22.5 Evolution of Humans
22.1 Origins of Life
A fundamental principle of biology states, “All living things are made of cells and that every cell
comes from a preexisting cell.” The question presented then is, “Where and how did the very
first living thing come into existence then?” Possibly the answer is that a slow chemical process
change occurred and produced the first cell -protocell/(chemical evolution)
The Solar System developed approximately 4.6 BYA. The Earth has atmosphere. The
atmosphere we have today is quite different than the first atmosphere due to gases and water.
Also heat played a huge role in the atmosphere from long ago.
Primitive Earth had the following energy sources:
1- Volcanoes
2- Meteorites
3- Radioactive Isotopes
4- Lightening
5- Ultra-violet Radiation
Macromolecules- RNA first hypotheses/ states that only macromolecule RNA was necessary to lead to formation of the very first cells.
Protein First Hypotheses/ suggests that amino acids collected together when exposed to dry heat forming portioned then returned to water to form microspheres, which have many of the same properties as cells.
The Protocell- could metabolize but could not reproduce-fermenter because of no free oxygen-if lipids and microspheres become associated a lipid-protein membrane occurs.
The True Cell- a true cell can reproduce and DNA replicates before cell division occurs. Proteins called, “Enzymatics” perform the replication process.
22.2 Biological Evolution
(1)Prokarytic cells are the first true simple cells of life. A feature of the prokaryotic cell is that they lack a nucleus.
(2)Next came the Eukaryotic Cells which do have a nucleus.
(3)Next came multicellularity along with other kingdoms.
Each of these types have their own evolutionary history starting with the very first cell.
Biological Evolution is the process of a species changing through time.
All living things have a common history of origin.
Adaptation is the species ability to survive and reproduce in its environment.
Adaptation is the explanation why there are so many types of living organisms….a particular species adapts to its unique environment.
Common Descent explains the sameness of a species to its ancestors.
Fossils prove evolution because they are the actual remnants of that particular species.
Fossils are 10,000 years or older- up to billions of years old.
“Traces” are remnants or evidence of past life. Traces can be trails, footprints, burrows, worm casts, or petrified droppings. Pieces of bone, plant impressions, species trapped in tree resins are all examples of fossils. Fossils are commonly found in sedimentary stone.
Sedimentation is the process of particle accumulation that forms layering of the Earth’s crust. A layer of sedimentation is called a strata.
When a species dies, it decomposes or is scavenged, so the remains are typically the hard encasement or bone material, which becomes imbedded in the sedimentary stone layer and is then layered over the top of.
Paleontology is the scientific study and discovery of fossils. The term. “Fossil Record” refers to the history of life recorded by fossils. Species have evolved through time so the fossil remains we find are different than the species is today.
Scientifically we know today that life has evolved from the simple to the complex.
Fossil records show the following progression:
1- unicellular prokaryotes
2- unicellular eukaryotes
3-multicultural eukaryotes
Transitional fossils have the characteristics of two species.
Whales are believed to have terrestrial ancestry. The presence of legs in Ambulocetus species
leads to the hypothesis of terrestrial mammals leading to the whale species.
The origins of mammals is well documented through fossilization of species.
(figure 22.4) page 471- The Archaeopteryx had combo of reptilian/bird characteristics.
Biogeographical Evidence studies the distribution of plants and animals in different places
throughout the world.( It is known as “Common Descent”) It hypothesis’ that specific species of
life took root in certain geographical areas and then spread out- but only were able to spread as
far as continent divisions allowed them to.
Anatomical evidence also supports common descent theory: it shows an explanation of
similarities anatomically and uses reason to support the theory.
Biochemical Evidence shows that all living organisms use the same identical basic biochemical
molecules, including DNA.
Intelligent Design: evolution is a theory based in science and evidence to support the theory.
Religious beliefs do not fit into the evolution theory but instead are based on faith. Faith based
creation is founded on creation started from God.
Natural Selection is a Darwinian theory used to describe a mechanism for adaptation. This
theory claims and has supportive evidence that states, “a species becomes suited to its
environment.”
Critical elements of natural selection are:
Variation- Individuals vary in physical appearance and can pass from generation to generation.
Competition for Limited Resources- Because of limited resources and competition for them
generational numbers remain about the same for particular species.
Adaptation- Advantageous traits are much more likely to be passed down generationally
because these particular traits can capture more of the resources.
Natural selection accounts for great diversity of life. Each and every organism is adapted and
designed for its particular way of life.
22.3 Classifications of Humans
Organisms are classified biologically by their evolutionary relatedness. “Binomial Name” of
organism gives it genus and also its species.
Same Domain refers to only general characteristics in common BUT those in the same “genus”
have A LOT of characteristics in common.
The three domain system used to classify (common ancestors)
(1) Bacteria
(2) Archaea
(3) Eukarya..
This classification shows that Archaea are closer to Eukarya than Bacteria.
DNA data is more commonly used and relied on today for species identification.
With DNA category classification scientists have determined that 2bya the domain Eukarya,
which consisted of a membrane-bound nucleus was the beginning of the category that humans
are in today (species Homo sapiens)
Primates are adapted to an arboreal life, which means living in trees.
Two sub-orders of primates are prosimians (lemurs tarsiers) and the anthropoids (monkeys,
apes, and humans)
Primate limbs are mobile and hand and feet have five digits.
Binocular Vision: snout is short so the eyes can move to the front of the head. Stereoscopic Vision
(depth perception is another characteristic, three different cone cells to differentiate the colors,
greens, blues, and reds.
Large Complex Brains are another characteristic of primaries.
Reduced Reproductive Rate: one birth at a time is normal in primates.
Human skeleton/Chimpanzee skeleton
Human = center spine exit
Ape= rear spine exit
Human= s-shaped spine
Ape= slight curved spine
Human= bowl shaped pelvis
Ape= Longer, narrow pelvis
Human= Inward at knees femur
Ape= Angle out femur
Human= Can hold weight on knees
Ape= Cannot hold much weight on knees
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The evolutionary tree shows that all primates originated from one common ancestor.
Humans and apes have been developing for approximately 7 mya.
Lineage is when to lines diverge from a common ancestor.
Bipedal posture is a feature that is hominid: another hominid feature is the face shape and the
brain size. There have been times when two or more hominids existed at the same time: such as
the Australopithecus robustus and the boisel and the Homo habillis.
Homo Erectus fossils are found in Africa, Asia, and Europe (1.9-.3 MYA) First to use fire.
Homosapiens (modern humans) evolved from erectus.
evolution diagram from a google search from the internet
The Multiregional Continuity Hypothesis states that the development of homo sapiens in various
parts of the world was very similar. This theory is disputed by those who believe the “Out of
Africa Hypothesis” which claims that homo sapiens only evolved out of erectus from Africa and
THEN migrated to Europe and Asia.
The out of Africa hypothesis suggests that human beings today are much more characteristically
the same.
Neanderthals (H. neandertalenis) massive brow ridges and their nose, jaw, and teeth protruded.
Thought to have been taken over (supplanted) by homo sapiens. Had large brains, lived in caves,
culturally advanced.
Cro-Magnons- Oldest fossils to be labeled homo-sapiens-
Human Variation consist of what we call today ethnicity. These are believed to have evolved due to adaptations to local environmental conditions.
A modern DNA study finds that modern man has a common ancestry link between all world populations approximately one million years ago. This finding concludes that we as humans are closely related to one another.
Bioethical Focus -page 487
Passing on the culture from one generation to the next generation is called Bio-cultural Evolution
and this type of evolution is not dependent on genetics but to adaptation to one’s environment.
It began with homo habillis who we believe were tool makers; Farming is thought to have begun
about 10,000 years ago by the ancestors of today; Population increases in the society then may
have influenced the necessity of more agriculture to meet the needs of the people. The industrial
revolution began in the 18th century and cultural adaptations were continued to be passed down
to the generations of more recent history: Much of the progress and adaptations are harming
and even causing extinction to many number of species because they can not adapt to the
changes in the environment quickly enough. It is possible that extinction could be the result for
the human species if we do not learn how to and become willing to work within the biosphere
better.
Chapter 23/ Global Ecology and Human Interferences
23.1 The Nature of Ecosystems
23.2 Energy Flow
23.3 Global Biochemical Cycles
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23.1 The Nature of Ecosystems
The biosphere is where organisms are found on Earth. The entire biosphere can be considered a giant Ecosystem.
“Abiotic” components of an ecosystem are non-living.
“Biotic” components are living and can be categorized by their food source.
Autotrophs- inorganic nutrients and outside energy source are the only requirements.
Heterotrophs- need organic nutrient source. They are considered “consumers”.
Herbivores are animals that graze.
Csrnivores eat meat.
Omnivores eat both meat and also eat plants.
Detritus feeders- organisms that feed on detritus (decomposing particles of organic matter).
Niche- means the role of an organism.
Energy flow and chemical cycling= Solar energy (sun) produces energy which helps trees and
plant life (producers) grow which feeds the animals (consumers) which then is put back into the system by waste and decomposition which then turns into inorganic nutrient pool which then has full cycled and replenishes the nutrients for the “producers” plants and trees.
23.2 Energy Flow
There are interconnecting paths of energy represented in an ecosystems such as a forest.
Forest has a food web that has trophic relationships (feeding).
Diagrams that show single path of energy flow are known as food chains.
Example: (Grazing Food Chain)= leaves=caterpillars=birds=hawks
Detrital Food Chain=Detritus=earthworms=shrews
Ecological Pyramids
The length of a food chain is determined by the loss of energy between trophic levels.
The flow of energy with large losses between successive trophic levels is depicted as an ecological
pyramid. Energy losses between trophics result in pyramids based on organism numbers.
Biomass is the number of organisms multiplied by the weight of organic matter within one
organism.
23.3 Global Biochemical Cycles
All organisms require both organic and inorganic materials.
Pathway for chemicals to circulate through ecosystems involve living (biotic) and non-living (geological/abiotic) components. These are known as biogeochemical cycles and can consist of gaseous material and sedimentary. A reservoir is an example of a chemical cycling.
The Water Cycle consists of evaporation, vaporized ware rises and falls as precipitation,
Water can also evaporated from plants (transpiration) gravity also eventually returns all fresh water to the sea, run off is water flowing directly into nearby streams, ground water can also be located in between layers of rock called aquifers.
The Carbon Cycle consist of organic matter (living and dead) to make up the reservoirs. Fossil fuels are the 300 mya remains of organic materials such as coal, oil, and natural gas.
CO2 along with other type gasses are being emitted because of human activities. Global warming and the Green house effect are two negative by products of human activity in our biosphere.
The Nitrogen Cycle
Plants cannot make use of nitrogen and nitrogen makes up approximately 78% of the Earth’s atmosphere.
Nitrogen fixation is the conversion of nitrogen into ammonium, which CAN be used by plants. Some cyan bacteria and free-living bacteria assist in this fixation process.
Some of the bacteria that help this process occur live in nodules on legume roots, such as beans, peas, and clover. They accomplish this by making available to host plants the nitrogen so they can produce the proteins and nucleic acids.
Production of nitrates during nitrogen cycle is called nitrification. It can occur by nitrogen gas turning into nitrate, from ammonium, nitrate producing bacteria and also assimilation (the process of plants taking up ammonia and nitrate from soil to use ions to make proteins and nucleic acids.
Denitrification is the process of conversion of nitrate back to nitrogen gas, which enters the atmosphere. Human activity interferes with the transfer rate significantly and poses a negative affect on our biosphere.
The Phosphorus Cycle
Phosphorus that has been trapped in oceanic sediments move onto land after a geological upheaval.
Slow weathering of rock puts up phosphate ions into the soil. Some of the phosphate material absorbs into the plant life that grows in the soil and then it is introduced into the animal life that ingests the plant life. The material is absorbed into their teeth and bone and takes a very long period of time to decompose back into the Earth. Some of the phosphate runs into the aquatic system. The phosphate that is then found in marine sediments does NOT become available to producers on land again until there is a geological upheaval.
Humans alter the ecosystem of the biosphere by mining, which boosts the supply of phosphates (fertilizers and production of detergents are two of the main culprits in the negative impact cycle)
Chapter 24/ Human Population, Planetary Resources, and Conservation
24.1 Human Population Growth
24.2 Human Use of Resources and Pollution
24.3 Biodiversity
24.4 Working Toward a Sustainable Society
24.1 Human Population Growth
Exponential growth refers to the number of reproducing humans increasing and then reproducing offspring.
Growth rate refers to the comparison of the number of births a year as compared to the number of deaths.
The Carrying Capacity refers to the maximum number of population that an environment can support.
MDC’s means the “More Developed Countries’ and the LDC’s refers to the “Less Developed Countries”.
MDC’s have experienced moderate growth in populations since the 1950’s. The USA has a higher than average population increase due to immigration and the baby boom between 1947 and 1964. There are still a large number of females within the child bearing age brackets.
LDC’s have lower death rates after WWII because of modern medicine. The birth rates in some countries is extremely high (5 offspring) and these two factors contribute greatly to the LDC’s high population numbers.
Replacement Population refers to when a couple reproduce only two off spring and no more.
24.2 Human Use of Resources and Pollution
Non-renewable resources are those that are limited in supply, such as, land, fossil fuels, and minerals.
Renewable resources can naturally be replenished such as, water, solar energy, harvested plants and animals for food.
A side effect of resource consumption is pollution, which is an undesirable alteration of the environment. Beach erosion is in part caused by humans living within close distance of the waters edge.
Desertification is the conversion of semiarid land to desert like conditions. It can be caused by humans allowing over grazing of lands.
Deforestation means the removal of trees. Soil loses its fertility and nutrients because of clearing of the natural foliage and trees.
Biodiversity can be loosed due to deforestation as humans often consume a food source from the deforested area that is now inhabited and the ecosystem that the animal lives within.
Water
Some areas of the USA and other places, exceed the renewable supply of water available and must then build dams or use aquifer systems to meet the needs of the populations in those areas.
Groundwater depletion is causing the settling of soil as it dries out, this is called subsidence. Withdrawal of groundwater can cause sink holes.
Saltwater intrusion is another consequence of aquifers. When the water table becomes low enough what usually was replenished by freshwater is then filled with saltwater. Saltwater intrusion reduces the available supply of freshwater along the coasts.
By 2025 2/3 of the world population may be living in areas that do not have enough fresh water supply to sustain the population. Countries and their governments must plan ahead and develop incentives for the people to work toward better water management and conservation measures.
Food
Food comes from three activities (1) growing crops (2) raising animals (3)fishing in the seas. Modern farming practices have increased the available food supply considerably but have also added some harmful practices as well:
(1) The planting of only a few (limited0 genetic varieties.
(2) Heavy use of fertilizers
(3) Generous irrigation
(4) Excessive fuel consumption
Intercropping is the farming practice of planting two or more different crops.
Soil degradation is occurring world wide. This means that the organic rich top soil is being eroded away.
Genetic Engineering: by altering plant genes genetically we may be causing more harm than good by the creation of super strain plants that actually draw more from the biosphere than they offset by the high yields and the amount of people that can be fed.
Domestic Livestock can add to the drain on resources and in high protein diet areas, such as the USA, much of the agricultural land is used for raising of livestock which uses up many of the non-renewable resources.
Energy
(Non-renewable Sources)
Nuclear power and also fossil fuel are both non-renewable energy sources and they make up approximately 81% of the types of energy we currently use to meet our energy needs.
Fossil fuels include: oil, natural gas, coal- they are derivatives of compressed remains of plants and animals that died thousands of years ago.
A person in an MDC uses in one day the amount of energy that A person in an LDC uses in a years time!
The burning of fossil fuels since 1850 has increase the level of carbon dioxide in the atmosphere considerably 9from 280 ppm up to 350 ppm) Greenhouse gasses include methane gas, carbon dioxide and other gasses released from the burning of fossil fuels. The Green house effect raises the temperature, which raises the water level because of the glacial melting.
Renewable Energy Sources- * include the following-
Hydropower- use falling water to convert to electricity through hydro-electric plants/ often used with large dams.
Geothermal- steam from energy conversion due to uranium, thorium, radium, and plutonium going through radioactive decay in the Earth.
Wind- wind power is believed to be used a lot more in the near future as an energy source/does not require as much land as some alternatives so this may be a better energy supplier.
Solar- Diffuse energy that must be collected, converted, and stored. Passive solar energy refers to such things as when a houses’ window faces the sun and the sunlight/energy enter the home and is stored .
Minerals are non-renewable raw materials that can be mined. These include fossil fuels, non-metallic raw materials (sand, gravel, phosphate). Many heavy metals are harmful to humans: such as, lead, mercury, arsenic, copper.
Surface mining of the Earth’s crust is one of the most negative types of activities that humans perform on the planet. The land becomes void of normal vegetation and also the rain run off then takes toxic waste into the streams and rivers and next the water supply.
Hazardous wastes refers to the build up of minerals which then leads to toxic/harmful levels being present to affect animals and humans in a variety of ways.
24.3 Biodiversity
“Variety of life on the planet Earth”
The loss of biodiversity is something that we face everyday. This includes habitat loss, alien species, pollution, over-exploitation, disease; which all lead to decline in natural species of specific area.
For a healthy balance in a particular ecosystem biodiversity is very important. This refers to the various species in an ecosystem all filling a particular function and niche in the system.
Medicines are an important by-product of biodiversity. Most of our drugs originated in living organisms.
Agriculture is highly affected by biodiversity and when certain crops fail for specific reasons more crops can be drawn from in the natural world of crops because there is a balance and diversity to the various kinds.
Bioethical Focus page 528
Discusses the intricate ecosystems in the coral reefs, which are often thought of as “underwater rain forests”. The ethical issue brought up in the article is the use of cyanide to catch the marine life found within the reefs. The ethical issue raised is the harmful effects of the cyanide to the ocean fish life, the actual changes in the reef and also to the humans who use the poison to catch the fish. Cyanide changes the entire environment and due to electron changes in the mitochondrial electrical impulse system, the entire eco system is damaged and altered for possibly thousands of years.
Biodiversity is a highly important resource. It is not just important for an individual species but when looking at the big picture it is even more important for the survival and adaptation of the entire ecosystem and even larger than that for the entire biosphere (earth).
Waste disposal is important, as is the availability of fresh water, as is the prevention of soil erosion, and the regulation of the climate helps shade and cool so the use of fans and air-
conditioning can be used less. What this all means is the human race overall must come to the awareness of the entire system working together in the biochemical cycles of nature so we do not run out of non-renewable resources and also we do not create more damage than can be overcome by the natural order of our planet.
24.4 Working Toward a Sustainable Society
In an ideal world we would always be able to provide the same amount of what we need and want as we do today as well as balancing biodiversity .
For a continuation of a sustainable society we must focus on not depleting our resources and also make efforts toward resource preservation. The LDC’s of the world create environmental
burdens and at the same time the MDC’s do the exact same thing.
Focusing on a natural ecosystem will be advantageous to us today as well as those generations of the future. We need to make use of our renewable resources and recycle what we use. Agriculture, business, preservation, pest management, mass transit, and energy efficiency are all ways we can address and help our environment.
