Table of Contents
I. Human Evolution
A. Origin of Life
B. Biological Evolution
C. Classification of Humans
D. Evolution of Hominids
E. Evolution of Humans
II. Global Ecology and Human Interferences
A. The Nature of Ecosystems
B. Energy Flow
C. Global Biochemical Cycles
III. Human Population, Planetary Resources, and Conservation
A. Human Population Growth
B. Human Use of Resources and Pollution
C.Biodiversity
D. Working Toward a Sustainable Society
I. Human EvolutionA. Origin of Life
1. Data suggests that a chemical produced the first cell (Protocell).
a. Using an outside energy source, small organic molecules were produced by resctions between early Earth's atmospheric gases.
b. Macromolecules evolved and interacted.
c. The RNA- first hypothesis- only macromolecule RNA was needed for the first cell(s).
d. The protein- first hypothesis- amino acids join to form polypeptides when exposed to dry heat.
e. The protocell, a heterotrophic fermenter, lived on preformed organic molecules in the ocean.
2. The protocell eventually became a true cell once it had genes composed of DNA and could reproduce.
B. Biological Evolution
1. Biological evolution explains both the unity and diversity of life.
a. Descent from a common ancestor explains the unity (sameness) of living things.
b. Adaptation to different environments explains the great diversity of living things.
c. Fossil evidence supports evolution- the fossil record gives us the history of life in general and allows us to trace the descent of a particular group.
2. Darwin discovered much evidence for common descent.
a. Biogeographical evidence- the distribution of organisms on earth is explainable by assuming that organisms evolved in one locale.
b. Anatomical evidence- the common anatomies and development of a group of organisms are explainable by descent from a common ancestor.
c. Biochemical evidence- all organisms have similar biochemical molecules.
3. Darwin developed a mechanism for adaptation known as natural selection.
a. The result of natural selection is a population adapted to its local environment.
C. Classification of Humans
1. The classification of humans can be used to trace their ancestry.
a. Humans are primates.
b. A primate evolutionary tree shows that humans share a common ancestor with African apes.
D. Evolution of Hominids
1. The first hominid, including humans, most likely lived about six to seven million years ago.
2. Certain features, such as bipedal posture, flat face, and brain, identify fossil hominids.
3. Ardipithecines were most likely hominids.
4. Evolution of Australopithecines: The evolutionary tree of hominids resembles a bush, not a straight line of fossils leading to modern humans.
a. Australopithecines, a hominid, lived about three million years ago.
b. They could walk erect, but they had a small brain.
c. This testifies to a mosaic evolution for humans (not all advanced features evolved at the same time).
E. Evolution of Humans
1. Fossils are classified as
Homo with regard to brain size (over 600 cm³), jaws and teeth (resemble modern humans'), and evidence of tool use.
a.
Homo habilis made and used tools.
b.
Homo erectus was the first
Homo to have a brain size of more than 1,000 cm³.
c.
Homo erectus migrated from Africa into Europe and Asia.
d.
Homo erectus used fire and may have been big-game hunters.
2. Evolution of Modern Humans: Two hypotheses of modern human evolution are being tested.
a. The multiregional continuity hypothesis suggests that modern humans evolved separately in Europe, Africa, and Asia.
b. The out-of-Africa hypothesis says that
Homo sapiens evolved in Africa but they migrated to Asia and Europe.
3. Neandertals and Cro-Magnons
a. The neandertals were already living in Europe and Asia before modern humans arrived.
b. They had a culture, but did not have the physical traits of modern humans.
c. Cro-Magnons are the oldest fossil to be designated
Homo sapiens. Their tools were sophisticated, and they had a culture.
II. Global Ecology and Human InterferencesA. The Nature of Ecosystems
1. Ecology is the study of the interactions of organisms with each other and with the physical environment.
a. Organisms interact with the physical and chemical environment, and the result is an ecosystem.
b. Terrestrial ecosystems are forrests (tropical rain forrests, coniferous, temerate deciduous), grasslands (savanna and prairie), and deserts, which includes the tundra.
c. Aquatic ecosystems are either saltwater (seashores, oceans, coral reefs, estuaries) or freshwater (lakes, ponds, rivers, and streams).
2. Biotic Components of an Ecosystem
a. In a community, each population has a habitat (residence) and a niche (its role in the community).
b. Autotrophs (producers) produce organic nutrients for themselves ant others from inorganic nutrients and an outside energy source.
c. Heterotrophs (consumers) consume organic nutrients.
d. Consumers are herbivores (eat plants/algae), carnivores (eat other animals), and omnivores (eat both plants and animals).
e. Decomposers feed on detritus, releasing inorganic substances back into the ecosystem.
3. Ecosystems are characterized by energy flow and chemical cycling.
a. Energy flows through the populations of an ecosystem.
b. Chemicals cycle within and among ecosystems.
B. Energy Flow
1. Various interconnecting paths of energy flow are called a food web.
a. A food web is a diagram showing how various organisms are connected by eating relationships.
b. Grazing food webs begin with vegetation eaten by a herbivore that becomes food for a carnivore.
c. Detrital food webs begin with detritus, food for decomposers and for detritivores.
d. Members of detrital food webs can be eaten by aboveground carnivores, joining the two food webs.
2. Trophic Levels- all the organisms that feed at a particular link in a food chain.
a. Ecological pyramids illustrate that biomass and energy content decrease from one trophic level to the next because of energy loss.
C. Global Biochemical Cycles
1. Chemicals circulate through ecosystems via biogeochemical cycles, pathways involving both biotic and geological components. Biogeochemical cycles:
a. Can be gaseous or sedimentary.
b. Have reservoirs (Ex: ocean sediments, the atmosphere, and organic matter) that contain inorganic nutrients available to living things on a limited basis.
c. Exchange pools are sources of inorganic nutrients.
d. Nutrients cycle among the biotic communities (producers, consumers, decomposers) of an ecosystem.
2. The Water Cycle
a. The reservoir is freshwater that evaporates from the ocean.
b. Water that falls on land enters the ground, surface waters, or aquifers and evaporates again.
c. All water returns to the ocean.
3. The Carbon Cycle
a. The reservoirs are organic matter (forests and dead organisms for fossil fuels), limestone, and the ocean (calcium carbonate shells).
b. The exchange pool is the atmosphere.
c. Photosynthesis removes carbon dioxide from the atmosphere.
d. Respiration and combustion add carbon dioxide to the atmosphere.
4. The Nitrogen Cycle
a. The reservoir is the atmosphere.
b. Nitrogen gas must be converted to a form usable by plants.
c. Nitrogen-fixing bacteria, in root nodules, convert nitrogen gas to ammonium, a form producers can use.
d. Nitrifying bacteria convert ammonium to nitrate.
e. Denitrifying bacteria convert nitrate back to nitrogen gas.
5. The Phosphorus Cycle
a. The reservoir is ocean sediments.
b. Phosphate in ocean sediments becomes available through geological upheaval, which exposes sedimentary rocks to weathering.
c. Weathering slowly makes phosphate available to the biotic community.
d. Phosphate is a limiting nutrient in ecosystems.
III. Human Population, Planetary Resources, and Conservation.A. Human Population Growth
1. Populations have a biotic potential for increase in size.
2. Biotic potential is normally held in check by environmental resistance.
3. Population size usually levels off at carrying capacity.
4. The More Developed Countries versus the Less Developed Countries.
a. The MDCs have a 0.1% growth rate since 1950.
b. The LDC growth rate is presently 1.6% after peaking at 2.5% in the 1960s.
5. Age-structure diagrams can be used to predict population growth.
a. MDCs are approaching a stable population size.
b. LDC populations will continue to increase in size.
B. Human Use of Resources and Pollution.
1. Five resources are maximally used by humans:
a. Land, water, food, energy, and minerals.
2. Resources are either nonrenewable or renewable.
a. Nonrenewable resources are not replenished and are limited in quantity (Ex: land, fossil fuels, and minerals).
b. Renewable resources are replenished but still are limited in quantity (Ex: water, solar energy, and food).
3. Land
a. Human activities, such as habitation, farming, and mining, contribute to erosion, pollution, desertification, deforestation, and loss of biodiversity.
4. Water
a. Industry ans agriculture use most of the freshwater supply. Water supplies are increased by damming rivers and drawing from aquifers. As aquifers are depleted, subsidence, sink hole formation, and saltwater intrusion can occur. If used by industries, water conservation methods could cut world water consumption by half.
5. Food- comes from growing crops, raising animals, and fishing.
a. Modern farming methods increase the food supply, but some methods harm the land, pollute water, and consume fossil fuels excessively.
b. Genetically engineered plants increase the food supply and reduce the need for chemicals.
c. Raising livestock contributes to water pollution and uses fossil fuel energy.
d. The increased number and high efficiency of fishing boats have caused the world fish catch to decline.
6. Energy- Fossil fuels (oil, natural gas, coal) are nonrenewable sources. Burning fossil fuels and burning to clear land for farming cause pollutants and gases to enter the air.
a. Greenhouse gases include CO2 and others. Greenhouse gases cause global warming because solar radiation can pass through, but infrared heat cannot escape back into space.
b. Renewable resources include hydropower, geothermal, wind, and solar power.
7. Minerals- nonrenewable resources that can be mined. These raw materials include sand, gravel, phosphate, and metals. Mining causes destruction of the land by erosion, loss of vegetation, and toxic runoff into bodies of water. Some metals are dangerous to health. Land mined can take years to recover.
a. Hazardous Wastes- billions of tons of solid waste are discarded on land and in water.
b. Heavy metals (lead, arsenic, cadmium, chromium).
c. Synthetic organic chemicals include chlorofluorocarbons (CFCs), which are involved in the production of plastics, pesticides, herbicides, and other products.
d. Ozone shield destruction is associated with CFCs.
e. Other synthetic organic chemicals enter the aquatic food chain, where the toxins become more concentrated (biological magnification).
C. Biodiversity- the variety of life on Earth.
1. The five major causes of biodiversity loss and extinction are:
a. Habitat loss, introduction of alien species, pollution, overexploration of plants and animals, and disease.
2. Direct values of biodiversity are:
a. Medicinal value (medicines derived from living organisms).
b. Agricultural value (crops derived from wild plants; biological pest controls and animal pollinators).
c. Consumptive use values (food production).
3. Biodiversity in ecosystems contributes to:
a. Waste disposal, through the action of decomposers and the ability of natural communities to purify water and take up pollutants.
b. Freshwater provision through the water biogeochemical cycle.
c. Prevention of soil erosion, which occurs naturally in intact ecosystems.
d. Function of biogeochemical cycles.
e. Climate regulation (plants take up carbon dioxide).
f. Ecotourism- human enjoyment of a beautiful ecosystem.
D. Working Toward a Sustainable Society
1. A sustainable society would use only renewable energy sources, would reuse heat and waste materials, and would recycle almost everything. It would also provide the same goods and services presently provided and would preserve biodiversity.
