An adaptive significance of morning sickness? Trivers-Willard and Hyperemesis Gravidarum.

Nausea during pregnancy, with or without vomiting, is a common early indication of pregnancy in humans. The severe form, Hyperemesis Gravidarum (HG), can be fatal. The aetiology of HG is unknown.

Effect of Registered Partnership on Labor Earnings and Fertility for Same-Sex Couples: Evidence From Swedish Register Data.

The expansion of legal rights to same-sex couples is a foot in a number of Western countries. The effects of this rollout are not only important in their own right but can also provide a window on the institution of marriage and the rights bundled therein. In this article, using Swedish longitudinal register data covering 1994-2007, we study the impact of the extension of rights to same-sex couples on labor earnings and fertility.

Girl adoption in China-A less-known side of son preference.

In 1987, 4 per cent of girls were adopted within China. Why? Unlike infanticide, abandonment rids parents of daughters while preserving the supply of potential brides. In fact, an erstwhile tradition common in Fujian and Jiangxi provinces had parents of sons adopting an infant girl to serve as a future daughter-in-law and household help.

Son-biased sex ratios in the 2000 United States Census.

We document male-biased sex ratios among U.S.-born children of Chinese, Korean, and Asian Indian parents in the 2000 U.

Trivers-Willard at birth and one year: evidence from US natality data 1983-2001.

Trivers & Willard (TW) hypothesized that evolution would favour deviations from the population sex ratio in response to parental condition: parents in good condition would have more sons and parents in poor condition would have more daughters. We analyse the universe of US linked births and infant deaths to white mothers 1983-2001, covering 48 million births and 310,000 deaths. We find that (i) married, better educated and younger mothers bore more sons and (ii) infant deaths were more male if the mother was unmarried and young.