Blanco Villegas M J, Fuster V
Departamento de Biología Animal, Universidad de Salamanca, Salamanca, Spain.
Ann Hum Biol. 2006 May-Jun;33(3):330-41. doi: 10.1080/03014460600627529.
Among determinants of the structure of human populations, consanguineous marriages can be useful in determining to what extent they influence the genetic structure of the population. This knowledge may be gained by comparing the reproductive performance of related and non-related couples. The population studied, La Cabrera, is a mountainous region in the Leon province (north-western Spain). It includes four neighbouring municipalities with similar geographic, climatic and ecological features with 37 parishes occupying an area of 784.2 km(2), of which only 1.5% is arable. The number of inhabitants remained stable from 1887 (9526 inhabitants) to 1960 (8984), when due to emigration it began to decrease. The average inbreeding coefficient (alpha) for the period 1880-1989 (up to third degree) was 4.82 x 10(-3).
The objective of this analysis was to evaluate the possible factors determining the differences between consanguineous and non-consanguineous families residing in La Cabrera during the period 1880-1959.
To study the structure and dynamics of each couple, families were reconstituted for the period 1880-1959 using demographic data corresponding to births, deaths and marriages obtained from parish registers. This procedure provided information on each couple's reproductive history through information concerning the mates' deaths as well as their offspring's births and deaths. Principal component analysis revealed the existence of three factors that together explained 57% of the reproductive pattern variability of La Cabrera.
The first component (eigenvalue: 3.56) correlated positively with the number of live births and with the duration of the reproductive period. Component II (eigenvalue: 1.54) had a positive correlation with variables describing the beginning of the marital union, and with those indicating its ending. Finally, component III (eigenvalue: 1.13) reflected a negative association with the two variables that described neonatal and post-neonatal mortality. The above demographic variables represented the reproductive process in La Cabrera adequately. Fertility was the variable that offered the best explanation of the reproductive pattern (32%), followed by the marital structure (13%) and the infant mortality (12%).
In the La Cabrera population, consanguinity appears as a socio-cultural process that affects the reproductive dynamic. Consanguinity modifies the marital structure and alters the reproductive pattern, prolonging the reproductive period, which results in a greater number of offspring. Lower infertility rates and the possible compensatory effect for infant mortality may reflect biological factors making the wife's reproductive period more efficient.
在人类种群结构的决定因素中，近亲婚姻有助于确定其对种群遗传结构的影响程度。通过比较近亲与非近亲夫妇的生育表现可获得这方面的知识。所研究的拉卡布雷拉地区是西班牙西北部莱昂省的一个山区。它包括四个相邻的市镇，地理、气候和生态特征相似，有37个教区，面积为784.2平方公里，其中只有1.5%为可耕地。从1887年（9526名居民）到1960年（8984名居民）居民数量保持稳定，之后由于移民开始减少。1880 - 1989年期间（至三级亲属关系）的平均近亲繁殖系数（α）为4.82×10⁻³。
本分析的目的是评估1880 - 1959年期间居住在拉卡布雷拉的近亲家庭与非近亲家庭之间差异的可能决定因素。
为研究每对夫妇的结构和动态，利用从教区登记册获得的出生、死亡和婚姻的人口统计学数据，对1880 - 1959年期间的家庭进行重构。这一过程通过配偶死亡以及其子女出生和死亡的信息，提供了每对夫妇生育史的信息。主成分分析揭示存在三个因素，它们共同解释了拉卡布雷拉生育模式变异性的57%。
第一个成分（特征值：3.56）与活产数量和生育期时长呈正相关。成分二（特征值：1.54）与描述婚姻结合开始以及结束的变量呈正相关。最后，成分三（特征值：1.13）与描述新生儿和新生儿后期死亡率的两个变量呈负相关。上述人口统计学变量充分代表了拉卡布雷拉的生育过程。生育率是对生育模式解释力最强的变量（32%），其次是婚姻结构（13%）和婴儿死亡率（12%）。
在拉卡布雷拉人群中，近亲结婚表现为一个影响生育动态的社会文化过程。近亲结婚改变婚姻结构，改变生育模式，延长生育期，从而导致更多后代。较低的不孕率以及对婴儿死亡率可能的补偿作用可能反映了使妻子生育期更有效的生物学因素。
