A study of some genetically determined features in Swedish, Spanish and North English populations
A survey has been conducted with the assistance of the reflectophotometric techniques within the populations of three different countries - Sweden, Spain and England - in order to study the pigmentary differences between and within them, and to what extent they obey to environmental instead of genetic diversity. In order to illustrate the differences between accurately determining the colour of a skin and looking at its adaptive role, a detailed exposition of the physics of colour has been undertaken in the introductory chapter. In recognition of the the effects of human behaviour and the physical milieu in moulding the phenotypical manifestations of the genetical structure of a population, extensive information was gathered about the ethnic origins of people and about their leisure and working habits. That information - together with other about non- cutaneous pigmentation, stature, blood groups and their reflectance readings - was codified and transformed into variables, in order to study their associations (if any) with each other. That task has been undertaken in chapters III to VII, where the combined effect of the behavioural variables was in certain cases found capable of explaining as much as 35% of the internal variability. Some significant differences were also found to parallel climatic factors such as insolation and precipitation. In chapter V11 a number of significant associations were found between pigmentation, blood groups and stature - and were attempted to be put in relation with certain racial strains. Chapter VIII constitutes an enquiry into the subject of mating preferences and its potential effect on the genetic structure of the populations under study. The author’s samples have, in the last chapter, been compared to other Caucasoid populations, arriving to the conclusion that a non-negligible part of the differences is probably due to plain instrumental error.