Prehistoric Man and His Environment

The excavations at Ban Chiang have opened a new chapter in our understanding of Southeast Asian prehistory, not only because of the richness of the material culture, but also because of the wealth of data on the environment and economy. Over five millennia of human occupation on the Khorat Plateau have transformed the landscape. Plant and animal communi­ties as well as the flow of water and even the nature of some soils bear little resemblance to the situation when pre­historic man first settled there. Some species are now locally extinct, others have been successively introduced. Natural marshland has been converted to rice fields, and extensive tracts of woodland have been cut down.

Wet and Dry Seasons

Some basic elements of the environment, however, are quite probably similar to those encountered by the prehistoric population. Thus the sharp distinction between the wet and dry seasons, which so affects the present adaptive behavior of plants and animals, probably obtained throughout the prehistoric period. This conclusion is based on the growth charac­teristics of prehistoric specimens of Pile ampullacea, a shellfish which adapts to the dry season by burrowing into soft soil and aestivating.

The vegetation best adapted to such marked seasonal fluctuations in rainfall is known as moist monsoon forest. The popu­lar conception of tropical Southeast Asia as being covered by a dense canopied rain forest is quite incorrect. The moist mon­soon forest comprises many tree species which lose their leaves during the long dry season (Fig. 1). Access of light to the forest floor promotes a thicker mat of herbacious plants and grasses than is the case in adjacent regions, where more evenly distributed rainfall sustains cano­pied, evergreen forest. Consequently, many animals are specifically adapted to the deciduous form. We should not, however, view the Khorat Plateau as a relatively flat landscape under a deciduous forest during the prehistoric period. Although nearly all the region lies between 150 and 340 meters above sea level, there is in fact much diversity. This environmental mosaic is particularly relevant for the rice cultivator.

The soils of the plateau differ between four major zones. There are the high, mid­dle, and low terraces, which are succes­sively younger in origin, and the flood plains (Fig. 2). Soils of the first two are excessively drained sandy loams which are currently avoided for wet rice cultivation. The low terrace bears relatively infertile soils, which, however, have higher water retention and are now favored for the cultivation of wet rice. The soils of the flood plains are best suited to wet rice, except that they are prone to severe flood­ing. In prehistoric times, the principal dis­tinction in terms of vegetation was prob­ably between the dry deciduous forest of the three terraces and the swamp grassland found on the perennially inundated flood plains. Swamp grassland would, of course, have been much restricted in small, incised tributaries of the major rivers. Wild rice is ane of the plants which was probably adapted to such areas. Indeed it is still found in parts of northeast Thailand.

The relationship between plant and animal communities was probably intimate. Such large herbivores as the rhinoceros, elephant, water buffalo and Schomburgk’s deer are historically recorded in the swampy flood plain habitat. Conversion of such areas to irrigated rice land through water central programs during the past 150 years, has practically eliminated all four. The Schomburgk’s deer is now extinct, while wild water buffalo survive only in remote parts of Uthai Thani province. The swamp land would also have sustained numerous species of fish, shellfish and amphibians. Rana tigrina, for example, is a frog adapted specifically to the flood plain habitat.

The drier woodland on the low to high terraces would also have had its own faunal association. The largest species are the wild cattle and sambar deer. Pig deer, wild pig and muntjac are found, and their predators were formerly the tiger, leopard and jackal.

It is self-evident, therefore, that we can obtain much information both from the location of sites like Ban Chiang, and from the animals exploited by their prehistoric inhabitants.

The Environment When First Settled

During early 1980 we undertook an intensive site survey in the area southwest of Ban Chiang and found numerous pre­historic inhumation burial sites (Fig. 3). Our analysis of the distribution of these sites revealed a significant affinity with small streams and low terrace soils. No such sites, however, were found near the flood plain soils of the large Phaa River. When we turn specifically to Ban Chiang we see that the first occupants there chose proximity to three small tributary streams and an extensive tract of low terrace soils. The basal levels of Ban Chiang included rich middens containing many fragments of bone. Rigorous sieving procedures there have made possible, for the first time in Southeast Asia. the study of a well provenanced biological sample from a large open settlement site. All bone and shell fragments have been analyzed and where possible, assigned to the species in question. Let us consider the prehistoric environment and economy as revealed by these bone fragments, and how each changed with time.

What does the earliest assemblage tell us about the environment when Ban Chiang was first settled? The remains of shellfish indicate a water regime which differed markedly from that found there today.

Among the shellfish collected at Ban Chiang are two species of the genus Pula. Modern specimens of Pile polity sought in the vicinity of Ban Chiang during 1978 were invariably associated with permanent, still water such as that found in lakes and swamps. The same applies to Pile ampuIlacea except that this species can survive by the process of a estivation if surface water evaporates completely dur­ing the dry seasan. Its preferred habitat then, is in swamp margins or seasonally fugitive bodies of water. Density decreases markedly with distance from such areas.

The gastropod Filopaludina lives in still, or slowly moving, water while Trochotaia lives today in still ponds and lakes. Both recur in early shell middens at Ban Chiang. The small gastropod Bythinia lives in small, slow moving streams. and was prob­ably collected unintentionally when hand dredging for other species. Taken in con­junction, this range of shellfish suggests an environment containing bodies of perma­nent, still water and clear, slowly moving streams.

There were also some remains of land snails at Ban Chiang. Of these, Cylophorus and Hemiplecta are interesting because they are currently found in Dipterocarp Forest with a well-drained leaf litter. This finding supports the conclusion that the low to high terraces were under a similar forest cover during the early part of the prehistoric sequence.

The faunal spectrum (Fig. 5) confirms the exploitation of species which adapted to permanent water. There are at least three varieties of fish, and probably many more were exploited. The three species represented have particularly durable bones and it is surely likely that there were smaller, more fragile specimens which have not survived. Trionyx and Chitra are soft-backed turtles, and Rana tigrina is the small frog described already as one adapted to flood plains. It is currently found in paddy fields araund Ban Chiang. There are also a few remains of the otter (Lutra). The lowest level at Ban Chiang is the only one to contain the bones of the squirrel. This animal is, of course, well adapted to wood­land. Three other small mammals, the mongoose (Herpestes), small Indian civet (Viverricula) and hare (Lepus) are, by con­trast, more often found in grassy forest clearings. Ground-dwelling mammals are numerically dominant in all phases at Ban Chiang. Pig remains are particularly numerous in the lowest layers, followed by those of cattle and deer.

Now the only site in northeast Thailand which is comparable with Ban Chiang in terms of area excavated is Non Nok Tha, where cattle and pig bones were found in association with the human burials. The cattle bones are demonstrably smaller than the modern, indigenous wild cattle of Thailand, and the shape of pigs’ crania is distinct from the wild form. Both, it is felt. come from domestic animals. There are fewer complete pig or cattle bones from Ban Chiang, but the same canclusion arrived at for fish bones is justified an the basis of the size of the specimens available. The first settlers introduced domestic herds, but also hunted wild animals.

The deer bones come from three species, all of which are adapted to the dry decidu­ous forest. All large antlers come from the Sambar rather than the Schomburgk’s deer. The latter is of similar body size as the Sambar, but has a broader spread of antlers, reflecting its adaptation to an open habitat.

The dog is also abundantly represented from the first use of the site. It was of the same size as the modern village dog, and descended, according to the shape of its skull, from the wolf. This is particularly interesting, because the wolf is not in­digenous to Southeast Asia. Indeed, China is the nearest area which sustains the wild wolf. The dog is the only exotic species found at Ban Chiang.

The sieving procedures at Ban Chiang ensured recovery of the smallest bone frag­ments, and so make it feasible to consider not only species present but those which were not represented. There are no animals specifically adapted to the evergreen rain forest. Absent too are the large animals adapted to flood plain swamps: there are no remains of water buffalo, elephant or rhinoceros.

There is tittle doubt that the initial economy at Ban Chiang was wide-ranging. Apart from the introduced domesticants, a wide range of species was exploited. We may envisage such activities as fishing and shellfish collecting in the permanent lakes and of trapping in or near forest clearings.

Hunted animals included the huge wild cattle, known as the Gaur and Banteng, as well as the deer and the tiger. Snails and tortoises were collected in the shaded forest, and the number of wild birds sug­gests that they, too, were sought. Only a handful of species was represented at Non Nok Tha, due to the hard nature of the soil there and lack of sieving procedures. Nearly fifty different species come from early Ban Chiang, presenting a picture of a vigorous, broad spectrum economy.

Changes During the Early and Middle Periods

There was little change during the Early Period. We can add as new species the rare and elusive fishing cat (Felis viverrina), the Bengal cat, (Felis bengalensis), the Burmese ferret-badger (Melogale per-sonata) and a spiny eel (Mastacembelus). These confirm an interest in aquatic and farest species. There are also a few bony scutes from the crocodile, and one bone from the water buffalo.

A more pervasive change in the animals represented had come by the Middle Period. While these may seem al little note individually, in conjunction they present a coherent and very intriguing picture. In the first place, we find that the water buffalo became relatively abundant. Moreover, the bones come from an animal identical in size to the modern domestic breed in Thailand and much smaller than the wild type. It may well be that the narrow flood plains of the small streams which flow past Ban Chiang were not extensive enough to sustain wild water buffalo, and that a domestic form was introduced by the Middle Period (the later Om Kaeo phase). As the water buffalo became established, many of the aquatic species became increasingly rare, or ceased to be repre­sented. Thus the otter was no longer found, while bones of fish diminished in frequency. The number of small mammals which prefer open terrain also diminished markedly. With the exception of the very latest layers, which may reflect access to firearms, bones of wild birds became rare. The domestic chicken, however, was rela­tively abundant throughout the sequence.

The bones described above reveal numerous instances of butchering and burn­ing consistent with food processing. It may be that changes with time in the frequen­cies of animals are due only to sampling bias, for only a tiny fraction of Ban Chiang has been excavated and perhaps other parts of the site would present a different pic­ture. On the other hand, the faunal spectra of two nearby sites, Ban Tong and Ban Phak Top, (Higham and Kijngam 1979) are very similar indeed to that described for Ban Chiang itself. This situation suggests ha L we are dealing with an economic pattern, and that we should seek to isolate possible reasons underlying it.

Rice Cultivation

At this juncture, it must be emphasized how unrealistic it would be to interpret the Ban Chiang faunal spectrum without incorporating other aspects of the culture responsible for it. For example, innovation in technology and the pressure created by any proposed population increase are critical factors which need consideration.

Of particular relevance is the nature of any rice cultivation which integrated with ani­mal husbandry and acquisitian of wild species.

The close association of all known sites like Ban Chiang with low terrace soils near tributary streams itself encourages the notion that the prehistoric occupants were concerned with the cultivation of rice (Fig. 10). Rice chaff is found as a temper in early pottery from Non Nok Tha and Ban Chiang (Yen 1977). For a study of the rela­tionship between Ban Chiang pottery and rice, see the article by Douglas Yen, pages 51-64 of this issue of Expedition.

There are several methods of cultivating rice in northeast Thailand. One is to remove competing plants by cutting and dry-season burning along the margins of lakes and swamps, and planting out the seed in the cleared terrain. This is known as wet swiddening, and may be easily under­taken in conjunction with collecting wild rice where available. Swiddening can equally be undertaken on the low terraces, but reliance on rainfall, and a longer cycle of fallow and the extra work entailed in clearing the dry deciduous forest are involved. The most widespread technique employed in northeast Thailand today is to create swampy conditions by arresting the flow of water from fields into the natural watercourses. This is achieved by building banks between fields. Where the land is flat, this is fairly straight forward, since soils are soft and easily worked. Increased slope, however, can involve considerable effort in restructuring the landscape. This ‘wet rice’ system (often known as paddy cultivation) is particularly productive when the soil is turned by the plow, because plowing aerates the soil, kills competitive weeds by up-ending them, and helps create a hard pan of fine soil particles below plow level which retains water in the field. Again, the slow percolation of water dis­seminates blue-green algae which fix nitro­gen, while upturned weeds decaying under anaerobic conditions release valuable plant nutrients. In a word, plow wet rice cultiva­tian allows annual cropping even on poor, sandy soils.

There is no evidence for wet rice cullivation during the earliest phases at Ban Chiang. There are no draft water buffalo, and cattle are most unlikely to have pulled a plow since their bones are so gracile that they must have been very small and slender animals. The faunal spectrum is consistent with some forest clearance and an interest in water resources however, so it is con­sidered likely that some form of wet swidden cultivation was undertaken during this time.

Further Change in the Middle Period

With the Om Kaeo phase, however, the situation changed markedly. Following the introduction of the water buffalo, aquatic species and the small grassland mammals declined. It is tempting to view these changes as the reflection of a basic shift to wet rice cultivation, for conversion of forest to rice paddies plays havoc with the water regime. Water which formerly reached the water table and fed perennial streams remains on the surface, where evaporation is high. Where this occurs today, streams dry out for part of the year, ruling out the survival of many species of fish. The direct access of monsoon rain­storms introduces turbid water into streams and lakes, endangering filter feeding shell­fish and those species which rely upon them. The availability of iron by this time would have expedited the process of forest clearance, due to its superior cutting quali­ties compared with bronze. Perhaps it was also used to tip plowshares.

Summary

We clearly need more evidence before accepting this interpretation of the Ban Chiang faunal spectrum. It would be help­ful to have, for example, prehistoric depictions of plowing, surviving plow­shares, or datable fossil fields. Such evi­dence is found elsewhere, but there is none in northeast Thailand. There are however, the bones of animals which may have been used for traction. Examination of modern Thai cattle and water buffalo bones reveals that draft animals develop large bony ridges at points of tendon attachment. Just the same growths are apparent on corre­sponding water buffalo bones from Ban Chiang. To this extent, there is supporting evidence for plowing there from the Om Kaeo phase.

But why should the prehistoric inhabi­tants have embarked on the labor intensive task of clearing forest and re-modelling the landscape? A transition from wet swidden to plow cultivation of rice in fixed fields among the Dyaks of Kalimantan (Borneo) has recently been studied by the geographer Seavoy (1973). He concluded that popula­tion pressure leading to demands for more rice was responsible. Documentation of population growth in prehistory is hard to demonstrate, but Pietrusewsky has argued that in fact, the population of Non Nok Tha did increase during the prehistoric period. There is no doubt that by the 1st millennium A.D., occupation sites up to fifty times larger than Ban Chiang existed.

Ban Chiang is located in a part of the Khorat Plateau which receives relatively high rainfall. South of the Dong Mun hills, the plateau becomes increasingly arid. Indeed, it may well be that occupation of the arid Mun-Chi valleys by rice cultivators became a practical possibility only after water control methods had been developed at sites like Ban Chiang. The data from this great site illuminate not only the popu­lation’s changing relationship with its environment there, but also the broader perspective of Thai prehistory.