Chapter 22
Human Evolution
Table of Concepts
- Origin of Life
- Biological Evolution
- Classification of Humans
- Evolution of Hominids
- Evolution of Humans
- Picture Reference
Origin of Life
Chemical Evolution
- Data suggest that a chemical evolution produced the first cell.
- Every living thing comes from cells and every cell comes from a preexisting cell.
- Chemical evolution may have produced the first cell.
- The Primitive Earth
o The planets, the sun, and the earth formed 10 billions years ago.
o The earth’s mass has a gravitational field that it is strong enough to have an atmosphere.
o Using an outside energy source, small organic molecules were produced by reactions between early earth’s atmospheric gases.
o Stanely Miller’s experiment suggested that the gases of early earth could have become the first organic molecules.
Stanely Miller’s experiment
o Macromolecules evolved and interacted.
o The RNA first hypothesis-only macromolecule RNA was needed for the first cell(s).
o The protein first hypothesis-amino acids join to form polypeptides when exposed to dry heat.
o A cell has a lipid-protein membrane.
o The protocell, a heterotrophic fermenter, lived on preformed organic molecules in the ocean.
o The protocell eventually became a true cell once it had genes composed of DNA and could reproduce.
- Biological Evolution
- The first true cell were the simplest of life forms.
o A prokaryotic cell, which lack a nucleus.
o Later the eukaryotic cell, which has nuclei, evolved.
o Then multicellularity and other kingdoms developed.
o Biological evolution is the process by which a species changes through time.
§ Has two important aspects
v Descent from a common ancestor explains the unity of living things.
v Adaptation to the different environments explains the great diversity of living things.
o Fossils are the best evidence for evolution because they are the actual remains of species that lived on earth at least 10,000 years ago and up to billions of years ago.
o Fossils can be the traces of past life or and other direct evidence that past life existed.
o The fossil record is the history of life recorded by fossils, and paleontology is the science of discovering the fossil record and, from it, making decisions about the history of life, ancient climates, and environments.
Fossils
o Biogeography is the study of the distribution of plants and animals in different places throughout the world.
o Anatomical evidence-the common anatomies and development of a group of organisms are explainable by descent from a common ancestor.
o Biochemical evidence- all organisms have similar biochemical molecules.
o Natural selection is a population adapted to its local environment.
o Example: that giraffe’s necks are long because they’re food was high in the trees and they adapted.
- Classification of Humans
- The binominal name of an organism gives its genus and species.
- Classification of humans can be used to trace their ancestry.
- Humans are primates.
o Primates are adapted to an orboreal life.
o Primate limbs are mobile and hands and feet both have five digits each.
o Primates have binocular vision.
o Have large and complex brain.
o Primates have on birth at a time.
- Comparing Human Skeleton to the Chimpanzee Skeleton
o Human and chimpanzee are 99% identical the difference is in various genes.
o A primate evolutionary three shows that humans share a common ancestor with African apes.
Evolution of Hominids
Evolution of Primates
- The first hominids most likely lived about 6-7 MYA. ( including Humans)
- The First Hominids
o Hominid is a term that refers to our branch of the evolutionary tree.
o Lineage is evolutionary line of descent.
o Molecular clock- mutational changes that accumulate at a presumed constant rate in regions of DNA not involved in adaptation to the environment.
o Bipedal posture walking on two feet.
o Shape of face- humans has a flatter face and more pronounced chin than apes do because humans have shorter jaws.
o Size of brain- chimpanzee have a brain size of 400 cm^3 and human have 1,300 cm^3.
o Sahelanthropus tschadensis, dated at 7 MYA, was found by Chad, located in central Africa.
o Orrorin tugenensis, dated at 6 MYA and found in eastern Africa, the early hominide because the limb anatomy suggests a bipedal posture.
o Ardipithecus kadabba, found in eastern Africa and dated 5.8 and 5.2 MYA, is closely related to the later appearing Ardiphithecus ramidus.
- Evolution of Australopithecines
o The hominid line of descent begins to earnest with the australopithecines, a group of species that evolved and diversified in Africa.
o Ardipithecines were most likely hominids.
o The evolutionary tree of hominids resembles a bush (not a straight line of fossils leading to modern humans).
o Australopithecines (a hominid) lived about 3 MYA.
o They could walk erect, but they had a small brain.
o This testifies to a mosaic evolution for humans (not all advanced features evolved at the same time).
- Evolution of Humans
o Fossils are classified as Homo with regard to brain size (over 600cm^3) jaws and teeth (resemble modern humans’) and evidence of tool use.
o Culture, which encompasses human behavior and products, depends upon the capacity to speak and transmit knowledge.
o H. habilis made and used tools and is known to have a culture first.
o H. erectus was the first Homo to have a brain size of more than 1,000 cm^3.
o H. erectus mirgrated from Africa into Europe and Asia.
o H. erectus used fire and may have been big-game hunters.
Evolution of Modern Humans
Human Evolution
o Homo sapiens (modern humans).
o The hypothesis that Homo sapiens evolved in several different locations is called the multiregional continuity hypothesis. (Europe, Africa and Asia).
o The out-of-Africa hypothesis, which proposes that H. sapiens evolved from H. erectus only in Africa, and thereafter H. sapiens migrated to Europe and Asia about 100,000 year BP (before present).
o The neandertals were already living in Europe and Asia before modern human arrived.
o They had a culture, but did not have the physical traits of modern humans.
o Lived in caves. They used and could control fire.
o They even buried their dead with flowers and tools, may have been capable to thinking symbolically.
Neandertal families
o Cro-Magnons are the oldest fossil to be designated H. sapiens.
§ Their tools were sophisticated and they had a culture.
o Cro-Magnons seen to have replaced neandertals in the Middle East and then spread to Europe.
o May have been the first to have a language.
o Culture included art, paintings they did in caves (located in Spain and France).
Cro-Magnons
- Picture Reference
§ Chemical evolution, Human Biology, page 468.
§ Stanely Miller’s Experiment
o http://www.kennislink.nl/upload/150080_962_1144771463083-oersoepexperimentMiller.jpg
§ Fossils, Human Biology, page 470
§ Evolution of Primates, Human biology, page 478
§ Human Evolution, Human biology, page 481
§ Neandertals, http://acacia.cnice.mecd.es/~jgaf0010/im%E1genes/neandertal-familia.jpg
§ Cro-Magnons, http://www.astrosurf.com/luxorion/Bio/cro-magnon-caverne.jpg
Chapter 23
Global Ecology and Human Interferences
Table of Concepts
- The Nature of Ecosystems
- Energy Flow
- Global Biogeochemical Cycles
- Picture References
The Nature of Ecosystems
The Major Terrestrail Ecosystems
- The biosphere is where organisms are found on planet Earth, from the atmosphere above to the depths of the oceans below and everything in between.
- The entire biosphere is one giant ecosystem, a place where organisms interact among themselves and with the physical and chemical environment.
- Humans can alter the interaction between organisms and change the ecosystem.
- Ecosystems
o Scientists recognize several distinctive major types of terrestrial ecosystems, also called biomes.
o Temperature and rainfalls define the biomes, which contain communities of organisms adapted to the regional climate the tropical rain forest, which occurs at the equator, is dominated by large evergreen, broad-leaved trees.
o Terrestrial ecosystems are forest (tropical rain forests, coniferous, temperate deciduous), grassland (savanna and prairie), and deserts, which includes the tundra.
o Aquatic ecosystems are either salt water (seashores, oceans, coral reefs, estuaries) or freshwater (lakes, ponds, rivers, and streams).
o The ocean is a marine ecosystem that covers 70% of the earth’s surface.
- Biotic Components of an Ecosystem
o The abiotic components of an ecosystem are the nonliving components.
o The biotic components are living things that can be categorized according to their food source.
o Autotrophs require only inorganic nutrients and an outside energy source to produce organic nutrients for their own use and for all the other members of a community. They are called producers-they produce food.
o Heterotrophs need a source of organic nutrients. They are the consumers-they consume food. Herbivores are animals that graze directly on plants or algae.
o Carnivores feed on other animals; birds that feed on insects are carnivores.
o Omnivores are animals that feed both on plants and animals. Humans are omnivores.
o Detritus feeders are organisms that feed on detritus, which is decomposing particles of organic matter. (Marine fan worms, earthworms, some beetles, termites and ants).
o Decomposers feed on detritus, releasing inorganic substances back into the ecosystem.
o Niche is the role of an organism in an ecosystem: how it gets its food and what eats it, and how it interacts with other populations in the same community.
o In a community, each populations has a habitat (residence) and a niche (its role in the community).
Energy Flow and Chemical Cycling
Energy Flow
o Energy flow and chemical cycling characterize ecosystems.
o Energy flow through the populations of an ecosystem.
o Chemical cycle within and among ecosystems.
Energy Flow
Food Web
- Various interconnecting paths of energy flow are called a food web.
- A food web is a diagram showing how various organisms are connected by eating relationships.
- Grazing food webs begin with vegetation eaten by an herbivore that becomes food for a carnivore.
- Detrital food webs begin with detritus, food for decomposers and for detritivores.
- Members of detrital food webs can be eaten by aboveground carnivores, joining the two food webs.
- Trophic Levels
o Diagrams that show a single path of energy flow are called food chains.
o A trophic level is composed of all the organisms that feed at a particular link in a food chain.
o The flow of energy with large losses between successive trophic levels is sometimes depicted as an ecological pyramid.
o Pyramids of biomass eliminate size as a factor because biomass is the number of organisms multiplied by the weights of organic matter within one organism.
o Ecological pyramids illustrate that biomass and energy content decrease from on trophic level to the next because of energy loss.
- Global Biogeochemical Cycles
- The pathways by which chemicals circulate through ecosystems involve both living (biotic) and nonliving (geological) components; therefore, they are known as biogeochemical cycles.
o Can be gaseous or sedimentary.
- Have reservoirs that contain inorganic nutrients available to living things on a limited basis.
- Exchange pools are sources of inorganic nutrients.
- Nutrients cycle among the biotic communities (producers, consumers, decomposers) of an ecosystem.
- The Water Cycle
The Water Cycle
o The reservoir of the water cycle is freshwater that evaporates from the ocean.
o Water that falls on land enters the ground, surface waters, or aquifers and evaporates again.
o All water returns to the ocean.
o During evaporation in the water cycle, the sun’s rays cause freshwater to evaporate from seawater, and the salt are left behind.
o Vaporized freshwater rises into the atmosphere, condenses, and then falls as precipitation (rain, snow, hail) over the oceans and the land.
o Runoff is water that flows directly into nearby streams, lakes, wetlands or the ocean.
o Humans interfere with the water cycle in three ways:
§ They withdraw water from aquifers
§ They clear vegetable from land and build road and buildings that prevent percolation and increase runoff
§ They interfere with the natural processes that purify water and instead add pollutants like sewage and chemicals to water.
The Carbon Cycle
The Carbon Cycle
o The carbon dioxide (CO2) in the atmosphere is the exchange pool for the carbon cycle.
o The reservoirs of the carbon cycle are organic matter (forests and dead organisms for fossils fuels), limestone, and the ocean (calcium carbonate shells).
o The exchange pool is the atmosphere
o Photosynthesis removes carbon dioxide from the atmosphere.
o Respiration and combustion add carbon dioxide to the atmosphere.
o Greenhouse gases are contributing significantly to an overall rise in the Earth’s ambient temperature, a phenomenon called global warming because of the greenhouse effect.
The Nitrogen Cycle
Nitrogen Cycle
o Nitrogen gas makes up about 78% of the atmosphere, but plants cannot make use of nitrogen gas.
o The reservoir of the nitrogen cycle is the atmosphere.
o Nitrogen gas must be converted to a form usable by plants (producers).
o Nitrogen-fixing bacteria (in root nodules) convert nitrogen gas to ammonium, to form producers can use.
o Nitrifying bacteria convert ammonium to nitrate.
o Denitrifying bacteria convert nitrate back to nitrogen gas.
The Phosphorus Cycle
The Phosphorus Cycle
o The reservoir of the phosphorus cycle is ocean sediments.
o Phosphate is ocean sediment becomes available through geological upheaval, which exposes sedimentary rocks to weathering.
o Weathering slowly makes phosphate available to the biotic community.
o Phosphate is a limiting nutrient in ecosystems.
- Picture References
Chapter 24
Human Population, Planetary Resources, and Conservation
Table of Concepts
- Human Population Growth
- Human Use of Resources and Pollution
- Biodiversity
- Working Toward a Sustainable Society
- Picture References
Human Population Growth
World Population Growth
- Populations have a biotic potential for increase in size.
- The growth rate of a population is determined by considering the difference between the number of persons born per year and the number who die per year.
- Biotic potential is normally held in check by environmental resistance.
- Population size usually levels off at carrying capacity.
- The MDCs Versus the LDCs
o More-developed countries (MDCs) typified by countries in North America and Europe, are those in which population growth is modest and the people enjoy a good standard of living.
o Less-developed countries (LDCs) typified by some countries in Asia, Africa, and Latin America, are those in which population growth is dramatic and the majority of people live in poverty.
o MDCs did not always have low population increases.
§ The MDCs have a 0.1% growth rate since 1950.
§ MDCs are approaching a stable population size.
o LDCs growth rate is presently 1.6% after peaking at 2.5% in the 1960s.
§ Age-structure diagrams can be used to predict population growth.
§ LDC populations will continue to increase in size.
Age Structure Diagrams
- Human Use of Resources and Pollution
- Five resources are maximally used by humans:
o Land
o Water
o Food
o Energy
o Minerals
- Resources are either nonrenewable or renewable.
- Nonrenewable resources are not replenished and are limited in quantity.
- Renewable resources are replenished but still are limited in quantity.
- Land
o Human activities, such as habitation, farming, and mining, contribute to erosion, pollution, desertification, deforestation, and loss of biodiversity.
o Industry and agriculture use most of the freshwater supply. Water supplies are increased by damming rivers and drawing from aquifers. As aquifers are depleted, subsidence, sinkhole formation, and saltwater intrusion can occur. If used by industries, water conservation methods could cut world water consumption by half.
o Food comes from growing crops, raising animals, and fishing.
o Modern farming methods increase the food supply, but some methods harm the land, pollute water, and consume fossil fuels excessively.
o Genetically engineered plants increase the food supply and reduce the needs for chemicals.
o Raising livestock contributes to water pollution and uses fossil fuel energy.
o The increased number and high efficiency of fishing boats have caused the world fish catch to decline.
o Fossil fuel are nonrenewable sources. Burning fossil fuels and burning to clear land for farming cause pollutants and gases to enter the air.
o Greenhouse gases include CO2 (carbon dioxide) and other gases. Greenhouse gases cause global warming because solar radiation can pass through, but infrared heat cannot escape back into space.
o Renewable resources include hydropower, geothermal, wind, and solar power.
o Minerals are nonrenewable resources that can be mined.
§ Include: sand, gravel, phosphate, and metals.
o Mining causes destruction of the land by erosion, loss of vegetation, and toxic runoff into bodies of water.
o Some metals are dangerous to health. Land ruined by mining can take years to recover.
o Heavy metals (lead, arsenic)
o Ozone shield destruction is associated with CFCs.
o Other synthetic organic chemicals enter the aquatic food chain, where the toxins become more concentrated (biological magnification).
- Biodiversity
- Biodiversity is the variety of life on Earth. The five major causes of biodiversity loss and extinction are:
o Habitat loss
Habitat loss
o Introduction of alien species
o Pollution
o Overexploitation of plant and animals
o Disease
- Direct Value of Biodiversity
o Direct values of biodiversity are:
§ Medicinal value (medicines derived from living organisms)
§ Agricultural value
§ Consumptive use values (food production).
- Indirect Value of Biodiversity
o Biodiversity in ecosystems contributes to:
§ Waste disposal
§ Freshwater provision through the water biogeochemical cycle
§ Prevention of soil erosion, which occurs naturally in intact ecosystems
§ Function of biogeochemical cycles
§ Climate regulation (plants take up carbon dioxide)
§ Ecotourism (human enjoyment of a beautiful ecosystem).
- Working Toward a Sustainable Society
- A sustainable society would always be able to provide the same amount of goods and services for future generations, as it does at present.
- 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.
Learning to Recycle
- Picture References
