Chapter 22: Human Evolution
22.1 Origin of Life
According to the theory of evolution, the Earth is estimated to have formed over a period of 10 billion years. The solar system has been in place for 4.6 billion years. Because of the mass of Earth, it has an atmosphere. It was composed of gases that were escaping volcanoes. As the earth cooled, the water vapors in the atmosphere rained on the earth forming the oceans. It is hypothesized that gases washed into the oceans exposed to radiation became organic compounds. Stanley Miller replicated this process in an experiment in 1953.
Artists’ interpretation of the beginnings of earth:
http://www.hopkins.k12.mn.us/pages/high/courses/online/astro/course_documents/earth_moon/earth/geologic_time/iron_catastrophe.htm
The small organic molecules found each other and formed macromolecules. One hypothesis formulates that ribonucleic acid (RNA) was the only macromolecule was needed to progress toward life because RNA can behave as a substrate and an enzyme during processing. The second theory is called the protein-first hypothesis. Sidney Fox demonstrated that amino acids join together when exposed to heat. This may have occurred in puddles when the water evaporated. They may have formed polypeptides with catalytic properties that became microspheres in the water.
Now when two lipids are in proximity of a microsphere, they unite and form a lipid-protein membrane which is called a protocell. This heterotroph needed food, but was not able to replicate.
A true cell reproduces and needs DNA and enzymatic proteins. In the RNA-first theory, DNA would have replicated from the RNA. In the protein-first hypothesis, the some of the proteins evolved into enzymes that synthesized DNA from nucleotides. The DNA would have directed enzyme synthesis so all the enzymes would be present and then DNA could be replicated.
22.2 Biological Evolution
It is reasoned that the first cells would have been the simplest, therefore they would have been prokaryotic cells (whose DNA is not in a nucleus). From there, multiple other types of cells evolved. Biological evolution is the process whereby a species from a common ancestor changes over time by adapting. In different areas, different adaptations would have occurred and this explains the diversity we have today.
The evolutionist, Charles Darwin observed that there were three types of evidence inferring evolution from a common ancestor:
Fossils: Smaller, older fossils are generally found deeper, in lower strata. Prokaryotes and unicellular eukaryotes are the earliest ones. Fossils with characteristics from two different species are called transitional.
Strata with fossils:
http://www.gutenberg.org/files/20417/20417-h/images/image158.jpg
Biogeography studies the placement of differing and similar plants and animals around the world. Certain species of animals can be located in one area on earth and not be found in a similar climate. This is interpreted to mean that the species evolved in that area and is therefore unique to it. Anatomical evidence shows similarities in anatomy between species which infers that they share a common ancestor. Biochemical demonstrates that all living things share similar molecules. DNA sequences also display a remarkable similarity between species.
Darwin described adaptation as a process whereby the stronger and healthier traits are passed on to the next generation. Weaker or less capable members were not able to survive or were not mated.
22.3 Classification of Humans
DNA data is most currently used to trace our roots. Mitochondrial DNA is used to determine the timing of evolutionary events because it changes frequently.
Primates are divided into 2 groups: Prosimians, which include lemurs, and anthropoids which includes monkeys, apes, and humans. Monkeys and apes have opposable thumbs and toes. Humans have opposable thumbs. The primates also have forward focusing eyes with stereoscopic vision (depth perception) to assist in judging placement of limbs while swinging around. Humans and apes also have colored vision. Primates have larger more intricate brains. The human brain is so large, it is wrinkled to increase area. Since the mode of movement in primates is to move from limb to limb, they have a reduced reproductive rate.
Genomes between humans and apes are 99% similar, but many differences exist between them. Speech, hearing and smell are dissimilar and also skeletal differences enable the human to walk upright and bear more weight on our knees.
22.4 Evolution of Hominids
An evolutionary tree traces the evolution of a group of organisms over the course of time to the original common ancestor. Included in this interpretation of evolutionary events are the approximated times of divergence from others in the group. When two groups diverge from a common ancestor the genes and proteins are nearly identical. These will develop separately and continue to digress from each other over time. Paleontologists use anatomical features when determining if a fossil is hominid. The primary hallmark is bipedal posture.
The hominid is believed to have started with the australopithecines, discovered in Africa in the 1920s. She is dated about 2.8 MYA (million years ago). Anatomy suggests that this hominid walked upright and had a relatively large brain (500cc).
Below is a chart of various discoveries and the interpretations of such:
http://www.mc.maricopa.edu/dept/d10/asb/anthro2003/origins/hominid_journey/timechart.jpeg
Some debates over the lineage of some fossils indicate that it is not always clear if the find is hominid or ape. One fossil, called Sahelanthropus tchadensis, dated 7 MYA, is a skull with hominid-like teeth but an apelike braincase. Orrorin tugenensis is another fossil, dated 6 MYA, with canine teeth, but has bipedal posture.
22.5 Evolution of Humans
Fossils with a brain size of 600cc or larger, human-like jaw and teeth configurations, and have evidence of tool use are labeled with the genus homo.
Homo habilis is thought to be the first ancestor to modern humans. The brain size is as large as 775cc (45% larger than the australopithecines) and the teeth indicate they may have been omnivores. Campsites with bones nearby have cut marks which indicate the use of tools. Their skulls suggest that they may have had the ability to communicate with speech also indicating that they may have hunted in groups.
Homo erectus is dated between 1.9 and .3 MYA. It is thought that dissimilarities in some discoveries suggests that different species have been included in this group. Homo ergaster is one such group and is thought to have migrated from Africa to Asia 1.6 - 1.9 MYA. By now, the homo erectus brain capacity is approximately 1000cc. It has a flatter face with a projected nose and is the first hominid to use fire. They wielded axes and cleavers.
Homo sapiens are believed to have evolved from homo erectus. Multiregional continuity hypothesis suggests that this evolution occurred simultaneously in several different geographical areas. Out-of-Africa hypothesis argues that the same result could not have occurred is all those different places. It suggests the H. sapiens evolved only in Africa and migrated to Europe and Asia only 100,000 years ago. This spawned a debate and most recently a study of DNA supports the out-of-Africa hypothesis.
Neandertals are dated around 200,000 years BP (before present). Their brains were larger than the homo sapiens, but the homo sapiens replaced them. They were more muscular and it is thought they needed the larger brain to control the additional muscles. They lived in caves or houses, used fire, and had a variety of tools. They also buried their dead and may have had a religion indicating they could think symbolically.
Before and after . . .
http://www.smh.com.au/ffximage/2007/10/26/neanderthal_narrowweb__300x340,0.jpg
Some debates over the lineage of some fossils indicate that it is not always clear if the find is hominid or ape. One fossil, called Sahelanthropus tchadensis, dated 7 MYA, is a skull with hominid-like teeth but an apelike braincase. Orrorin tugenensis is another fossil, dated 6 MYA, with canine teeth, but has bipedal posture.
22.5 Evolution of Humans
Fossils with a brain size of 600cc or larger, human-like jaw and teeth configurations, and have evidence of tool use are labeled with the genus homo.
Homo habilis is thought to be the first ancestor to modern humans. The brain size is as large as 775cc (45% larger than the australopithecines) and the teeth indicate they may have been omnivores. Campsites with bones nearby have cut marks which indicate the use of tools. Their skulls suggest that they may have had the ability to communicate with speech also indicating that they may have hunted in groups.
Homo erectus is dated between 1.9 and .3 MYA. It is thought that dissimilarities in some discoveries suggests that different species have been included in this group. Homo ergaster is one such group and is thought to have migrated from Africa to Asia 1.6 - 1.9 MYA. By now, the homo erectus brain capacity is approximately 1000cc. It has a flatter face with a projected nose and is the first hominid to use fire. They wielded axes and cleavers.
Homo sapiens are believed to have evolved from homo erectus. Multiregional continuity hypothesis suggests that this evolution occurred simultaneously in several different geographical areas. Out-of-Africa hypothesis argues that the same result could not have occurred is all those different places. It suggests the H. sapiens evolved only in Africa and migrated to Europe and Asia only 100,000 years ago. This spawned a debate and most recently a study of DNA supports the out-of-Africa hypothesis.
Neandertals are dated around 200,000 years BP (before present). Their brains were larger than the homo sapiens, but the homo sapiens replaced them. They were more muscular and it is thought they needed the larger brain to control the additional muscles. They lived in caves or houses, used fire, and had a variety of tools. They also buried their dead and may have had a religion indicating they could think symbolically.
Before and after . . .
http://www.smh.com.au/ffximage/2007/10/26/neanderthal_narrowweb__300x340,0.jpg
Cro-Magnons lived 45,000 to 10,000 years ago and may have caused the neandertals extinction. They may have lived together in Europe 40,000 years ago, but did not interbreed as evidenced by the differences in DNA. If this is true, then the Neandertals are cousins and not ancestors. The Cro-Magnons were the first to throw spears and make blades. The may be responsible for the extinction of mammals like the giant sloth, mammoth, sabor-toothed tiger and ox.
Human variation is another topic for biologists. It is suggested that adaptations occurred to accommodate the environment in which the people were living. Darker skin is more protective against UV rays. White skin produces more vitamin D. Short, bulky people adapt better to cold climates. A tribe in E. Africa have long limbs and a light build which is helpful for cooling. Perhaps other differences without a known adaptive reason, are merely due to genetic drift.
The cycle of life . . .
http://www.bios.niu.edu/johns/evolution.jpg
One more. . .
http://www.joe-ks.com/archives_apr2006/EvolutionOfMan.jpg
Chapter 23: Global Ecology and Human Interferences
23.1 The Nature of Ecosystems
Where ever organisms are found, they live in a biosphere. The biosphere, Earth, is an ecosystem wherein organisms react with other organisms and matter. Homeostasis is maintained between all creatures and substances, somewhat like the homeostasis within our bodies.
A biome is defined by temperature and rainfall amounts in areas of similar communities of plants, animals, and soil organisms also referred to as ecosystems. There is the rain forest and the desert, tropical grasslands (savannas) and temperate grasslands (prairies), The taiga – cold northern coniferous forest, and the tundra at the North Pole which has a short growing season and long winters. These are just a few.
Aquatic ecosystems are divided into the types of water (salt or fresh). Oceans, reefs and marshes comprise the salt water category. Lakes, rivers and ponds comprise the fresh.
Abiotic components are without life. Biotic components are living things and they are categorized according to what they eat. Autotrophs eat abiotic substances and use an outside energy source to create organic matter. Plants and algae are the major photosynthesizers on land.
Heterotrophs eat biotic components. They are herbivores – plant diet, carnivores – animal diet, and omnivores – plant and animal diet. Detritus feeders are decomposers that feed on dead organic matter. Every part has a niche or role in the ecosystem.
Chapter 23: Global Ecology and Human Interferences
23.1 The Nature of Ecosystems
Where ever organisms are found, they live in a biosphere. The biosphere, Earth, is an ecosystem wherein organisms react with other organisms and matter. Homeostasis is maintained between all creatures and substances, somewhat like the homeostasis within our bodies.
A biome is defined by temperature and rainfall amounts in areas of similar communities of plants, animals, and soil organisms also referred to as ecosystems. There is the rain forest and the desert, tropical grasslands (savannas) and temperate grasslands (prairies), The taiga – cold northern coniferous forest, and the tundra at the North Pole which has a short growing season and long winters. These are just a few.
Aquatic ecosystems are divided into the types of water (salt or fresh). Oceans, reefs and marshes comprise the salt water category. Lakes, rivers and ponds comprise the fresh.
Abiotic components are without life. Biotic components are living things and they are categorized according to what they eat. Autotrophs eat abiotic substances and use an outside energy source to create organic matter. Plants and algae are the major photosynthesizers on land.
Heterotrophs eat biotic components. They are herbivores – plant diet, carnivores – animal diet, and omnivores – plant and animal diet. Detritus feeders are decomposers that feed on dead organic matter. Every part has a niche or role in the ecosystem.
23.2 Energy Flow
Energy flow and chemical cycling is the process whereby producers derive energy from the sun and take in inorganic nutrients and begin chemical cycling. After photosynthesis, they produce organic matter for themselves and the consumers. The energy flow is passed as nutrients which are converted to heat and dissipates back into the biosphere. Even undigested nutrients eliminated as waste is digested by the detritus feeders and returned to the cycle as water and carbon dioxide.
Below is a picture depicting the energy flow of a trophic food web:
http://www.absc.usgs.gov/research/seabird_foragefish/marinehabitat/images/Food_Web3.gif
Trophic (feeding) relationships are demonstrated by the levels in which they are placed. The size of the organic matter does not necessarily correlate with the size of it’s contribution. Dead, organic matter from the detrital food web is a rich source of energy.
Only 10% of energy is passed on from one level to the next. That explains why there are fewer carnivores in each food web.
Picture depicting ecological pyramid:
http://openlearn.open.ac.uk/file.php/1656/SK220_2_003i.jpg
23.3 Global Biogeochemical Cycles
The Water Cycle – the sun heats up bodies of water causing evaporation. The evaporated water rises to form clouds and rains down on earth. Water runs off the terrain back into the bodies of water and some of the water is absorbed into the ground to become an aquifer. Humans interfere with the water cycle by 1) using water from the aquifers 2) cover terrain with buildings and roads eliminating absorption of rain into the soil and 3) add pollutants to water.
23.3 Global Biogeochemical Cycles
The Water Cycle – the sun heats up bodies of water causing evaporation. The evaporated water rises to form clouds and rains down on earth. Water runs off the terrain back into the bodies of water and some of the water is absorbed into the ground to become an aquifer. Humans interfere with the water cycle by 1) using water from the aquifers 2) cover terrain with buildings and roads eliminating absorption of rain into the soil and 3) add pollutants to water.
The water cycle:
http://www.usgcrp.gov/usgcrp/images/ocp2003/WaterCycle-optimized.jpg
The Carbon Cycle – the CO2 in the atmosphere is where carbon is exchanged. Plants take up carbon dioxide from the air and incorporate is into nutrients for the other webs. It is then returned to air as carbon dioxide and the cycle repeats itself. In aquatic systems, CO2 combines with water to form a bicarbonate ion. Algae uses this and produces food for themselves and other webs. In turn, respiration gives off carbon dioxide which becomes the bicarbonate ion and the cycle repeats itself. Organic carbon is present in the living and dead organisms in the reservoirs of the world. Decomposition contributes CO2 to the atmosphere as well.
The destruction of forests and burning of fossil fuels is disturbing the equilibrium in transfer rates of CO2. The gasses humans are producing (CO2 andothers) are thought to be producing a “greenhouse effect” which in turn is warming the planet unnaturally. Predictions of a major disruption in temperature and flooding and droughts.
The Carbon Cycle:
http://www.uwsp.edu/geo/faculty/ritter/geog101/textbook/earth_system/carbon_cycle_NASA.jpg
The Nitrogen Cycle – makes up 78% of the atmosphere. It is not used by plants and is perceived as a limiter of plant growth. Nitrogen is converted to ammonium and is then utilized by plants. Some bacteria are able to affix nitrogen to hydrogen to form ammonium thereby making it available to plants to form proteins and nucleic acids. Nitrogen combined with oxygen forms nitrates and is also utilized by plants. This reaction occurs when atmospheric phenomenons produce enough energy. Cosmic radiation, meteor trails and lightning are examples of these. This is called nitrification.
Bacteria is once again responsible for converting nitrate back to nitrogen gas and back into the atmosphere. Humans alter the transfer rates of nitrogen by producing fertilizers. The runoff causes overgrowth of algae in lakes which, in turn, burns up too much oxygen and kills fish. Fossil fuels also contribute nitrogen oxides and sulfur dioxides which combine with water vapor to produce “acid rain”. This corrodes marble, metal and stonework and kills natural vegetation.
The Phosphorus Cycle – used by plants and will become part of a variety of molecules including phospholipids, DNA and RNA, and ATP. Phosphorus is trapped in oceanic sediments and will deposit on land after an upheaval. Weathering of rocks deposits it into the soil and becomes available to plants. Animals eat the plants and the phosphorus becomes incorporated into bones, teeth, and shells. Decay causes the phosphate ions to become available to producers again. Phosphorus is not found in the air, so this is a sedimentary cycle. Human beings mine phosphate for use in fertilizer and detergents. This results in cultural eutrophication (overenrichment) of waterways. Biological magnification is the overconsumption or absorption of substances resulting accumulation of higher levels not normally attained. PCP and DDT have been found in breast milk, we are the final consumers. Our seas have been exploited for 50 years resulting in alarming decline of some species of marine life.
http://www.uwsp.edu/geo/faculty/ritter/geog101/textbook/earth_system/carbon_cycle_NASA.jpg
The Nitrogen Cycle – makes up 78% of the atmosphere. It is not used by plants and is perceived as a limiter of plant growth. Nitrogen is converted to ammonium and is then utilized by plants. Some bacteria are able to affix nitrogen to hydrogen to form ammonium thereby making it available to plants to form proteins and nucleic acids. Nitrogen combined with oxygen forms nitrates and is also utilized by plants. This reaction occurs when atmospheric phenomenons produce enough energy. Cosmic radiation, meteor trails and lightning are examples of these. This is called nitrification.
Bacteria is once again responsible for converting nitrate back to nitrogen gas and back into the atmosphere. Humans alter the transfer rates of nitrogen by producing fertilizers. The runoff causes overgrowth of algae in lakes which, in turn, burns up too much oxygen and kills fish. Fossil fuels also contribute nitrogen oxides and sulfur dioxides which combine with water vapor to produce “acid rain”. This corrodes marble, metal and stonework and kills natural vegetation.
The Phosphorus Cycle – used by plants and will become part of a variety of molecules including phospholipids, DNA and RNA, and ATP. Phosphorus is trapped in oceanic sediments and will deposit on land after an upheaval. Weathering of rocks deposits it into the soil and becomes available to plants. Animals eat the plants and the phosphorus becomes incorporated into bones, teeth, and shells. Decay causes the phosphate ions to become available to producers again. Phosphorus is not found in the air, so this is a sedimentary cycle. Human beings mine phosphate for use in fertilizer and detergents. This results in cultural eutrophication (overenrichment) of waterways. Biological magnification is the overconsumption or absorption of substances resulting accumulation of higher levels not normally attained. PCP and DDT have been found in breast milk, we are the final consumers. Our seas have been exploited for 50 years resulting in alarming decline of some species of marine life.
The Phosphorus Cycle
http://vincejtremante.tripod.com/images/phosphorus.jpg
Chapter 24: Human Population, Planetary Resources, and Conservation
24.1 Human Population Growth
The human population is experiencing exponential growth. This began after 1750 and began to steeply increase in less-developed countries (LDC’s) around 1950. It is expected that the world population will increase 78 million annually. The growth rate of a population is determined by the difference between deaths and births per 1,000 people per year. It is currently at 1.2% globally. The carrying capacity is the maximum amount of population that the environment can support. We don’t know what the Earth’s capacity is for the human population.
http://vincejtremante.tripod.com/images/phosphorus.jpg
Chapter 24: Human Population, Planetary Resources, and Conservation
24.1 Human Population Growth
The human population is experiencing exponential growth. This began after 1750 and began to steeply increase in less-developed countries (LDC’s) around 1950. It is expected that the world population will increase 78 million annually. The growth rate of a population is determined by the difference between deaths and births per 1,000 people per year. It is currently at 1.2% globally. The carrying capacity is the maximum amount of population that the environment can support. We don’t know what the Earth’s capacity is for the human population.
Population growth by region:
More developed countries (MDC’s) have a lower growth rate than the LDC’s. MDC’s have a better quality of living. Much of the LDC populations live in poverty. As a whole the MDC’s growth rate is 0.1%, the US is 0.6%. The LDC’s growth rate is 1.6%, but some countries still average higher rates where women are having more than 5 children each. The LDC’s population may increase from 5 billion to 8 billion by 2050. Asia has 56% of the world’s population and only 31% farmable land. Of the 15 most polluted cities in the world, 12 are in Asia. Because of the large percentage of women entering their reproductive years in LDC’s, they are most certainly going to grow in population even if they produced only 2 children per household.
24.2 Human Use of Resources and Pollution
Resources are described as nonrenewable (land, fossil fuels, and minerals), or renewable (water, solar or wind energy, plants, and animals). As humans utilize resources, pollution occurs. The greater the population, the more pollution is produced.
Land is a limited resource. Forty percent of the population live by the coast. Many of the naturally occurring habitats for wildlife are destroyed from this choice. We have filled in wetlands to use for our own habitation to the detriment of many types of animals.
Overgrazing and foraging causes desertification of semiarid lands. Deforestation is the removal of trees for settling or building materials. This can also lead to desertification.
Example of deforestation
http://www.sadashivan.com/sitebuildercontent/sitebuilderpictures/deforestation.jpg
Water is considered to be renewable, but is scarce in some areas. Where water is available, is should be drinkable, but is impure in some areas. Seventy percent of all clean freshwater is used to irrigate crops. in the MDC’s, more water is used for flushing toilets, bathing, and lawns, than for drinking.
Dams provide water and electricity, but prevent rivers from running as they used to. Drawbacks are seepage and evaporation, increased salinity downstream, and the filling of the reservoir with sediment. People have been removing water from the aquifers (underground stores of water). The High Plains Aquifer stretches from South Dakota to Texas, and has been reduced by more than half because of groundwater pumping. This causes subsidence, settling of the soil, which may produce sink holes. Saltwater may back into streams and aquifers reducing the supply of freshwater. There are technologies available to reduce the demand of freshwater, but they are seldom used.
The food supply has expanded to accommodate the growing population, but some harmful methods have been implemented. Some farmers only plant one crop. This makes it more vulnerable to devastation by one parasite. Fertilizers, pesticides and herbicides have polluted groundwater and beneficial soil organisms. Irrigation methods have reduced the aquifers. Farmers also use a lot of fossil fuels to accomplish their tasks.
Soil loss and degradation are problems facing farmers. Simply, the rows utilized to accommodate tractors has caused the US and Canada to have the highest rates of soil erosion in the world. The accumulation of minerals in the soil from irrigation practices, has rendered the land unsuitable for growing crops. Scientists developed wheat and rice varieties for the LDC’s, which are causing the same issues over there. Genetic engineering is another approach to developing hardy and resistant crops. The consequences of these are not fully understood. Domestic livestock is a huge consumer of resources and produces a lot of pollution as well.
Energy is renewable and nonrenewable. Nuclear power provides 6% of the world’s energy supply. Disposal of waste is an issue, because it is radioactive. Fossil fuels provide 75% of the energy supply. The US is only 5% of the world’s population, but uses half of this resource. This is best explained by this statement: one person in the US uses as much energy in one day as a person in an LDC uses in a year. The burning of fossil fuels releases carbon dioxide into the atmosphere which is theorized to contribute to a global warming trend. This continues to be a debatable point, even in scientific circles. Renewable resources are growing in availability. Hydropower is produced from dams and is not without problems as mentioned earlier.
http://www.sadashivan.com/sitebuildercontent/sitebuilderpictures/deforestation.jpg
Water is considered to be renewable, but is scarce in some areas. Where water is available, is should be drinkable, but is impure in some areas. Seventy percent of all clean freshwater is used to irrigate crops. in the MDC’s, more water is used for flushing toilets, bathing, and lawns, than for drinking.
Dams provide water and electricity, but prevent rivers from running as they used to. Drawbacks are seepage and evaporation, increased salinity downstream, and the filling of the reservoir with sediment. People have been removing water from the aquifers (underground stores of water). The High Plains Aquifer stretches from South Dakota to Texas, and has been reduced by more than half because of groundwater pumping. This causes subsidence, settling of the soil, which may produce sink holes. Saltwater may back into streams and aquifers reducing the supply of freshwater. There are technologies available to reduce the demand of freshwater, but they are seldom used.
The food supply has expanded to accommodate the growing population, but some harmful methods have been implemented. Some farmers only plant one crop. This makes it more vulnerable to devastation by one parasite. Fertilizers, pesticides and herbicides have polluted groundwater and beneficial soil organisms. Irrigation methods have reduced the aquifers. Farmers also use a lot of fossil fuels to accomplish their tasks.
Soil loss and degradation are problems facing farmers. Simply, the rows utilized to accommodate tractors has caused the US and Canada to have the highest rates of soil erosion in the world. The accumulation of minerals in the soil from irrigation practices, has rendered the land unsuitable for growing crops. Scientists developed wheat and rice varieties for the LDC’s, which are causing the same issues over there. Genetic engineering is another approach to developing hardy and resistant crops. The consequences of these are not fully understood. Domestic livestock is a huge consumer of resources and produces a lot of pollution as well.
Energy is renewable and nonrenewable. Nuclear power provides 6% of the world’s energy supply. Disposal of waste is an issue, because it is radioactive. Fossil fuels provide 75% of the energy supply. The US is only 5% of the world’s population, but uses half of this resource. This is best explained by this statement: one person in the US uses as much energy in one day as a person in an LDC uses in a year. The burning of fossil fuels releases carbon dioxide into the atmosphere which is theorized to contribute to a global warming trend. This continues to be a debatable point, even in scientific circles. Renewable resources are growing in availability. Hydropower is produced from dams and is not without problems as mentioned earlier.
Unknown Dam
Smaller dams with less output and less environmental impact may be the answer. Geothermal energy is emitted from underground naturally-occurring radiatioin that heats rocks which are in contact with water. Steam and hot water are produced and can be used to run steam-driven turbogenerators.
The most active geothermal resources are usually found along major plate boundaries where earthquakes and volcanoes are concentrated. Most of the geothermal activity in the world occurs in an area called the Ring of Fire. This area rims the Pacific Ocean.
http://www.eia.doe.gov/kids/energyfacts/sources/renewable/geothermal.html
Wind and solar power are viable energy producing options. Hydrogen fuel cells are very promising developments and give off water as a byproduct.
Solar plant:
The mining of minerals causes damage to the area of mining and heavy metals are dangerous to our health. These wastes build up in our environment as well. Some of these disrupt our endocrine systems. Could this be why so many people have Thyroid disorders? Chloroflourocarbons were instrumental in the thinning of our ozone and since their ban, the ozone is predicted to recover by 2050. Because pollution is absorbed along the food-chain, contaminants have been found in human breast milk.
24.3 Biodiversity
Biodiversity refers to the variety of species in a given area. Loss of habitat can cause a species to become extinct. It’s possible that all coral reefs will disappear in the next 40 years. Species unnaturally introduced into an area can become invasive and crowd the natural wildlife out of their existence. Pollution produces acid deposition, global warming, ozone depletion, and the deposition of synthetic organic chemicals. Overexploitation for obvious reasons, reduces resources and/or wildlife and can leave an area decimated and unlivable.
Biodiversity is valued for various reasons. Three main reasons for maintaining biodiversity are
Medicinal Value: Biota are the sources of most prescription drugs. It is surprising where these miracle cures are found. Flowers in Madagascar have increased the survival rate of leukemia from 10% to 90% in children. Similar tales are abundant. In agriculture, natural predators are being used to combat viruses and pests. Maintaining populations of species for consumption is also to our benefit.
Rosy Periwinkle, surprising lifesaver
Partially treating sewage and allowing decomposers to finish the job benefits our environment. Also, biological communities can also remove heavy metals and pesticides and save $50,000 per 2.47 acres. Forests and other ecosystems slowly release water back into rivers reducing the occurrence of flooding. These also prevent soil erosion. Biogeochemical cycles that occur naturally keep vital elements and energy in balance.
24.4 Working Toward and Sustainable Society
The population growth of the LDC’s and the consumption of the MDC’s both need adjustments if we are to achieve a sustainable society. New innovations and foresight must be embraced and each person must make lifestyle changes to support these choices. If we learn from the natural systems in place, we will use renewable resources. In urban areas, we should preserve our topsoils, the richest in nutrients. Composting, multi-use farming, natural pest control, planting of multi-purpose trees, maintaining and restoring our wetlands, using renewable energy and buying locally will all impact our environment positively. In the city, we need to incorporate green belts and use roof tops for gardening as well. Using solar or geothermal energy and utilizing old, run-down areas in the city before building outward would also benefit the environment.
Chicago Rooftop
We need to assess what it is we value in order to prioritize our commitments and move forward.
1 comment:
Nice Blog! The information is condensed appropriately. Unfortunately I miss a topic with human responsabilities and knowlodge, because cry and pray is not enough too sustain the life on earth.
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