Gilbert K, Danker H
Acta Anthropogenet. 1981;5(2):89-110.
The changes of the secondary sex ratio in Bremen (North Germany) from 1826 up to 1978 are compared with those of Germany in the period from 1872 to 1978. To some extent there are marked differences. The oscillation of the secondary sex ratio in Bremen is more extended in Germany. On the average in Bremen the values are lower in the 19th century than in the 20th. For Germany higher values are observed in the years between 1915 and 1959. The changes of reproductive performance, indicated by birth rate. Supposing that the primary sex ratio is dependent on the time of insemination within the intermenstruum, the same figures of monthly distribution of secondary sex ratio and birth frequency can be expected. In fact, the seasonal variations proved to be not significant and do not show the expected parallel figures.
将不来梅（德国北部）1826年至1978年的第二性比变化与德国1872年至1978年期间的变化进行了比较。在某种程度上存在显著差异。不来梅的第二性比波动在德国更为明显。不来梅平均而言，19世纪的值低于20世纪。德国在1915年至1959年期间观察到较高的值。以出生率表示的生殖性能变化。假设第一性比取决于月经周期内的授精时间，那么第二性比和出生频率的月度分布数字应该相同。事实上，季节性变化被证明不显著，也没有显示出预期的平行数字。
