All humans today share a single grandma, circa 175,000 BCE. We know this because all humans alive today share our ancestor’s haplogroup L genes — from our X chromosome. She was one of many thousands of women living in eastern Africa. Many maternal lines survived for many generations but ultimately over time all the other female lineages died out.

In the shadowed forests of the Late Carboniferous, long before mammals, birds, or even dinosaurs,







