Harvard and Yale Birth Rates 
interval in years and fractions of years 
between graduation and marriage. This 
is strictly a true figure, but it is only of 
relative interest. If we do not know 
the age at graduation, we do not know 
the age at marriage, and this is of par- 
ticular interest in determining whether 
marriage has been postponed, and if 
so, how much. ‘To answer this I have 
computed age at graduation at Har- 
vard for two five-year periods, 1861-65 
and 1886-90. For the first period the 
age is 21.8 years and for the last 22.8 
years, a difference of one year. Wecan 
say then, since the interval between 
graduation and marriage has been a 
nearly constant one for 40 years, that 
the graduates married only one year 
later during the latter part of the 
period than during the earlier part. 
Strictly speaking, the age has increased 
from a little over 30 years to just about 
31 years. This was arather unexpected 
result, for it is commonly supposed that 
the age of marriage of professional men 
has advanced very much. Hankins, 
however, showed? that our native popu- 
lation from native parents marry earlier 
now than they used to. The uncharted 
period since the Class of 1890 may show 
a slightly greater age at marriage, but 
it is unlikely that there will be a 
marked change. 
“The ‘Average Number of Children 
Born per Capita per Married Gradu- 
ate’ is the next column, and this is very 
close to a perfect figure, because it is 
based only on those individuals who 
had a clear record, and there were not 
enough names discarded to vitiate the 
result. 
“The ‘Average Number of Children 
per Capita per Graduate’ is a true 
index, except that it is slightly under 
the real figure. It is obtained by 
dividing the total number of children 
born by the total number of graduates 
for each class and decade. 
SURVIVING CHILDREN 
“The next three columns have to do 
with surviving children. They repre- 
sent the children who grew up to at 
least several years of age, and in most 
567 
cases escaped infant mortality. These 
figures are based on the children sur- 
viving at the last report for the class in 
question. The twenty-fifth report is in 
all cases the earliest report consulted. 
For the four decades at Harvard we 
have latest reports averaging as follows: 
First decade, 48 years; second decade, 
43.7 years; third decade, 32 years; 
fourth decade, 26 years. 
“The question arose at this point: 
How old were the children of graduates 
at the time of the twenty-fifth year 
class report? To answer this only one 
period, 1886-90 for Harvard, was com- 
puted. The average was found to be 
13.1 years, showing that most of the 
children were past the dangers of the 
first five years of infancy at the time of 
the twenty-fifth year class report, and 
liable only to the much lower death-rate 
of advanced childhood. Also it may 
be noted that the twenty-fifth year 
report includes very nearly all the 
children born to the class. I wrote, 
however, to several class secretaries 
and it appears from these letters that 
only thirty-five children have been 
born to the classes 1881, 1882, 1889 and 
1890 since their twenty-fifth year re- 
ports. This is only about 2% of the 
total born to these classes before the 
twenty-fifth year report, so that we can 
safely accept all twenty-fifth year 
reports, where this is necessary. 
“The last two columns show the 
average number of childless marriages 
in each class, for each decade, and also 
the per cent of childless marriages in 
each decade. The figures will be found 
inaccurate for the first decade of 
Harvard graduates. All the others are 
reliable. 
“The mass of data from which this 
report is drawn would make a large 
book. In working it up, 5,618 names 
were considered for Harvard and 4,522 
for Yale. I have, therefore, thought it 
best to give only two final tables repre- 
senting all the figures just considered, 
but showing only grand averages for 
the four decades between the classes of 
1850 and 1890 for each college. There 
does not appear to be anything in the 
2 JOURNAL OF HEREDITY (1914), Vol. v, pp. 361-7. 
