Relationships by isonymy between persons with monophyletic and polyphyletic surnames from the Monterrey metropolitan area, Mexico

Human Biology, Dec 1994 by Rojas-Alvarado, M De Los Angeles, Garza-Chapa, Raul

In 1990 the state of Nuevo Leon in northeastern Mexico (Figure 1) had a population of 4,492,500 inhabitants. (Figure 1 omitted) The Monterrey metropolitan area is located in the central-western area of the state, and nearly 80% of the state's population is concentrated in Monterrey (Direccion de Estadistica y Procesamiento de Datos del Gobierno de Nuevo Leon 1978).

During the colonization period, between 1557 and 1596, people with unique surnames (those now designated as monophyletic) arrived, and currently their main geographic distribution is located in northeastern Mexico and southern Texas (Mendirichaga 1982). People with multiple-origin surnames (designated as polyphyletic) have repeatedly introduced surnames into this region (del Hoyo 1979) that are also widely distributed throughout Mexico (Montemayor-Hernandez 1971).

Several studies of the historical antecedents and the genetic composition of the populations of the state of Nuevo Leon have been done (Garza-Chapa 1983; Garza-Chapa et al. 1978; Garza-Chapa, Brandi-Escamilla et al. 1982; Garza-Chapa, Leal-Garza et al. 1982; Cerda-Flores and Garza-Chapa 1989; Cerda-Flores et al. 1987, 1991), but only one paper has been published about surnames using listings from a telephone directory (Garza-Chapa et al. 1991).

The present study was undertaken because surnames can be used as a neutral genetic marker (Lasker 1980, 1986) with a vast amount of polymorphism (Weiss and Chakraborty 1982); surnames have also been used as an indicator of ethnicity (Devor 1980; Devor and Buechley 1980; Enstrom and Operskalski 1978; Samet et al. 1980). Because the Ibero-American surname system (Pinto-Cisternas et al. 1985) yields two surnames for each person, it is possible in Monterrey to analyze the patronymic (paternal origin) and the complementary matronymic (maternal origin) surnames separately. Therefore, to know more about the genetic structure of the Monterrey population, we formulated the following objectives for this study: (1) to determine whether the immigration process has modified the genetic composition of the population, (2) to examine isonymy coefficients in maternal and paternal names complementary to selected monophyletic and polyphyletic surnames, and (3) to determine the isonymy and relationship by isonymy between the descendants of the founder immigrants (persons with monophyletic surnames) and between persons who have immigrated repeatedly to the area (persons with polyphyletic surnames). We hypothesize that the relationships between individuals with monophyletic surnames are closer than those between individuals with polyphyletic surnames.

Materials and Methods

Three thousand two hundred eleven males and females insured by the Instituto Mexicano del Seguro Social (IMSS) who visited a doctor's office or a clinic laboratory and who reside in Monterrey were selected for having as their patronymic or matronymic surname one of the following: for monophyletic surnames, Cant, Chapa, Garza, Montemayor, and Trevino; for polyphyletic surnames, Garcia, Gonzalez, Martinez, Rodriguez, and Sanchez. These 10 surnames are the 5 most common names in the telephone directory in either group (Garza-Chapa et al. 1991). Also, in the 1990 telephone directories the selected monophyletic surnames are 24 times more frequent in Monterrey than in Mexico City (5.35% and 0.22%, respectively), and the selected polyphyletic surnames are almost equally frequent (11.82% and 8.35%).

When a patient reported that one of his or her close relatives had already been interviewed, the data for that person were laid aside, as were data for a member of the same family attending on the same date. From the interviews information was collected about the maternal and paternal complementary surnames. In both cases alternative spellings were accepted and listed under the most common form found in the telephone book, and the prefixes de, del, and de la were omitted; for example, Gonzales was recorded as Gonzalez, and de la Garza was recorded as Garza. Thus the population was divided into two groups (monophyletic and polyphyletic), and each group was subdivided according to whether the selected surname was patronymic or matronymic. In this way a person called Maria Sanchez Vargas would have the surname of her mother (Vargas) included in the list of complementary surnames to Sanchez, and elsewhere in the tables and analyses she would be listed under "paternal polyphyletic" because Maria has as one of her surnames Sanchez, one of the selected polyphyletic names, as her paternal surname. Similarly, a man named Jose Trevino Garcia would be included twice: under Trevino, as the complementary name to the maternal polyphyletic name Garcia; and under Garcia, as the complementary name to the paternal monophyletic name Trevino. Hence the number of instances of any of these surnames was 3815.

For each selected monophyletic or polyphyletic, patronymic or matronymic surname, we determined the distribution of complementary surname frequencies, their occurrence x, the number of names that occurred x times [f(x)], the total number of surnames [n = Sigmaf(x)x], and the number of different complementary surnames [k = Sigmaf(x)]. Also we determined the percentage of unique complementary surnames [f(1) x 100/n], the percentage of different complementary surnames [k(100)/n], and the percentage of the most common complementary surname [the highest f(x) x 100/n].