Whatʼs in a name?: Comment on “Surname distribution in population genetics and in statistical physics”

Abstract

The practice of naming human individuals is probably as old as spoken language. In ancient, small human groups, the given name may have been enough to distinguish one individual from another and facilitate social gossip—thus social cohesion [1]. As groups grew larger and social organization became more complex, the addition of family names to given names was a convenient way to signal social status or to protect a legacy. The use of family names became prominent in different cultures at different times. However, despite significant differences in the historical acquisition of this habit and in the fidelity of inheritance of family names, the current distribution of surnames presents remarkable similarities all over the world, to the point of having systematically attracted the attention of scientists from quantitative disciplines in the last century and a half. In a comprehensive revision [2], Paolo Rossi goes over the many models, mostly similar in spirit, that have attempted to capture the universal features of surname distributions. Common patterns in surname abundance arise from a few simple dominating mechanisms (demography, vertical inheritance, and occasional introduction of new surnames) which form the core of most modelling attempts. Nowadays, however, the field is ripe enough to shift attention from the commonalities to the dissimilarities. The abundance of surnames in cultures with a small genealogical depth, for instance, still keeps memory of the historical situation when the inheritance of surnames was adopted. An example is Japan, with a genealogical depth of 4–5 generations (patrilineal inheritance of surnames began in year 1870) that yields a relatively narrow distribution of surname abundances [3], the large number of different surnames notwithstanding (over 290 000). The opposite situation is that of China and other neighbouring countries, which have the largest genealogical depth and a very high fidelity of transmission due to its writing system [4]. As a consequence, there are as few as 7000 different surnames at present, with a distribution of abundances depleted in rare surnames and clearly departing from a power-law. To compensate for this lack of diversity, individuals in the Chinese culture are distinguished thanks to a remarkable variety of given names [5]. The introduction of the spatial structure of surnames abundance speaks for inbreeding habits and reveals migratory phenomena thanks to its relation with the Y chromosome. However, few studies have related patterns of surname abundance and genetic markers. There seems to be a tacit agreement that genetic signals should be more reliable than cultural traits. Still, in groups where their cultural identity has been preserved in the face of foreign contributions,