Abstract
AT the February meeting of the Swedish Anthropological Society Prof. Wittrock read a paper on the hereditability of colour of the eyes. The speaker had been requested by Prof. Alphonse De Candolle, of Geneva, to make observations on this point, which, together with those made in Switzerland, North Germany, and Belgium, had formed the material for M. De Candolle's paper, “Hérédilé de la couleur desyeux dans l'espèce humaine” (Archives des Sciences Physiques et Naturelles, 3e période, t. xii., Genève, 1884). From the same the remarkable fact was derived that brown eyes were more common in men than women; of the individuals examined 41.6 per cent, of men and 44.2 percent, of women had brown eyes. Further, in families where the parents had the same colour of eyes 80 per cent, of the children of parents with brown eyes had brown eyes, whilst of children of parents with blue eyes 93.6 per cent, of them had eyes of that colour. The unconformity was no doubt due to atavisme or the hereditary influence of ancestors. Of the children of parents of whom the father had brown and the mother blue eyes 53.3 per cent, had brown, whilst where the reverse was the case 55.9 per cent, had blue eyes. As the percentage of brown-eyed children of parents with bi-coloured eyes was highest, it seemed as if brown eyes were always on the increase to the detriment of blue ones. It appeared also from these researches that women with brown eyes have better prospects of marrying than those with blue. 52 per cent, of the married women had brown eyes, and only 48 per cent, of them blue—a circumstance which is the more remarkable as the number of women with brown eyes in Italian Switzerland is only 44 per cent. Another remarkable discovery was that the average number of children of parents with eyes similar in colour was 2.7, whilst that of those with different colour was 3.18, which was an additional proof of the fact that children of parents with similar organisation were as a rule of weak constitution. Comparing the colour of the eyes of the children where the parents were bi-coloured, with those of each of the latter, it was discovered that the eyes of the father were inherited by 48.8 per cent, of the children, and those of the mother by 51.2 per cent., which, divided between sons and daughters, showed that 47 per cent, of the former and 49.5 per cent, of the latter inherited the eyes of the father, whereas 53 per cent, of the sons and 50.5 per cent. of the daughters inherited those of the mother. Since Prof. Candolle had published his paper, he (the speaker) had continued his researches in Sweden, and from the material he had collected he had discovered results differing from Prof. Candolle's. Of the individuals reported to him 29.6 per cent, of the men and 30.7 per cent, of the women had brown eyes, so that even in that country the latter were more numerous than the former, but this was no doubt due to the circumstance that he had been most anxious to obtain particulars from bi-coloured parents. In accordance with Candolle's results, 75.6 per cent, of children of parents both with brown eyes inherited this colour, whilst of those with blue eyes 97 per cent, inherited that colour. It was but natural that this should be the case in Sweden, where blue eyes predominated. As regards the bi-coloured parents the case was different in Sweden too. If the father had brown and the mother blue, 59.9 per cent, of the children had brown eyes, whilst where the reverse was the case 53 per cent, of them had brown ones. These figures were the reverse of Candolle's. But of all bi-coloured parents 56 per cent, of the children had brown eyes, i.e. that in Sweden too the latter are on the increase. He could not say what rôe the colour of the eyes played in the selection of a wife in Sweden, as he had no statistics of the distribution of brown eyes in general, but there was a tendency similar to that stated above, as, of the parents embraced by these researches, the majority of wives had brown eyes. With reference to the number of children in Sweden of con-coloured and bi-coloured parents, that of the former was 4.49 and that of the latter 4.03, whilst 52.6 per cent, of the children inherited the eyes of the father and 47.4 per cent, those of the mother; of the sons 51.8 per cent, inherited the eyes of the father, and 48.2 per cent, those of the mother, which figures as regards the daughters were respectively 53.5 and 46.5 per cent. This shows that in Sweden the eyes are not pre dominantly inherited from the mother alone, and that the off spring of equally-constituted parents should not be weaker. The speaker stated in conclusion that he is continuing his researches. He excludes children under ten years of age from the same, and classifies blue-grey or grey eyes as blue.
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Heredity . Nature 32, 543 (1885). https://doi.org/10.1038/032543a0
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DOI: https://doi.org/10.1038/032543a0