Path: utzoo!utgpu!watserv1!watmath!uunet!bionet!PUCC.PRINCETON.EDU!AEBAKER%CSUGREEN
From: AEBAKER%CSUGREEN@PUCC.PRINCETON.EDU (ann baker biology dept 303 491 5307)
Newsgroups: bionet.population-bio
Subject: sex ratios
Message-ID: <9012091712.AA22144@genbank.bio.net>
Date: 9 Dec 90 04:55:53 GMT
Sender: daemon@genbank.bio.net
Lines: 13

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