AEBAKER%CSUGREEN@PUCC.PRINCETON.EDU (ann baker biology dept 303 491 5307) (12/09/90)
George Seidel (Physiology Department, Colorado State University) said the most extensive data on sex ratios are for cattle. Under optimal conditions of health and nutrition about 55% males, 45% females will be born. Under average to poor conditions, the ratio will be 50%. Two reasons for the shift are Y-bearing sperm swim faster in an albumen gradient (= homolog? of oviduct) and male embryos are more susceptible to a variety of problems. George put these reasons as a possible explanation for differential sex ratio with social status in the Chinese village: more males born to high-status families, more females born to low-status families. He reasoned that lower social status might be associated with poorer nutrition or healthcare. AEM Baker