Saturday, December 17, 2016

The Arrival Of Rice Domestication In India

The wild form of rice has been gathered and eaten in parts of India since the Holocene climate optimum began ca. 7000 BCE, but domesticated rice appeared much later, although it did pre-date the arrival of the Indo-Aryan in India. This timing largely coincides with the arrival of the linguistically Austro-Asiatic Munda people (in a male dominate migration) to India from Southeast Asia.
The nature and timing of rice domestication and the development of rice cultivation in South Asia is much debated. In northern South Asia there is presently a significant gap (c.4200 years) between earliest evidence for the exploitation of wild rice (Lahuradewa c.6000 BCE) and earliest dated evidence for the utilisation of fully domesticated rice (Mahagara c.1800 BCE). The Indus Civilisation (c.3000–1500 BCE) developed and declined during the intervening period, and there has been debate about whether rice was adopted and exploited by Indus populations during this ‘gap’. 
This paper presents new analysis of spikelet bases and weeds collected from three Indus Civilisation settlements in north-west India, which provide insight into the way that rice was exploited. This analysis suggests that starting in the period before the Indus urban phase (Early Harappan) and continuing through the urban (Mature Harappan/Harappan), post-urban (Late Harappan) and on into the post-Indus Painted Grey Ware (PGW) period, there was a progressive increase in the proportion of domesticated-type spikelet bases and a decrease in wild-types. 
This pattern fits with a model of the slow development of rice exploitation from wild foraging to agriculture involving full cultivation. Importantly, the accompanying weeds show no increased proportions of wetland species during this period. Instead a mix of wetland and dryland species was identified, and although these data are preliminary, they suggest that the development of an independent rice tradition may have been intertwined with the practices of the eastern most Indus peoples. 
These data also suggest that when fully domesticated Oryza sativa ssp. japonica was introduced around 2000 BCE, it arrived in an area that was already familiar with domesticated rice cultivation and a range of cultivation techniques.
J. Bates, et al., "Approaching rice domestication in South Asia: New evidence from Indus settlements in northern India" Journal of Archaeological Science (November 21, 2016).

From the body text:
2. Background 
2.1. Rice domestication and South Asia 
Modern domesticated rice, Oryza sativa, has a complex history as it is the product of repeated instances of hybridization. Current genetic evidence suggests that it developed from the hybridization of two other domesticated forms: O. sativa ssp. japonica, which is a Chinese rice domesticated from wild O. rufipogon around 4000 BCE ( Fuller and Weisskopf, 2011), and O. sativa ssp. indica, which is a domesticated version of the South Asian O. sativa ssp. nivara (Fuller et al., 2010). Based on this evidence, Fuller, 2005, Fuller, 2006 and Fuller, 2011 has suggested that O. sativa ssp. indica may have been domesticated many times, including during what he has referred to as a ‘proto-indica’ phase of cultivation (Fuller, 2011). Using a combination of genetics, the modern distribution of wild rice species, and archaeological evidence, Fuller, 2002, Fuller, 2005, Fuller, 2006, Fuller, 2011 and Fuller and Weisskopf, 2011) has also suggested that one of these domestication events may potentially have taken place in the Ganges region of India. 
Fuller and Madella (2002) have, however, long argued that the archaeological evidence for rice exploitation in South Asia is patchy and often inconclusive. Based on what is available, Fuller (2011: 82) has proposed that the “independent rice tradition in north India […] never […] proceeded on its own to full domestication” until the arrival of O. sativa ssp. japonica c.2000 BCE. 
The earliest evidence for rice cultivation in South Asia comes from the site of Lahuradewa, which is situated in the Middle Ganges plains in north India.  Tewari et al. (2008) have recovered charred rice grains from the site that have been radio-carbon dated to 6409 BCE (8359 cal BP) (Tewari et al., 2008: 350), and based on grain length, width and thickness ratios they have suggested that the rice was a domesticated variety. Fuller et al. (2010) have, however, noted that the morphometrics for these grains from Lahuradewa overlap significantly with those of wild grains, and have therefore argued that Lahuradewa could instead represent the beginnings of a long history of cultivation of wild rice that continues throughout the sites occupation. Other sites such as Balu, Banawali and Kunal ( Saraswat and Pokharia, 2000, Saraswat and Pokharia, 2002 and Saraswat and Pokharia, 2003) provide evidence of rice that is poorly dated but roughly place its use within the third millennium BC (see below) while wild rice was also noted at Senuwar 2 in the Middle Ganges (Saraswat, 2005). Until recently the earliest evidence for domesticated rice based on spikelet base evidence was from the site of Mahagara in the same region, c.1800–1600 BCE. However, as Fuller et al. (2010) have remarked, this attestation is representative of the end of the process of domestication, and is likely to date close to the point when there was a hybridization between O. sativa ssp. indica/O. nivara and O. sativa ssp. japonica. 
The presence of rice at sites like Kunal, Balu, Banawali and Harappa (Saraswat and Pokharia, 2000, Saraswat and Pokharia, 2002, Saraswat and Pokharia, 2003 and Weber, 2003) has led scholars to question the role of the Indus Civilisation in the development of rice cultivation systems and even in rice domestication (e.g. Fuller and Madella, 2002 and Fuller, 2011). Evidence for rice in northern South Asia in the period between the first exploitation of rice (whether wild or domesticated) at Lahuradewa and the later appearance of clearly domesticated agriculturally grown rice at sites like Mahagara has been eagerly sought, and it has been suggested that Indus Civilisation settlements could provide it (e.g. Fuller, 2002, Fuller, 2006 and Fuller, 2011). The next section will explore how these debates have evolved. 
2.2. Rice exploitation by Indus Civilisation populations 
Indus Civilisation populations inhabited the north-west of South Asia between c.3000–1500 BCE, and although settlements were primarily distributed in the Indus and Punjab drainage basin, Indus populations also occupied parts of the Kanuma-Ganges doab, where theoretically they could have come in contact with, and adopted, rice from the Gangetic region (Fuller and Madella, 2002). 
Arguments for and against the use of rice by Indus populations began when impressions of rice grains were observed in pottery from Indus settlement sites in Gujarat and Rajasthan (e.g. Ghosh and Lal, 1963 and Vishnu-Mittre and Savithri, 1975). Evidence of rice grains has also been recovered from several sites in northwest India (e.g. Early Harappan Kunal, Saraswat and Pokharia, 2003; Early Harappan Balu, Saraswat and Pokharia, 2002; Mature Harappan Banawali), but these attestations have not been securely dated, and the chronology presented in the reports is opaque. Evidence of rice phytoliths from Harappa was presented by Fujiwara et al. (1992) who tentatively dated some of their samples to the Mature Harappan period, confirmed by Madella (2003) in contexts c. 2200 BCE, although the only macrobotanical evidence for rice grains from the site places it in the Late Harappan period ( Weber, 1997 and Weber, 2003). As such Possehl (1999: 246) has argued that there is no evidence for rice cultivation before the Mature Harappan period (i.e. pre-c.2500 BCE). Fuller and Madella (2002: 336–7) have argued that “rice was available as a crop […] but not adopted” and “there is no reason as yet to believe it was an important crop”, while Fuller and Qin (2009) have argued that there is no evidence of rice agriculture until the Late Harappan period c.2000 BCE, when it is likely O. sativa ssp. japonica arrived. More recently Madella (2014: 230) has considered whether the role of rice changed over time from a secondary crop in the late Mature Harappan to become a staple crop either in the Late Harappan periods or the Early Historic periods. He suggested that rice may have been a secondary but sought after product by Indus Civilisation peoples, explaining its appearance at Harappa, outside its natural habitat and in only small quantities. Madella (2014: 230) also argued that rice only became a staple when its status as a rare crop was lost as superior strains were introduced c. 1900BCE, and as diversification in agricultural strategies occurred during the Late Harappan period and into post-Harappan periods. 
Three major issues arise from these interpretations. Firstly, there has been a consistent lack of systematic archaeobotanical sampling from Indus sites and many of the rice remains recovered have been of the larger and more obvious grains (Bates, 2015). Secondly, models that differentiate wild gathering, semi-domesticated or wild cultivation, and domesticated agriculture have been developed without an assessment of the spikelet bases at Indus settlements to ascertain how the numerical proportions of wild and domesticated varieties changed over time. Furthermore, the dating of rice use at Indus Civilisation settlements remains problematic (Petrie et al., 2016a). 
A lack of systematic archaeobotanical sampling has long bedevilled South Asian archaeology, and the evidence from Indus sites has typically been presented as presence/absence data with little indication of how crop seed grains were recovered. Furthermore, although it has long been argued that grains alone are not suitable for analysis of domestication (Thompson, 1996, Harvey, 2006 and Fuller and Weisskopf, 2011), archaeobotanical publications for South Asian sites typically only discuss grains, and neglect to consider weeds and crop processing residues. 
There have been several attempts to differentiate wild and domesticated rice in South Asia. Harvey (2006) conducted studies comparing the length: width: thickness ratios of rice reference and archaeological material and concluded that there was too much overlap in the morphometrics of wild and domesticated species, in particular between the wild O. nivara and O. rufipogon, and between O. nivara and its domesticated form, O. sativa ssp. indica. Recently Castillo et al. (2015) have re-evaluated the use of grain morphometrics to distinguish domestication in rice, and have suggested that some distinction can be made between O. sativa ssp. indica and japonica, but they also note that no distinction can be made between wild and domesticated rice grains using this method. In contrast, spikelet bases have been observed to change morphologically during the domestication process, due to changes in seed dispersal mechanisms (Thompson, 1996). Wild spikelet bases have smooth scars as the rachis shatters to allow for seed dispersal, while domesticated spikelet base scars are rough, because the rachis is non-shattering (Harvey, 2006 and Thompson, 1996). Spikelet bases are far smaller than grains, and are often not visible to the naked eye in soil, so they are likely to have been missed at sites where only hand-collecting of remains has been carried out. Analysis of the smaller fractions of floated samples is necessary for gathering such data, but this approach is not often carried out in South Asian excavations (Harvey, 2006). 
The complexities of this situation are compounded by the fact that the dating of Indus rice in particular remains vexed. Although rice grains have been noted from the Early and Mature Harappan site of Balu (Saraswat and Pokharia, 2002 and Saraswat, 2002), the contexts from which these grains come is unclear, and the date of rice use is difficult to ascertain. For example, the Early and Mature Harappan occupation at Balu has been given the date range of 2300–1700 BCE (Saraswat and Pokharia, 2002 and Saraswat, 2002), which spans both the Mature and Late Harappan periods (Petrie et al., 2016a). The presence of rice has also been noted at Kunal (Saraswat and Pokharia, 2003), but the lack of clear contextual information again makes assessing the precise date of its use difficult to ascertain (Petrie et al., 2016a). 
In addition to these issues, the date and impact of the shift to wetland rice cropping has also been debated. For example, Coningham (1995: 66–67) has hypothesised that during the post-Indus period there were changes in the methods of growing crops, particularly rice, with a shift from dry to wet land rice. He speculated that with wetland rice exploitation there might have been an increase in yield (kg per acre), which could have supported the rise of even larger urban centres than seen in the preceding Indus Civilisation period (Coningham, 1995: 66–67). This argument was based on the presumed preference for different ecologies of the two main rice crops, as both the wild nivara and domesticated indica grow in drier conditions than rufipogon or japonica. However, Fuller and Qin (2009) have noted that all rice species prefer wetter conditions, and can be exploited in a wide range of conditions. They have instead argued that hybridization did not necessarily have to lead to a sudden shift in cropping system towards wetland irrigated rice, and that a more mixed strategy may have been seen, with a range of wet and dry cropping exploited an it is today in some areas of South Asia (Fuller and Qin, 2009). Exploring when wetland rice was introduced and the impact it had is, however, important as wetland systems do increase yield as noted by Coningham (1995). In order to identify this transition, the weed flora must be considered, but it is often not reported in detail in archaeobotanical studies (Fuller and Qin, 2009). In the absence of weed data, Fuller and Qin (2009: 104) relied on the percentage-presence of wet and dry weed taxa from several sites across northern India from the Neolithic to Early Historic periods, and suggested that an increase in the amount of wetland species and a decrease in the presence of dryland species is evident, with only dryland species disappearing over time. However, their study does not take into account the role of the Indus Civilisation in this process. Given the new finds of securely dated rice grains (Petrie et al., 2016a) and the associated spikelet bases reported in this study, the Indus Civilisation becomes an important part of the picture of rice cultivation strategies in the subcontinent. 
Our understanding of rice exploitation by Indus populations and the development of rice agriculture during this period in South Asia thus remains patchy and poorly understood, as highlighted by Fuller and Madella in 2002. This paper will attempt to fill some of these gaps and consider how rice exploitation may have developed over time in north-western South Asia. To do this, it will present new archaeobotanical data from settlement sites in northwest India, which lies in the north-east of the Indus region.
The study itself made the core finding that while domesticated rice was present in the Mature Harappan period (pre-1900 BCE), that most rice consumed was of the wild type. In contrast, only domesticated rice was used after that time period in the Late Harappan period.

Table 1.
Periodisation of the Indus Civilisation (after Possehl, 2002:29).
Early Harappan3200–2600 BCE
Early-Mature Harappan Transition2600–2500 BCE
Mature Harappan2500–1900 BCE
Late Harappan1900–1300 BCE
Painted Grey Ware (PGW) (early Iron Age)1300–500 BCE
Table 2.
Number of spikelet bases per 20l sediment and as a proportion of spikelet bases from Mature and Late Harappan contexts at Masudpur VII.
Rice spikelet base typeContext 514Mature Harappan (%)Context 515Late Harappan (%)

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