WITSCHI E
Science. 1959 Aug 14;130(3372):372-5. doi: 10.1126/science.130.3372.372.
Certain characteristic patterns of physiologic sex determination are not causally linked with types of genic and chromosomal constitution (XX-XY or ZW-ZZ). The observed widespread but not universal parallelism in the distribution of genetic and physiologic patterns among vertebrate groups expresses genealogic relationship. On the basis of this interpretation one may estimate the approximate evolutionary age of the mechanism of genetic sex determination. It is concluded that in all tetrapod vertebrates these mechanisms originated during the Jurassic period. Environmental conditions seem to affect the progress of this evolution.
某些生理性别的确定特征模式与基因和染色体组成类型（XX - XY或ZW - ZZ）并无因果联系。在脊椎动物群体中观察到的遗传和生理模式分布广泛但并非普遍的平行现象体现了谱系关系。基于这种解释，可以估计遗传性别决定机制的大致进化年龄。得出的结论是，在所有四足脊椎动物中，这些机制起源于侏罗纪时期。环境条件似乎会影响这一进化的进程。
