Catalogue of the exhibition, July 24th to July 30th, 1912 / First International Eugenics Congress, London, University of London, South Kensington.

  • International Eugenics Congress 1912 : London, England)
Date:
[1912]
Catalogue details

Licence: Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0)

Credit: Catalogue of the exhibition, July 24th to July 30th, 1912 / First International Eugenics Congress, London, University of London, South Kensington. Source: Wellcome Collection.

    27/92 (page 15)
    Exhibit С 39—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. С 39 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 33J years, his first born grandchild 6з§ 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 С 40 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 С 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 С 38-43 give what is biologically of greatest С 38-43 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).