
proportion of the sexes, the great 
majority of children being males. 
I visited these natives in 1898 and the 
statistical information reproduced about 
five years later from my diary was given 
as a résumé of the complete census made 
during my expedition, the originals of 
which had been mislaid. 
Not very long ago, these detailed sheets 
of my census were found. They cover 
not only the whole Tirub tribe, but also 
the larger part of the Bribri of the Costa 
Rican Talamanca. In view of the 
numerous researches and publications 
referring to sex determination and con- 
trol, these data appear so interesting 
that I now undertake to prepare them 
for publication. I do this also in 
justice to the readers of my former 
article and because such information 
may throw some light on the process of 
disintegration of a race. 
The above cited paper dealt with a 
|: 1903, I published in the Serlin 
portion only of the Tirub, and showed 
a proportion of thirty-six females to 
100 boysamong the children. It further 
stated that since the first known census, 
in 1700, when the tribe numbered about 
2,300, there has been among them a 
steady and rapid decrease in the natality 
until in 1898, there were left fifty-seven 
individuals, among whom were fourteen 
boys and five girls under marriageable 
age. The real figures at that time as 
shown below should have been given 
as eighty-nine individuals with thirty- 
one boys and eleven girls, and a slight 
predominance of the males among the 
adults. Among the children, however, 
the given sex ratio remains the same 
with the new totais. 
It was shown further that the same 
process of rapid extinction, indicated 
not only by a lesser natality but also 
by a great exaggeration of the sex 
ratio, existed in another Costa Rican 
tribe, the Guatusos, living at the head- 
waters of the Rio Frio. In 1896, 
Bishop Thiel found it to consist of 
only 203 individuals, seventy of whom 
were females, the ratio being fifty-two 
of these to each 100 males. 
In the same expedition during which 
the Tirub information was gathered, 
I made also, as stated above, an exten- 
sive survey of the inhabitants of the 
valleys and mountains of Uren in the 
Costa Rican Talamanca. These people 
belong to the Bribri tribe, another part 
of which inhabits the district of Arari, 
which I did not visit at the time. There 
1 Similar disproportionate sex-ratios are said to have been found among the Indians of Guate- 
mala and Nicaragua, and parts of South America, but in no case has the state of affairs been 
described by such an accurate census as Mr. Pittier was able to make. E. Westermarck cites 
the travelers’ accounts in his ‘‘History of Human Marriage,’ Chapter XXI. Among other 
primitive peoples, it would appear that the proportion of girls born is sometimes equally excessive. 
In civilized countries there appears an extraordinarily steady ratio of something like 105 boys to 
100 girls born.—The Editor. 
406 
