Humans and Environments
HUMANS AND ENVIRONMENTS
Even if humans had never evolved, Europe would look different compared with the same area ten thousand years ago. In about 9500 b.c. this peninsula of the Eurasian continent still was recovering from the last great manifestations of the glaciations that had been occurring for about 2 million years (the Pleistocene period, followed after 9500 b.c. by the Holocene period, the current period) and that had been at their height about 18,000 years ago. In 9500 b.c., however, the only major sheet of ice was over Scandinavia, with smaller outliers on the mountains of Scotland and northern England. Nonetheless there was sufficient ice on the globe to lock up a great volume of water, and so sea level was well below where it is in the early twenty-first century. For example, Sardinia and Corsica were joined, the Black Sea was isolated from the Mediterranean, and England was still connected to the major landmass, though Ireland had been separated for many centuries.
life after the ice age
Even if the great polar ice masses were pretty well bereft of nonhuman life above ground, at their margins there were populations of phytoplankton and zooplankton, fish, migrant seabirds, penguins, seals, and whales. In the north whales, seals, arctic foxes, and polar bears were found at the margins of sea ice and land. Thus the world in 9500 b.c. was nowhere entirely deprived of life, even though proto-Europe itself was a far colder place than it later became.
It is no surprise therefore that an array of increasingly complex and biologically diverse ecological systems covered the landmass south of the Scandinavian ice and that, as the climate ameliorated, these systems moved northward. By 9500 b.c. the formation (usually called a "biome," meaning an integrated system of soils, plants, and animals) nearest the ice, the tundra, was restricted in area and was largely maritime in distribution. The bulk of the Continent was covered in boreal forest, dominated by coniferous trees and containing a great deal of wetland and with a mammal fauna that included moose, beaver, and reindeer. Open land at higher elevations was home to reindeer and wild horse, as was the tundra. To the south was a broad band of temperate forest dominated by a mixture of temperate species, such as oaks, elms, linden, and hazel. A small admixture of conifers was found on poorer soils and at high altitudes. The fauna included red deer and roe deer as well as wild ox, or aurochs. The Mediterranean fringe was covered in steppe and grassland.
One feature of the deglaciated land of Europe was a scattering of lakes, some long and thin in valleys formerly occupied by glaciers and others more round in hollows in glacial debris or in front of ice sheets, as with the Scandinavian basin that was to become the Baltic Sea. The whole was flanked to the west and south by saltwater seas, the open Atlantic and its inlets to the west and the more enclosed and warmer Mediterranean in the south. Where major rivers entered the sea, long branched estuaries with salt marshes and freshwater fens kept pace with rises in sea level.
Such a banding of biomes was home to huntergatherer populations of the types usually labeled Upper Palaeolithic. Some groups depended upon coastal fishing and others on mammal populations, such as reindeer or wild horses. Still others inhabited the depths of the deciduous woodlands, and the farther south the groups were, the greater the vegetable content of their diets. All had to show adaptability in the face of the biological and climatic changes that were to come.
early holocene warming
One of the lessons from the present plethora of research into climatic history is that change is not necessarily gradual. In the case of Europe the transition from the tail end of the ice ages to a much more temperate climate was quite rapid. About 9500 b.c. amelioration started to produce warm surface waters (above 14°C [57.2°F]) around the coasts of western Europe, and warming rates may have reached about 1°C (1.8°F) per century in these waters. On land, rates of 3 to 4°C (5.4 to 7.2°F) per 500 years have been postulated for France and even 1.7 to 2.8°C (3.06 to 5.04°F) per century in not yet insular Britain. Overall the climates of Europe may have reached levels similar to those of the twentieth century or even a little warmer by 7000 b.c.
The consequences for the natural world and hence for human habitats were profound. The vegetation belts and their associated fauna shifted northward, so most of Europe was a cool temperate forest zone with dominance by broad-leaved trees. There were montane variants in the Alps, and over much of Scandinavia and eastern Russia the overwhelming dominance of conifers meant that a taiga, or open forest, was the land cover. A taiga biome also penetrated some of the loess lands of the northern European plain, and the Black Sea had a broad penumbra of moist steppe, which was in essence treeless grassland. Within all these biomes, the better conditions encouraged rapid plant growth, so many lakes left in glaciated regions began to fill with organic debris and the area of open water shrank when colonized by marginal vegetation.
A major result of the warming was more free water in the oceans as the polar, mountain, and Laurentide ice sheets melted, producing what are termed "eustatic" rises in sea level. Such increments, however, often were in opposition to isostatic rises in land levels as land surfaces rose when freed from the weight of the ice that had depressed them. The northern part of the Gulf of Bothnia has risen about 850 meters during the Holocene and is still rising at 9 millimeters per year. Northern Britain is still rising, too, though at less than 3 millimeters per year, and the south is sinking at up to 2 millimeters per year. Thus many European coasts during the era of barbarism were the outcomes of competition between eustasy and isostasy, with the latter winning easily to the north. The shorelines and harbors from which the Vikings launched their ships were almost 8 meters above the modern sea level.
The largest-scale physical consequence of sea-level change is found in the Baltic. The region underwent a four-stage evolution in which there was an interaction of ice retreat, eustatic rises of sea level, and isostatic rebound. During the Terminal Pleistocene the Baltic essentially was an ice-dammed freshwater lake, but the retreat of ice in central Sweden led this lake to fall by about 28 meters and become connected to the Atlantic, thus turning brackish. By 7000 b.c. this outlet was closed, and the new but narrow outlet that developed in the region of the Great Belt allowed the Baltic to become a freshwater lake again. After 6500 b.c. more saltwater penetrated, since increased eustasy was accompanied by decreasing isostasy, bringing about the twenty-first-century salinity gradients of the Baltic–Lake Ladoga region.
the holocene optimum
Between c. 7000 and 4000 b.c. the climate in Europe reached its optimal level (the Hypsithermal) in the present interglacial. It was not, however, uniform in its onset. In the British Isles the maximal warmth was about 6000–4500 b.c., whereas in northern Europe 4000–2500 b.c. saw the highest average temperatures. There are of course no instrumental records, but data from fossil pollen and other organic remains, the stratigraphy of lakes and bogs, and from tree rings suggest that temperatures were at least 1 to 2°C (1.8 to 3.6°F) above those of the late twentieth century. This implies of course that the spread of agriculture into much of Europe and the development of all the more complex societies of Celtic Europe and their early medieval successors took place in periods of climatic deterioration (albeit with warmer remissions). The huntergatherers had had the best of the weather.
The consequences for the natural environment are obvious to some extent. The forest belts extended northward, so mixed deciduous forest was dominant over much of Europe, save from mid-Scandinavia northward, where conifers and birch predominated, and in mountainous areas. Here there were always more conifers, though not to the extent familiar in the Alps, for example, where there was more beech (Fagus spp.). The steppes of the east retreated in favor of woodland cover. Within the forests, too, species that were adapted to greater warmth flourished. The lime (Tilia spp.) is a good example, along with ivy (Hedera sp.), holly (Ilex), and mistletoe (Viscum). The European pond tortoise (Emys orbicularis), confined to the Mediterranean in the twenty-first century, was found in Denmark and southern Sweden. The presence of insect and molluscan faunas also reflected the warmth, but of greater importance for human communities were the large mammals, such as the red and roe deer, wild ox, wild pig, and beaver. As the optimal period peaked, agriculture became important, and it is clearly critical that such cereals as wheat and barley were able to ripen even in the British Isles and southern Scandinavia.
Another feature of the optimal period was its water relations. In the early part the climate over most of Europe was drier than in the twenty-first century, but as time passed there was a move to wetter conditions, especially in the west. In part this change reflected the increasing influence of the sea as its levels rose. A leading consequence of this continued eustasy was the formation of the Dover Strait and then the submergence of the low-lying terrain between England and the Low Countries to form the North Sea. By c. 7400 b.c. the British Isles were insulated from the rest of Europe, and it took the completion of the Channel Tunnel in the 1990s to make it possible again to walk from Dover, England, to Calais, France. In cultural terms this separation took place in the Mesolithic. The adoption of agriculture in the British Isles necessarily was preceded by a sea passage of some kind of mix of ideas, people, seeds, and young cattle.
Wetter conditions are reflected to some extent in higher lake levels and thus the renewal of lake-fringe successions, but they are most apparent in upland areas and the western fringe of Europe. Two processes are notable. The first is the leaching of minerals down the profiles of many types of soils, particularly from those on such acid substrates as sandstone and gritstone. The redeposition of minerals, such as iron and manganese, in solid horizons ("pans") made the soils prone to becoming waterlogged, and hence their floras moved away from large tree species toward wet- and acid-tolerant species, such as birch, and to dwarf shrubs of the Ericaceae family. On some uplands in Scandinavia and the British Isles great blankets of peat formed on low slopes where the rainfall exceeded about 700 millimeters per year. It is possible that there was some human involvement in the inception of these miry spreads, whose surface often was one of the bog mosses of the genus Sphagnum.
population and environment at 5000 b.c.
A synoptic look at this time reminds one that the fundamental change in the human condition, namely the adoption of agriculture, had penetrated to most regions in which cereals would ripen. The breeding of hardier varieties and the extensive use of oats (Avena spp.) in the coolest and wettest places later extended this zone. Along with cereals and pulses, cattle and sheep were essential ingredients of the agro-ecosystems that developed. All this implies that human communities were responsible for new genotypes as economies based on domestication got farther away from the southwestern Asian heartland and moreover that new ecosystems were an inevitable consequence of the new cognition of nature that grew out of the imperatives of farming as a way of life. The rises in sea level were helpful in allowing drift in the North Atlantic onto coasts north of 50 degrees latitude in places where otherwise ice might be expected. A few places nonetheless retained hunters or developed herders; only the latter groups (e.g., the Saami) were to persist beyond "prehistoric" times.
barbarian lands through to medieval times
The next major environmental changes of wide significance to human societies in Europe were a significant deterioration in climate after 700 b.c., with a better phase during a.d. 1–600 and then a period of warmth between c. a.d. 900 and 1250 known as the Little Optimum or the Medieval Warm Epoch (MWE). The very existence of this latter fluctuation is to some extent uncertain, but it seems best attested to in northern and western Europe. This forms a convenient terminal point because certainly by the end of this period the whole of Europe possessed some form of Christian culture. The implication, however, is that the development of the relatively complex societies that were labeled barbarian by the Greeks, the Romans, and then Christendom were all constructed in a period of relatively poor climate (with temperatures perhaps 1 to 2°C [1.8 to 3.6°F] below those of the more recent past). This was a time in which a series of fluctuations produced, among other effects, southward and downward movements of tree lines, more conifers in mountains and central Scandinavia, more rapid peat growth, more sea ice in the North Atlantic basin, and a lowering of sea temperatures.
The evidence from ice and peat cores, too, shows that there were short-term fluctuations caused by volcanic eruptions, especially in Iceland. A major expulsion of debris into the atmosphere can produce demonstrable decreases in temperature (a kind of "nuclear winter") and no doubt declines in crop yield. Within the period of most interest, fallout of volcanic ash ("tephra") from Icelandic sources (especially the mountain Hekla) can be detected much farther south, with tephra horizons at 1525–1850 b.c., 635–1100 b.c., a.d. 365–415, and a.d. 850–1050. Estonia felt two impact craters c. 4000 and 2000 b.c. The whole of Europe (and perhaps a wider area) suffered from extreme cold in the years around a.d. 540. The MWE, by contrast, usually is thought to have caused the retreat of sea ice, which allowed Norse colonization of Iceland and Greenland. Temperatures 1°C (1.8°F) higher than those of the late twentieth century have been suggested for northwestern Europe.
None of these deleterious influences prevented the occupation of Europe by a series of societies based on agriculture, whose accomplishments were by no means negligible, even if they lacked the literate attainments of classical peoples. All the different types of environments contained successful and indeed apparently sustainable economies, which were subject only to the usual environmental hazards of preindustrial economies. Crop failure, animal diseases, warfare, and civil breakdown are all recorded, and no doubt the pressures of population growth upon the resource base were critical, at least locally. Most coasts, except those facing north, attracted economies in which fish were important, provided that a cereal could be grown or traded. The tundra–boreal forest (taiga) zone developed reindeer herding. The deciduous forest proved amenable both to shifting cultivation and to permanent clearance for mixed farming. The mountains sustained valley agriculture, in which transhumance of animals eventually formed an integral part of food production. The introduction of irrigation into the Mediterranean, however, was the result of Islamic influence upon the classical cultures; it was not one that any barbarians adopted, except in areas they reclaimed after attacking parts of the Roman Empire. In all of these areas the influence of environment cannot be gainsaid, yet in none of them is there certainty that human culture and choice were negligible. There were always roads not taken.
human impacts on the environment over eleven millennia
Accepting that agriculture spread into northern and western Europe during the period 6000–4000 b.c., then some westernmost parts housed 4,000 years of Holocene hunter-gatherers. More central and southerly regions had hunter-gatherer populations from the Late Pleistocene right through to the time when farming became an irreversible way of life. The notion that food-collecting economies do not manage their environments in the manner of agriculturalists has long been abandoned, especially with the realization that fire is a potent management tool at the landscape scale. There is evidence of considerable burning in the Late Pleistocene and Early Holocene in the northern European plain, the Low Countries, and the lowlands of northeastern England, for example—though it is always possible that the tundra and birch-scrub vegetation could have been set alight by lightning in what was then a more Continental climate.
In the wetter uplands of the British Isles and Norway, however, fire apparently was used to combat the upward spread of forests and to maintain openings in woodlands that dominated the Middle Holocene. The presence of shrubs such as hazel (Corylus avellana) probably was deemed to be advantageous as direct food sources as well as browse for forest mammals, and so closed-canopy high forest was not an optimal source of food. Where trees were removed or prevented from growing, their water-pump effect was lost. The subsequent waterlogging and acidification of soils (accelerated where charcoal clogged the soil pores) were instrumental in the growth of blanket peat over wide areas, a process whose inception could happen at later times if forests disappeared and whose enlargement thereafter was sensitive to climate. On drier sites with acid soils, heath developed. Its continued existence depended on being grazed and burned; otherwise it would be colonized by scrub and then oak woodland.
If many hunter-gatherers existed in a mosaic of woodland and open areas, little adaptation would have been needed for early agriculturalists. Although the idea that the pioneers were all shifting slash-and-burn farmers has been superseded, the growth of cereals in small clearings that also housed domestic stock whose dung maintained soil fertility would scarcely have been ecologically radical even if it was culturally revolutionary. The practice of feeding leafy branches to domestic stock would have thinned out canopies, and the success of sedentary farming, letting populations expand, would have diminished the area of forests and increased the cover of secondary woodland and open grassland. Hence the gatherer-hunters and the prehistoric farmers together changed many of the European ecosystems—especially those of the mixed deciduous forest zone—into a cultural landscape with more natural patches. The reindeer herders, on the other hand, seem to have exerted environmental influence only near settlements, and there is no evidence that prehistoric populations had lasting effects upon populations of sea creatures.
Between the onset of Neolithic farming cultures and the end of "barbarianism," all human communities dependent on agriculture had in common the need to maintain the fertility of the fields and to cope with any expansions in human populations. The period also may have seen substantial migrations of human groups across Europe, though DNA-based evidence calls some of this movement into question while reinforcing various older interpretations. By one means or another new ideas found their way across the Continent. For example, the transmission of rye as an addition to the cereal repertoire allowed more intensive use of the southern fringe of coniferous lands in Russia and Scandinavia, with the results still visible in their bakeries. The moldboard plow allowed cultivation of heavier soils, and no doubt contact with Roman methods encouraged more intensive use of land even outside the limes.
In some forested zones the prehistoric farmers practiced shifting cultivation (which persisted in Finland into the nineteenth century). This was a good adaptation to woodland and a low population density, but it was less effective than permanent clearances that are well manured. Hence much agriculture between the Neolithic and the High Middle Ages was a variant on keeping up the fertility of the grain-, pulse-, and hay-producing fields. Their drainage, irrigation, fertilization, and general management all have environmental linkages, which involve manipulation of the preexisting ecosystems (many of which would certainly not be "natural").
Alongside these processes, those of the modification of the genetics of plants and animals proceeded. The differentiation of the plow horse and the warhorse is a simple example. Some periods stand out as particularly important. The age of the development of iron technology is certainly one of them. In many palaeoecological investigations across Europe, the beginning of the Iron Age saw intensified forest clearance, as this became altogether easier with the use of a hard-edged axe. At the same time the production of iron exerted an environmental impact. Apart from the digging for ore, the smelting process required significant amounts of charcoal. Then iron-tipped plows allowed the turnover and aeration of heavier soils in a kind of snowball effect of environmental change, which also contributed more silt to the river floodplains from higher soil-erosion rates; river estuaries and deltas changed shape and biological components.
Beyond the fields, Iron Age economies changed woodlands, as cattle and pigs were allowed to graze and browse in them and the woods were managed to provide leaf fodder. Wetlands were reclaimed as coastal communities learned to construct banks that kept out the tides. Egil's Saga, written in Iceland in about a.d. 1230, records a visit to the Frisians that details their occupation of the salt marsh–fen–wood zone of the coasts of the Low Countries. The tidal marshes were the scene of salt production in the Iron Age, and thereafter the heaps of waste from this activity in turn provided raised settlement sites for villages and fields. Inland peat bogs, too, were reclaimed, at least at the edges. There is some suggestion, too, that pagan Saxon aristocracies were keen enough on hunting to have areas set aside for the pleasure of the chase, though not on the scale of their Christian Norman successors. Many "barbarian" societies had notions of sacred space, which very likely meant the setting aside of land and water. The Early Mesolithic site at Star Carr in northern England is neatly on the kind of peninsula that taiga communities in Russia later used as sacred locations; part of southern England was, in one interpretation, an "isle of the dead" in the Neolithic. The ambiguity of the woodlands and wild terrain generally as sources of useful materials, as land banks, and as places of some dread are encapsulated in later European folklore and fairy tales. The element of fear is well expressed in the famous narrative poem Beowulf of Anglo-Saxon times.
In most of Europe the division of the landscape into "owned" units is evident in the landscape. Even if some of them were communally rather than privately owned, there were nevertheless few resources—and hence few parts of nature—that did not in some way belong to human communities or individuals. In a sense a stratification of human societies occurred (described for the Celts in some of the most detailed written accounts of European societies outside the classical world), which was accompanied by a fragmentation of nature. There were fields, the "waste," mountains, and moors that were of less value and even frightening, and there were eventually proto-urban settlements with different social groupings and with expanding trade networks (e.g., the Viking routes that encircled Europe by c. a.d. 850 and impinged upon the Caspian by a.d. 880). Many parts of the natural world became commodities to be exploited and sold. No doubt the example of the Romans flowed over into later societies in that respect.
As with most preindustrial societies, there is no doubt that the inhabitants of barbarian Europe were closer to the natural world than their fossil-fueled successors. The story is one of a generally one-way movement toward more intensively productive agro-ecosystems capable, in the end, of supporting craftspeople, aristocrats, merchants, and townsfolk. Granted there were reversals when the pollen diagrams record the recolonization of scrub and woodland, when disease was regionally devastating, or when an authoritative power withdrew, as when the Romans left some parts of northern Europe or when a lord decided to punish his neighbors. In essence, however, the peoples under scrutiny created distinct cultural landscapes, just as happened in the classical world. Many signs of those environments are present in the twenty-first century for the discerning eye and the careful spade to discover.
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