India at the Cross-Roads of Human Evolution
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Human evolution in India 729 India at the cross-roads of human evolution R PATNAIKa,* and P CHAUHANb aCentre of Advanced Studies in Geology, Panjab University, Chandigarh 160 014, India bThe Stone Age Institute and CRAFT Research Center (Indiana University), 1392 W Dittemore Road, Gosport, IN 47433, USA *Corresponding author (Email, [email protected]) The Indian palaeoanthropological record, although patchy at the moment, is improving rapidly with every new fi nd. This broad review attempts to provide an account of (a) the Late Miocene fossil apes and their gradual disappearance due to ecological shift from forest dominated to grassland dominated ecosystem around 9–8 Ma ago, (b) the Pliocene immigration/evolution of possible hominids and associated fauna, (c) the Pleistocene record of fossil hominins, associated fauna and artifacts, and (d) the Holocene time of permanent settlements and the genetic data from various human cultural groups within India. Around 13 Ma ago (late Middle Miocene) Siwalik forests saw the emergence of an orangutan-like primate Sivapithecus. By 8 Ma, this genus disappeared from the Siwalik region as its habitat started shrinking due to increased aridity infl uenced by global cooling and monsoon intensifi cation. A contemporary and a close relative of Sivapithecus, Gigantopithecus (Indopithecus), the largest ape that ever-lived, made its fi rst appearance at around 9 Ma. Other smaller primates that were pene-contemporaneous with these apes were Pliopithecus (Dendropithecus), Indraloris, Sivaladapis and Palaeotupia. The Late Pliocene and Early Pleistocene witnessed northern hemisphere glaciations, followed by the spread of arid conditions on a global scale, setting the stage for hominids to explore “Savanahastan”. With the prominent expansion of grassland environments from East Africa to China and Indonesia in the Pliocene, monkeys and baboons dispersed into the Indian subcontinent from Africa along with other mammals. Though debated, there are several claims of the presence of early hominins in this part of the world during the Late Pliocene, based primarily on the recovery of Palaeolithic tools. Fossils of our own ancestor and one of the fi rst globe-trotters, early Homo erectus, has been documented from the Early Pleistocene of East Africa, Western Asia and Southeast Asia, thus indirectly pointing towards Indian subcontinent as a possible migration corridor between these regions. The only defi nite pre- Homo sapiens fossil hominin remains come from the Central Narmada Valley and are thought to be of Middle to late Pleistocene age, and the cranium has been shown to be closely linked to archaic Homo sapiens/H. heidelbergensis of Europe. Around ~74,000 yrs ago, a super volcanic eruption in Sumatra caused the deposition of Youngest Toba Tephra, that covered large parts of the Indian peninsula. Just around this time anatomically-and-behaviorally modern humans or Homo sapiens possibly arrived into India as evidenced by the so called Middle and Upper Palaeolithic assemblages and associated symbolic evidence. The available genetic data reveals that the gene pool to which modern Indians races belong was extremely diverse and had variable mixed links with both European and Asian populations. [Patnaik R and Chauhan P 2009 India at the cross-roads of human evolution; J. Biosci. 5 729–747] DOI 10.1007/s12038-009-0056-9 1. Introduction the early primates, the order to which, we humans belong. In fact, recent fi nds of anthropoid primates from the Early According to the “Out of India” hypothesis, several Eocene lignite mines situated in Eastern Gujarat, India groups of modern Asian organisms had their roots in the (Bajpai et al. 2008) and Oligocene of Pakistan (Marivuax northwardly moving Indian plate (Bossuyt and Milinkovich et al. 2005), may hold clues to the origin and dispersal of 2001; Karanth 2006). One of these groups could have been our earliest ancestors. These recent fi nds have lent support Keywords. Genetics; human evolution; Indian subcontinent; palaeoclimate; phylogeny; primate http://www.ias.ac.in/jbiosci J. Biosci. 34(5), November 2009, 729–747, © IndianJ. Biosci. Academy 34(5), of November Sciences 2009 729 730 R Patnaik and P Chauhan to some of the long-standing assertions that Asia was the and Ramapithecines were the African Dryopithecines, centre of anthropoid origins (Ciochon 1985; Culotta 1995; which may have arrived in southern Asia during the Early Beard et al. 1996). Miocene (Begun et al. 2003). Our aim here is to broadly review the palaeoanthropo- The Middle Miocene was the time of warm and humid logical records of India (with a few examples from Pakistan) climate and evergreen to deciduous tropical forests covered from the Miocene onwards, which essentially begins with a large part of the northwestern Indian subcontinent. These the emergence and disappearance of fossil apes, followed by ecological conditions are very well refl ected in the fossil the possible presence of early hominins in the late Pliocene as well as sediment record (Ashton and Gunatilleke 1987; and Early Pleistocene in the context of changing climate Nanda and Sehgal 1993; Prasad 1993; Thomas et al. 2002). and ecology. We also briefl y touch upon the Holocene Sivapithecus fossils have been found from the Potwar by reviewing data related to the gene fl ow of modern Plateau of Pakistan in the west and from Nepal in the east human races into and out of India. Finally, we conclude by from 13.5-8.4 Ma (Barry et al. 2002; Nelson 2003; Patnaik evaluating the lacunae in the fossil and technological record, et al. 2005). There were at least three species of Sivapithecus and suggesting possible future directions of research to fi ll that occurred in the Siwaliks, namely Sivapithecus indicus, S. these gaps in our knowledge of human evolution in India sivalensis and S. parvada. Sivapithecus indicus ranged from (e.g. Chauhan 2006; Petraglia and Allchin 2007). 12.5 to 10.3 Ma and S. sivalensis ranged between 9.8 to 8.4 Ma. S. parvada comes from a site dated to 10 Ma (Berggren 2. The Miocene et al. 1985; Kappelman et al. 1991; Flynn et al. 1995; Barry et al. 2002). S. sivalensis shows sexual dimorphism, with Though short-lived, India had its share of fame associated males averaging around 45 kg whereas females weighed with Ramapithecus, the Miocene ape from the Siwaliks. around 20 kg. S. parvada males were as large as modern Lewis (1934) fi rst recognized and named Ramapithecus orangutan males (Kelley 1986). Low crowned, thick brevirostris, the Rama’s ‘short-faced ape’ and placed it in the enameled molars of Sivapithecus indicate a tough diet, Hominidae, the family to which all bipedal Australopithecines such as nuts and fruits with tough rinds (Kay 1981). Dental and we belong. At the time of its discovery and soon after, microwear studies of their occlusal surfaces have been Ramapithecus was widely known to be the ancestor of found to indicate a diet similar to those of modern fruit- Australopithecus, the “ape of the South”, which in turn gave eating apes, with some hard-object feeding (Nelson 2003). rise to our own genus Homo. This idea of Ramapithecus being Kelley and Pilbeam (1986) have shown that the cranio-facial a hominid gained general acceptance (Simons and Pilbeam morphology of Sivapithecus is heavily buttressed, pointing 1972) and researchers started assigning Miocene specimens towards an adaptation to either withstand prolonged from Kenya (Leakey 1962; Andrews and Walker 1979); cyclical loading or to generate high occlusal loads. As far as China (Woo and Wu 1984), Nepal (West 1984); Turkey locomotion is concerned, Sivapithecus postcranials indicate (Andrews 1982); Hungary (Kretzoi 1975; Fleagle 1988) and that it was more like a pronograde quadruped that walked Greece (Pilbeam et al. 1977) to the Ramapithecines. In fact, above the branches very similar to most of other Miocene von Koenigswald (1976) went further, by proposing that hominoids, but might have also been an active climber (Rose Ramapithecus should be the right candidate to be at the root 1986). Sivapithecus does not show any specializations for of hominid evolution that gave rise to Australopithecus as extensive terrestriality (Kelley and Pilbeam 1986). Kelley Ramapithecus bearing Siwaliks are located geographically (1997), based on enamel growth lines of a Sivapithecus between fossil hominid yielding Africa and Southeast Asia. parvada juvenile, found that the life history pattern with However, with the discovery of key facial and postcranial a prolonged growth and maturation period of Sivapithecus remains of Sivapithecus in the early nineteen eighties, was similar to that of modern great apes. Morphology of Ramapithecus lost its place in Hominidae (Andrews 1982; Sivapithecus and its life history pattern, suggest that this Andrews and Cronin 1982; Pilbeam 1983). The advent of large-bodied frugivore must have been vulnerable to periods analysing molecular clocks, which indicated ~5 Ma as the of ripe fruit shortages and may have relied heavily upon time of divergence between humans and apes, ultimately different fallback foods, such as hard seeds and nuts (Nelson made this contention more convincing (Sarich and Wilson 2005). 1967). Nevertheless, Ramapithecus still appears to hold an With the advent of Late Miocene global cooling and spread important place in primate evolution, as it belongs to the of arid conditions, these forests began to shrink (Kennett and pool of Late Miocene hominoids one of which gave rise to Hodell 1986; Scott et al. 1999). In Nepal it has been found later hominids (Ciochon and Fleagle 1985). This change in (Hoorn et al. 2000) that from the late Middle Miocene to the phylogenetic position of Ramapithecus (fi gure 1) has early Late Miocene (~11.5–8 Ma), the Himalayan foothills been well illustrated by Kennedy (2003: 119). Possible and the Gangetic fl oodplain were forested with subtropical to ancestors to these Middle to Late Miocene Sivapithecines temperate broad-leafed and tropical forest taxa, which were J.