Why do humans “default” to female in fetal development?

Question

Is there any inherent reason why the body becomes female unless “told” by the Y-chromosome to be male as opposed to the other way around?

In: Biology

Answer 1

The birds, snakes and butterflies have it the other way around — males have two identical, “complete” (ZZ) chromosomes, while females have one “depleted” (WZ) chromosome. So other evolutionary lines show us, that a different system is possible.