Egg yolk gene remnants point to mammals’ egg-laying past

When children learn about different animals and how to classify them, they are often taught that three features unite mammals: hair, milk, and live birth. This last trait is likely taught to contrast mammals with the many other vertebrates that lay eggs. But this last point is not correct. Nearly all mammals give birth to live young, but a handful …

Continue reading Egg yolk gene remnants point to mammals’ egg-laying past