Tuesday, November 29, 2016

Human Evolution: The Paleolithic In The Indian Subcontinent

Came across this article by anthropologist Sheila Mishra on the Paleolithic of the Indian subcontinent and its significance in understanding human evolution.

The Indian Subcontinent is one of the areas occupied by hominins since Early Pleistocene times. The Lower Palaeolithic in the Indian Subcontinent is exclusively Acheulian. This Acheulian is similiar to the African Acheulian and has been labeled "Large Flake Acheulian" (LFA). The Middle Palaeolithic in the Indian Subcontinent is a poorly defined entity and the author has suggested that this phase should be considered the final phase of the Large Flake Acheulian from which it evolved. Microblade technology has recently been shown to be older than 45 Ka in the Indian subcontinent and is certainly made by modern humans as it has a continuity from this time until the bronze age. Presently, the nature of the transition from Acheulian technology to Microblade technology is not well understood as few sites have been dated to the relevant time period.

The continuity of the Lower Palaeolithic in the Indian Subcontinent is due to its ecological features. The Indian Subcontinent extends from approximately 8°-30° N which would normally encompass equatorial, tropical and temperate latitudinal zones. However, the influence of the monsoonal climate and sheltering effect of the Himalayan mountains results in a sub-tropical grassland vegetation extending both northwards and southwards of its normal distribution. Rainfall, rather than temperature, is the most important ecological variable which has a longitudinal rather than latitudinal variation. Thus, the Indian Subcontinent has a more homogenous environment than any comparable landmass and one eminently suitable for hominins. In contrast, the African climate zones are strongly latitudinal in distribution. The Indian Subcontinent during the Early and Middle Pleistocene has close connections with Sundaland. The fauna associated with Homo erectus in Java is derived from the Indian Pinjor faunas. During low sea levels the area of land exposed in the Sunda shelf is equal in size to the Indian Subcontinent. Sundaland has an important buffering effect on the Indian Subcontinent, with favourable conditions for Hominins in Sundaland coinciding with unfavourable ones in the Indian Subcontinent.

She interprets the ecology and tool record as suggesting that Homo erectus evolved in the India-Sundaland region and not in Africa. This scenario implies there was a migration of Homo erectus into Africa from Asia by 1.8 million years ago or so.  She points out that a number of African mammal species appear in the Indian Siwaliks (Himalaya foothills)  by 3-2.5 million years ago and so presumably an ancestral species (Australopithecus? early Homo?)  may have migrated out of Africa at that time. There have been recent announcements of putative 2.6 million year old stone tools from the Siwaliks, but their significance is still up for debate. And given the paucity of skeletal remains in India, her theory is going to be a hard sell.

There is  also a really good description of the geological context in which Paleolithic stone tools are found in the Indian subcontinent. They have been often described as "surface" sites but Mishra points out that they have been eroding from fluvial sediments. Volcanism, sedimentation and tectonics in the African rift valley and parts of Java lead to conditions favoring both burial and preservation and later exhumation of fossils and tools. The situation in India is different. Since Mio-Pliocene most of Peninsuslar India has been an erosive landscape with sedimentation occurring in a few fluvial systems with a depositional regime. Thick fluvial successions are rare. Preservation potential on the Indian landscape was low. The implication is that India may have had a larger population of hominins through the Pleistocene than the rarity of remains suggest.  Caves are the other context in which hominin fossils have been found in Africa, Europe and Asia. Have caves been adequately explored in India?

A very interesting article. Open Access.

No comments:

Post a Comment