Microscopic, biochemical and stable isotopic investigation of seven multi-nutritional food-balls from Indus archaeological site, Rajasthan (India)

Highlights

• Seven human made spheroidal balls were found in rural Indus settlement of western India.

• Microcopic, biochemical and GCMS analyses indicate balls contained plenty of agri-food.

• Cereals and legumes dominated the composition.

Abstract

During excavation of a Harappan archaeological site 4MSR (29°12′24.48″N, 73°09′20.16″E) from western Rajasthan (India), seven closely spaced similar sized spheroids (food-balls) were recovered. Detailed microscopic, biochemical (organic), elemental and stable isotopic composition of the spheroidal-material was studied. δ¹³C value of organic fraction (−22.5‰) indicated agricultural origin of organic matter. Significant excesses of Magnesium (Mg) and Calcium (Ca) and Potassium (K) further supported organic (food material) dominance in the spheroids. Gas chromatography mass-spectrometry (GCMS) analysis showed dominance of plant derived organic compounds in the spheroid sample. Microscopic stain analysis using safranin and iodine dyes confirmed bulk of the spheroids was composed of organic material. Majority of starch granule morphotypes found in spheroid-material were made of legumes and cereals dominated by Mung (Vigna radiata). Siliceous phytoliths, Ca and Mg oxalate crystals along with a few Mg sulphate crystals were also observed in spheroids composition. We surmise these spheroids were mainly made up of food grains comprising both cereals and legumes. The concept of offerings for some ritual or multi-nutritive compact food balls for instant nutrition as food-supplement, perhaps prevailing during that period. The presence of bull figurines, hand held copper adze and a Harappan seal in the vicinity of these seven food balls signify that humans revered all these commodities due to their utility and importance to them.

Introduction

Archaeological sites belonging to Indus Valley Civilization (IVC) era possess valuable information about the ancient farming strategies, agricultural-food consumption and contemporary climate. Knowledge gleaned from IVC archaeological sites spread along the northwestern stretch of Indian subcontinent can potentially provide clues about complex human-environment relationships having significant implications on vulnerable looking human sustenance amidst concurrent anthropogenic climate change era. Understating climatic imprint of resident human population from remnants of the past human (cultural) activities has always been challenging and debated owing to its inherent complexities, nonetheless, overall human subsistence is considered to be intimately linked to regional climate (monsoonal activity) (Dixit et al., 2014, Dixit et al., 2018, Pokharia et al., 2017, Pokharia et al., 2014). The cultural/agricultural activities of early humans have been linked to the prevailing climate since Neolithic period (Kotsakis et al., 2018). The early phase of Indus (Harappan) civilization (~3300 to ~ 2600 BCE) is known for its agricultural and pastoral activities (Sharma et al., 2020a). Earlier reported data from IVC archaeological sites suggest that early settlers induced substantial changes in agricultural strategies according to contemporary regional climate (monsoonal) changes (Farooqui et al., 2013, Pokharia et al., 2014, Pokharia et al., 2017; Khonde et al. 2017) and overall subsistence, cropping patterns, crop-manuring and animal husbandry were linked with prevailing climate. A number of sculptures, deities/ terracotta figurines, seals (of Swastika signature), fire alters have been reported from many of the IVC archaeological sites excavated from India and Pakistan (Jarrige and Lechevallier, 1979, Bisht, 1997, Lal et al., 2003, Shinde, 2016). Here we report, finding of seven similar sized closely kept spheroids that were recovered from a cultural layer of archaeological site 4MSR excavated in the District Anupgarh (western Rajasthan, India) (Fig. 1). The 4MSR site spans from the early phase (2880 ± 30 BCE) to the end of mature phase of Indus era (1691 ± 100 BCE) (Sharma et al., 2020b). The investigated site (4MSR) showed no remnants of the late phase of IVC.

Aforementioned dark brown color spheroids visually appear human-made and compositionally different from host soil-sediment (Fig. 1D). Two small bull figurines and a hand-tool (copper adze) were also found in the close proximity of these spheroids indicating a plausible feast activity (Fig. 1E). We carried out a comprehensive multi-proxy biochemical, stable isotopic and microscopic investigation of the spheroidal-material in order to explore the composition of material used in the making of the spheroids. Obtained results provide important insights into types of agri-food grains used in making of these food-balls, which reveal contemporary farming practices of Indus era.