HUMANS Homo sapiens

On a small branch of the tree of life, among the Mammals, a group emerged

Visual, tree dwelling, grasping hands and feet, most similar to Prosimians of today

This group radiated from a common ancestor <60MYA

1758, Linnaeus named the group Primate - “chiefs of creation”

Named 3 genera based on limited species -Lemur, Simia, Homo

Good fit to current view – prosimians, monkeys, apes

In Homo, Linnaeus included Chimpanzees, Orangutan, and Humans. Gorillas and Gibbons were not yet known. Today all separate genera

Jane Goodall

Divergences (common ancestors) indicated by fossils and molecular data

Apes and Old World monkeys < 30MYA

Humans and Chimps <10 MYA

The human lineage (“Hominan”) contains many extinct species, exact relationships not certain due to lack of genetic data

Hominans have many distinctive traits

Bipedal locomotionPrecision gripTool useReduced sex size dimorphismReduced jaw, Meat eatingLarge BrainCulture, Language

3.5 MYA

While very closely related to the great apes, humans are clearly significantly different.

Recall the CetaceaRecall: Camels are more closely related to whales than to horses.

Given sufficient “adaptive opportunity”, change can be rapid

What is the key hominan adaptive “innovation”?

Is this a contradiction?

Australopithecus sp. – 4-2 MYABipedal, brain 30% “Lucy”

Homo erectus

1.7 MYA

Brain 60%

Migrated as far as Indonesia

Extinct 200,000 YA

Out of Africa

Possible exception – Homo floresiensis (discovered 2004)

                                                                                                                                                    

                                                                         

http://magma.nationalgeographic.com/ngm/0504/feature1/index.html

Size of Australopithecus

Skull of H. erectus

Existed on Flores Island as late as 18,000 years ago

Various hypotheses Island induced dwarfism?

Homo neanderthalensis – 200,000 years ago, Europe

Brain 100%

Extinct 30,000 years - DNA

Replaced by Homo sapiens

Used fire

Homo sapiens

Oldest fossil - 160,000 years - Ethiopia

Asia by 50,000 yearsNew World, 15,000 years

Global dispersal

African origin – all genetic variation

One species – could have been different

National Geographic March 2006

National Geographic March 2006

Adaptation (mainly cultural) to a wide variety of habitats - biomes Primary mode – “hunter-gatherer” for most of history Strong dependence on natural environment

Omnivory – balance abundance and nutrition

Pastoralism: Evidence of plant and animal domestication <10,000 years

Slash & Burn common

Many groups mixed hunting-gathering with small scale cultivation

Agricultural civilizations <8,000 years

1-4/1-3

Hunter-Gatherer => Pastoralism => Agriculture

Increasing control over resource species, less dependent on ecosystem controls, change in “knowledge”

Ecosystem forces - primarily antagonistic, nature must be “dominated” rather than understood

Persistent exponential growth in humans suggests that we have not yet encountered significant environmental deterioration.

Question: Do we want to?? Do we want to reach KHuman?

No one knows what KHuman is

Humans have become a dominant force in the biosphere

Ecological Footprint: In addition to total numbers, level of resource use (culturally variable) by individuals determine the total impact on the biosphere

1.7/1.5

Can the earth support our footprint?

Recall – biosphere is thin

Classifying human impacts – problem because of multiple effects and interactions. E.g., coal mining – impacts on land, water, air, energy future

About 20 mi. thick“2-dimensional”

Life has altered it greatlyHumans might also

One classification scheme1. Ecosystem replacement a. urban, suburban b. agriculture, rangeland & soil erosion c. mining2. Alteration of existing systems a. over-harvesting b. fragmentation c. non-native species 3. Global impacts a. chemical pollution b. nutrient enrichment c. climate change

Potential consequences – biodiversity loss, reduced “ecosystem services”, soil erosion, climate & sea level changes

Human Impacts

Cities

Urban areas 2% of land area 48% of population

Often on productive land

City expansion - population growth - urban sprawl

Human Impacts –1a

Urban population

Ecosystem replacement

1952 1967

1972 1995

Las Vegas, NV

Human Impacts –1a

Urban support systems

Where does food come from? Agriculture – 77% Rangeland – 16% Fisheries – 7%

Over 30% of (non-polar) land area converted to agriculture – from forest and grassland

80% of food produced by industrialized agriculture – for people & animals

Cities need resources from large areas - photosynthesis

Human Impacts 1b

7-1/8-1

Ecosystem replacement

Rangeland

Less productive grasslands used for grazing livestock

40% of land

Replace native grazers eliminate predators overstocking non-native grasses

Human Impacts 1b Ecosystem replacement

Tropical deforestation

Logging of tropical forest

One-time Weathered soils Nutrients in biomass main fate – grazed grassland

Human Impacts 1b Ecosystem replacement

Soil ErosionHuman Impacts 1b

Recall – soil crucial, takes many 100s, 1000s of years to form

Erosion – natural process – loss/movement of soil due to wind & water accelerated with plants removed (agriculture, rangeland, deforestation)

7-6/8-4

Major effort in soil conservation after dust bowl in US

Ecosystem replacement

Mining

Extraction of materials from rock - diverse Surface & Subsurface

Not sure how much land surface involved.

Water runoff affected - acidity, heavy metals

Fossil fuels – burning releases CO2

Human Impacts 1c Ecosystem replacement

Overharvesting

We still directly harvest from native ecosystems – e.g., fisheries, forests

Living populations are “renewable” – can be harvested in the long term

Overharvesting - decreased sustainable harvest - risk of extinction - ecosystem alteration

Human Impacts 2a

Increasing “traditional” populations stress systems wood gathering, “bushmeat”

Alteration of existing systems

7-4/8-14

Human Impacts 2aMost fisheries are overharvested

Alteration of existing systems

Short-rotation forestry 6-1/6-4

Human Impacts 2a

Most current forestry practices are not sustainable

Alteration of existing systems

Fragmentation

Remaining systems are reduced in size, isolated

Viable populations often require large, continuous tracts

Fragmentation invariably leads to reduced biodiversity – often delayed

Fairfax Co., VA

Human Impacts 2b Alteration of existing systems

Non-native species

Human activities have increased spread of many species

Some have become “invasive” – displacing native species

5-9/7-9 Argentine Fire Ant

Purple Loosestrife

Human Impacts 2c Alteration of existing systems

Chemical Pollution

Thousands of chemicals are emitted by modern industry – products, byproducts, and breakdown products regulation difficult

Human Impacts 3a

Generally point sources, but diffuse in air & water

Some bioaccumulate & biomagnify

Classic case: DDT

5-12/7-12

Global impacts

Nutrient Enrichment

We are increasing key plant nutrients, N, P and CO2

N & P for agricultural production

CO2 is increasing due to fossil fuel burning & deforestation

Phosphorus – rocks mined & ground into fertilizerNitrogen – industrial N-fixation, planting of legumes - human N-fixation now exceeds all others annually

All these inputs spread globally

What’s the problem, isn’t it good to increase plant resources?

Human Impacts 3b Global impacts

Eutrophication – effect of increased nutrients on ecosystems first studied in aquatic systems from runoff of agriculture

- soil, fertilizer & animal waste now seen in terrestrial systems

Increased NPPReduced biodiversityAlgal bloomsIncreased decomposition => reduced O2

Anaerobic - Fish kills, methane production

Human Impacts 3b

8-19/9-21

Global impacts

Climate Change

Elevated CO2, Methane and Nitrous Oxide from fossil fuel burning and other sources add greenhouse gases

This can change patterns of weather and increase average global temperature

Human Impacts 3c

12-8/12-19

1979 2003

Ice in polar regions and at high altitudes declining - reduces reflection - rise of sea level

Human Impacts 3c Global impacts

20,000 YA

17 ft (5m)W. Antarctic sheet

170 ft (50m)

E. Antarctic sheet

NOAA

Human Impacts 3c Global impacts

Snows of Kilamanjaro may be gone in 15 years

Human Impacts 3c Global impacts

Major impact – species are adapted to prevailing levels of resources, NPP and climate.

Changes in these levels - fundamentally alter the relative fitness of species - the range of essentially every species is predicted to shift. But can they move?

Human Impacts 3b,c Global impacts

Consequences of human impacts – environmental “problems”

Check out the “Millennium Ecosystem Assessment”

http://www.millenniumassessment.org/en/index.aspx

Loss of Biodiversity - major consequence of many human impacts

Extinction is fast & foreverMany species threatened

Biodiversity is a kind of knowledge, a “library”

What will you tell your grandchildren if we let the gorilla go extinct?

Speciation takes a while

5-6/7-6

We’ve gotten this far by learning to cooperate

How much farther can we go?

What is your vision of Utopia?

The End

End