Faculty of Natural and Agricultural Sciences
School of Biological Sciences
Department of Zoology and Entomology
Selected Highlights from Research Findings
Traditional wisdom suggests that mothers may be able to influence the sex of their offspring by altering their diet. Recent research in the Mammal Research Institute (MRI) indicates that these myths may not be so far-fetched. Evolutionary theory proposes that mothers would maximise their descendants if they had sons when they had excess resources to invest, and daughters when there are limited resources. While recent reviews of studies in mammals have supported this notion, it has not been clear how such variation might arise. Researchers have proposed that glucose levels might play a role in mediating the development of newly fertilised eggs. Researchers at the University of Pretoria and the University of Nevada, Reno, USA, experimentally tested whether the manipulation of glucose levels (using a steroid additive in drinking water) during early development influenced sex ratios. Surprisingly, the team’s study confirmed the role of glucose. The glucose levels of steroid-treated females dropped, and these females only gave birth to 42% sons compared to the untreated females who gave birth to 54% sons. This is the first study to show a causal link between glucose levels and offspring sex ratios in a living animal
Contact person: Prof EZ Cameron.
The Mammal Research Institute also undertook a study on the sex-ratio manipulation of human children. They focused on whether there was any indication that humans with extra resources (indicated by wealth) gave birth to more sons. Billionaires were identified using the Forbes List, and their ratio of sons to daughters was recorded. The study indicated that billionaires gave birth to 60% sons, compared to 51% in the rest of the population
Contact person: Prof EZ Cameron.
|
