Coming from zero background in biology, I am looking for expert opinion on evidence regarding Trivers-Willard hypothesis (1973) and humans.
In short the hypothesis states that if
- "Condition" of offspring during their whole life are correlated to that of their mother during pregnancy
- Males have better on average better reproductive success (more genes in next generation) than female when in "good condition", and vice versa if you compare male/females in "bad condition".
- Females objective is "eventual reproductive success" down the generations.
Then it makes sense for females to vary sex ratio, more males when in "good condition" and more females when in "bad condition".
I think it is safe to say that plenty of evidence exists on assumption one. The second assumption seems more nuance in todays environment, but one would imagine that during most human history it does hold true. On the third one I think is safe to assume it is true based on the theory of evolution by natural selection.
Any (rigorous) reference (articles, researchers, journals) or comments would be superb!
Reported association that I am already aware of are:
Reduced gender ratio at times of war and famine (Ansari-Lari & Saadat, 2002; Song, 2012; Valente, 2015) and after natural disasters (Fukuda et al. 1998).
Darwin (Descent of man); Norberg, 2004; Almond & Edlund, (2007); Hamoudi & Nobles, (2014) divorce or "unmarriedness" correlated with lowered gende ratio.
Negative association between parents age and gender-ratio, Jacobsen, Møller, & Mouritsen, (1999).