Questions tagged [sex-ratio]

the ratio of males to females in a population. Use this tag in questions related to sex ratio in a population or species, or regarding the principles and calculations about sex ratios.

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Evidence of condition-dependent sex-allocation in regards to humans

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 ...
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7 votes
2 answers
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Does knowing the sex of each of a couple’s first N children have any marginal value in predicting the sex of child N+1?

Does knowing the sex of each of a couple’s first N children have any marginal value in predicting the sex of child N+1? By “marginal” I mean predictive power beyond other known effects, e.g., the race ...
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6 votes
2 answers
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How can sex ratios remain Fisherian (1:1) in species where only the dominant male gets to mate

In certain species only the dominant male gets to mate (or given strong preference), and yet the sex ratio remains 1:1. (I'm thinking in particular of gorillas). How does this happen? It doesn't seem ...
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In what animal species is the sex ratio skewed in favour of the fertile female?

Ants have something like a single fertile female to several males. The same applies to bees, and larger animals - elephants too. Is the sex ratio universally skewed in favour of the female? What ...
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19 votes
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Are human fetuses more likely to be male? [duplicate]

Question: From a physiological point of view, when sex is determined in a human fetus, is it equally likely to be male or female? Studies in this area typically measure age at birth, where the data ...
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