Mochena Borago

Mount Damota, which is a trachytic volcano, is currently dormant, and rises 2908 meters above sea level at its summit. It was last active from around 2.94 million years ago to the Late Quaternary.[4] The volcano's coordinates are 6°54′12.9″N 37°46′45.8″E. Damota touches the administrative capital of the Wolaita Zone, Sodo, at its southern foot, and it lies between the Southwest Ethiopian Highlands and the Ethiopian Rift Valley from west to east, and between the central Rift Valley lakes and Bilate River from north to south.[2] The rockshelter itself is about 70 m wide, 12 m high, and around 20 m from the east wall to the waterfall located at the mouth of the site to the west.[1] It has an area of around 600m², and is located at 2300m asl.[5] The waterfall comes from a ravine that runs down Mount Damota and over Mochena Borago.[1] This ravine serves as a year-round source of freshwater for the locals of Mount Damota, and comes from streams of precipitation that fall from the top of the mountain chain.[5] The rainy season on Damota runs from June to September, during which half of annual rainfall, 2000 mm, falls.[4]

Excavations being carried out at Mochena Borago

The high biodiversity as well as prevalence of plant and animal resources, both wild and domesticated, in the area surrounding Mount Damota is consistent environmentally with other regions in the southwest Ethiopian Highlands. On and around Mount Damota there exists a series of vertical ecozones caused by the variations of physiographic features and altitude, wherein vegetation differs. There are three important agro-ecological zones that can be found in the Mount Damota area, as identified by local farmers. Mochena Borago is located within the zone known as 'woyna dega.'[4] The walls of the rockshelter are made of volcaniclastic flow and volcanic ash. Boulders that have fallen from the roof of the shelter lie on the floor and beneath its surface.[3]

About 125-100 ka during Marine Isotope Stage (MIS) 5, when conditions were warm and humid, the first dispersals of Homo sapiens out of Africa and into Asia took place. These dispersals were halted when the colder and more arid MIS 4 occurred. With the more favorable conditions of the early MIS 3 (~57-29 ka), humans spread throughout Africa and to almost every continent, which we know from both genetic and archaeological evidence. The Refugium Theory states that, under the harsher conditions of MIS 4 within Africa, populations of humans would have seen a decrease, and would have been forced into environmental refugia. It has been proposed that in the Mid-Pleistocene these refugia were where many African innovations took place, equipping Homo sapiens with the behavioral tools needed to survive during MIS 4, and subsequently to populate the globe by the end of the Pleistocene, once MIS 3 brought better conditions for this migration.[1]

Students from Wolaita Sodo University visiting Mochena Borago

Mochena Borago is an important site for testing this hypothesis, as it is one of a few sites outside of South Africa with securely dated MIS 3 deposits. The other sites include Mumba Cave in Tanzania, and Haua Fteah Cave in Libya. Further excavation and dating at Mochena Borago could possibly show the presence of MIS 4 deposits as well. As a potential refugium, archaeological excavations at Mochena Borago may be able to provide vital links between human innovations in technology, organization, mobility, etc. and climatic events around the time of the second major dispersal of Homo sapiens into the rest of Africa and the world.[1]

Excavation areas within Mochena Borago Rockshelter

Archaeology at Mochena Borago began in 1995 with survey work done under the direction of French archaeologist Roger Joussaume with the Groupe pour l’Etude de la Protohistoire de la Corne de l’Afrique (GEPCA), a group most interested in the Mid- to Late Holocene deposits at the site.[4] Excavations were first carried out by GEPCA from 1998 to 2001 in the Holocene layers and some of the Late Pleistocene deposits under new director, Xavier Gutherz from the University of Montpellier in France.[5] Xavier Gutherz directed a project at the site from 2000 to 2002 that focused on recovering evidence of food production during the Holocene occupations. The about 20m² that Gutherz excavated along the northern section of the rockshelter have come to be called the "Block Excavation Area" or (BXA).[1] Gutherz also opened the excavation areas known as MB1, MB2, MB3, and MB4.[3]

Direction of the site was transferred in 2006 to Dr. Steven Brandt and Dr. Elisabeth Hildebrand, who started the Southwest Ethiopia Archaeological Project (SWEAP), beginning the focus on the Pleistocene deposits of Mochena Borago.[4] They opened the excavation area MB5, located in the eastern part of the site, and deepened MB1. Later, areas MB1 and MB3 were deepened, and MB5 and MB6 were expanded by SWEAP and co-director at the time, Ralf Vogelsang.[3] The project initially intended to investigate Mochena Borago for evidence of MIS 2 habitation, specifically during the last glacial maximum. However, 19 charcoal dates from the site showed the archaeologists that the rockshelter may not yield information about refugia in the southwest Ethiopian highlands during MIS 2, but that it could be very important for studying MIS 3 or possibly MIS 4 refugia in the region instead.[1] SWEAP partnered with the Collaborative Research Center 806 (CRC 806) at the University of Cologne to conduct joint research at the rockshelter on human behavioral change corresponding to dispersals out of Africa, beginning in 2009 and excavating each season from 2010 to 2014.[4] Since 2015, SWEAP has continued excavations at Mochena Borago, with other focuses on site formation processes and micromorphological sampling.[1]