Mary and Louis Leakey are considered two of the foremost fossil hunters of the 20th century. Convinced that they would find evidence that humans evolved in Africa, they spent nearly 30 years scouring the Olduvai Gorge for fossil evidence. Finally, in 1959 they found a hominid jaw bone. Their legacy continues as several of the Leakey children and grandchildren continue to reasearch and study in east Africa.
Mary Leakey is credited with the discovery of Proconsul africanus, Australopithecus boisei and Homo habilis. Perhaps one of her most significant discoveries though was that of an 86 foot long trail of footprints, dating back 3.5 million years, that proved that our ancestors were walking upright by that time.
Leakey, A Century of the Leakey Family in East Africa - www.leakey.com