Humans and their distant ancestors have been part of Ngorongoro’s landscape for millions of years. The earliest signs of mankind in the Conservation Area are at Laetoli, where hominid footprints are preserved in volcanic rock 3.6 million years old. The story continues at Olduvai Gorge, a river canyon cut 100 m deep through the volcanic soil of the Serengeti Plains. Buried in the layers are the remains of animals and hominids that lived and died around a shallow lake amid grassy plains and woodlands. These remains date from two million years ago. Visitors can learn more details of this fascinating story by visiting the site, where guides give a fascinating on-site interpretation of the gorge.