Evidence on Human Origins A Rediscovered Source in the Upper Siwaliks of Northern Pakistan

Abstract

The Siwalik deposits of northern Pakistan are one of the world's most continuous and detailed terrestial geological sequences of the Miocene to early Pleistocene (18 million to 1 million years ago). Most of these deposits are fluvial, and many have had their age determined by palaeomagnetism, and by potassium–argon dating when they contain volcanic ashes. They have also been extensively tilted, uplifted, and sometimes rotated and faulted, through the orogeny of the Karakorum and Himalayas, and provide one of the best records of this process. Siwalik deposits are often rich in vertebrate fossil remains, including those of animals ancestral to existing Asian apes. In addition to showing the evolution of Asian mammalian faunas, the quality of detail in Siwalik deposits can also illuminate our understanding of how the fossil record in general was formed in fluvial environments. In the last 30 years, scientific interest in the Siwaliks has been eclipsed by the East African Rift Valley, particularly because of the discovery there of fossil hominid remains. The present paper looks at the Upper Siwaliks of northern Pakistan, which have been reinvestigated by British and Pakistani teams over the last decade, to see what light these studies throw on human origins and the evolution of faunal communities in Asia.