The Mammoth Steppe and the origin of Mongoloids and their dispersal (Prehistoric Mongoloid dispersals) [1 ed.]

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11. The Mammoth Steppe and the origin of Mongoloids and their dispersal R. Dale Guthrie

Introduction I would like to proffer a new theory: that the complex of characters which we identify with Mongoloid peoples are the product of a special Holarctic biome, the Mammoth

Steppe. And further, that this Mammoth

Steppe environment

is

the key to understanding both the adaptive features of Mongoloids and much of their dispersal history. The roots go deep. The collision of the Indian Plate with the Asian Plate starting 40 million years ago created the Himalayas, building mountains higher than any the earth had known. This series of massive upward

thrusts affected atmospheric circulation by blocking southern monsoonal air flow which normally

This

moves

mountain

northwestward

building reached

from the Pacific.

a crescendo in Pleistocene

times

(Molnar

1989). An almost permanent high pressure cell developed behind the Himalayas,

resulting in a cold and arid climate. The flora and fauna which persisted in these conditions had some unusual aspects due to the combination of low latitude (30° to 45° North) but moderately high altitude (2000 to 5000 meters). The cold, dry

grassland which developed behind the south face of the Himalayas (the Tibetan Plateau on the north to Mongolia) became the heartland of the Mammoth Steppe (Fig. 11.1), and, I propose, was also the evolutionary homeland of the Mongoloid peoples. During Pleistocene cycles of low solar input this grassy biome spread eastward across Europe to the Atlantic, northward to the Arctic Ocean onto the huge exposed continental shelf north of Asia, and eastward to North America via the exposed Bering land bridge. Most woody plants were eliminated by combinations of cold and aridity, but these same factors favored certain arid-adapted grasses

and

forbes

(Guthrie

1982,

1990a;

Hopkins

ef al.

1982). The

woodlands

which occurred along the southern border of this steppe were more open, without modern analog (Guthrie 1990a). The expanding Pleistocene steppelands were invaded by a diverse group of mammals, predominantly grazers. Fossils show both large and small mammals in this special habitat underwent considerable evolution during the Pleistocene. The woolly mammoth (Mammuthus primigenius) epitomizes this fauna and the biome name was coined from a mix of fauna and flora: the Mammoth Steppe. The Mammoth Steppe became the largest grassland ever seen on earth. It was unusual, underlain in many places with permanently frozen ground. While it was geographically quite diverse, *yoven with a variety of woodland/s on its southern

The Mammoth Steppe and the origin of Mongoloids and their dispersal

173

Fig. 11.1 Map of the Mammoth Steppe heartland, where I suggest all Mongoloids arose, and most recently, northern Mongoloids. Arrows indicate how storm tracks moderated the climate on the margins of Eurasia at the glacial maximum. The south face of the Himalayas blocked monsoonal moisture to the interior, resulting in a cold dry grassland environment in the high uplands even at moderately low latitudes. The horizontal line represents 40 degrees north latitude.

margins, it had an overall integrity. Past models using pollen profiles of simple Pleistocene vegetational communities moving north and south are not consistent with the no-modern-analog reconstructions using macropaleontological samples of whole communities (Guthrie 1990a). Most Pleistocene communities indeed have no good modern analogs. Certainly among these is the Mammoth Steppe. The stable high pressure system, diverse land forms, reduced tree cover, dramatic insolation variations, proximity to glaciers, and other factors produced consider-

able wind in all seasons on the Mammoth Steppe (Guthrie 1982). Wind, incompletely vegetated surfaces, and newly generated glacial silt produced a dusty landscape, of which the thick loess deposits bear witness. In addition to the woolly mammoth, other large mammals

rhino (Coelodonta

included: woolly

antiquitatis), steppe bison (Bison priscus), caballine horses

(Equus ferus), hemionids (Equus hemionus), reindeer (Rangifer tarandus), muskoxen (Ovibos moschatus), saiga antelope (Saiga tatarica), and other less numerous

species (Guthrie 1982). These species developed unique adaptations to life on the

windswept, tree-barren steppes. Natural selection in this environment was apparently very intense (from mammoths to collared lemmings, these northern

174

R. Dale Guthrie

Pleistocene species exhibit some of the most rapid evolutionary changes documented among mammals). And the enormous body size attained by many species suggests that those which developed adaptations to survive the harsh winters

found the steppes a bountiful landscape during the growing season (Guthrie 19844). The cold-adapted anatomical and physiological features found in the Mammoth Steppe species include heat-exchange vein-artery arrangement, the ability to alternately flush and restrict blood flow to vulnerable appendages in Lewis waves, and integumentary insulation of thick woolly pelage and concentrated subcutaneous fat. Appendages were reduced, minimizing heat loss; this occa-

sionally involves shorter limbs but almost always smaller ears and tail. Mammoth Steppe reindeer, mammoth, rhino, bison, and horse were unusually short eared and tailed compared to their phylogenetic-ecological counterparts to the south: deer (Odocoileus), elephant (Loxodonta), white rhino (Ceratotherium), cattle

(Bos), and asses (Equus asinus). While these adaptations to cold and aridity conserved caloric energy, the extreme winter cold demanded absolutely more calories. This need for more calories, which meant chewing more food when only poor quality food is available, affected dental evolution. The complex highcrowned teeth of northern grazing species allowed them to eat a greater volume of marginal quality winter forage (Guthrie 1990a). The conditions which produced the Mammoth Steppe were widespread, but they were not identical in every region. Europe is basically an Atlantic peninsula, which is now kept unusually warm and moist for its high latitude by the warm Gulf Stream Atlantic current. This warm current was diverted southward toward North Africa during the last glacial maximum, but southern Europe still retained aspects of a moderate climate. Even during the glacial maximum, southern France and Spain had relict temperate floras, including oak, hazel, and pine in sheltered valleys. The wooded valleys apparently interfingered with steppelands and the characteristic steppe mammals: bison, horse, woolly mammoth, and reindeer predominate in Paleolithic art and camp middens. Yet I think we should view the Paleolithic peoples who inhabited the European border of the cold steppe perhaps more like the red deer, wild boar, roe deer, cattle, and moose. All were mammals that infiltrated the southern margins of the steppe but never moved out far onto the vast grasslands that were undiluted by woodland corridors. A moderating coastal influence can also be observed on the Pacific side of the Mammoth Steppe. It is most apparent by plotting the southern periphery of the

Mammoth Steppe fauna in relation to what is now the coast of China, Japan, and Korea (Kalke 1976). The southern distribution of these steppe species arcs upward

to the east,

not

hitting

the

coast

until

Hokkaido

(Kalke

1976).

The

heartland of the Mammoth Steppe remained just north of the Himalayas where the climate was most continental. Morphological details of individuals of the mammoth fauna also reveal a less extreme adaptation to cold and aridity on these coastally moderated margins. The tails of steppe bison in southern Europe are much

northern Asia and Alaska (Guthrie

1990a).

longer than bison tails from

Also, European woolly mammoth

-

The Mammoth Steppe and the origin of Mongoloids and their dispersal

175

(ails are quite a bit longer than those from mammoth mummies found in northern Asia. Geomorphological and floral evidence too support the view that late Pleistocene climate in Europe and eastern Asia was not so harsh or extremely

continental as in central and northern Asia. The fossil record across Eurasia and Alaska demonstrates that a rich diversity of large ungulates existed on the Mammoth Steppe. Our Holocene bias suggests that such a diverse large mammal community must imply rich resources, so surely

early people everywhere would have improvised a technology to allow them to pursue the mammoth fauna out onto the open steppes. While the data recognize the presence of the resource, there is no evidence that people were able to hunt and live out on the undiluted steppes. Rather, during the peak of the last glaciation when the Mammoth Steppe was at its greatest extent, the northern perimeter of human settlement was driven far to the south (see Gamble and Soffer 1990). I think this is because the climate of the Mammoth

Steppe not only inhibited

human occupation but virtually prevented it. At glacial maximum, the area covered by the Mammoth Steppe, most of the palearctic, was unpeopled except along its southern margin. As I have pointed out, the ecological nature of the coastally moderated margins of the Mammoth Steppe were different from those at the heartland.

Mongoloids as an adaptive complex of the Mammoth

Steppe

The biological evidence suggests that one group of people were able to handle conditions at the southern portion of the Mammoth Steppe heartland. This region north of the Himalayas was still harsh, but apparently habitable for tough and enterprising people who became the Mongoloids. The archaeological record is not in disagreement with this heartland locus as the most likely one for

Mongoloid origins (Olsen 1992). All of the late Pleistocene human remains to the west of this heartland—Europe across the Middle East into Siberia—seem to be Caucasoid (Turner 1990). Pleistocene human remains from far eastern Asia are of controversial identity, but are not Neo-Mongoloid (Kamminga and Wright 1988). This leaves the harsh interior as the only place for Neo-Mongoloids, the people who express the extreme version of Mongoloid characteristics, to have evolved. One would predict that, similar to other mammals, peoples living just north of the Himalayas were subjected to a dramatically different selection regime than those in southern Europe or Pacific margins of Asia. In central Asia, even toward

its south central border, the climate would have been more continental and much more rigorous than in Europe. But on the southern border of the Mammoth Steppe, backed up against the Himalayan plateau, there was apparently some

occupiable habitat. In the 1950s authors began concluding that the characters which distinguished Mongoloids were an adaptive response to cold (e.g. Coon et al. 1950), but this

emphasis became unfashionable in the counterculture mood of the 1960s and 1970s, when the first stage of antiracism was to deny all differences. But times have changed, and I would like to revive that view and re-portray it in a more

| | | TUeTE——

176

R. Dale Guthrie

complex light as an explicit suite of evolutionary responses to the rigors of a par. ticular landscape, the Mammoth Steppe. In particular I find the morphologicy| and physiological characteristics of Mongoloids fit a consistent pattern of mam.

malian adaptations which occurred

on the Asian

portion

of the Mammoth

Steppe. Although the technology of clothing and fire buffered people from natura| selection pressures relating to climate, it apparently fell short of completely doing so. Eskimos (Mongoloids who had simply extended their range further north in Holocene times) have dramatically different physiological responses to cold than either people of European or African origin (see Roberts 1978 for a review). For example, when hand temperatures drop below freezing, Eskimos (and most other northern Mongoloids) flush the peripheral capillary beds with warm body blood in a cyclic pattern of vasoconstriction and vasodilatation—the Lewis waves [ referred to earlier. This automatic physiological response both minimizes heat loss and keeps limbs from freezing. Europeans, subjected to the same temperatures, have a very irregular response and Africans no Lewis waves at all (Overfield 1985). This is but one facet of a suite of Mongoloid physiological and morphological

adaptations to cold and aridity. There

also seem

to be genetic

racial behavioral differences with regard to comfort thresholds at low temperatures (Roberts 1978). As others have suggested, the extreme development of these

features, as seen in northern or Neo-Mongoloids, seems to have been a product of the last glacial maximum (Kamminga and Wright 1988). Perhaps these central Asian people had already undergone some initial cold adaptedness during the

previous warmer interstade (isotope stage 3), living in the high arid cold heartland, prior to their dispersal. Researchers have referred to these groups as Protoor Paleo-Mongoloids (Filippinos, Burmese, Polynesians, etc.). That is, Mongo-

loids are not at all a homogenous group with regard to the complex of characters we associate with Mongoloids; some could have dispersed out of this Mammoth Steppe heartland during the late Pleistocene and others in the Holocene. The resultant complexity now is probably the result of many factors, including multi-

ple dispersals, intermixing, gene flow, and Holocene evolution, but underlying all of this current heterogeneity of different ethnic histories there is still visible the remnant of a pattern which points to an essence of a Mongoloid adaptive

complex. So keep in mind that each of these characters I am discussing has a quite variable expression and that we are reconstructing the past from the diverse and fragmented present.

The Mongoloid cold/arid adaptive complex While all other parts of the body may be insulated with clothing, the sensory organs of the human face must be exposed under almost all conditions. We

simply must see and breathe. This exposure makes facial features more constantly subject to natural selection than any other part of the body, and it is in the face that one sees the most extreme adaptations (Roberts 1978). Many Mongoloids have reduced lip eversion, reducing the exposure of vascularized surfaces. The

The Mammoth Steppe and the origin of Mongoloids and their dispersal

177

c‘,icanthic fold a{ld fatty upper lid over the eye reduces radiative heat loss (the

¢yes are the main infrared black-spots in the body). The eye’s wet surface accelerates convective and conductive heat loss, making it especially vulnerable 1o cold and wind exposure. The fatty insulation in the upper lid even reduces

heat loss when the eye is closed. Eyelid folds also reduce glare in open country. The low profile of the Mongoloid nose also significantly reduces the potential for heat loss and frostbite. The more general blanket of facial subcutaneous padding around the eyes and on the cheeks, jaw, and chin act as important insulating tissue. The more round, brachycephalic, Mongoloid head form is an efficient heat-retaining design (Roberts 1978). All of these Mongoloid facial traits combine in a smoothed facial profile against wind and cold. One has to be able to function all winter long in a life based on hunting terrestrial mammals. Unlike fishing or whaling, long-term food stores are difficult to amass for terrestrial hunters (red meat is nutrient rich but calorie poor). Working, walking, stalking for long episodes of —40°C or —60°C temperatures is more than difficult. Exposed skin freezes in one minute at these temperatures with a breeze of 7km/h (Folk 1974). It is in such extreme sorts of situations that subtle differences in

performance can make all the difference. I can speak from personal experiences on those issues, as I have had my Caucasian eyes freeze shut and have had severely frostbitten cheeks and nose more than once during my 30 years in Alaska. As with other large northern mammals, frostbite avoidance is a critical factor for humans; however, this can be accomplished with Lewis wave warming. Probably equally important in the long run is the overall effect of these anatomical structures of Mongoloids on the heat budget. But the interacting forces are complex; for example, while Eskimo anatomy is extremely heat conserving, the physiological responses to cold are directed at much greater heat production and keeping extremities warm and operational (Roberts 1978). In relation to that equation of heat budget, one can observe that cold, windy, arid climates are places where overall body proportions can be important in heat retention just as heat dissipation requirements in Australian 40 °C and 50 °C temperatures has influenced Aboriginal Australian body build. It is not by chance

that Australians and African Nilotics are at opposite poles to northern Mongoloids in body proportion (Fig. 11.2a), the relative length of appendages in relation to torso length (that is, sitting height to standing height), and span arm reach compared to height (Houghton 1980; Hanihara 1986; Harrison et al. 1988). As a general figure, northern Mongoloids have a sitting height-stature index of 55; Caucasians, 50; and Black Africans and Aboriginal Australians, 45. Northern Mongoloids have a higher proportion of supernumerary vertebrae and a smaller proportion with subnumerary vertebrae than other groups (Kaufman 1974). Hip width is normally greater among Mongoloids in proportion to shoulder width

(Overfield

1985).

Mongoloids

also tend to have reduced waist constriction

(Hanihara 1986). Long torsoed, with large chests, Mongoloids have reduced lumbar curvature producing a straight profile. Mongoloid body shapes are further accented by disproportionately

shorter and comparatively

thicker distal limbs,

shortened digit length and the well developed appendage musculature and fat

178

R. Dale Guthrie

(a )

R Fig. 11.2

@

L

M~

N

A portrayal of some differences between Mongoloids and other races discussed

in the text. (a) These outline figures represent characteristic stature and body conformation of four males from (left to right) Mongoloid, Caucasoid, Australoid, and Nilotic groups. (b) The skull on the left is from a Caucasoid and the one on the right from a Mongoloid, illustrating some of the structural differences. (c) On the left half of this mandibular arch are characteristic Mongoloid teeth and on the right those of other races. The black arrows suggest evolutionary differences in bite emphasis: an anterior emphasis for

Mongoloids and a posterior or more diffuse emphasis for other groups. The Mongoloid dentition shows shovel-shaped incisors and an elaboration of the first molar and the loss

of the third molar.

deposits. Subcutaneous fat, more equally distributed throughout the body compared to other racial groups, is characteristic of northern Mongoloids (Hanihara 1986), and one of the more important heat conserving mechanisms (Folk 1974).

Breasts and buttocks are not used as major fat depots in Mongoloids asin most other groups. Lean torsos with large breasts and buttocks dissipate heat more readily than

The Mammoth

Steppe and the origin of Mongoloids and their dispersal

179

fat smooth torsos. These differences in body proportions result in an estimated

10% difference in surface area-to-mass between Australians and Mongoloids—a rather significant figure in times of great temperature stress at the extremes.

Reduced surface area in relation to body mass reduces non-visible perspiration

water loss (Harrison et al. 1988), which greatly affects heat loss. The Mongoloids’ comparatively shorter legs have repercussions in engineering of locomotor con-

figuration, requiring a more bowed and flattened femur and head angle different from that of other groups (Houghton 1980). Even skin structure can be a significant adaptive factor to the north. The light skin of northern Mongoloids allows critical vitamin D synthesis even when most of the skin is clothed during winter when UV levels are low. Yet the thick skin cuticle and abundant carotene (Edwards 1953; Szab6 1975) help screen UV damage at high altitudes and in intense sun, whether from reflective surfaces or direct sun rays. Thus the pale yellow skin that results from these features is an excellent compromise for northern climates. The virtual absence of coarse body hair among Mongoloids reduces sebaceous gland production and simplifies cleaning and ectoparasite removal, when one is clothed in the same garments for many months, especially being unable to expose the body to sunshine or washing. Reduced apocrine gland numbers also reduces the amount of skin secretions available for ectoparasites, and heat loss. A disproportionally large percentage of eccrine perspiration occurs on the face of

Mongoloids (Overfield 1985), decreasing the degree of insulation loss resulting from sweaty clothing. Perhaps this trait was also at a selective advantage given the necessity of well insulated clothing in a cold climate. The general absence of

moustache hair under the nasal exhaust would climates where ice accumulates on face hair. In summary,

likewise be an advantage in

this suite of anatomical adaptations forms a consistent pattern,

which apparently gave northern Mongoloids a significant edge in reducing heat loss, requiring comparatively fewer calories for maintenance, while the physio-

logically greater heat production (Roberts 1978) is a resistance to reduced peripheral and core temperature preventing hypothermia and reducing the likelihood of frostbite. Together, they greatly enhance the ability to function at temperatures

and wind chill conditions well below the normal operating range of other peoples.

Specialized masticatory architecture as part of the complex 1 would propose further that the dental changes and the facial architecture which predominate adaptation, were few or mal tissues,

among Mongoloids were selected for, as part of this same cold/arid because they effectively allowed northern peoples, living where there no carbohydrate resources, to exploit more thoroughly large mamthe more marginal gristle and bone. One can compensate for severe

cold by greater caloric expenditure, keeping the body operating at higher temperatures. This is of course done by increasing consumption—by simply eating much more. Johnson and Mark (1947) found that male Eskimos operating normally on days in which the temperature

was

—27 °C consumed an average

180

R. Dale Guthrie

of 5235 calories per day, almost twice that of males in temperate climates, Humans have the potential of increasing metabolic rate 12-15 times greater than

basal metabolic rate (Folk 1974). The cold and the higher metabolic set-point of northern Mongoloids itself would have increased caloric requirements, a pressure to more thoroughly use marginal resources, prompting an intense focus for dietary efficiency. Ultimately, this means a lot more eating. The rarity of fue

meant much meat would be eaten raw and even frozen. We know that among northern peoples in historic times raw meat was eaten often (the word Eskimo is an Indian word for ‘people who eat meat raw’). For these demanding uses of coarse animal tissue one has to make greater use of the forward bite. This resulted in a more massive mandible with a more upright ramus, enlargement and forward rearrangement of jaw muscles, expanding the anterior slips of the masseter and temporal muscles. Both the anterior zygoma and mandibular angle are flared anteriorally to accommodate these anteriorly emphasized muscle origins, which gives northern Mongoloid faces much of their characteristic rounded facial pro-

files (Fig. 11.2b). Selection favoring this forward emphasis of power bite (Hylander affected the structure of individual teeth (Fig. 11.2c). Hanihara

(1968)

1977) also first iden-

tified the Mongoloid dental complex. The first incisors are reinforced by shovel shaped patterns, and even double shovels (Turner 1987). Mizoguchi (1985) found that shoveling is primarily a northern trait associated with a powerful anterior bite and concluded that it was a cold adapted feature derived from meat-eating

specializations. The incisors are relatively large when compared to those of other races, especially the second incisior (Scott 1991). The premolars are also quite robust in comparison to those of Europeans. The anterior molars are excep-

tionally large. The first lower molar has a quite complex crown (six cusps, deflecting wrinkle and protostylid) often reinforced with a supernumerary third root. Also the enamel extends down the neck onto the tooth root. As part of this anterior dental emphasis, there is reduction of cheek teeth from the rear; the third molars are usually vestigial or absent among Mongoloids. Although Turner does not see these as part of a functional pattern, but due

to random drift, I think they fit a distinctive complex of more forward

dental

empbhasis of greater use intensity. Among historic northern Mongoloids the teeth are used so intensively that they are worn down by early adulthood. Again, it is exactly these extremities of use or conditions which can provide intense selection pressures, because minor differences start to matter, and northern Mongoloid teeth have evolved rapidly. We see a similar rapid evolutionary change in the dentition of Mammoth Steppe microtines, horses, mammoths, and bison. As

with people, their teeth were often worn out while still living, and it seems to have been selectively important, because the fossil record clearly shows a increase in dental complexity with time. Turner argues correctly that in a human

social

they do not function, but this only shifts the stress to other family members,

caus-

setting one can be supported by other individuals if one’s teeth are so worn that ing them to wear their teeth down doubly fast, taking over your functions. One’s

performance is always subtly relative to that of other families. This is the kind

The Mammoth

of grist of which

Steppe and the origin of Mongoloids and their dispersal

181

natural selection is made. Selection is only about relative

performance.

The great wear seen among prehistoric and historic teeth of northern Mongoloids indicates they had stepped into a lifestyle in which evolution had not yet produced a tooth form commensurate with its uses. Mongoloids, despite other enhanced technological capacities, had not found a substitute for over-exploiting a critical biological organ. As such, they were laid bare to selection pressure. I suspect the tooth character of northern Mongoloids was, until this century, probably not in an evolutionary equilibrium—it was still evolving rapidly. The fact that the incidence of three-rooted first lower molars is higher in Eskimo-Aleuts than Amerindians or Asiatics (Turner 1990) suggests that their teeth have continued to evolve unidirectionally in the Holocene, as a result of Pleistocene-like dental demands of the far-north. In the same manner, but in a different direction, the teeth of most Holocene agriculturalists have been reduced in size and complexity along with those of their domestic mammals (Scott 1991) in a rather short period of time. Australian Aboriginals also experience tremendous dental attrition, but their diet has been basically different from that of northern Mongoloids. The Australian diet of many coarse raw carbohydrates is at the opposite end of the spectrum from the northern Mongoloid diet of coarse raw animal tissue. Coarse carbohydrates require mainly posterior buccal processing using the whole molar and

premolar battery. Australian Aboriginals have huge cheek teeth, including well developed third molars and even frequent supernumerary fourth molars (Allegro 1982), consistent with a posterior emphasis opposite that of the Mongoloid anterior emphasis.

Ecological context required for rapid adaptations to cold On the basis of other mammals,

I would argue that a certain level of intensely

cold, Arctic-type conditions are required to initiate this Mongoloid complex of traits. Furthermore, this complex could not have occurred in cold conditions even in northern temperate climates. Among temperate mammals there are anatomical responses to selection for cold tolerances, say, in the form of thicker pelages and well furred ears dnd tail, but ears and tails remain quite long. This is different from that seen in Subarctic and Arctic mammals that have not only well-furred ears, but also have greatly reduced the size of the ear and tail. Cold, wet conditions experienced in severe, but short, winters of temperate climates are not sufficient to create extreme anatomical adaptations, like those seen among Mongoloids. The reason for this is that most mammals have a comparatively broad thermal neutral zone, that plateau on the graph in which capillary bed symphonics can regulate body temperature without actually increasing metabolic rate (Fig. 11.3). At more extreme temperatures, one must increase metabolic rate. In this part of the curve, individual variations in ability to conserve heat, especially on exposed surfaces, are magnified (Fig. 11.3). This magnification greatly influences selection intensity and hence evolutionary rate, especially when these conditions

182

R. Dale Guthrie Two Well-Clothed Individual Genetic Variants

Comparison of Individual Metabolic

T

Rate Differences at Cold and

.

Very Cold Temperatures

Metabolic Rate

Basal Metabolic Rate

A

B

Thermal Neutral Zone

T

50

ocC

-50

Ambient Temperatures

Fig. 11.3 A graph to illustrate how variation in individual differences in cold resistance could theoretically be much

more dramatic outside the thermal neutral zone

(that range

of temperatures in which metabolic rate is constant). Given similar clothing, individual genetic and anatomical and physiological differences produce different metabolic responses (between individuals A and B) to windy cold weather. Individual A has to increase his metabolic rate at a much steeper angle than individual B to ever colder temperatures. It is in this extreme of the cold range that natural selection would greatly favor the anatomy and physiology of the characters possessed by individual B. I argue that this cluster of cold adapted traits are the Mongoloid adaptive complex.

persist for many months of the year. And of course, Fig. 11.3 cannot tell all of the story, because at these cold extremes Eskimos are staying warmer, as shown by core and finger tip temperatures, than are Europeans. In short, it takes sustained temperatures toward the extreme end of the thermal neutral range to create the features we see as a Mongoloid complex. Given that there are no Pleistocene

archaeological sites in the far north, these conditions are most likely to have been experienced in the heartland of the Mammoth

Evolutionary rates on the Mammoth

Steppe.

Steppe

The late Pleistocene was a turbulent time for the world’s biotas, notable for unusually rapid evolutionary rates. Changes in body shape and size are able. Bison, for example, go from being a gigantic creature with huge much smaller short-horned forms (Guthrie 1990a). Even in Holocene can see dramatic changes in animals experiencing new habitats. For

remarkhorns to times we example,

The Mammoth Steppe and the origin of Mongoloids and their dispersal

183

moose (Alces alces) move northward with the Eurasian boreal forest, invading

northeastern Siberia and then Alaska in post-Glacial times (Guthrie 1990b). From Alaska, moose colonized more temperate parts of North America across to the Atlantic. This Holocene moose colonization happened so recently that American moose exhibit virtually no mtDNA variations, yet there are significant genetic anatomical, ecological, and behavioral evolutionary differences among

populations—certainly sufficient for separation at subspecific rank. It is interest-

ing that this closely parallels the time in which northern Mongoloids moved into North America. Stone sheep (Ovis dalli stonei), and Dall sheep (Ovis dalli dalli), separated during the last glacial maximum, became literally black and white, their respective colors. There are numerous such cases of rapid mammalian evolution in the late Pleistocene and Holocene. We can understand that humans might also have experienced and responded to some of these local contextual pressures, especially

as they moved into new conditions.

Neo-Mongoloids versus Paleo-Mongoloids Whenever Mongoloids occupied southeast Asia, they seem to have been originally derived from the north. For despite their residence now in tropical and subtropical conditions they do share some of the cold/arid adapted complex which, if my argument is sustainable, could have been only acquired in the north. So either they moved southward in the Holocene or sometime in the late Pleistocene. The latter would explain Pleistocene Mongoloid fossils found in southeast Asia.

One can only assume that, during isotope stage 2, the last glacial maximum, 25 to 13 Ka, the severe climatic conditions which produced the heterogeneous peoples who we cluster as northern or Neo-Mongoloids (Buryat, Eskimo, Chukchi, north Chinese, etc.) were maximally powerful. However, climatic conditions

were also severe during the last interstade, isotope stage 3, 40 to 25 Ka, but not so extreme. Thus, the ancestors of the heterogenous group of peoples we cluster as southern or Paleo-Mongoloids (Filippinos, Polynesians, Burmese, etc.), as

well as the ancestors of northern or Neo-Mongoloids, could have been produced in the Mammoth Steppe heartland during isotope stage 3 or have been influenced by gene flow from such peoples. Though people like the Brazilian Indians have

not been in their new home for sufficient time to lose many of their cold driven Mongoloid traits (trunk-limb proportions, small breasts, complex teeth, etc.), many

traits

are

beginning

to evolutionarily

‘bleach

out’

(physiological

cold

tolerance, eyelid folds, etc.), moving toward a more appropriate physiology for their new homeland.

Northern dispersal of Mongoloids The Mammoth Steppe began to disintegrate during the moderating influences in the waning phases of the last glacial maximum. The pattern of that break-up was

complex, but it resulted in a winnowing out of adaptive themes. The biota shifted

184

R. Dale Guthrie

from what I have described elsewhere (Guthrie 1984b) as a complexly patterneq plaid to a much simpler set of stripes. Some threads were lost in extinctions, by many colours changed when the loom was rethreaded in a new and simpler Holocene pattern. Reindeer and saiga are emblematic of this change (Guthrie 1990c). They occurred together throughout most of Eurasia and Alaska during the Late Pleistocene, but at the beginning of the Holocene, reindeer and saiga distributions rapidly separated, one moving north and the other south.

At the outset of the Holocene, forests invaded the Mammoth Steppe from the south and with them came mammals which depended

on trees, such as moose

and people. The Pleistocene winds began to wane. Winters were still cold in the north but there was wood for fuel and trees to break the wind and deeper snow to help with lodge insulation. The people most likely to move into this new

habitat were Mongoloids—and they did. The climatic border which formed their northern limit was lifted. Linguistic, morphological, and genetic evidence (Greenberg et al. 1986) corroborates the archaeological record (Haynes 1982; Powers 1990) of Mongoloids into northeastern Siberia, Alaska, and from there New World about 12Ka. As with other mammals dispersing in American Mongoloids underwent some adaptive changes to local

of an explosion throughout the the Holocene, conditions; for

example, body size (Molnar 1975).

Conclusions Mongoloids were people of the Mammoth Steppe. The pattern of morphological and physiological traits which constitute being Mongoloid are the result of adaptive responses to a special environment. This suite of traits apparently evolved very rapidly in the late Pleistocene, as Mongoloids encamped at frontiers to human dispersal in the rigorous climate of the Asiatic heartland of the Mammoth Steppe. The northward dispersal of Mongoloids occurred as that climateecological barrier disintegrated with the extinction of the Mammoth Steppe.

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