Objectives

1. Discuss the earliest migrations of people (anatomically modern humans!) into the New World

2. Discuss Paleoindian lifeways in North America

· As soon as Europeans landed in the Americas, they wondered about who Native Americans were, and where they came from

· It wasn’t until 1926 that archaeologists began to realize the antiquity of human occupations in the New World

· Folsom projectile point (discovered 1926) associated with extinct bison

· Clovis projectile point (discovered 1932) associated with extinct mammoth

· When the Folsom point was discovered, it was clear that human beings had occupied North America since at least the end of the last ice age

THE EARLIEST MIGRATIONS

· BUT the Folsom point didn’t answer two important questions:

· WHERE did Native Americans come from?

· WHEN were the earliest migrations? Clearly, people were here since at least the end of the last ice age…but is there evidence for earlier occupations?

WHERE

· There is NO fossil or archaeological evidence for non-modern humans in the New World

· Since only modern humans have occupied the New World, they had to have migrated here from somewhere else

· Archaeologists generally accept that the earliest Native American populations came from Asia

· This interpretation is usually based on morphological evidence

· For example, modern American Indian dentition generally looks a lot like modern Asian dentition (e.g., shovel-shaped incisors)

· What is not agreed upon is

· what route they took from Asia to the New World

· exactly where in Asia they were coming from

· the number/size of migrations

Routes

1. Beringia (the Bering Land Bridge)

· exposed between 25,000 and 14,000 years ago

· archaeologists who emphasize Beringia also tend to emphasize big-game hunting to the exclusion of all other subsistence resources (people were relying almost exclusively on big game, and had to go wherever the game went)

2. Maritime route

· subsistence resources other than big game

· allows for a different route into South America and the North American interior

Asia during the Upper Paleolithic

· We would assume that if the earliest Americans migrated across the Bering Land Bridge, that we would see some archaeological parallels between Siberia and the earliest North American sites

· Upper Paleolithic big-game hunters moved into northeast Asia and Siberia during the closing millennia of the Wisconsin (Würm) glaciation

· The Dyukhtai tradition (18,000 to about 12,000 ya)

· hunted big game, including mammoth and musk ox

· bifacial projectile points and knives

· microblades produced on small, wedge-shaped cores

· Dyukhtai was widespread in northeast Asia by about 14,000 ya

PROBLEM:

· Big-game hunting traditions that produced Folsom and Clovis points don’t really resemble Dyukhtai!!!

· BUT there is a lot of technological variability within the Americas…Folsom and Clovis only occur in North America

· FURTHERMORE there are pre-Clovis technologies that resemble Dyukhtai technology

· This suggests that Folsom and Clovis technologies developed in North America after the first migrations into the New World had taken place

· So there are some similarities between archaeological cultures in Siberia and the Americas at the end of the last ice age

· BUT this doesn’t mean that Dyukhtai peoples picked up and moved to the Americas en masse!

Multiple Migrations?

Linguistic evidence

· Joseph Greenberg (1950s) identified 3 major linguistic groups: "Amerind", Na-Dene, and Aleut-Eskimo

1. Amerind was earliest, at 9000 ya

2. Na-Dene at 7000 ya

3. Aleut-Eskimo at 2000 ya

· There is an implicit assumption that the earliest Americans ("Amerind" speakers???) migrated in one huge wave

PROBLEM:

· Kennewick Man!!!

· He doesn’t look like modern Native Americans OR like modern Asians

SOLUTION:

· It is more likely that there were multiple, sporadic migrations, perhaps both across Beringia and along the coast

· Some of these people just didn’t make it

· Kennewick man is one of the people who couldn’t hack it

· REMEMBER: genetic drift (founder’s effect, population bottlenecks)

WHEN

· The "Clovis barrier" 11,500 years ago

· BUT there are a number of possible "pre-Clovis" sites

· Bluefish Caves, Yukon 13,000 ya (also 23,500 ya…questionable)

· limestone rock shelters and caves

· remains of mammoth, horse, bison, elk, and caribou, and a number of small mammals

· many bones have cut marks

· wedge-shaped microblade cores

· Meadowcroft Rockshelter, Pennsylvania 15,000 ya

· remains of white-tailed deer and small game

· blade technology

· Miller lanceolate points

· Monte Verde, Chile 13,000 ya

· excellent preservation of perishable materials

· log-framed houses

· specialized activity areas

· evidence for year-round exploitation of mastodon, small game and plants…indicates sedentism

· BUT many other early sites have very questionable dates

· Pedra Furada, Brazil 40,000 ya

· "tools" recovered from this rock shelter may actually be stones that fell from the quartzite cliffs overhead

PALEOINDIAN LIFEWAYS

· "Paleoindian" is the name given to the North American big-game hunting traditions, including Clovis

· Paleoindian occurs throughout North America

· BUT there is a higher density of Paleoindian sites in the east, and Paleoindian assemblages in the east exhibit more variability than assemblages in the west

· Dates from about 11,500 BP to 9,000 BP (depending on where in North America you’re talking about)

· Technology includes large, fluted bifaces, endscrapers, sidescrapers, drills, etc.

· Paleoindian technology focused on the exploitation of big game resources, including mammoth and bison

· Paleoindian hunting and butchery sites occur at locations where it would have been easy to ambush large game

· In the western US, there is evidence for massive bison drives, in which whole herds of bison were driven into arroyos/off cliffs and then dispatched (e.g., Olsen-Chubbock, Colorado)

· Paleoindian peoples were HIGHLY MOBILE

· Settlements include base camps (e.g. Lindenmeier, Colorado) and special-purpose camps for hunting, butchering, and quarrying

· Paleoindian settlement patterns contrast markedly with the evidence from Monte Verde, for example

· Paleoindian peoples illustrate some of the problems with applying ethnographic analogies in prehistory

· We don’t have any modern analogues for Paleoindians

· For example!

· Lewis Binford suggested that highly mobile hunter-gatherers will gather lithic resources during subsistence rounds (he called this "embedded" procurement)

· The idea is that hunter-gatherers will minimize the time and effort necessary for raw material procurement by "embedding" raw material procurement in subsistence activities (Pick up rocks while you’re picking up food. In other words, killing two birds with one stone!)

· Well, Paleoindians contradict Binford’s idea

· CASE STUDY: Nobles Pond, Ohio

· 11 distinct clusters of occupation

· a wide range of lithic materials, including fluted points, scrapers, and debitage

· lithics could be re-fit among the occupation clusters

· the frequencies of different raw materials were nearly the same from cluster to cluster

· these clusters did NOT accumulate as the result of a series of independent, small-scale occupations

· rather, Nobles Pond was an aggregated encampment where several Paleoindian groups came together

· each of these groups was using the same raw materials…it would be too much of a coincidence to suggest that they all passed through the same quarries (even the frequencies of different COLORS are the same)…it is more likely that these raw materials were cached (stored) someplace nearby, where groups could access materials while camped at Nobles Pond

· Paleoindian peoples went to great lengths to get select raw materials to make their fluted points, and re-sharpened and re-used tools a lot

Megafaunal Extinctions; The Colonization of Australia

Copyright © 2000 Stanley H. Ambrose

Anthropology 102 lecture of 24 April, 2000

Overview:

During the Late Pleistocene there were two major (actually 4) invasions of continents by behaviorally modern humans. We have already examined modern African entrance into the Levant and Western Eurasia by 47,000 bp, and the perimeter of the Indian Ocean (southern Australasia), probably sometime earlier in the last glacial. Humans also entered Australia and the Americas. These immigrations occurred in parallel with the process of invading more challenging environments within continents. One dramatic change that occurred in parallel everywhere is the gradual and sometimes abrupt extinction of the Pleistocene megafauna. It occurred fastest in North America and slowest in Africa. Extinction rates were intermediate in Eurasia. What caused this dramatic wave of extinctions? How did humans respond to the change in resource structure? This period sets the stage of intensification and diversification of subsistence strategies known as the Broad Spectrum Revolution. The social and ecological transformations that occurred at the end of the Pleistocene then set the stage for the beginning of agriculture in many parts of the world.

MEGAFAUNAL EXTINCTIONS: OVERKILL OR CLIMATE CHANGE?

In the New World 35 large mammal genera became extinct between 20-12 ka, Including camels, ground sloths, yaks, bison, elephants, horses, lions, sabre tooth cats and bone-crushing dire wolves (resembled hyenas). Similar waves of extinction affected Eurasia and Australia in the last Ice Age. Woolly mammoths, rhinoceroses, cave bears, cave lions, Irish elk, large bison and many other giant species disappeared after the advent of the Upper Paleolithic, and all had disappeared by 10-12 ka, except on island refuges in the Mediterranean, where pygmy hippos survived, and an island in Siberia, where pygmy mammoths only 6,000 years old were recently discovered.

In Africa, the rate of megafaunal extinction was slower, and in many ways, the African faunal community is still a pale reflection of the Pleistocene: Elephants, rhinoceros, giraffe and hippo, and their predators, still survive. The diversity of large mammals was, however, greater in the Pleistocene. Recent extinctions include Megalotragus (a giant relative of the wildebeest), Pelorovis (a giant buffalo), a large warthog, and Antidorcas (a large springbok). Two species (a zebra and a relative of the wildebeest) have become extinct within the last two centuries.

Why are large mammals prone to extinction?

Large mammals tend to have lower reproductive rates than small animals, so they are likely to recover from population crashes more slowly and predators can prevent them from recovering or even reduce their population sizes if they are effective killers. The problem with being large is there is no place to hide. Large herbivores also tend to have low quality diets and high total food intake needs. If the food supply is reduced long enough they may starve. Think about our most endangered species: they include the giant panda, blue whale, gorilla, rhinoceros and elephant. All are animals with large bodies and low quality diets.

Large mammals have slow reproductive rates for the following reasons:

1 Long gestation period.

2 Long time to weaning.

3 Long interbirth interval.

4 Single rather than multiple birth.

5 Long time to sexual maturity.

What caused the extinctions?

1 Climate change and Equability Hypotheses:

An increase in seasonality led to greater winter stress on herbivores and their predators. This seems unlikely to me because it happened 24 times in the last 2.5 million years.

Abrupt Climate Change: The end of the ice age involved a complicated series of climate changes. The Yonger Dryas, which interrupted the more gradual warming of the end of the ice age, was a sharp return to cold conditions. The end of the Younger Dryas was a very abrupt event, where the transition from full ice-age to full interglacial conditions may have occurred within 10-20 years. This also seems unlikely because severe ice ages occurred 8 times inthe last 800 ka..

2 Keystone Species Hypothesis:

A chain reaction following the loss of important species that modified the environment. For example mammoths and mastodonts disturb environments creating niches for smaller herbivores and birds. They knock down trees, dig up the soil and cause other disturbances that promote microhabitat and plant diversity and open up feeding opportunities for other mammals. Elephants often maintain access to water in dry environments by digging holes in dry river beds. this allows smaller animals to obtain water. In winter, wolly mammoths may have cleared the snow with their tusks to get at the grass. Smaller animals may have also fed in these exposed patches during the winter. Large carnivores like sabretooth cats and dire wolves (they were similar to hyenas) preyed upon the mega herbivores and left scavenging opportunities for smaller carnivores.

This are examples of feeding successions or commensalism. Commensalism is where one species has higher darwinian fitness because of opportunities created by another, with no effect on the species creating the opportunity (contrasted with parisitism, or predation, which lowers the fitness of the exploited species, and symbiosis, where two species are mutually beneficial - where both have increased fitness in the presence of the other). Loss of the Keystone species can make symionts and commensals prone to extinction. The predators on these species may also be at risk. Finally, competitors that were once regulated by their predators, can now wipe out the competition.

3 Habitat Shift: Effects of rainfall on soil and plant chemistry and herbivore digestion.

Loss of grasslands; replacement by woodlands and forests with less nutritious leaves for herbivores, led to the extinction of grazers that had dominated herbivore biomass. Grasslands typically have more digestible plant material, with more protein in the leaves, and lower concentrations of chemicals called secondary compounds, that deter herbivores from eating them. Grassland soils tend to be more fertile, so when plants lose leaves to herbivores they can replace them at little cost. When soils are less fertile, it is harder for the plant to replace lost nutrients so they develop stronger chemical defenses against herbivory. Herbivore biomass is typically lower in forest and woodland environments because a smaller proportion of the available plant biomass is edible, and is generally more toxic. Herbivores must become more eclectic feeders.

Why did forests replace grasslands at the end of the Pleistocene? Grasslands are often maintained by a combination of low rainfall, frequent fires (which kill small trees), and high herbivore feeding intensity, by eating fresh tree seedlings. When rainfall increases, trees tend to grow faster and fires become less frequent. Grasslands can shift to woodlands and forests if rainfall is high enough. When rainfall increases nutrients are leached from the soil, becoming less available to grasses and trees. Most grasses like nutrient-rich unleached soils and they have nutrient rich leaves to feed herbivores. The flora becomes dominated by woody plants with chemically defended leaves. Increased rainfall thus sets into motion a series of changes that shift the balance from fertile soils with nutritious grasslands and large herds of grazers, to less fertile soils supporting woodlands with lower densities of browsers. Temperature increases at the end of the Pleistocene probably also accelerated chemical reactions in the soil, permitting faster weathering and leaching of soil nutrients.

4 Predator/Prey Ratio Increase: In Africa, open grasslands have high and highly variable herbivore and high carnivore population densities. Herbivore populations can grow rapidly in years of high and reliable rainfall, producing more potential prey than carnivores can eat. When herbivore populations get too high, they exceed the food supply and their populations crash, leaving far less prey for the carnivores. Occasional droughts have the same effect. Carnivores are unable to regulate the populations of their prey in grasslands. Herbivore populations are regulated by their food supply.

However, in forests and woodlands, where prey densities are lower and long term variability in environmental carrying capacity is lower, predators have a more reliable food supply. They have many places to hide and ambush prey, so predator/prey ratios increase and carnivores can regulate herbivore population densities. Woodland herbivore prey population sizes are thus regulated by their predators rather than their plant food supply. Since prey population densities are low and predator population densities proportionately high in more wooded environments, could this tip the balance of some species toward extinction?

5 Paleoindian Overkill Hypothesis: 70% of extinctions occurred between 12-10 ka. The animals may not have been able to adapt to the tremendously effective and dangerous human predators with their sophisticated weapons (spears with spear-throwers, bow and arrow?, boomerang, etc.). The low reproductive rates of large mammals did not permit them to sustain high rates of predation. Some extinctions seem to have occurred before there is firm evidence for humans, so environmental change must have played a role too, unless humans were actually in the Americas before 13 ka. Madagascar, New Gunea, New Zealand and the Pacific Islands had large and diverse faunas before colonization, but extinctions occurred soon after initial colonization. A few Pleistocene megafauna survive in Africa where humans and animals have co-evolved for the longest time.

The best explanation for the overall pattern of extinctions in North and South America would be a combination of climate change, causing an increase in inedible woody vegetation that could not support the megafauna, plus human overkill, increase in predator/prey ratios and the loss of Keystone species. The extinctions in Africa, Australia and Eurasia that occurred between 40- 12 ka may also be attributed to climate change, combined with increased efficiency of human hunting.

Why didn’t early modern humans and neanderthals cause extinctions during the last interglacial (oxygen isotope stage 5), 128 ka?

Extinctions probably did not occur at the transition to the previous interglacial because Middle Paleolithic peoples were less effective predators. Recall that they tended to exploit the youngest and oldest age classes of their more dangerous prey species and were unable to capture fish and flying birds throughout most of the Middle Paleolithic/MSA. This prevented them from lowering the reproductive capacity of the prey herds, because the breeding females could replace the offspring lost to predation, and the oldest animals may have been at the end of their reproductive careers.

MSA/MP moved more erratically across the landscape and did not seem to be able to seasonally schedule their use of the landscape to take advantage of windows of opportunity such as seasonal migrations of herbivores or fish runs. They are often argued to have scavenged as much they as hunted.

Would the Old World extinctions have occurred if human hunters never became more effective than their MSA and Middle Paleolithic antecedents? I don't think so. Perhaps this is why extinctions occurred at a slower pace during the previous two million years (12 genera in N. America) even though climate was cycling in and out of ice ages, causing the same kinds of natural environmental changes described above.

INVADING NEW WORLDS: AUSTRALIA

Genetic evidence suggests that eastern African populations crossed the Bab El Mandeb Straits at the southern end of the Red Sea some time during the early last Glacial, probably during a time of low sea level. Sea levels would have been lowest during oxygen isotope stage 4, between 60-70 ka. They continued to move east into more favorable tropical environments, ultimately arriving in Australia.

HOW?: Colonization by boat across Wallace Divide. The crossing out of Africa would have required travel by boat as well.

ROUTE?: Island -hopping trips: the minimum distance between islands is about 50 miles (87 km) at lowest sea level. No evidence of boats has been found, but none is expected because the coastal sites at the time of colonization would be underwater. During low sea level, Tasmania was connected to Australia and was also colonized.

WHEN?: Lake Mungo, Willandra Lakes occupied 33 ka, but 14C dates are unreliable at this age, and the sites could be older. They contain anatomically modern humans and formal burials. More recently reported sites have Thermoluminescence (TL) and Opticially Stimulated Luminescence (OSL) ages on burned stone tools and unburned sand grains in excess of 40 ka. These lake sites are in the arid interior of Australia. Near modern coastlines, the earliest occupations in New Zealand are at least 40 ka. Were the earliest sites located on continental shelf (now underwater), and the interior colonized only later? This explanation would account for the age difference.

Since 1990 some archaeologists have been using Optically Stimulated Luminescence of sand grains to date sites to over 50 ka, and even as old as 116 ka at one rock shelter site called Jinmium, in Queensland, Northern Australia. Jinmium is claimed to have the oldest artwork on earth, in the form of circular depressions ground into the rockshelter face. This dating of this site has enormous problems, especially the fact that the radiocarbon dates are less than 10 ka! The rockshelter is made of the same rock as the dated sands so the samples dated may be contaminated with decomposed sandstone that was not reset by exposure to sunlight before burial in the site. The OSL dating technique is like TL (see p. 359 in the textbook) because it relies on the absorption of radiation from the surrounding rock, sediment and internal radioactivity. It can even be affected by the amount of moisture in the sediment, which may have varied over time. One must make assumptions about many factors (variables) that cannot be controlled, so the dates are only as accurate as the estimates of the values of the unknown variables. One can obtain a wide range of dates depending on assumptions. This is not a great problem with radiocarbon dating.

The bottom line here is that dates of older than 40-50 ka for the colonization of Australia remain unconfirmed. This puts them inthe time range when they could still be derived from modern Africans rather than the Javan populations represented by Ngandong (late, large-brained H. erectus).

Who were the first Australians? The antecedents of Australians may have either been H. erectus or African moderns or Asian moderns. The fossil record north and east of Australia contains only a few human fossils older than 30 ka. The Ngandong (Java) material is clearly a late descendant of a regional population of Homo erectus and may date to 50-100 ka. At Niah Cave, Borneo, there is one modern skull associated with a date of ~40 ka, but it may be intrusive from younger levels, and be less than 30 ka. The genetics suggest a recent African ancestry, post-dating 70 ka.

What do the Australian human fossils show? The oldest fossils, from Lake Mungo, date to 33 ka. They are lightly-built, rather modern-looking individuals. The younger skulls, from Kow Swamp and Keilor, dated to around 13-15 ka. Although half the age of Lake Mungo, they look more similar to Ngandong! They have angled occipitals, sloping, flat foreheads and large browridges and noses. The sloping forehead is apparently due to artificial cranial deformation (head-binding). These features are also shared with modern Australians. The Kow Swamp and Keilor skulls have been used to support the hypothesis of regional continuity and multiregional origins of Australians from Asian Homo erectus. However, this is inconsistent with their younger age than the more modern Lake Mungo skulls. One explanation is that the earliest immigrants were the leading edge of the African immigrant wave, who later evolved regional Australian features, which coincidentally resembled Ngandong. A second hypothesis is that more than one population immigrated to Australia. A third hypothesis is that there are no differences: At Mungo only females were recovered and at Kow Swamp and Keilor, only males. I prefer the first hypothesis.

Willandra Lakes Hominid 50 (WLH-50) is also said to be similar to Ngandong because it has features related to cranial bone thickening. However, the thickening of the cranial bones is not like erectus or heidelbergensis. The spongy bone layer in the middle of the inner and outer dense bone has thickened. This often occurs in chronic anemia due to malaria. By this criteria there are many skulls only 10,000 years old in Africa that look like Ngandong. This does not bode well for the regional continuity model.

MEGAFAUNAL EXTINCTIONS

50 species of Australian marsupial (metatheria) mammals died out 40-15 ka. They included giant marsupial kangaroos, and marsupial carnivores that even resembled sabre tooth tigers. What was the role of humans and climate change in this wave of extinctions? No true (Eutherian) mammals larger than bats or rodents crossed into Australia without human assistance. Did human hunting or the depradations and diseases brought by other mammals force the extinctions?