Full text: papers communicated to the first International Eugenics Congress held at the University of London, July 24th to 30th, 1912

Exhibit C 30—43.15 
In the generations' up to the third inclusive, reproduction may 
be considered as terminated, but in the fourth, and especially the 
fifth and sixth, it still is in progress. 
Age intervals separating the various generations. 
Taking into account all the families investigated, the average 
length of time between the birth of the originator of the family and 
his first born son was 33^ years, his first born grandchild 63^ years, 
and his first born great grandchild 95^ years. The curves become 
gradually flatter, because the possible difference between minimum 
and maximum age distance from one generation to another increases 
in arithmetical progression. 
Prolificness of first marriages in the 19th century. Taking the 
entire period from 1811 to 1890 together the percentage of large 
families (six children or more) and of small families (one-two 
children) produced by all first marriages, excluding childless 
ones, is indicated by the horizontal centreline. The positive or 
negative deviations from the average during each decade are 
entered respectively above and below this line. The note in Figure 
C 38 referring to the families which may have emigrated while still 
productive applies here also. The temporary increase in prolific 
marriages after 1870 may be in connection with the material decrease 
in the age of those contracting marriage for the first time, as com­ 
pared with the preceding decade. (Men 28.65 in the earlier period 
as against 27.41 in the later, and women 25.92 against 24.68 years.) 
The extinction of the families is undoubtedly due partly to other 
causes than the voluntary limitation of families—to a process 
of degeneration. A very remarkable proof of the degenerative 
character of the dying out of families is given by Pontus Fahlbeck in 
his book, “ The Aristocracy of Sweden ” (Fischer, Jena, 1903). 
The six Figures C 38-43 give what is biologically of greatest 
interest in it. Note how the terribly quick extinction of the families 
of the nobility is inaugurated by catastrophic changes : rapid fall in 
the frequency of marriages, in the number of fertile marriages, and 
in the number of their progeny. The curves of the surviving fami­ 
lies (red in the original tables) are for comparison. That 
we have to deal here with a natural and not a voluntary process is 
shown by the rapid increase in the mortality of male youth- in the 
last generations; also by the extraordinary change in the proportion 
of the sexes of the children—which, of course, is beyond any con­ 
trol , marked preponderance of girls amongst the survivors (pos­ 
sibly also by the frequency of stillborn male children).C 39 
C 40 
C 38-43
        

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