Tyson further explains how the influence of other planets in the Solar System have small effects on the Earth's spin and tilt, creating the various ice ages, and how these changes influenced early human's nomadic behavior.
Tyson menunjukkan bahwa planet-planet lain di Tata Surya juga memengaruhi putaran dan kemiringan Bumi sehingga menyebabkan beberapa zaman es, serta cara perubahan-perubahan tersebut memengaruhi perilaku nomaden manusia awal.