利手与语言功能偏侧化的遗传模型

利手与语言功能偏侧化现象不仅具有跨文化一致性和发生、发展上的关联性, 还具有明显的生态学优势, 从遗传角度探讨它们的成因是必要的。早期遗传模型认为, 存在一对等位基因分别决定左、右利手。当代单基因模型则将语言功能偏侧化也纳入进来, 认为等位基因不仅可以决定具有方向性的偏侧化, 而且可以使偏侧化有一定几率向左或向右。在这个框架下形成了方向-随机等位基因模型、X-连锁隐性基因模型和右侧位移理论, 它们对等位基因的位置和功能有不同表述, 对利手的划分标准、性别差异以及遗传和环境的关系也有不同阐释。今后需加强对语言偏侧化的数据验证, 进一步阐明语言感知、理解与利手的关系, 并注重基因怎样决定表型、基因多效性和多基因合作等问题的研究。

The Genetic Model of Handedness and Language Lateralization

Handedness and language lateralization are the phenomena with transcultural coherence, relevance in human ontogenesis and development, as well as great ecological advantages. So it is necessary to explore the cause of their formation from genetic aspect. It has been proposed that left and right handedness were determined by a pair of alleles respectively in the early genetic model. Recently, with a suggestion to include the language lateralization, the current monogenic model assumed that the alleles could not only determine directional asymmetry, but also affect the odds of its right or left orientation. Under this framework, directional-chance alleles model, recessive X-linkage model and right shift theory were proposed. The models differ in how they account for the location and function of alleles, the distinctions of handedness, sex differences, and the relationship between heredity and environment. Further research should lay emphasis on data validation of language lateralization, and the correlation between handedness and language perception or comprehension. Besides, issues on the genetic pleiotropy, multiple genes collaboration, as well as how genes determine the phenotype are to be explored.