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Eurasian Steppes: Origin and Evolution
The Eurasian steppes (after the Russian stepj) are a grassland “biome,” “zone,” “belt,” or “ecoregion” (among other monikers), which occupies the 4,000 to 5,000 mile-long and mid-latitude, variably-wide, geographical space running from central Europe (western border of Hungary) to Asia (eastern border of Mongolia). (1-2) Most of the Eurasian steppes are in Asia.
The most important word relating to the Eurasian steppes is “grassland.” At its simplest, grassland is “a habitat dominated by grasses,” declares David J. Gibson, author of Grasses & Grassland Ecology (2009). “Beyond this, an all-encompassing definition is elusive,” he says. Indeed, “many authorities do not provide a definition, assuming merely that we know a grassland when we see one,” he notes. (1) Below is a collection of grassland definitions assembled by Gibson:
The main elements shared by these definitions are
Other factors that have helped characterize grasslands are “deep, fertile, organic-rich soils; frequent natural fire; and large herds of grazing mammals.” (1) Grasslands have many synonyms, including “steppe,” “prairie,” “pampas,” “high veldt,” “savannah,” and “downland.” (2) The reason for so many synonyms is the worldwide extent of grasslands. Globally, grasslands occur on every continent (excluding Antarctica), covering 31-43% of the earth’s surface. (1) The wide range in estimates (31-43%) “reflects differences in defining grassland by different authorities, particularly in the extent to which cropland, tundra, or shrublands are included,” says Gibson. (1) Grasslands thus occupy more of the earth’s surface than the other major cover types, i.e., forests and agriculture. Grasslands are most extensive in sub-Saharan Africa, followed by Asia (excluding the Middle East), and the grasslands of Europe, North America, and Oceania (including New Zealand and Australia), according to one classification. (2) Here we focus on the steppe grasslands of Eurasia, combining Asian and European grasslands, since they occur in a continuous belt.
Grasses are relatively recent arrivals to the earth’s surface. The vast majority of dinosaurs living on earth between 230 and 65 million years ago, for example, did not eat grass (at least not until very late in dinosaur history), because there was no grass to eat. Instead, plant-eating dinosaurs ate clubmoss and horsetails (some horsetails reached 30 feet high), ferns, cycads, ginkgoes (evolved around 280 million years ago), conifers (date back to 310 million years ago), and monkey puzzle tree (dates to 220 million years ago). (3) The first true land plants on earth (Psilophytes and Rhyniophytes) show up in the fossil record about 428 million years ago, during the Silurian (444 to 416 million years ago).
The earliest accepted fossil records of the grasses are phytoliths. A phytolith is silicified plant tissue, or “plant stone,” which is an archaeologically robust microscopic body found in many plants. It appears to lend to the plant structure and support and make the plant distasteful to ruminants. In 2005, Prasad, et al., found phytoliths preserved in Late (Upper) Cretaceous (Cretaceous—146 to 66 million years ago) coprolites in central India, specifically in Pisdura at the eastern edge of the Deccan Trap basalts. (4-5) A coprolite is fossilized excrement, feces or dropping from ancient animals. (6-7) Prasad, et al., noted at least five different kinds of grasses in their coprolite, in addition to conifers, palms, and dicotyledons. Gibson says about Prasad’s discovery, “The taxonomic diversity of these phytolite morphotypes suggests an evolution, diversification, and spread of basal Poaceae [grasses] 65-71 million years ago in Gondwana before India became geographically isolated. Recall that Gondwana is the southern precursor supercontinent that included most of the landmasses in today’s southern hemisphere, including Antarctica, South America, Africa, Madagascar, Australia-New Guinea, and New Zealand, Arabia, and India.
Thus, grasses have a sparse and equivocal Cretaceous fossil record. In fact they also do not have an extensive (other than pollen) or especially reliable Paleogene (65 to 23 million years ago, including Paleocene, Eocene and Oligocene epochs) fossil record, aver Crepet and Feldman. (8) This fact vexes paleobotanists, because “the grasses are one of the largest families of flowering plants and the single most important family to the economy of humankind. The history of civilization is intimately related to the cultivation of grasses, which also have great ecological significance.” (9) The earliest evidence of mega (macro) fossils confirmed as grasses is from the Eocene epoch (56 to 34 million years ago) in the Wilcox formation (circa 54 million years ago) of western Tennessee, U.S.A. There Crepet and Feldman found sediments containing macrofossils of spikelets, inflorescence fragments, leaves, and whole plants, which clearly fit the fossil plants in the Poaceae. Gibson says, “These fossils represent the earliest clear evidence of grasses, and of wind-pollinated herbaceous monocots. Furthermore, the well-defined nature of these plants (their affinities, although uncertain, do not suggest a primitive grass) is consistent with an Upper Cretaceous origin of the family.” (10) The second oldest grass macrofossil is a female spikelet of the extant genus Pharus (Bambusoideae) found by Poinar and Columbus in the Dominican Republic in association with mammalian hair preserved in amber from around 20-15 million years ago (Middle Miocene). (10-12) “Hooked hairs on the lemma provide the earliest evidence for dispersal via attachment to mammal fur (epizoochory),” explains Gibson. “Assignment of the fossil to a modern-day extant genus is further support for the idea that diversification of the grass family had occurred quite a bit earlier than indicated in the fossil record. By the time the following Oligocene epoch (34-23 million years ago) ended, it is quite clear from the fossil record that grasses representing several separate extant tribes and genera were present.” (10)
Thus, grasses gained a foothold on earth during the Eocene, an epoch that witnessed a sudden global warming event (increase of 6 degrees Centigrade over 20,000 years) with changes in oceanic (raised sea levels) and atmospheric circulation. Scholars attribute this sudden warming event to a sudden release of carbon dioxide and/or methane at about the same time as continental breakup around 55.5 million years ago. (13) Grasses simultaneously increased in amount and diversity during this time, and many major mammalian orders, including the cloven-hooved animals (e.g., sheep), horses, and even the primates, appeared and spread across the globe. (14) In summary, grasses were relatively late comers to earth, originating at the end of the Cretaceous around 66 million years ago, as compared with the earliest earth land plants, which the fossil record indicates were present as early as 444 million years ago. The earliest grasses did not live on open arid land; rather, they lived in deep shade or forest margins, say Gibson and Kellogg. (15-16) There was little diversification of the grasses in these habitats for millions of years, i.e., from 66 to 15 million years ago. Major diversification of the grasses occurred with their spread into open habitats in the mid-Miocene epoch (20-15 million years ago). (15) How do we know this? Kellogg says the fossil record shows “a marked increase in the amount of grass pollen in the mid-Miocene epoch.” (16) The point here is that grasses slowly evolved for some 50 million years and then suddenly diversified around 20 million years ago, spreading into open arid areas. Why did this happen? The climate became more arid at the time the grasses diversified. Gibson notes, “Climatically, the diversification of grasses and the spread of grasslands coincides with increased aridity, especially during the Oligocene (34-23 million years ago).” (15) “In North America, for example, the Rocky Mountain uplift led to aridity of the Great Plains causing a retreat of the forests in the late Oligocene and Miocene (23-5.3 million years ago). In Africa, increased continental elevation led to increased aridity, also during the Oligocene, allowing the spread of grasslands.” (15) The Himalayan Mountain uplift led to aridity of what is now the Eurasian steppe region. India first collided into Asia about 40 to 50 million years ago, and in just 50 million years, produced the Himalayas, which are still growing in height. (17) Gibson notes that the Himalayas block warm, moist air from the Indian Ocean, so there is very little precipitation. “Nothing blocks northern arctic winds, though, so [Eurasian steppe] winters are very cold and windy.” (18) How do mountain ranges produce aridity? They produce aridity by reducing precipitation delivered to the affected land. The mountains block the passage of rain-producing weather systems, casting a “shadow” of dryness behind them. The steppe orientation of Eurasia trends east to west (horizontally on a map) because the affected land is parallel to the Himalayas, which trend east to west. The prairie of North America by contrast trends north to south (vertically) because the affected land parallels the Rocky Mountains, which trend north to south. (19)
Unlike woody trees, the grasses were able to spread during periods of increased aridity because they possessed certain traits that adapted them well for drought: “basal meristems, small stature, high shoot density, deciduous shoots, below-ground nutrient reserves, and rapid transpiration and growth.” (10) Guthrie explains, “One characteristic of monocotyledonary plants (grasses and some grasslike plants) is that they grow not from the tip, but from the base, that is, their meristematic tissue is near the ground. These meristems are precious; they contain the highest concentrations of nutrients and are major investments for each plant.” Damage to the plant above the ground does not kill the plant, because new growth is from below. “Dicotyledonary plants (forbs [e.g., a sunflower and milkweed] and broad-leaf woody plants) do not work this way. Their meristematic tissue is on the twig tip.” When the tip dies, it does not regenerate. (20) The first appearance of extensive, open grasslands varied worldwide. In Eurasia, aridity began to increase during the Miocene epoch (23 to 5 million years ago). (21) Extensive steppe vegetation began to appear, and the grasses became abundant. In North America, prairie developed toward the end of the Miocene (8-5 million years ago. In South America, grass-dominated ecosystems may have arisen as early as the Eocene-Oligocene boundary (34 million years ago). (15) Grasses, as noted above, are members of the family Poaceae, alternatively known as the Gramineae, within the Class Lilopsida, better known as monocotyledons. A monocotyledon seedling has one seed-leaf, in contrast to dicotyledons, which have two. The number of species within the monocotyledon class varies according to different sources, but everyone agrees there are many. For example, Gibson cites 7,500 to 11,000 species of grass divided among 600-700 genera. The largest genera are Panicum (panic grass), Poa (bluegrass), Festuca (fescue), Eragrostis (lovegrass), Paspalum (paspalum), and Aristida (threeawn). “Economically, all the important cereal crops are grasses, including the wheats (Triticum spp.), rice (Oryza sativa), maize (Zea mays), oats (Avena spp.) and barley (Hordeum vulgare), sorghum (Sorghum spp.) millets (Panicum spp., Pennisetum spp.) and sugar cane (Saccharum officinarum). Furthermore, grasses represent major sources of forage. (22)
Lavrenko and Karamysheva note that perennial bunch grasses predominate in Eurasian steppe grass communities. “These grasses are usually species of the genera Agropyron, Cleistogenes, Festuca, Helictotrichon, Koeleria and Stipa. Dominants also include bunch species of sedges (Carex) and in Central Asia, of species of bunch forbs (Allium and Filigolium). Chernozems and chestnut oils are typical of many types of steppes. (23)
Lavrenko and Karamysheva continue: Plants in the dominating synusia [structural part of a plant community, which includes those species that are similar in a biological and ecological sense] grow during the whole vegetative period, but during droughty months in summer (July and early August) their rate of development is retarded over much of the steppe region. This period of semi-dormancy occurs throughout the steppes of the European part of the former Soviet Union, as well as in the northern part of Kazakhstan and south-western Siberia. In these regions growth is most rapid during June, the month of greatest precipitation… Other synusiae are of lesser importance than the synusia of bunch grasses and other bunch herbs. A synusia of forbs (herbaceous dicotyledons and non-gramineous monocotyledons, usually of the families Iridaceae [iris] and Liliaceae [lily]) is often associated with the dominating synusia [bunch grasses]…The rhizomatous grasses and sedges do not form a clearly defined synusia in zonal steppe communities…A synusia of sparse shrub thickets often occurs, especially in areas of sandy soils. The genera Calophaca, Caragana and Spiraea are well represented among these species of shrubs. (23)
Russian geobotanists traditionally distinguish three or (more often) four zonal types of steppe, which successviley replace one another from north to south with increasing aridity of climate, as demonstrated by decreasing precipitation, increase of temperature summations, and lengthening of the frost-free period,” explain Lavrenko and Karamysheva. (24) In other words, the most arid zone of the Eurasian steppes is in the south, closest to the Himalayas. The same steppe transition occurs from east to west in the North American Great Plains, i.e., the most arid zone is in the west, closest to the Rocky Mountains. (25) Lavrenko and Karamysheva classify Eurasian steppe grasslands as follows:
The origin and evolution of mammals as told in the fossil record falls is complex, as noted elsewhere. (27) A seminal event in the evolution of mammals, however, occurred 65 million years ago following the mass extinction marking the close of the Mesozoic Era (when dinosaurs went extinct). Several mammal lineages survived this horrific event and “within a mere 2-3 million years had radiated explosively to produce a plethora of new small forms but also, for the first time, mammals of middle to large body size. This was the commencement of the great Tertiary radiation of placental” mammals, explains Kemp. (28) Since the mid-Miocene (15-11 million years ago), “central Asia has been the focal point of the transformation in Eurasia towards more [a] open and dry environment,” notes Pushkina. (29) Variations in climate and vegetation over the short and long term shaped the geographical ranges of large terrestrial mammals during the Miocene and Pliocene (5 to 2.5 million years ago) epochs. Climatic fluctuations intensified during the Pleistocene (1.8 to 10,000 years ago). Indeed, the Pleistocene geological record gives evidence of 20 cycles of advancing and retreating continental glaciers. Much of this glaciation occurred at high latitudes and high altitudes, especially in the Northern Hemisphere. (30)
Kemp notes “about 4,600 species of animals today are called mammals because, despite an astonishing diversity of form and habitat, they all share a long list of characters not found in any other organization, such as the presence of mammary glands, the single bone in the lower jaw, and the neocortex of the forebrain.” (27) Of the 4,600 extant species, 4,350 belong to Placentalia (i.e., they do not belong to Monotremata [egg-laying mammals of Australasia] or Marsupialia [pouched mammals]). Of these 4,600 mammal species in the world today, about 90 species call the Eurasian steppes their home, and of these 90 species, about one third (31 species) are steppe endemics, meaning the mammal is found only on the Eurasian steppes. (31) The lists of mammals below do not include the long-exterminated yak (Bos mutus), auroch (Bos primigenius), European bison (Bison bonasus) and some others.
Except for the antelope and gazelle in the endemic mammalian species of the Eurasian steppes, the mammals are on the small side.
The reader is referred to Formozov’s article for additional lists of 1) species of mountain-steppe and tundra (13-14 species) and 2) forest species penetrating into the steppes along intrazonal biotopes (12 species). (33) Formozov notes that herbivorous mammals living on the Eurasian steppes have a wide choice of forage. He continues: The period of plant production in the southwestern steppes is very lengthy: plants break dormancy as early as February and continue to grow until November. Herbivorous species here [in the Eurasian steppes] are provided with fresh green food throughout the greater part of the year. In contrast, in more arid parts of the steppes vegetational growth of the majority of plants ends early but quite often resumes in the autumn of there are rains. Also, in late summer and autumn the dead plant parts are utilized by grazing mammals for an additional time as “standing dry hay.” In the steppes this “hay” preserves its nutrient value better than in zones with abundant precipitation, which leaches out soluble substances form the dead leaves and stems. Study of the winter pastures of horses in the steppes of Kazakhstan has established that the forage obtained by the animals from beneath the snow “equals average and even good hay in it high content of digestible protein.” Steppe forage plants are rich in ash elements, and some species are even overloaded with salts. This explains the absence in steppe herbivores of the intense mineral hunger which is so common in ungulates and rodents in areas of abundant or excessive precipitation (tundra, taiga, upper belts of mountains, tropical rain forest). In the steppes there is no such adaptive activity by mammals, such as searching for mineral springs, eating weathered bones or mass visits to areas of saline soil. The abundance and accessibility of adequate plant forage is the main reason the mammal populations of the steppes have both abundance and diversity of rodents and ungulates, the consumers of the fresh green grass and dry hay. (34) Formozov notes that even though the Eurasian steppes are rich in nutrients, the plant cover does not provide reliable shelters for the mammals from intense insolation, wind, cold and enemies. Thus, the mammals dig burrows. Formozov continues: Steppe grass is usually low, and the leaf surface of xerophytes (organisms that can survive in an environment with very little available water) is relatively small. This condition (as has long been known) causes steppe mammals to use burrows as their main or sole place of refuge. The lives of 72 of the 90 species found in the Eurasian steppes are closely connected with burrows. Excavation associated with the construction and repair of burrows is brief in some species but seasonal or even year-round in others. This is a very widespread form of activity in steppe mammals and in the majority of cases its adaptive character is easily discernible. It is also well known that the majority of mammals in the steppes have cryptic coloration similar to the color of dry grass and bare ground. Less is known about one peculiar feature in the behavior of small mammals at moments of danger. Whether running toward the burrow or remaining concealed at feeding sites, they cling firmly to the ground. The ability of Lagurus lagurus [plump lemming], Citellus pygmaeus [squirrel] and others to sprawl flat, completely blending into the substrate, is remarkable. Airplane observations have shown me that diurnal mammals which are cryptically colored are betrayed by their shadow if they stand erect or move without flattening out. The sprawling reaction changes the outlines of the bodies, helps to shrink the shadow to a minimum and produces a maximum effect of cryptic coloration. In related forest species there is no “sprawling reaction.” On the other hand, the sparseness and low growth form of grasses facilitates visual orientation of the animals and contact with neighboring individuals and families by means of optical and acoustic signals. The fundamental protection reaction in burrowing animals is a hurried flight into the burrow. But the majority of them are heavily built, short-legged, and they cannot run quickly. That is why it is so important for them to notice danger as early as possible. Upon leaving the burrow, and at foraging sites, marmots, ground squirrels, steppe pikas and some species of voles repeatedly and attentively view their surroundings by standing up to their full height on their hind legs. Only in the steppes is it possible to see so frequently these rodents, as well as their mustelid [ermine] predators, standing like “little pillars.” Because of the importance of this uninterrupted visual field, ground squirrels (Citellus pygmaeus, C. fulvus) and marmots (Marmota bobac) decidedly avoid places with high spear grass, and in thick wheat fields inhabit only the edges, or thin spots with sparse low stems. (34) The Eurasian steppes lack sufficient shade while the hot sun heats the soil surface during the summer months. Mammals of the Eurasian steppes adapt to these realities by modulating their daily activity, as follows: Species that are active during the entire period of daylight in spring and autumn feed only in the cool morning and evening hours during the summer. However, young Citellus pygmaeus sometimes graze during the hot hours. During such times their behavior is very characteristic: short periods of feeding are rhythmically interspersed with an 8-10 minutes’ stay in the burrow, after which the refreshed animal comes out again to the surface, thus eliminating the danger of overheating. Most steppe areas are characterized by a sharp contrast between dry summer and cold winter, with great severity of the weather. Nineteen species of steppe mammals (exclusive of bats and hamsters) avoid the effect of unfavorable seasons by becoming torpid [decreased mental and physiologic activity]. In some species (Citellus pygmaeus, C. fulvus), [torpor] begins in summer and lasts for 7-8 months. The winter life of small animals with year-round activity proceeds hidden under a thick snow cover, and only larger animals--hares, foxes, wolves, ungulates--spend the winter on the open surface and are able to withstand the winds and frosts. Animals that hibernate in well-protected burrows comprise 85% and more of the entire local population of steppe small mammals. The inaccessibility of hibernating small animals sharply reduces the hunting chances of red and corsac foxes (V. vulpes, V. corsac), forcing them to migrate often hundreds of kilometers from their summer burrows in search of easier hunting. (35) Burrow-building Eurasian steppe mammals are very clever at adapting to their environment. For example, “during the summer marmots completely renew the lining of their nests and, moreover, if ectoparasites (fleas, ticks) annoy the inhabitants of the burrow too much, they [the marmots] plug the entrance to the old nest chamber with a compact earth plug and move to a new nest. During the first half of the summer, marmots deposit their feces in a special small cavity located on one of the burrow entrance mounds. Later they use one of the blind passages in the depth of the burrow as a ‘latrine.’ When sealing the burrow entrance for the winter, the animals take droppings from this refuse pile, which serve to cement together small stones and clay in the plug. The length of the plug is from 1.5 to 3 meters; it is so strong that during excavations it has to be broken with a pick.” (36) Formozov continues: In these animals, burrow modification is also characterized by other special features. Systems that have been inhabited for a long time always have a number of empty passages and tunnels, wherein a marmot or suslik [type of rodent] that is pursued by a predator can hide or, if necessary, dig deeper and leave behind an earth plug. Steppe sciurids [rodents] actually spend the greater part of their lives underground: 7-8 months of yearly hibernation and, during summer activity, the period of a lengthy night and brief day rest. Outside their burrows they spend only a few hours in feeding, in inevitable migration to new sites and in searching for neighboring individuals. The brevity of the active period facilitates the existence of dense colonies, because a smaller area is needed when each family grazes for 4-5 months instead of the year around. These animals, when cut off from their burrow, are rather helpless and are unable to render any resistance to an attack. Their attachment to the burrow is very permanent. Sites suitable for settlement are used continuously for centuries. Owing to frequent rearrangement of passages and chambers such sites become covered by large earth mounds (up to 15-20 meters long). This is a characteristic element in steppe microrelief. There is a better field of view from the mound, water is shed from them and does not get into the burrow, and for this reason they possess a special “attraction” for the animals. Thus, colonial hibernating rodents not only are well adapted to life in the steppes, but also remodel in part the terrain in accordance with their demands. (36) “Steppe geophiles” (“rooteaters”) are Eurasian steppe mammals (e.g., Spalax) that eat roots and feed on subterranean parts of plants (e.g., tubers, bulbs, germinating seeds) in their burrows year round. Formozov writes: They live solitary lives and inhabit burrows of complicated structure. These burrows consist of a network of subterranean galleries, hundreds of meters long, which run horizontally at a depth of from 10-40 cm. This layer contains the greatest density of underground plant parts. The burrows of geophiles have virtually no exits to the surface. Each branch tunnel necessary to throw out the earth excavated from the galleries is immediately blocked by the animals with an earth plug when work has been completed on the nearest stretch of the underground passage. The root-eaters are agile in their subterranean passages but slow and clumsy on the surface. In contrast to marmots and susliks, they are extremely quiet with feeble voices. One of the most important features in the behavior of geophiles is their constant behavioral effort to isolate their burrow from the outside world. This is adaptive in that it maintains a relatively constant temperature and moisture in the closed system of passages as well as barring entrance to snakes, weasels (Mustela nivalis) and other small predators. (37)
Soils freeze in the greater part of Eurasia during winter, which greatly decreases availability of rhizomes for ingestion by geophiles. They counter this dilemma by mass storage of food in the autumn. “In summer, the food reserves in their burrows rarely exceed amounts needed for 1-2 days. However, in autumn, in the burrows of Spalax microphthalmus food stores of 14 kg (30.8 lbs.) have been found. Four to 10 storerooms occur in one burrow, some are up to 3.5 m long. Apparently, these reserves are ample for the winter, because up to 2-3 kg of unused food (4.4 to 6.6 lbs.) have been found in the spring. At the end of the autumn storage period of Myospalax dybowski, up to 9 kg (19.8 lbs) of food have been discovered. After snow covers the ground, geophiles make passages in the snow and begin to dig out plants, working not upwards from the depth of the soil, as is usually done, but from the wintering bud downwards along the roots.” (38) Geophiles demonstrate high levels of adaptation to the steppe environment. There are relatively few extant species of Eurasian steppe ungulates, which Formozov describes as “forage-consumers, not having lairs, gregarious, cursorial large animals with year-round activity.” Recall that an ungulate is a mammal that uses the tip of his toes, usually hoofed, to sustain the body during movement. Common ungulates are horses, zebra, donkey, cattle/bison, rhinoceros, camel, hippopotamus, goat, pig, sheep, giraffe, okapi, moose, deer, tapir, antelope and gazelle. Ungulates that inhabit the Eurasian steppes today include Equus hemionus (onager, wild ass), Equus przewalskii (Przewalskii horse), Gazella sungutterosa (gazelle), Saiga tatarica (saiga antelope), and Procapra gutturosa (Mongolian gazelle). Other ungulates have been exterminated, including the wild ox (Bos primigenius), bison or zubr (Bison bonasus), wild yak (Bos (Poephagus) mutus), and some races of mountain sheep (Ovis ammon). How have the ungulates adapted to the environment of the Eurasian steppes? Eurasian steppe ungulates have adapted to their environment through “gregariousness, great running speed and mobility, and ability to use steppe pastures with their varied but sometimes scarce vegetative cover.” (39) A close relationship between individuals (even though changing somewhat depending upon the season) and a coordination of their behavior characterizes herds of ungulates. “Primarily this facilitates the defense of weaker members of the herd, mainly the young animals, from the attacks of large predators. In the Eurasian steppes the greatest danger comes from wolves. During the summer, wolves feed mostly on small rodents, locusts, etc. In autumn and winter, after the disappearance of this food, they pursue ungulates.” Formozov continues: To hunt successfully such a fast animal as saiga (which can run up to 75 kph [47 mph]) living in extensive herds, the wolves aggregate in packs of up to 15-20 individuals. Such a large pack, however, cannot always be formed. In many places the only victims of smaller wolf packs are male saigas who are very exhausted from the breeding period. Such selective predation on males is considered beneficial for the species. With kulans, a herd consists of a group of mares with foals, led and protected by a strong stallion able to drive off an attacking predator. In winter during severe weather several herds of kulans (wild asses) join into a group of 50-100 head. “Turning with their rumps to the wind and standing in a compact lot, the kulans create an additional protection from the wind by their own bodies. The young stand in front of the herd, i.e., on the leeward side.” When a kulan herd is grazing in deep snow, the stronger individuals proceed, the weaker following them. “Young of the year and yearlings use feeding craters made by the adults or make their own craters in snow loosened by kulans moving ahead of them.” Finally, the herd progresses in single file through deep snow thus conserving the strength of weaker members of the group that form the rear guard. During lengthy steppe migrations, which were characteristic of kulans in Central Kazakhstan, they assembled in herds of 1,000 and more. Saigas formed herds of up to 10,000, and this has been again recorded during recent years; for instance, in the semidesert on the northwestern coast of the Caspian Sea. A migrating herd of saigas that meets a sudden obstacle such as a flock of sheep guarded by sheep dogs and shepherd executes complicated maneuvers very rapidly and with amazing coordination. Continuous muffled cries of the saigas can be heard only at close range by members of the herd, but the distinctive marks (“croupe mirror”) and characteristic “vision jumps” in which the animals jump steeply upwards with their body remaining nearly vertical, can be seen at a great distance. (39)
Formozov continues: Saigas, dzerens [Mongolian gazelle], kulans [Asian wild ass] and others of this life form of animals have fine sight and an acute sense of smell, but their hearing is weak. In steppe conditions and in deserts it is especially important for species that run at a high speed to use optical signals, because acoustic signs are easily deadened at a distance by the wind and the thud of hoofs of a large herd. Sound signals are, however, of substantial importance for saigas, as mentioned above, and between the members of small family herds of kulans. In their travels, herds of saigas and dzerens often cover a distance of 80-120 km and more a day. Saiga females with month-old young have been found at a distance of several hundred kilometers from the place where the young animals were born and tagged. When escaping from a pursuit, dzerens develop speeds up to 60-65 km an hour, kulans-up to 60-70 km an hour. These and saigas have great endurance. For their night rest all three species choose flat, open spaces, where it is easy to notice an approaching danger from a distance and where it is possible to flee without encountering natural obstacles. Extensive plains or even vast valleys are most attractive for these species. They definitely avoid places with a greatly dissected relief, but under some conditions must use them. Thus, in winter they hide from cold winds or snow storms behind sand dunes or in ravines, while in the summer they find here cooler places for resting during the heat of the day. During the hot season both antelopes very skillfully use even small patches of shade cast by bushes or by escarpments. Also, saigas often rest on earth mounds left by ground squirrels, digging down until a cooler layer of soil is reached. In contrast to burrow-dwellers, who have subterranean homes with a relatively stable microclimate, the nomadic ungulates look for a suitable place to rest several times a day, seeking out the most advantageous combination of local biotope and immediate weather conditions. Of some importance here also is the problem of camouflage. Thus, newborn saigas usually lie still on the bare clay ground where they are hardly noticeable, thanks to their ginger color. Representatives of this group roam all year round, forming herds the size of which depends both on the species of the animals and on the season of the year. Despite their ability to feed on many plant species (saigas, for instance, eat more than 100 kinds of plants) the steppe ungulates use in each region of their range a relatively limited assortment of food. Only 10-20 species are favored, and quite often the animals eat only the most succulent or tender parts of the plants. In grazing they seek definite plants and advance rapidly, constantly moving from place to place. Movement to different pastures often results from a deterioration in forage quality at certain phenological phases of particular plant associations, or from an attempt by lactating females to find patches with more juicy vegetation, or nearer to watering places. The absence in antelopes of any permanent attachment to a definite territory permits them to roam extensively and use, each season, pastures most suitable to their needs. Particularly significant are spring migrations of pregnant female saigas and dzerens onto breeding grounds, where mass birth takes place. On the right bank of the lower Volga River such a region was located for many years 30- 40 km east of Lake Sarpa. There is here a large open plain with sparse semi-desert vegetation. During different years on various sections of this plain tens of thousands of saigas concentrate with a density of from 3-5 up to 30 per hectare. During this period the herds contain no more than 2-3% males. During their first days of life, newborn saigas lie motionless in one spot; at the same time the lactating does are also relatively sedentary, and stay near their young, grazing within an area of 2-3 square km. As youngsters become stronger they, together with the does, move to regions with fresher and more succulent grasses, sometimes much in advance of the nomadic herds of males. Similar migrations in search of regions suitable for mass reproduction have also been established for the dzerens of Mongolia. Another period of relatively sedentary life for the polygamous saiga falls at the end of November and in December. This is the period of harem formation and copulation. During this period a male retains around himself a group of 5-10 females (more rarely up to 40-50) and drives off with his horns any other males that try to take part of the harem. The place of mating occupies only several hundred square meters and during this period the male eats only snow while the females graze on a limited space. Dzerens mate within the herd and no changes in their movement patterns have been recorded. Both species of antelopes, and the kulans, are permanently roaming animals, but regular seasonal migrations are not typical of all populations, since their nomadic habits vary considerably depending upon the crop of forage grass, the conditions of watering places and character of snow cover in winter. Yet within certain parts of their ranges there are regions of seasonal aggregation. Particularly well defined are places of winter aggregation in regions with good and easily accessible food, owing to the absence or small amount of snow, compared to spring and summer range. The distances between these summer and winter ranges vary from 100 up to 700 km. During years of extreme summer droughts or very severe winters with abundant snow cover, the usual large nomadic herds resort to panicky flights. The animals become dispersed in all directions, quite often getting into very unsuitable habitats and perishing in great numbers. Thus, in the northern steppes, during lengthy snow storms saigas blunder onto the ice of the Caspian or onto islands with dense thickets of rush in the delta of the Volga. (39) Homo sapiens have dwelled on the Eurasian steppes for thousands of years. Indeed, the Eurasian steppes have formed a “vital connector between Orient and Occident for millennia—ever since a few of its inhabitants got the idea of domestic animals from the Near East in the late Neolithic (around 4000 BC) along with a starter set of already tame sheep and cattle,” notes Barber. (40) She continues, “As long as the grass grows well, it is far easier to herd hay-munching ruminants than to grub out the tough-rooted grass to make room for fields and then go through the endless heavy work of plowing, planting, weeding, watering, harvesting, and processing the crops. Farming is an exhausting life, herding much easier—lazier, even—especially when one can control a herd from on horseback.” (40) Ruminants are mammals with a first stomach called a rumen, e.g., cattle, goats, sheep, bison, yaks, deer, and antelope. Steppe people were responsible for domesticating wild horses, which included Equus caballus in the interior steppe, Equus hydruntinus north of the Black Sea (the last one was hunted to extinction between 4000 and 3000 B.C.) and Equus hemionus (onager, endangered in the wild today). (41) These wild horses were “stout-legged, barrel-chested, stiff-maned animals that probably looked very much like modern Przewalski horses, the only truly wild horses left in the world. A horse skull from the Ukrainian site of Dereivka, dated to about 4000 BC, shows tooth wear compatible with a horse chomping on a bit for several hundred hours during its life. (40) Thus, steppe horsemen not only domesticated, but closely controlled, horses. Barber writes: The effect of using horses to manage the other animals [i.e., flocks of ruminants] was tremendous, since the horse riders could move so much faster than the herds (let along humans on foot) and thus govern such large flocks that people had no need of other forms of livelihood. The change created a completely new lifestyle that still persists in parts of Central Asia. And the life of herding is preferred. Only those who lose their flocks will farm, and the will do so only until they can build up enough capital to start a new herd. (40) What happens during droughts, when the grasslands dry up, causing starvation and death among herds? “Some of the humans who depend on them for food must die or change their ways temporarily,” declares Barber. “More often than not, afflicted Eurasian [steppe] nomads have chosen to move, moving in particular into the greener fields of the nearest farmers—usually the Europeans or the Chinese—who, like the proverbial ants, regularly and industriously stored up grain against an uncertain future. Some such hiccup in the weather and grazing patterns may have led to the migrations that destroyed the Hittite Empire and flung the peak-hated Phrygians into Anatolia….This same pulsing rhythm of periodic migrations out of the steppes [has occurred] many times…Since the dawn of nomadism, perturbation anywhere on the [Eurasian] steppe seems to have sent ripples of upheaval across grassland from one end to the other—from Hungary to China and back again.” (40) Even when there is no drought, nomads of the steppe must keep moving around to find fodder for their herds. “Sheep in particular force the issue; they bite off the grass right down to the roots, preventing cattle and horses from grazing in the same place. This is why sheep were so unwelcome among the cowboys of the Old West,” avers Barber. “But moving means taking everything with you. The ingredient that made the nomadic lifestyle gel, therefore, was the wheeled cart, which appeared on the steppes north of the Black Sea and Caspian before 3000 B.C.” “Wheels, even on slow oxcarts, provided the high-volume storage and transport abilities that were essential in order to exploit the dispersed resources of the deep steppe in a predictable and reliable manner. By carrying supplies of tools and food along, as well as shelter in the form of felt tents, the herders could manage on their own out in the wilderness for six, eight, even ten months at a time, returning once a year to the settled trade centers. There they could obtain materials from far away, such as obsidian or (later) metal for knives and other essential tools, as well as get grain and other cultivated foodstuffs to round out their diets. The earliest wheel yet found in the steppes –in Ukraine–dates to about 3200 B.C. Soon after, with wheels under them, these people began to expand to the east, west, and south.” (42) Who were the Eurasian steppe peoples across the span of human history? Barber states that 80,000 to 40,000 years ago, modern human populations expanded across Europe and Asia, eventually reaching New Guinea and Australia before heading to the Western Hemisphere.” Certain regions became “spread zones,” meaning they became centers form which waves of people radiated, taking their languages with them. The most famous spread zone of all was the central Eurasian steppe region. The first of these Eurasian expansions was undertaken by a proto-Indo-European people hailing from somewhere in the Eurasian steppes near the Caucasus Mountains, between the Black Sea and the Caspian Sea, sometime around 3000 B.C. Next came massive expansions, during the third and second millennia B.C., of the Indo-Iranian branch of the Indo-European people. Indic speakers of the Indo-Iranian branch made their way to India, while Iranian-speaking tribes flowed into an “area running from southwestern Siberia, Russian Turkestan, and the Iranian plateau all the way to western Ukraine.” (43) Seven or eight centuries later a new wave of people emanated from Central Asia, vanquishing Mediterranean cultures in Greece, Turkey, Syria, and up to the gates of Egypt. “Interestingly, the intruders the Egyptians fought don’t appear to have been steppe folk themselves, but rather some peoples displaced southward, domino-like, by incursions from the northern steppes into lands bordering the Mediterranean Sea…Later, when the dust settles and the smoke blows away, we find the Hittites, for example, living in Syria, just south of their former home in Anatolia, while Anatolia is filled with new Indo-European groups like the peak-hatted Phyrgians,” notes Barber. Then came six rounds of steppe horsemen. The Huns were the first invaders to emerge from the Eurasian steppes. The Huns were a Turkic-speaking group led into Central Europe by Attila in the fifth century A.D. Then came the Avars (Turkic invaders of the sixth to eighth century A.D.), the Bulgars (Turkic speakers who invaded the Balkans in the seventh century and left their name to Bulgaria), the Magyar (Finno-Ugric ancestors of the modern Hungarians who swept into Hungary in the ninth century), and the Seljuk Turks (who began invading Turkey in the eleventh century). These were chased in the thirteenth century by the most feared invaders of them all, the Mongol hordes, who killed 90 percent of the population around Kiev and penetrated as far west as Budapest, burying that city on Christmas Eve of 1241 A.D., says Barber. “All six of these groups (Huns, Avars, Bulgars, Magyar, Seljuk Turks and Mongols) spoke Uralo-Altaic languages. Magyar (Hungarian), still spoken in Hungary, belongs to the Uralic half, being a distant relative of Finnish, while the other five are Altaic, explains Barber. “The Altaic superfamily includes Mongol, Tungusic, and the Turkic tongues. To Turkic belong not only the Huns, Avars, Bulgars, Seljuks, and the Ottoman or Osmanli Turks now in Turkey, but also the Uyghurs, who by the tenth century had moved from Siberia into the Tarim Basin, today the Uyghur Autonomous Region. As [linguist] Johnanna Nichols points out, each of these language spreads seems to have its center farther and farther east within Eurasia.” (43) China also suffered from the ferocious onslaught of the Eurasian steppe horsemen. The Xiongnu, probably ancestors of the Huns, tormented the Chinese for over two thousand years. “Chinese defense troops even adopted nomad-style horse riding and trousers, around 400 B.C., to meet and fight the intruders on their own swift terms…Finally, [in 1260 A.D.] the Central Asian nomads won. Led by the great Kublai Khan, the Mongols overpowered the Chinese altogether and set up their own government on Chinese soil. For a short while this Mongol domain stretched from the Pacific Ocean to the Black Sea, the largest empire ever assembled before modern times.” (42) The Eurasian steppe grasslands originated during the Miocene epoch following uplift of the Himalayas when India collided with the Asian continent. For many millions of years before this collision, grasses were happy to live in the shade and on the margins of forests. When the climate grew more arid because the new mountains blocked precipitation coming from the south and horrendous cold and winds during winter persisted from the north, the sturdy drought-resistant grasses moved into the new Eurasian steppe niche. Plant-eating mammals exploited the new Eurasian steppe niche as well. They adapted to the aridity by burrowing into the ground (e.g., rodents) or moving considerable distances (ungulates) to find new fresh pastures to forage. Humans exploited the Eurasian steppes, too, by domesticating the wild horse, which they used to herd their domesticated flocks (e.g., sheep, cattle, goats). They also used their horses for warfare to conquer new regions in part to obtain pasturage for their flocks. Notes:
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