Corballis M C
Department of Psychology, University of Auckland, New Zealand.
Psychol Rev. 1997 Oct;104(4):714-27. doi: 10.1037/0033-295x.104.4.714.
At some point in hominid evolution, a mutation may have produced a "dextral" (D) allele, strongly biasing handedness in favor of the right hand and control of speech toward the left cerebral hemisphere. An alternative (chance [C]) allele is presumed directionally neutral, although there are probably other genes that influence asymmetries and that may create a weak bias toward right-handedness (and other asymmetries). Simulations show that the D allele could have spread quite quickly through a population, given even a minuscule advantage of CD heterozygotes over CC and DD homozygotes in terms of reproductive fitness. This heterozygotic advantage would also explain the apparent stability in the relative proportions of left-handers and right-handers. This putative, uniquely human allele may have emerged with the evolution of Homo sapiens in Africa some 150,000 to 200,000 years ago.
在人类进化的某个阶段，一个突变可能产生了一个“右旋”（D）等位基因，极大地使惯用手偏向右手，并使语言控制偏向左侧大脑半球。另一个（随机[C]）等位基因被认为在方向上是中性的，尽管可能有其他影响不对称性的基因，并且可能会对右利手（以及其他不对称性）产生微弱的偏向。模拟表明，即使CD杂合子在生殖适应性方面比CC和DD纯合子只有极小的优势，D等位基因也可能在种群中迅速传播。这种杂合优势也可以解释左利手和右利手相对比例的明显稳定性。这个假定的、独特的人类等位基因可能是在约15万至20万年前非洲智人进化过程中出现的。
