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These findings shed light on the evolution of sex chromosomes and inform understanding of diseases related to genes on these chromosomes in both apes and humans.

The genome consists of 2.9 billion base pairs, which form 23 autosomal chromosomes, and X and Y sex chromosomes.

Female birds have two different sex chromosomes, designated W and Z, while males have two Z chromosomes.

They screen for chromosomal disorders such as trisomy 13 and 18, which often end in miscarriage or stillbirth, Down syndrome and extra or missing copies of sex chromosomes.

A stud published this week in the journal Cell says it might boil down to the most fundamental difference between biological men and women: the difference in sex chromosomes.