The researchers examined lake sediments from Olduvai Gorge in northern Tanzania, looking for biomarkers -- fossil molecules -- from ancient trees and grasses.
The researchers examined lake sediments from Olduvai Gorge in northern Tanzania, looking for biomarkers -- fossil molecules -- from ancient trees and grasses.
!["SHO Time" 1](http://news.psu.edu/sites/default/files/styles/multimedia_most_popular/public/4951807427.jpg ""SHO Time" 1")
