Daphne Gallagher, University of Oregon (IMAGE) University of Oregon Caption Daphne Gallagher, an anthropologist at the University of Oregon, has pushed back the history of harvesting shea tree nuts by local populations in West Africa to A.D. 100. Her research in Burkina Faso focused on layers of households that had been built atop one another from some 1,600 years. Credit Photo by Charlie Litchfield Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.