Prehistoric Life - York University · SC/NATS 1510, Prehistoric Life 1 Prehistoric Life The Hunting...

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SC/NATS 1510, Prehistoric LifeSC/NATS 1510, Prehistoric Life 11

Prehistoric LifePrehistoric Life

The Hunting and Gathering PeriodThe Hunting and Gathering Period

22SC/NATS 1510, Prehistoric LifeSC/NATS 1510, Prehistoric Life

The Origin of Life on EarthThe Origin of Life on EarthAt some point in the 4At some point in the 4½½ billion years of billion years of the Earththe Earth’’s past, the environmental s past, the environmental conditions were right for complex conditions were right for complex chemical compounds to formchemical compounds to form——the the organic compoundsorganic compounds——necessary for life.necessary for life.From those compounds evolved amino From those compounds evolved amino acids; from amino acids, proteins; from acids; from amino acids, proteins; from proteins, nucleic acids; and ultimately proteins, nucleic acids; and ultimately plants, then animals. plants, then animals.


When?When?Current estimates are that there were Current estimates are that there were some life forms in the seas 3some life forms in the seas 3½½ billion billion years ago; plants emerged 400 million years ago; plants emerged 400 million years ago; land animals, 360 million years ago; land animals, 360 million years ago.years ago.Life on land was well established at the Life on land was well established at the time of Pangaea. When the continents time of Pangaea. When the continents separated, life evolved differently on separated, life evolved differently on different continents.different continents.

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EcosystemsEcosystemsPhotosynthesisPhotosynthesis

All life depends on sunAll life depends on sun’’s energy through s energy through photosynthesisphotosynthesis——the only way that energy is the only way that energy is introduced into our ecosystem.introduced into our ecosystem.Only about 0.2% of sunOnly about 0.2% of sun’’s energy is s energy is converted into matter.converted into matter.

PhotosynthesizersPhotosynthesizers provide the basic provide the basic energy input. These include:energy input. These include:

Plants, trees, grasses.Plants, trees, grasses.This is the bottom of the food chain.This is the bottom of the food chain.


The Food Chain The Food Chain The basic food chain consists of:The basic food chain consists of:

PhotosynthesizersPhotosynthesizers Herbivores Herbivores Carnivores Carnivores Top CarnivoresTop Carnivores

PhotosynthesizersPhotosynthesizers are:are:Broken down in the soil by decomposers, e.g., fungi.Broken down in the soil by decomposers, e.g., fungi.They are also eaten by herbivores. They are also eaten by herbivores.

Herbivores are eaten by carnivores.Herbivores are eaten by carnivores.Top carnivores eat both herbivores and other Top carnivores eat both herbivores and other carnivores.carnivores.When these animals die, their carcasses rot When these animals die, their carcasses rot and elements are recycled.and elements are recycled.


Hierarchy of Ecosystems Hierarchy of Ecosystems

The higher an animal is in the food chain, the rarer it will be.•A cow can store only 0.6% of the primary production of grass.

Only a small number of carnivores can exist in an ecosystem, compared with the number of primary producers.

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The Flow of Energy The Flow of Energy Example: A deciduous forest Example: A deciduous forest

88% of primary production by 88% of primary production by photosynthesizersphotosynthesizers falls to the ground and falls to the ground and decomposes.decomposes.Another 8% is stored as dead wood. Another 8% is stored as dead wood. About 3% is available for herbivores to eat. About 3% is available for herbivores to eat. Even less is available for the carnivores Even less is available for the carnivores living off the herbivores.living off the herbivores.


The Flow of Energy in an The Flow of Energy in an EstuaryEstuary


Orderly Series of Changes in Orderly Series of Changes in Ecosystems Ecosystems

The culmination of orderly change is a The culmination of orderly change is a ““climaxclimax”” system with the maximum system with the maximum number of possible plants and animals.number of possible plants and animals.

Thousands of years are required to go Thousands of years are required to go from bare rock to lichens and mosses to from bare rock to lichens and mosses to ferns, plants, and trees to create a climax ferns, plants, and trees to create a climax forest, which can survive for very long forest, which can survive for very long periods periods without human interference.without human interference.

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Different Types of Different Types of Ecosystems Ecosystems

Ecosystems vary depending on Ecosystems vary depending on temperature and rainfall.temperature and rainfall.They are found in broad bands between They are found in broad bands between the poles and the equator.the poles and the equator.Changes in earthChanges in earth’’s climate cause bands s climate cause bands to change location by hundreds of miles to change location by hundreds of miles over several thousands of years.over several thousands of years.


Tundra Tundra

Near the poles: low rainfall, low temperatures, permafrost.Near the poles: low rainfall, low temperatures, permafrost.Poorly drained, acidic soils are covered in low scrub.Poorly drained, acidic soils are covered in low scrub.

Productivity is low because of cold and lack of sun.Productivity is low because of cold and lack of sun.The food chain is short and simple.The food chain is short and simple.


Taiga Taiga

Further from the pole, but only in the Northern Further from the pole, but only in the Northern Hemisphere (no land in the right place in the southern).Hemisphere (no land in the right place in the southern).Great coniferous forests.Great coniferous forests.

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Temperate Forests Temperate Forests

Further still from the polesFurther still from the polesRich secondary flora, better soils, high leaf drop.Rich secondary flora, better soils, high leaf drop.Large quantity of decomposers.Large quantity of decomposers.


Grasslands Grasslands

Less rain.Less rain.Poorer soils.Poorer soils.


Desert Desert

Confined to about 30 degrees N and 30 degrees S of the equator.Confined to about 30 degrees N and 30 degrees S of the equator.Due to large masses of very dry air.Due to large masses of very dry air.

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Tropical RainforestsTropical Rainforests

High rainfall.High rainfall.High temperatures.High temperatures.Many local variations.Many local variations.


Coral Coral Reefs Reefs

The open ocean is like a desert.The open ocean is like a desert.But coral reefs and estuaries teem with life, at levels equivaleBut coral reefs and estuaries teem with life, at levels equivalent of the nt of the tropical forests.tropical forests.


Productivity of Tropical Productivity of Tropical Forests Forests

Tropical forests produce 40% of all terrestrial Tropical forests produce 40% of all terrestrial primary plant production.primary plant production.

They contain about half of all the plants and animals They contain about half of all the plants and animals on earth.on earth.

They are remarkable for their diversity.They are remarkable for their diversity.A typical 4 sq miles of forest will contain the A typical 4 sq miles of forest will contain the following numbers of following numbers of species species (not individuals):(not individuals):

1500 flowering plants, 750 trees, 125 mammals.1500 flowering plants, 750 trees, 125 mammals.400 birds, 100 reptiles, 60 amphibians, 150 butterflies.400 birds, 100 reptiles, 60 amphibians, 150 butterflies.50,000 insects (probably there are 20 million species of 50,000 insects (probably there are 20 million species of insects in all tropical forests).insects in all tropical forests).

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Poor Soil of Tropical Poor Soil of Tropical Forests Forests

Tropical forests different from temperate Tropical forests different from temperate forests, which have rich soils.forests, which have rich soils.

¾¾ of nutrients are held in the plants and of nutrients are held in the plants and trees.trees.Only 8% of nutrients are in the soil.Only 8% of nutrients are in the soil.Very little rainwater runs into soil.Very little rainwater runs into soil.Over Over ½½ of this evaporates; most of rest is of this evaporates; most of rest is absorbed directly by plants and trees.absorbed directly by plants and trees.


Vulnerability of Tropical Vulnerability of Tropical Forests Forests

Soil is thin, acidic, and of poor quality. Soil is thin, acidic, and of poor quality. It contains little humus, which has most of It contains little humus, which has most of the lifethe life--giving properties of soil.giving properties of soil.If the ecosystem is destroyed through forest If the ecosystem is destroyed through forest clearance, most nutrients are destroyed too. clearance, most nutrients are destroyed too. Exposed ground quickly turns into hard clay.Exposed ground quickly turns into hard clay.


What is Soil?What is Soil?

Soil is a product of an ecosystem.Soil is a product of an ecosystem.Created by living plants and animals.Created by living plants and animals.Relies on them to remain fertile.Relies on them to remain fertile.Built up over thousands of years.Built up over thousands of years.

Rock is weathered into minute fragments.Rock is weathered into minute fragments.Incorporated with remains of dead plants and Incorporated with remains of dead plants and animals. animals. Forms a medium that supports bigger plants and Forms a medium that supports bigger plants and trees.trees.

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Fertility in an EcosystemFertility in an Ecosystem

An ecosystem develops toward a climax.An ecosystem develops toward a climax.Fertility is an active process through the interaction Fertility is an active process through the interaction of plant cover, existing soil, decomposers, rainfall, of plant cover, existing soil, decomposers, rainfall, and temperature.and temperature.One acre of soil from a temperate region will contain One acre of soil from a temperate region will contain 125 million small invertebrates. 125 million small invertebrates. 30 grams of that soil will contain 1 million bacteria of 30 grams of that soil will contain 1 million bacteria of just one type, 100,000 yeast cells, and 50,000 just one type, 100,000 yeast cells, and 50,000 fungus mycelium.fungus mycelium.

Soil creation is so slow that it is, in effect, a Soil creation is so slow that it is, in effect, a nonnon--renewable resource.renewable resource.


Fragility of Ecosystems Fragility of Ecosystems

Ecosystems develop naturally in a way that Ecosystems develop naturally in a way that protects the soil they depend on.protects the soil they depend on.

On dry grasslands, roots of grass hold together a On dry grasslands, roots of grass hold together a poor soilpoor soilIn temperate forests, leaf drop in the autumn and In temperate forests, leaf drop in the autumn and large number of decomposers maintain fertile soil.large number of decomposers maintain fertile soil.In tropical forests, ecosystem protects the poor soil.In tropical forests, ecosystem protects the poor soil.

Once an ecosystem is destroyed or damaged Once an ecosystem is destroyed or damaged the underlying soil is easily destroyed or the underlying soil is easily destroyed or eroded.eroded.


Feedback Loops in an Feedback Loops in an Ecosystem Ecosystem

If one species of animal is wiped out, there are If one species of animal is wiped out, there are ramifications up and down the food chain.ramifications up and down the food chain.

Population of plants and animals forming its diet will increase.Population of plants and animals forming its diet will increase.Population that hunted it will decrease.Population that hunted it will decrease.This will bring further disruption at other levels.This will bring further disruption at other levels.

Disruption of primary producers, e.g. through forest fire Disruption of primary producers, e.g. through forest fire or deliberate clearance, is an attack on the base of the or deliberate clearance, is an attack on the base of the food chain, with disastrous effects.food chain, with disastrous effects.Ecosystems themselves are part of a greater whole Ecosystems themselves are part of a greater whole ––the earth itself.the earth itself.

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The Earth is a Closed The Earth is a Closed SystemSystem

Resources are finite.Resources are finite.Nothing gets out. Waste products must Nothing gets out. Waste products must go somewhere.go somewhere.Recycling is essential.Recycling is essential.Problems arise when artificial wastes are Problems arise when artificial wastes are disposed of in ecosystems, e.g. dumping disposed of in ecosystems, e.g. dumping at sea or into the air.at sea or into the air.


Humans in Ecosystems Humans in Ecosystems

Two factors distinguish humans from other Two factors distinguish humans from other members of ecosystems.members of ecosystems.

We are the only species capable of endangering We are the only species capable of endangering and/or destroying ecosystems on which we depend.and/or destroying ecosystems on which we depend.We are the only species to have spread into every We are the only species to have spread into every terrestrial ecosystem, and then dominated it.terrestrial ecosystem, and then dominated it.

The problem for human society is to balance The problem for human society is to balance our various demands against the ability of our various demands against the ability of ecosystems to withstand pressures.ecosystems to withstand pressures.


Human OriginsHuman Origins

The dinosaurs all died out about 65 The dinosaurs all died out about 65 million years ago.million years ago.When then did, there were already some When then did, there were already some small mammals that had found an small mammals that had found an ecological niche that supported them.ecological niche that supported them.The mammals became dominant and The mammals became dominant and evolved into many different forms.evolved into many different forms.

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PrimatesPrimates

From within the order of mammals, a particular From within the order of mammals, a particular group developed with grasping hands and group developed with grasping hands and stereoscopic vision, the stereoscopic vision, the primates.primates.Out of the primates, developed the monkey, Out of the primates, developed the monkey, about 50 million years ago.about 50 million years ago.

The monkey developed differently in different parts The monkey developed differently in different parts of the world.of the world.

Out of the African monkeys came the Out of the African monkeys came the apes, apes, about 30 million years ago.about 30 million years ago.


ApesApes

The apes are our The apes are our direct ancestors and direct ancestors and have many have many anatomical features anatomical features in common with in common with humans.humans.At right is a At right is a chimpanzee, the chimpanzee, the closest living relative closest living relative to humans.to humans.


HomonidsHomonids

Out of the apes evolved a series of species Out of the apes evolved a series of species with features more and more humanwith features more and more human--like.like.As a group, we call these As a group, we call these homonidshomonids, meaning , meaning simply humansimply human--like.like.

There are several stages of There are several stages of homonidshomonids. Of greatest . Of greatest interest are those that developed anywhere from 5 interest are those that developed anywhere from 5 million to 1 million to 1 ½½ million years ago. This is the species million years ago. This is the species we call we call Homo erectus, Homo erectus, or or ““upright man.upright man.””

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Homo erectus Homo erectus

Fossils of Fossils of Homo Homo erectus erectus date from date from about 2about 2--1.5 million 1.5 million years ago.years ago.These are the direct These are the direct ancestors of ancestors of modern humans.modern humans.

The possible appearance of Homo erectus.


Traits of Homo erectus Traits of Homo erectus

Earlier fossil remains show Earlier fossil remains show ““humanhuman”” traits: traits:

Upright posture (up to 3.5 Upright posture (up to 3.5 million years agomillion years ago——hard to hard to date)date)ToolmakingToolmaking in stone.in stone.

Homo erectusHomo erectus had an had an enlarged brain capacity (1,100 enlarged brain capacity (1,100 cc = cc = ¾¾ modern brain size)modern brain size)Probably emerged in Africa.Probably emerged in Africa.Survived until 100,000 years Survived until 100,000 years ago.ago.


Homo sapiens Homo sapiens

Anatomically modern skeletons, from 100,000 Anatomically modern skeletons, from 100,000 years ago.years ago.

Homo sapiens lived in camps and hunted in groups.Homo sapiens lived in camps and hunted in groups.

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Homo sapiens Homo sapiens sapienssapiens

From 30,000 years ago.From 30,000 years ago.Widespread through the Widespread through the world.world.These are essentially These are essentially anatomically identical to anatomically identical to ourselves.ourselves.


Almost all of our PastAlmost all of our Past

Humans (including Humans (including Homo Homo erectus) go back erectus) go back 2 million years. 2 million years.

In all but the last few thousand years, humans In all but the last few thousand years, humans have subsisted by hunting and gathering. have subsisted by hunting and gathering. They lived in small mobile groups.They lived in small mobile groups.They had minimal effect on the environment.They had minimal effect on the environment.

During this time humans spread all over the During this time humans spread all over the globe and into every terrestrial ecosystem.globe and into every terrestrial ecosystem.

Evidence is scanty, hence interpretations Evidence is scanty, hence interpretations disputed.disputed.


Hunting and Gathering Hunting and Gathering This has been the universal human way of life for This has been the universal human way of life for 99% of human history.99% of human history.It is now restricted to a handful of groups such as, It is now restricted to a handful of groups such as,

The San, or Bushmen, of SW Africa.The San, or Bushmen, of SW Africa.Pigmy groups in equatorial Africa.Pigmy groups in equatorial Africa.HadzaHadza of east Africa.of east Africa.A few groups in India and SE Asia.A few groups in India and SE Asia.Aborigines in Australia, Inuit.Aborigines in Australia, Inuit.Native groups in tropical S. America. Native groups in tropical S. America.

All these groups are now marginal, having been All these groups are now marginal, having been pushed aside by agriculture.pushed aside by agriculture.

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A Better Life in the Past A Better Life in the Past Before being pushed to marginal land, Before being pushed to marginal land, hunting & gathering was a much hunting & gathering was a much easier way of life.easier way of life.

Food could easily be extracted, taking Food could easily be extracted, taking only a small part of the day.only a small part of the day.Generally the diet was nutritionally Generally the diet was nutritionally adequate and varied.adequate and varied.Personal possessions were few.Personal possessions were few.There was no concept of food ownership.There was no concept of food ownership.


E.g., the San, or Bushmen, E.g., the San, or Bushmen, of SW Africa of SW Africa

The San, or Bushmen, The San, or Bushmen, of the Kalahari Desert of the Kalahari Desert in South West Africa is in South West Africa is one of the worldone of the world’’s s oldest human groups, oldest human groups, going back long before going back long before the invention of the invention of agriculture.agriculture.


The San (Bushmen) The San (Bushmen) They have remained a hunting and They have remained a hunting and gathering culture, and preserve as gathering culture, and preserve as much as possible of their traditional much as possible of their traditional way of life.way of life.Anthropologists trying to reconstruct Anthropologists trying to reconstruct the past will often study such cultures the past will often study such cultures for indications of how all humans for indications of how all humans must have lived thousands of years must have lived thousands of years ago.ago.

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The The MongongoMongongo NutNutThe mainstay of their diet is the The mainstay of their diet is the mongongomongongo nut,nut, from a from a drought resistant tree.drought resistant tree.

It is a reliable source of food that keeps for over a year. It It is a reliable source of food that keeps for over a year. It contains 5x the calories and 10x the protein of an equivalent contains 5x the calories and 10x the protein of an equivalent amount of cereal crops. amount of cereal crops. ½½ lb of nuts has the calories of 2 lb of nuts has the calories of 2 ½½ lbs lbs of cooked rice and the protein of 1 lb of beef.of cooked rice and the protein of 1 lb of beef.

San women gathering mongongo nuts.


The San Diet The San Diet The San use 23 of the 84 edible plants The San use 23 of the 84 edible plants available.available.There are 54 edible animals. 17 are regularly There are 54 edible animals. 17 are regularly hunted.hunted.This diet is more than adequate.This diet is more than adequate.

It requires on average 2 It requires on average 2 ½½ days a week in food days a week in food obtaining & production.obtaining & production.

Work is steady throughout year (unlike Work is steady throughout year (unlike agriculture).agriculture).It rarely involves traveling more than 6 It rarely involves traveling more than 6 miles a day.miles a day.


GatheringGathering

Women gather nuts and Women gather nuts and berries and roots.berries and roots.

Women and men devote Women and men devote the same amount of time the same amount of time overall to food.overall to food.Women, who do the Women, who do the gathering, bring in twice gathering, bring in twice the amount of food as the amount of food as men, who hunt. men, who hunt.

Women work about 1Women work about 1--3 3 hours a day.hours a day.

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Hunting Hunting

Men do the huntingMen do the huntingHunting more intermittent.Hunting more intermittent.A week of hunting is often A week of hunting is often followed by no activity for followed by no activity for 22--3 weeks.3 weeks.Hunting is less successful Hunting is less successful than gathering, especially than gathering, especially with primitive weapons, but with primitive weapons, but can provide superior can provide superior nutrition.nutrition.


Leisure Leisure

About 40% of the population are not involved in About 40% of the population are not involved in food production: food production:

1 in 10 are over 60. 1 in 10 are over 60. The young do not participate until marriage (20 for a The young do not participate until marriage (20 for a woman, 25 for a man).woman, 25 for a man).

Leisure time is valued highly.Leisure time is valued highly.


Where Gathering Fails Where Gathering Fails

A Hunting and Gathering group spearing fish.A Hunting and Gathering group spearing fish.In ecosystems farther from equator, plant food In ecosystems farther from equator, plant food needs to be supplemented, often by fishing.needs to be supplemented, often by fishing.

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Hunting as the Sole Hunting as the Sole Source of FoodSource of Food

Only in Arctic areas where there is little plant Only in Arctic areas where there is little plant food does hunting dominate.food does hunting dominate.


Population ControlPopulation ControlAll hunting & gathering groups tried to All hunting & gathering groups tried to control their numbers.control their numbers.

Infanticide was one method.Infanticide was one method.Twins, the handicapped, and a proportion of female Twins, the handicapped, and a proportion of female offspring were killed.offspring were killed.Inuit killed about 40% of female children.Inuit killed about 40% of female children.

Protracted weaning provided birth control.Protracted weaning provided birth control.Abandonment of old people was accepted.Abandonment of old people was accepted.Thus demand on resources was kept at Thus demand on resources was kept at manageable levels.manageable levels.

Total population about 10,000 years ago Total population about 10,000 years ago was less than 4 million. was less than 4 million.

The size of the Greater Toronto Area population.The size of the Greater Toronto Area population.


Causes of the Spread of Causes of the Spread of Humanity cross the Globe Humanity cross the Globe

1. Brain size1. Brain sizePower of abstract thought, required for technology.Power of abstract thought, required for technology.

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Causes of the Spread of Causes of the Spread of Humanity Across the Globe Humanity Across the Globe

2. 2. BipedalismBipedalismWalking upright on two Walking upright on two legs freed hands to, e.g., legs freed hands to, e.g., make tools.make tools.



3. Speech3. SpeechIncreased cooperation.Increased cooperation.Social organizations.Social organizations.



4. Tool making4. Tool makingStone toolsStone tools--choppers, choppers, pebbles, hand ax.pebbles, hand ax.Wooden spears.Wooden spears.Bolas.Bolas.Wood, skins, fire.Wood, skins, fire.

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Out of AfricaOut of Africa

Home erectusHome erectus had spread out of Africa by 1had spread out of Africa by 1½½ million years ago.million years ago.The first migrations were to the MiddleThe first migrations were to the Middle--East, India, south China, and East, India, south China, and parts of Indonesia.parts of Indonesia.


Limitations on Migration Limitations on Migration At first migration was very restricted.At first migration was very restricted.

Survival was only possible in semiSurvival was only possible in semi--tropical areas with a variety of easily tropical areas with a variety of easily gathered vegetable materials given the gathered vegetable materials given the tools they had.tools they had.In other climates hunting would be more In other climates hunting would be more important, but they did not have important, but they did not have sufficient weaponry.sufficient weaponry.


Migration to EuropeMigration to EuropeSettlement from 730,000 to 350,000 Settlement from 730,000 to 350,000 years ago. years ago.

Often intermittent and only in interglacial Often intermittent and only in interglacial periods.periods.

Permanent settlement only during last Permanent settlement only during last glacial period, 80,000 to 12,000 years glacial period, 80,000 to 12,000 years ago. ago.

Marked a major advance in human ability Marked a major advance in human ability to adapt to harsh environment.to adapt to harsh environment.

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Ice Age Inhabitants of Ice Age Inhabitants of EuropeEurope

Living off of animalsLiving off of animalsThe usual view is that humans hunted animals The usual view is that humans hunted animals randomly.randomly.

But this is too erratic.But this is too erratic.Success rate would be too low.Success rate would be too low.

Instead, humans were dependent upon animal Instead, humans were dependent upon animal herds.herds.The herds were managed with minimum The herds were managed with minimum disturbance. disturbance.

Herds were followed and culled selectively. This could Herds were followed and culled selectively. This could only support a small number of people.only support a small number of people.E.g. 1500 reindeer would support 3 families of 15 each.E.g. 1500 reindeer would support 3 families of 15 each.


Example: France and Example: France and Spain at height of Ice Age Spain at height of Ice Age

Subsistence was Subsistence was based on large herds.based on large herds.Dense human Dense human populations managed populations managed without migrating with without migrating with herds.herds.Hunting was Hunting was supplemented by supplemented by fishing.fishing.Great cave paintings.Great cave paintings.


Way of Life Dependent on Way of Life Dependent on the Icethe Ice

When the ice age subsided, the herds When the ice age subsided, the herds migrated north and the basis of migrated north and the basis of human subsistence collapsed.human subsistence collapsed.

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Developments in TechnologyDevelopments in TechnologyNew tools and new New tools and new materials from 40materials from 40--30,000 years ago.30,000 years ago.

Thin parallel sided Thin parallel sided blades, and small blades, and small light blades for light blades for projectiles. projectiles. More complicated More complicated manufacturing and manufacturing and heat treatment.heat treatment.


Australia Australia and the and the BoatBoat

The settlement The settlement of Australia of Australia required boats.required boats.


Settlement of Australia, 2Settlement of Australia, 2It was settled 40,000 years ago when It was settled 40,000 years ago when sea levels were at their lowest. sea levels were at their lowest.

A voyage of 60 miles would have been A voyage of 60 miles would have been needed (from Asia).needed (from Asia).Tasmania was linked to Australia until Tasmania was linked to Australia until 15,000 years ago. 15,000 years ago. New Guinea became an island 8000 years New Guinea became an island 8000 years ago.ago.

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Settlement of Australia, 3Settlement of Australia, 3The environment was more benign The environment was more benign than Europe. To live here did not than Europe. To live here did not require technological sophistication.require technological sophistication.

Initial settlement was maybe 25 people.Initial settlement was maybe 25 people.Population grew rapidly to 300,000.Population grew rapidly to 300,000.

Settlement here did not lead to more Settlement here did not lead to more complex social organization as was complex social organization as was common elsewhere.common elsewhere.


America America

Almost the last stage.Almost the last stage.Migration to American depended on the ability to survive the Migration to American depended on the ability to survive the harsh climate of Siberia and then advance to the Bering Strait.harsh climate of Siberia and then advance to the Bering Strait.The crossing made at the height of ice age, when the Bering The crossing made at the height of ice age, when the Bering Strait was a land bridge.Strait was a land bridge.


Settlement of America Settlement of America Migration out of Alaska to the south Migration out of Alaska to the south could have taken place either 30could have taken place either 30--23,000 years ago or 13,000 years ago23,000 years ago or 13,000 years ago

Once into the south, the living was easy.Once into the south, the living was easy.Compared to the climate of Siberia and then Compared to the climate of Siberia and then across the Bering Strait, the environment to across the Bering Strait, the environment to the south in America was enormously rich.the south in America was enormously rich.

The population multiplied rapidly.The population multiplied rapidly.It spread all the way to the southern tip of It spread all the way to the southern tip of South America in a few thousand years.South America in a few thousand years.

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Adaptations for Life in Adaptations for Life in America America

On the plains of North America there On the plains of North America there were few large plants to be gathered.were few large plants to be gathered.

Subsistence depended on hunting.Subsistence depended on hunting.Exploitation of herds of bison resulted.Exploitation of herds of bison resulted.

The animals were often killed in a crude and The animals were often killed in a crude and highly wasteful way, such as driving them highly wasteful way, such as driving them into narrow canyons or over cliffs.into narrow canyons or over cliffs.


Adaptations for Life in Adaptations for Life in America, 2America, 2

A single kill in Caspar, Wyoming about 10,000 years A single kill in Caspar, Wyoming about 10,000 years ago involved 74 animals. ago involved 74 animals. Another in Colorado set off a stampede resulting in 200 Another in Colorado set off a stampede resulting in 200 corpses, most of which could not be used.corpses, most of which could not be used.


Final Phase: Pacific and Final Phase: Pacific and Indian OceansIndian Oceans

Migration here was carried out by groups who had a primitive Migration here was carried out by groups who had a primitive form of agriculture and also relied on occasional hunting.form of agriculture and also relied on occasional hunting.

Polynesians undertook the most extensive voyages.Polynesians undertook the most extensive voyages.People travelled from New Guinea to Tonga and Samoa about People travelled from New Guinea to Tonga and Samoa about 1000 BC, to Marquesas about 300 AD, and Easter Island 1001000 BC, to Marquesas about 300 AD, and Easter Island 100--200 200 years later.years later.

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Humans Humans Across Across the the GlobeGlobe

All major areas of the world were settled by All major areas of the world were settled by humans (except Antarctica). humans (except Antarctica).

They adapted to every environment, from semiThey adapted to every environment, from semi--tropical in Africa to icetropical in Africa to ice--age Europe, from Arctic to age Europe, from Arctic to SW African deserts. SW African deserts.


Living in Harmony with the Living in Harmony with the Environment? Environment?

The usual assumption:The usual assumption:These groups lived in close harmony with These groups lived in close harmony with the environment and did minimal damage the environment and did minimal damage to natural ecosystems.to natural ecosystems.


Arguments in Arguments in FavourFavour::They required detailed knowledge of They required detailed knowledge of where resources were found and where resources were found and habitats of animals.habitats of animals.Some of these groups tried to Some of these groups tried to conserve resources to maintain conserve resources to maintain subsistence over a long period of subsistence over a long period of time.time.

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Efforts of Primitive Cultures Efforts of Primitive Cultures to Preserve the Environment to Preserve the Environment

Totemic restrictions on hunting particular Totemic restrictions on hunting particular species at certain times of year.species at certain times of year.Only hunting an area every few years.Only hunting an area every few years.Sacred areas where hunting was forbidden.Sacred areas where hunting was forbidden.

E.g. Cree in Canada, used rotational hunting: E.g. Cree in Canada, used rotational hunting: returning to an area after a considerable length returning to an area after a considerable length of time, allowing animal populations to recover.of time, allowing animal populations to recover.

But the main reason why they avoided over But the main reason why they avoided over exploiting is that their numbers were small.exploiting is that their numbers were small.


Damage to the Environment Damage to the Environment from Hunters and Gatherers from Hunters and Gatherers

Many activities did alter the Many activities did alter the environment and cause damage.environment and cause damage.Examples from present day hunterExamples from present day hunter--gatherer societies:gatherer societies:

The The HadzaHadza of Tanzaniaof TanzaniaAborigines of TasmaniaAborigines of TasmaniaMaoris of New ZealandMaoris of New Zealand


The The HadzaHadza

A (male) A (male) HadzaHadza hunter and a (female) hunter and a (female) HadzaHadzagatherer digging for roots.gatherer digging for roots.

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The The HadzaHadza, 2, 2

The modern The modern HadzaHadza of Tanzania are of Tanzania are careless about their environment.careless about their environment.

The hunters destroy wild beehives to The hunters destroy wild beehives to obtain a small amount of honey, instead obtain a small amount of honey, instead of resealing the honeycomb.of resealing the honeycomb.The women digging for tubers pull up the The women digging for tubers pull up the whole plant, leaving no part to whole plant, leaving no part to regenerate.regenerate.


Deliberate InterventionDeliberate InterventionThe The HadzaHadza approach is careless rather than approach is careless rather than deliberate. deliberate.

They are highly nomadic, moving on at short They are highly nomadic, moving on at short notice to wherever better hunting and gathering notice to wherever better hunting and gathering seems available.seems available.

More settled hunterMore settled hunter--gatherer societies gatherer societies intervene in their environment deliberately intervene in their environment deliberately to produce some to produce some favouredfavoured benefit.benefit.

They can do this by burning areas.They can do this by burning areas.Fire alters habitat by Fire alters habitat by favouringfavouring annual plants annual plants that grow well in new ground.that grow well in new ground.


Australian Aborigines Australian Aborigines

Aborigines use fire Aborigines use fire regularly to regularly to encourage an encourage an edible bracken on edible bracken on Tasmania. (Maoris Tasmania. (Maoris did the same.)did the same.)They also set fires They also set fires to drive kangaroos to drive kangaroos when hunting.when hunting.

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Prehistoric Uses of Fire Prehistoric Uses of Fire Early hunterEarly hunter--gatherer groups used fire gatherer groups used fire frequently to clear areas for plants.frequently to clear areas for plants.Evidence remains from, for example:Evidence remains from, for example:

In New Guinea from 30,000 years agoIn New Guinea from 30,000 years agoForest clearing by felling, ring barking, and fire. Forest clearing by felling, ring barking, and fire. Done to encourage food plants: yams, bananas, taro. Done to encourage food plants: yams, bananas, taro. Also the sago tree.Also the sago tree.

In postIn post--glacial Britainglacial BritainPatches of woodland cleared by fire to encourage Patches of woodland cleared by fire to encourage forage for red deer.forage for red deer.

Most groups also transplanted wild plants and Most groups also transplanted wild plants and weeded. Even some irrigation.weeded. Even some irrigation.


Effect of Hunting on the Effect of Hunting on the Environment Environment

The most dramatic intervention of hunterThe most dramatic intervention of hunter--gatherers was through hunting wild gatherers was through hunting wild animals:animals:

It is much easier to damage this part of an It is much easier to damage this part of an ecosystem since numbers are smaller and ecosystem since numbers are smaller and populations of larger animals take a long time to populations of larger animals take a long time to recover from overrecover from over--hunting.hunting.There is some evidence of attempts not to overThere is some evidence of attempts not to over--hunt, buthunt, but

there is far more evidence of uncontrolled hunting and there is far more evidence of uncontrolled hunting and extinction of species.extinction of species.


Bison Bison

Bison hunts in North America could kill Bison hunts in North America could kill hundreds when only a few were required.hundreds when only a few were required.

The bison population was huge (50The bison population was huge (50--60 million), 60 million), so it could sustain very large hunts.so it could sustain very large hunts.However, it was nearly wiped out.However, it was nearly wiped out.

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Sea OtterSea OtterEffect made worse by Effect made worse by tendency to concentrate tendency to concentrate on one species to the on one species to the exclusion of others.exclusion of others.On the Aleutian Islands in On the Aleutian Islands in the north Pacific the the north Pacific the population concentrated on population concentrated on killing sea otter for over killing sea otter for over 1000 years from settlement 1000 years from settlement in 500 BC until they were in 500 BC until they were virtually extinct and the virtually extinct and the subsistence base of the subsistence base of the community was wiped out.community was wiped out.


Flightless Birds Flightless Birds Large flightless birds were common on islands Large flightless birds were common on islands where there were no large mammals.where there were no large mammals.

They were defenseless against humans.They were defenseless against humans.

An Australian emu.


Large Unusual Mammals Large Unusual Mammals MadagascarMadagascar

Within a few hundred years of human settlement, many of Within a few hundred years of human settlement, many of the larger animals, including a big flightless bird and a the larger animals, including a big flightless bird and a pigmy hippopotamus were extinct.pigmy hippopotamus were extinct.

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The New Zealand Problem The New Zealand Problem Maoris could not grow their traditional Maoris could not grow their traditional crops in the temperate environment of New crops in the temperate environment of New Zealand.Zealand.

The traditional Polynesian crops included The traditional Polynesian crops included banana, breadfruit, and coconut.banana, breadfruit, and coconut.

These would not grow in the colder temperate climate These would not grow in the colder temperate climate of New Zealand.of New Zealand.Even yams and taro grew only on the North Island.Even yams and taro grew only on the North Island.

They had to shift to other foods, such as:They had to shift to other foods, such as:Wild plants, such as bracken fern, for which they Wild plants, such as bracken fern, for which they cleared large areas of forest by setting fires.cleared large areas of forest by setting fires.They also fished and hunted.They also fished and hunted.


The MoaThe Moa

Artist’s reconstruction of extinct Moas.


The Moa, 2The Moa, 2

The moa was a huge flightless bird The moa was a huge flightless bird native to New Zealandnative to New ZealandThe Maori settlers hunted them to The Maori settlers hunted them to extinction.extinction.

In 600 years, 24 species of moa were In 600 years, 24 species of moa were extinct plus 20 other birds.extinct plus 20 other birds.

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The Moa, 3The Moa, 3A large number of A large number of flightless birds: flightless birds:

Kiwi, Kiwi, wekaweka, and , and many species of many species of moa were hunted moa were hunted ruthlessly and their ruthlessly and their eggs eaten too.eggs eaten too.

Most moa were 6 ft Most moa were 6 ft high, one type was high, one type was 12 feet tall if it stood 12 feet tall if it stood erect.erect.


Continental Impact Continental Impact Even on land masses as large as Even on land masses as large as continents, hunting and gathering can continents, hunting and gathering can have major impact.have major impact.

In Eurasia, 5 large animals became In Eurasia, 5 large animals became extinct in a few thousand years. extinct in a few thousand years.

This was partly due to climate change, as the This was partly due to climate change, as the ice age receded, but hunting ice age receded, but hunting maymay have helped have helped to push them to extinction.to push them to extinction.

The woolly mammoth, the woolly rhinoceros, the The woolly mammoth, the woolly rhinoceros, the giant Irish elk, the musk ox, the steppe bison,giant Irish elk, the musk ox, the steppe bison,as well as other large carnivores were destroyed.as well as other large carnivores were destroyed.


Large Animal Extinctions in Large Animal Extinctions in Eurasia, 1 Eurasia, 1

Woolly mammoth. Recreated museum model.Woolly mammoth. Recreated museum model.

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Wooly rhinoceros. ArtistWooly rhinoceros. Artist’’s recreation.s recreation.



Giant Irish Elk. ArtistGiant Irish Elk. Artist’’s recreation.s recreation.



Musk Ox. Driven to extinction in parts of the world.Musk Ox. Driven to extinction in parts of the world.

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Steppe Bison. ArtistSteppe Bison. Artist’’s recreation.s recreation.


Far worse in Australia and Far worse in Australia and the Americasthe Americas

But extinction of species in Europe But extinction of species in Europe and Asia were relatively small and Asia were relatively small compared to Australia and the compared to Australia and the Americas.Americas.


Australian Extinctions Australian Extinctions Over the last 100,000 years, 86% of the Over the last 100,000 years, 86% of the large animals have become extinct.large animals have become extinct.

This happened in an area where climatic impact This happened in an area where climatic impact was minimal.was minimal.

The most likely explanation is:The most likely explanation is:Hunting by Aborigines in the last 40,000 years.Hunting by Aborigines in the last 40,000 years.

Even if not hunted to death, human Even if not hunted to death, human disruption of the ecosystem could have led disruption of the ecosystem could have led to extinction: to extinction:

By killing smaller herbivores, or destroying By killing smaller herbivores, or destroying habitats.habitats.

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The Americas The Americas Large animal extinction: Large animal extinction:

South America: 80% loss.South America: 80% loss.North America: 73% loss.North America: 73% loss.

Extinctions in every type of ecosystem.Extinctions in every type of ecosystem.These happened well after the ice age so These happened well after the ice age so climatic changes could not be the cause.climatic changes could not be the cause.E.g. the plains camel (found only in North E.g. the plains camel (found only in North America), other giant species: 3 genera of America), other giant species: 3 genera of elephant, 6 of giant edentates, 15 ungulates, elephant, 6 of giant edentates, 15 ungulates, many rodents and carnivores disappeared.many rodents and carnivores disappeared.

The first American settlers left a trail of The first American settlers left a trail of destruction across the continent.destruction across the continent.


Summary Summary By 10,000 years ago, humans had spread By 10,000 years ago, humans had spread from southern and eastern Africa to every from southern and eastern Africa to every continent. continent. This migration depended on:This migration depended on:

Growth in brain size allowing for abstract Growth in brain size allowing for abstract thought and technological solutions.thought and technological solutions.

E.g., fire, clothing.E.g., fire, clothing.As humans moved away from tropics, new As humans moved away from tropics, new techniques had to be developed.techniques had to be developed.

More intensive hunting and herding.More intensive hunting and herding.Better tools.Better tools.Complex food processing.Complex food processing.


Change of Pace Change of Pace 40,000 years ago:40,000 years ago:

The pace quickened. The pace quickened. Humans had become the only animals to Humans had become the only animals to dominate and exploit every niche. dominate and exploit every niche. Overall impact was still small because of low Overall impact was still small because of low population and limited technology. population and limited technology. But human presence was already felt in:But human presence was already felt in:

Extinctions of animals.Extinctions of animals.Subtle modifications of the environment.Subtle modifications of the environment.

Then, about 10,000 years ago, the most Then, about 10,000 years ago, the most fundamental change of all: Agriculture.fundamental change of all: Agriculture.

Prehistoric Life - York University · SC/NATS 1510, Prehistoric Life 1 Prehistoric Life The Hunting...

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