Paleoecological and paleoanthropological excavations of in situ breccias at Makapansgat, South Africa

Ohio State University Research Foundation -Do Not Use, Columbus OH

Investigators

Abstract

Knowledge of our evolutionary past, along with observations of changes in the ecological community in which our predecessors lived, is vital to helping us understand how we got here and what the human place in nature is today. The Makapansgat Valley has yielded a wealth of fossil fauna that reveal past environments through time, along with an important sample of an early human-like species known as Australopithecus africanus - our earliest known predecessors of southern Africa. The Australopithecus fossils from the Makapansgat Limeworks, considered to between about 2.8 and 3.2 million years old , may be the oldest from southern Africa. As these fossils are broadly contemporaneous with the early Australopithecus sample from East Africa, they hold key clues to understanding the emergence and diversity of human ancestors across the continent. Moreover, the rich assemblage of fossil fauna from the limeworks has provided valuable insights into the ecological context of human origins and evolution in southern Africa, although interpretations have varied. Our plan is to augment our current knowledge base with a well-controlled excavation from which the fossils can be studied in a detailed context. We will excavate the known Australopithecus-bearing layers of the Makapansgat limeworks, as well as lower levels of the sediments that promise to reveal earlier stages of the valley's prehistoric changes. In addition, other sites in the Makapansgat Valley preserve a record of environmental change from the well over 3 million years ago through to the present. For example, recent excavations at Buffalo Cave have yielded a rich mammalian sample from between 1 and 2 million years ago. Fossils and stone artifacts from the Cave of Hearths represent much of the past several hundred thousand years of human occupation in the area. The Makapansgat Valley thus provides a valuable opportunity to understand how global and continental environmental changes were reflected in a tightly constrained local context. Fossils from Makapansgat have conjured up many images of pre-human behavior, ranging from our ancestors having been "killer apes" to visions of a more docile creature at the mercy of a wide variety of predators. Given the significance of the Makapansgat Valley's sites for interpretations of our past, it is important to understand that the earliest sequence from the Limeworks has only recently undergone preliminary systematic excavation of in situ fossils - i.e. those in their original context. For the past half-century fossil collecting at the site focused almost exclusively on the waste dumps of breccia (fossil bearing sandstones) left behind by limestone miners decades ago. This simple fact - that most of Makapansgat's fossil fauna has been recovered from mine dumps - helps explain the difficulty in reaching consensus concerning paleoenvironmental and ecological reconstructions of this important fossil site. For this reason, the primary objective of the proposed research is to continue and enhance systematic in situ paleoanthropological excavations of Makapansgat limeworks in order to recover fossils of known context, and to better analyze how this reflects ancient environments and ways of life.