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 Biogeochemical Cycles
III. Human Population, Planetary Resources, and Conservation
A. Human Population Growth
B. Human Use of Resources and Pollution
C. Biodiversity
D. Working Towards a Sustainable Society
I. Human Evolution
A. Origin of Life chemical evolution
1. The primitive Earth
a. early Earth's atmosphere different than today's
b. atmosphere formed by gases escaping from volcanoes
c. atmosphere made up of H2O, N2, CO2, small amounts of H2, CO
d. water only existed as gas until Earth cooled, it rained forming oceans
2. Small organic molecules
a. rain washed gases into oceans
b. many sources of energy: volcanoes, meteorites, radioactive isotopes, lightning, ultraviolet radiation
c. energy + primitive gases react to produce small organic cmpds = nucleotides, amino acids (demonstrated in closed sys by Stanley Miller 1953)
3. Macromolecules new small organic molecules joined=macromolecules
a. RNA-first hypothesis - RNA as substrate and enzyme
b. protein-first hypothesis - amino acids joined to form microspheres
4. The protocell
a. microsphere + lipids = lipid-protein membrane
b. formation of protocell, probably a heterotroph & fermenter
5. The true cell
a. RNA-first hypothesis - genes of RNA specified protein synthesis (enzymes), enzymes used RNA to form DNA
b. protein-first hypothesis - proteins evolved enzymatic ability to synthesize DNA from nucleotides in ocean, DNA then specifies protein synthesis
Figure 22.1 illustrates chemical evolution.
The following table from Professor Frolich's presentation lists some of the major events in Earth's history.
B. Biological Evolution1. Common descent
a. Charles Darwin - naturalist - theory of evolution
b. fossil evidence supports evolution
i. examples: traces - trails, footprints, burrows, worm casts, droppings; fossils - bone, impressions of plants, insects trapped in amber
ii. sediment -> strata - allows dating of fossils
iii. fossil record - most direct evidence that evolution has occurred, shows life has progressed from simple to complex (prokaryote->eukaryote->multicellular organism
c. biogeographical evidence - migration of ancestral species to isolated geographies allows evolution into different species
d. anatomical evidence - common descent hypothesis explains anatomical similarities among organisms of different species, despite functional differences
i. homologous structures - evidence of relatedness between organisms
ii. analogous structures
iii. vestigal structures - more evidence of common descent
iv. similarities in embryological development - eg paired pharyngeal pouches, postanal tail
Figure 22.6 from the text shows homologous structures.
e. biochemical evidence - same basic biochem molecules across almost all living organisms: DNA, ATP, enzymes, same triplet code in DNA, same 20 amino acids
2. Intelligent design
a. idea that diversity of life had to arise from the involvement of an "intelligent agent"
b. can not be tested in a scientific way
3. Natural selection - Darwin
a. described a mechanism for adaptation
b. variation - physical characteristics passed down to next generation
c. competition for limited resources - because of limited resources, not all individuals in a population survive
d. adaptation - those characteristics that give advantage to secure resources will be passed down to next generation. Over time, environment selects for the better-adapted traits
e. accounts for great diversity in life
Figure 22.9 from the text contrasts Jean-Baptiste Lamarck's process of acquired characteristics with Charles Darwin's process of natural selection.
C. Classification of humans
1. DNA data and human evolution
a. DNA/rRNA/protein sequencing data used compare and determine relatedness between species
2. Humans are primates adapted to arboreal life
a. mobile forelimbs and hindlimbs - easy grasping
b. binocular vision - accurate focusing
c. large, complex brain - sight, good hand-eye coordination
d. reduced reproductive rate - 1 birth at a time, extended junvenile dependency, learned behaviors, complex social interactions
3. Comparing human skeleton to the chimpanzee skeleton
a. human-spine exits center of skull-places skull in midline of body, chimpanzee-spine exits rear of skull
b. human spine s-shaped-trunk's center of gravity squarely over feet, chimp spine-slight curve
c. human pelvis & hip joint broader-no swaying when walking, chimp-narrow
d. human neck of femur longer-femur angles in at knees, chimp-femur angles out
e. human knee joint larger-supports body weight, chimp-smaller
f. human big toe not opposable, foot has arch-allows long walking and running, chimp opposable toe
D. Evolution of Hominids
1. The first hominids
a. first hominids and apes divereged from common ancestor - at time of divergence, genes and proteins of two lineages very similar
2. Hominid features
a. bipedal posture
b. shape of face- flatter face, more pronounced chin - human jaw shorter, smaller, l
i. flatter face, more pronounced chin b/c human jaw is shorter
ii. smaller, less specialized teetch
iii. larger brain
Figure 22.13 from the text shows the evolution of primates
3. Earliest fossil hominids
a. fossils found that date back to the time of ape and human lineage split
b. date between 7mya and 5mya
4. Evolution of autralopithecines
a. marks the earnest beginning of the hominid line of descent
b. gracile (slender) and robust (powerful) types
Figure 22.14 from the text shows a reconstruction of Lucy, the australopithecine, and footprints of A. afarensis.
5. Southern Africa
a. Australopithecus africanus - gracile type dated 2.8 mya
b. A. robustus - 2 to 1.5 mya
c. both walked upright, limb proportions apelike
6. Eastern Africa
a. 250 fossils of hominid A. afarensis - Lucy - found by Donald Johanson
b. walked bipedally
c. example of mosaic evolution (small apelike brain with bipedal ability)
E. Evolution of Humans
1. Early Homo
a. Homo habilis - 2.0-1.9mya, omnivores, used tools, cooperative hunting, hunters and gatherers shared food
b. Homo erectus (Asian form?)
i. larger brain, flatter face, nose projected - compared to H. habilis
ii. Homo ergaster (African form) - taller, robust, heavily musculed skeleton, small birth canal
iii. first to use fire, more advanced tools
Figure 22.15 from the text shows human evolution.
Figure 22.16 from the text show the skeleton of a 10 year old boy of the species Homo ergaster.
2. Evolution of modern humansa. multiregional continuity hypothesis
b. out-of-Africa hypothesis
3. Neandertals 200,000 years BP
a. massive brow ridge, nose, jaw, teeth protruded, low & sloping forehead, lower jaw lacked a chin
b. brain larger than Homo sapien's, maybe to control extra musculature
c. culturally advanced - built houses, used many tools & fire, buried dead
Figure 22.18 from the text illustrates how Neandertals may have looked and lived.
4. Cro-Magnons
a. oldest fossils to be designated Homo sapiens
b. entered Asia and Europe from Africa 100,000 yrs BP
c. DNA very different from Neandertal DNA - Neandertals probably cousins to Homo sapiens
d. made advanced tools (compound), experienced hunters may have caused extinction of larger animals
e. hunted cooperatively, women remained home with children
f. first to have language
g. culture included art
Figure 22.19 from the text illustrates the Cro-Magnons.
5. Human variation
a. humans geographically distributed
b. body shape and environment
i. cold temps - short limbs (Allen's rule), bulkier build (Bergmann's rule)
ii. warm temps - elongated limbs, slighter build
c. genetic evidence for a common ancestry
i. genetic differences in mDNA between different ethnic groups low - support out-of-Africa hypothesis
Definitions from Chapter 22 can be found here.
II. Global Ecology and Human Interferences
A. The Nature of Ecosystems
1. Ecosystems
a. tropical rain forest - at equator, large evergreen, broad-leaved tree
b. savanna - tropical grassland supports grazing animals
c. temperate grasslands (less rain than) temperate forests (trees lose leaves during winter)
d. desert - little water, no trees
e. taiga - very cold, norther coniferous forest
f. tundra - borders North Pole, very cold, long winters, permafrost
g. freshwater aquatic ecosystem - standing water (lakes, ponds), running water (rivers, streams), marshes where rivers meet sea
h. saltwater aquatic ecosystem - oceans, have coral reefs
Figure 23.1 from the text show the major terrestrial ecosystems.
Figure 23.2 from the text shows the major aquatic ecosystems.
2. Biotic components of an ecosystem
a. autotrophs (producers)-use inorganic nutrients plus energy source to produce organic nutrients, for self & for other members of community. Algae & plants
b. hetertroph (consumers) - need a source of organic nutrients
i. herbivores
ii. carnivores - primary, secondary, tertiary consumers
iii. omnivores
iv. detritus feeders - feed on detritus (decomposing particles of organic matter), break down dead organic matter & release inorganic substances that are taken up by plants. eg: earthworms, termites, ants, bacteria, fungi
Figure 23.3 shows some examples of bitotic components.
3. Energy flow and chemical cycling
a. most ecosystems require continual supply of energy from the sun
b. as organic nutrients are passed up the food chain, a smaller percentage of nutrients is available to higher-levels>
Figure 23.4 from the text illustrates energy flow and chemical cycling.
B. Energy Flow
1. Trophic levels
a. trees - producers - first trophic level
b. first series of animals eating trees - primary consumers - second trophic level
c. next group of animals - secondary consumers - third trophic level
2. Ecological pyramids
a. illustrates loss of 90% of energy between trophic levels.
b. therefore, few carnivores can be supported in food web
C. Global Biogeochemical Cycles
1. The water cycle
a. evaporation, precipitation, transpiration, gravity=water returns to sea, runoff, aquifers
b. human activities
i. withdraw water from aquifers
ii. clear vegetation from land, build roads, building - prevent percolation and increase runoff
iii. interfere with natural processes that purify water, add pollutants
Figure 23.9 from the test illustrates the hydrologic cycle.
2. The carbon cycle
a. CO2 in atmosphere is exchange pool for carbon cycle
b. plants take up CO2 - thru photosynthesis incorporate carbon into nutrients
c. carbon is returned to atmosphere as CO2 through respiration by organisms
d. CO2 in air combines with H2O to produce HCO3 bicarbonate ion. Source of carbon for algae
e. CO2 given off by aquatic organisms becomes bicarbonate ions
f. reservoirs for carbon=living & dead organisms, fossil fuels
g. human interference = burning of fossil fuels, destruction of forests puts more CO2 into atmosphere than is being used up
h. greenhouse gases allow solar radiation to pass thru but hinder the escape of infrared rays back into space
Figure 23.10 from the text illustrates the carbon cycle.
3. The nitrogen cycle
a. nitrogen fixation - N2->NH4 (form of nitrogen plants can use, by cyanobacteria and free-living bacteria in soil
b. nitrification - N2->NO3, needs high energy source, NH4->N02 by by soil bacteria, NO2->NO3
c. assimilation
d. denitrification
e. human interferences - N2 fertilizers, runoff causes overgrowth of algae, rooted aquatic plants.
f. acid deposition from burning fossil fuels: nitrogen oxides and sulfur dioxide enter atmosphere, combine w/water vapor to form acids
g. smog - nigrogen oxides and hydrocarbons combined
Figure 23.12 from the text illustrates the nitrogen cycle
4. The phosphorus cycle
a. phosphorus trapped in sediments moves to land after geological movement
b. weathering of rocks places phosphate ions into soil
c. plants use some (phospholipids, ATP, nucleotides)
d. animals eat producers, incorporate phosphate into teeth, bones, shells
e. death and decay make phosphate ions available to producers again
f. phosphate runoff into aquatic ecosystems, algae acquire some
g. humans boost supply by mining, runoff from fertilizer, animal waste, sewage planst results in cultural eutrophication of waterways
Figure 23.15 from the text illustrates the phosphorus cycle.
Figure 23.16 lists sources of surface water pollution.
Definitions for Chapter 23 can be found here.
III. Human Population, Planetary Resources, and Conservation
A. Human Population Growth
1. The MDCs - more developed countries
a. growth rate as a whole .1%, down from 1850-1950 when the population doubled
b. US growth rate .6%, immigrants, baby boom
c. total population expected to be at 1.2 billion by 2050
2. The LDCs - less-developed countries
a. growth rate at 1.6%
b. by 2050, population expected to jump from 5 to 8 billion
2. Comparing age structure
a. 3 age groups: prereproductive, reproductive, postreproductive
b. LDCs growth will continue, more young women in reproductive years
c. other than the US, MDCs have a stabilized age-structure diagram
Figure 24.1 from the text shows the human population growth.
Figure 24.2 shows the age-structure diagrams for MDCs and LDCs.
B. Human Use of Resources and Pollution
1. Land
a. beaches and human habitation - people like to live near the coastline - a place for fish spawning, habitats for terrestrial species, protection for coastal areas during storms
b. semiarid lakes and human habitation - humans allow animals to overgraze, they clear the land, use for fuel, fodder, water then runs off instead of being aborbed by remaining plants or replenishing wells, land becomes lifeless desert=desertification
c. tropical rain forest and human habitation - deforestation in tropical rain forests can cause desertification, loss of biodiversity
2. Water
a. increasing water supplies
i. dams - provide water, electricity. Rivers not making it to oceans, water loss to evaporation & seepage to rock beds, increase salinity, silt buildup
ii. aquifers - rain collected over hundreds of thousands of years ago, resource depletion - causes subsidence, sinkholes, saltwater intrusion
b. conservation of water - drought, salt-tolerant crops, drip irrigation, industries adopting conservation measures
3. Food food supply has increased since the 50s
a. modern/harmful farming methods - monoculture, fertilizers (production energy intensive, water pollution, kills good soil bacteria), irrigation, fuel consumption
b. positive practices - polyculture, contour farming, no-till
c. soil loss and degradation - erosion of topsoil (richest soil), sediment ends up in lakes and streams
d. green revolutions - varieties developed to yield more for in LDCs required same amount of fertizlier, water, pesticides, genetic engineering
e. domestic livestock - accounts for much pollution associated w/farming. 2/3 of cropland in US devoted to grow feed livestock. Much energy required to make food to feed livestock
Figure 24.10 from the text shows several methods of conservation.
4. Energy
a. nonrenewable sources - nuclear power, fossil fuels
b. burning of fossil fuels emites gases - rising temps threaten melting of glaciers, habitats threatened
c. renewable sources - hydropower, geothermal energy, wind power, solar
d. solar-hydrogen - using solar power to extract hyrdogen from water via electrolysis. Hydrogen can then be used as a clean-burning fuel
Figure 24.12 from the text shows 4 types of renewable energy sources.
5. Minerals
a. eg. fossil fuels, nonmetallic raw materials (sand, gravel, phosphate), metals (aluminum, copper, iron, lead, gold)
b. harmful to humans - heavy metals: lead, mercury, arsenic, cadmium, tin, chromium, zinc, and copper. Used to make batteries, electronics, pesticides, medicines, paints, inks, dyes
c. hazardous wastes - contributed by the consumption of minerals
d. 4 most common heavy metal contaminants - lead, arsenic, cadmium, chromium
e. 5 most common synthetic organic cmpds - trichloroethylene, toluene, benzene, polychlorinated biphenyls (PCBs), and cloroform.
f. synthetic organic chemicals - halogentaed hydrocarbons, used in production of plastics, pesticides, cosmetics, coatings, solvents...Chlorofluorocarbons (CFCs) - thinning of Earth's ozone. MDCs no longer use.
C. Biodiversity
1. Loss of biodiversity
a. habitat loss due to human interference
b. alien species
c. pollution - acid deposition, global warming, ozone depletion, synthetic organic chemicals
d. overexploitation
e. disease
2. Direct value of biodiversity
a. medicinal value - rosy periwinkle, penicillin, limulus in blood of horseshoe crab
b. agricultural value - natural predators, pollinators
c. consumptive use value - aquatic organisms, wild fruits, vegetables, trees
3. Indirect value of biodiversity
a. waste disposal - decomposers extremely useful to humans
b. provision of freshwater - after a storm forests soak up water and then release over a long period of time, preventing flooding
c. prevention of soil erosion - deforestation causes erosion, erosion causes silt buildup in dams and ecosystems
d. biogeochmeical cycles - keeps excess pollutants in environment under control
e. regulation of climate - trees provide shade, take up CO2, when cut, they release CO2, contributing to global warming
f. ecotourism
Figure 24.17 from the text provide examples of the direct benefits of wildlife.
D. Working Toward a Sustainable Society
1. Today's sustainable society
a. overpopulation of LDCs and overconsumption by MDCs both account for increasing poullution and extinction of wildlife
b. land used for human purposes
c. agriculture - big use of fossil fuels, use of pesticides, create pollution, use of freshwater
d. demand on freshwater
e. growing demand on energy sources
2. Characteristics of a sustainable society
a. use renewable energy
b. recycle materials
c. protect natural ecosystems
d. efficiency
e. rural sustainability - preserve ecosystems, cover crops, multiuse farming, composting, low flow or trickle irrigation, cultivars, precision farming, integrated pest management, plant variety of species, multipurpose trees, protect wetlands, buy local
f. urban sustainability - energy efficient transportation sys, solar/geothermal energy, green roofs, improve storm water mgmt, plant native grasses, greenbelts, revitalize old sections before developing new, control light and noise pollution, encourage recycling
3. Assessing economic well-being and quality of life
a. GNP - strictly economic
b. ISEW (index of sustainable economic welfare) - takes into account forms of value in addition to monetary value (environmental damage, natural resource depletion, distributional equite etc)
c. GPI (genuine progress indicator) - considers quality of life
d. use value, option value, existence value, aesthetic value, cultural value, scientific & educational value
Figure 24.18 from the text shows several unsustainable activities.
Definitions from Chapter 24 can be found here.
REFERENCES:
Mader, Syliva S. Human Biology. New York, NY: McGraw-Hill (2008).
Links provided throughout the summary take you to online sources.
IMPORTANT NOTE: Any time "text" or "the text" is referenced in the above summary, I am referring to the textbook Human Biology by Sylvia Mader (cited directly above).
