EARTH'S MAGNETIC FIELD REVEALS WHAT DROVE EARLY HUMANS OUT OF AFRICA

A core of rock and sediment drilled from the bottom of Lake Chala, a crater lake on the border of Tanzania and Kenya, contains records of wobbles in the planet’s magnetic field.

- STEPHANIE PAPPAS

It also contains information about the climate over the past 150,000 years, when modern humans were flowing out of Africa into the Arabian Peninsula and on to Europe and Asia. To use ancient sediment records to reconstruct the past climate, though, researchers need a way to date the sediment. That’s where variations in Earth’s magnetic field co