By studying fossils belonging to our ancestors, researchers have concluded that six million years ago they took a giant leap forward when they started climbing down trees to pick up food that had accidentally fallen from their hands while eating. Everything that man did from then on from colonizing every corner of the earth, to going to the moon, to building the pyramids is consequent to the crucial step of climbing down trees. For another million years our ancestors continued to climb back up trees. However, when down they also started to know one another better than when hanging from branches. Forms of organization followed that required planning and finding solutions to problems as well as abstract thinking. Grunts became language and social relationships became more complex. Five million years ago our now intellectual ancestors had fewer reasons to climb back up trees and more reasons to find a place where to sleep down below. Huts, villages, little towns and New York followed. Now with climate change the risk is that everything will be destroyed and that we might have to start all over again this time without trees from which to climb down.