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Evolution

The Big Bang Theory

  • The origins of the universe are one of the great mysteries of our world

  • While we have no first-hand evidence of the formation of the universe, we do have substantial secondary data

  • These various forms of evidence have led to the formation of the Big Bang Theory


  • Key stages to consider in the formation of our universe include:

    1.) The Big Bang (13.8 billion years ago)

    • The universe began as a hot, dense point

    • Space, time, and matter were created

    2.) Inflation (Fractions of a second after the Big Bang)

    • The universe expanded faster than the speed of light for a very short time

    • This made the universe smooth and uniform

    3.) Formation of Fundamental Particles (First few seconds)

    • Energy turned into quarks, electrons, and neutrinos

    • Quarks combine to form protons and neutrons.

    4.) Nucleosynthesis (3-20 minutes after the Big Bang)

    • Protons and neutrons fused to create hydrogen, helium, and lithium nuclei

    • The universe was too hot for atoms to form yet

    5.) Recombination (380,000) years later - Formation of Atoms

    • Electrons joined with nuclei to form neutral atoms

    • The light was finally able to travel freely, creating the Cosmin Microwave Background (CMB)

    6.) The Dark Ages (After recombination - a few hundred million years)

    • The universe was mostly dark and filled with gas

    • No stars or galaxies existed yet.

    7.) Formation of Stars and Galaxies (A few hundred million years later)

    • Gravity pulled hydrogen and helium together to form the first stars

    • Stars grouped into galaxies, including the Milky Way

    8.) Formation of Our Solar System (4.6 billion years ago)

    • A giant cloud of gas and dust that collapsed, forming the sun

    • the leftover material formed planets, moons, and asteroids

    9.) Present-Day Universe

    • The universe continues to expand

    • Stars are born and die, forming new elements

    • scientists study dark matter and dark energy to understand the future of the universe

The Formation of Chemical Elements

  • Chemical elements are substances that ordinary chemical processes cannot decompose into simpler substances.

    • The number of protons in their nucleus makes them different from one another

    • Some of the most common elements in living things include: Carbon, Hydrogen, Oxygen, Nitrogen, and Phosphorus.

  • The first elements to form were also the simplest: Hydrogen and Helium were the first to form and are key to the fusion reactions occurring within stars.

    • One of the main sources of energy in the universe (and therefore on Earth) is solar energy

  • The name of the theory which best explains the formation of the solar system is called the Solar Nebula Theory

    • About 4.6 billion years ago, a huge cloud of gas and dust floated in space

    • It began to spin, and the high-density high-pressure core became a protostar, and eventually, the sun

  • Evidence for solar nebula theory includes:

    • The placement of the rocky planets, then the gas giants both with the debris that never became a planet between them

    • All planets orbit in the same direction

    • Some meteorites are 4.6 billion years old, the same age as the sun and planets


The Conditions of Early Earth

  • 4.6 billion years ago

    • The atmosphere was toxic: CH4, H2, H2O, N2, NH3)

    • There was substantial volcanic activity

    • Meteorite impacts were a regular occurrence

    • Temperature changes were extreme (due to the lack of ozone & those factors listed above)


Key events in Early Earth

  • Key events in the formation of Early Earth:

    • Formation of Earth (4.6 billion years ago)

    • First life (prokaryotic bacteria, 3.5 billion years ago)

    • Photosynthesis evolved (2.5 billion years ago)

    • Oxygen revolution (2.4 billion years ago)

    • First multicellular organisms (600 million years ago)

    • First land plants and animals (500 million years ago)

    • First mammals and dinosaurs (230 million years ago)

    • First humans (200,000 years ago)

The Evolution of Photosynthesis

  • The jump from single-celled life to complex multicellular life:

    • The jump from simple life to complex life begins 2.4 million billion years ago

      • Photosynthesis: A ‘mistake’ mutation

        • using sunlight to turn into food

      • Cyanobacteria - the first bug to use photosynthesis

      • The cyanobacteria thrive, but the waste product is oxygen, which accumulates in the atmosphere, leading to significant changes in Earth's environment and paving the way for aerobic life forms.

    • Most of life on earth is killed off by oxygen, leading to the evolution of new species that adapted to utilize oxygen for respiration, ultimately resulting in a diverse array of aerobic organisms.

      • As oxygen was released, it changed the entire chemistry of the planet

      • it reacted with the earth’s atmosphere, turning the planet very cold - a snowball planet (lasts for 200 million years)

      • After volcanos rewarm the earth, multicellular organisms thrive and they use oxygen to survive.

  • What is photosynthesis

    • The process by which plants and other autotrophs can convert solar energy into chemical energy

    • The first organisms to evolve the ability to do photosynthesis were bacteria, specifically cyanobacteria

    • One of the waste products of photosynthesis is oxygen, which over millions of years changed the composition of the Earth’s atmosphere.

      • Organisms that can exist in the presence of oxygen are called aerobes while those that cannot are anaerobes


The Rate of Speciation

  • Speciation is the process through which new species form

  • It has been a critical process over the billions of years during which life has evolved on our planet

    • It occurs through natural selection

    • The rate of speciation has been inconsistent over our planet’s history

  • The primary influencing factor on changes in speciation rate is environmental conditions

    • Under some conditions, selection occurs quickly or radically

    • Consider a species of snails that had been living with the same basic form for many thousands of years, layers of their fossils would appear similar for a long time.

    • When a change in the environment takes place, such as a drop in the water level, a small number of organisms are separated from the rest in a brief period

    • , essentially forming one large and one tiny population, the tiny population faces new environmental conditions

    • Because its gene pool quickly became so small, any variation that surfaces and that aids in surviving the new conditions becomes the predominant form.


What is Evolution

  • Evolution is the change in the heritable characteristics of biological populations over successive generations

  • A population is a group of individuals of the same species living in the same place at the same time which can interbreed

    • Individuals cannot evolve in the biological sense

  • Before Darwin:

    • Jean-Baptiste Lamarck: Organisms adapt to their environment

    • Georges Cuvier: organisms change over time (fossil evidence)

    • Charles Lyell: the Earth is billions of years old (geological changes)

    • Thomas Malthus: overproduction (economic models)

    • Charles Darwin: Natural Selection


Who was Charles Darwin


  • Charles Darwin was born in 1809, the son of a wealthy English society doctor, he began to formulate his theory in the 1830s and spent almost 20 years perfecting it before he published his book On the Origin of Species

  • Alfred Wallace was born in 1823, the son of an English mother and Scottish father who struggled financially

  • Both men were naturalists, they studied patterns in nature and were eager to explore the world to study more new species.

  • In 1858, just one year before Darwin published his book both men presented their ideas to the Linnaean Society and both men’s ideas were very simillar



What is Natural Selection

  • Natural selection occurs through the following mechanism:

    • 1.) Variation: Within a population of one species, there is genetic diversity, which is called variation

    • 2.) Adaptation: Due to natural variation, some individuals will be fitter than others

    • 3.) Overproduction: Fitter individuals have an advantage and will reproduce more successfully than individuals who are less fit.

    • 4.) Descent with modification: The offspring of fitter individuals may inherit the genes that give that advantage


Differing Selection Pressures

  • A selection pressure is an evolutionary force that causes a particular phenotype to be more favorable in certain environmental conditions

  • A trait that gives only small benefits to survival and/or reproduction has a low selecting pressure (such as slightly better food gathering)

  • A traut that gives significant benefits to survival and/or reproduction has a high selection pressure (such as antibiotics and bacteria)

  • Many pests have evolved resistance to pesticides over time

    • Pesticides are chemicals that are designed to kill pests such as insects that eat crops

Sources of Variation

  • sexual reproduction is one of the most significant ways in which genetic variation enters a population

    • When two parents combine their haploid gametes this significantly increases the variation in their offspring and the more chromosomes the species have (n) the more possible combinations there are.

    • 2^n = possible combinations where “n” is the haploid number of a species

    • Sexual reproduction requires considerably more work, more risk, and more energy consuming than asexual reproduction.

  • Throughout the process of meiosis and sexual reproduction, there are several other ways in which variation is increased.


  • 1.) Independent Assortment of chromosomes in Metaphase I and II or meiosis

  • 2.) Crossing over of non-sister chromatids on homologous chromosomes during Prophase I or meiosis

  • 3.) Occurs during interphase and is completely random: Mutations

    • They can be harmful, beneficial, or neutral



Evidence for Evolution

  • A theory is a well-substantiated explanation of an aspect of the natural world that can incorporate laws, hypotheses, and facts

    • To substantiate the theory of evolution we require evidence, there are several types which we will discuss

  • What is a fossil?

    • Fossils can be formed in many ways and may be considered trace fossils or body fossils

    • Trace fossils are fossils of footprints, trails, burrows, feces, or other trace of an animal rather than of the animal itself.

    • Body fossils are the remains of plants, animals, and microorganisms preserved in a geologic context and are what most people think of when they think of a fossil

  • Fossil Evidence: types

    • From Body fossils (preserved bones, teeth, shells, etc.):

      • What the organism looked like (size, shape, structure)

      • How species have changed over time (evidence for evolution)

      • What the organism ate (from teeth shape and stomach contents)

      • Relationships between species (comparing fossils to modern organisms)

    • From Trace fossils (Footprints, burrows, feces, etc.)

      • How the organism moved (walking running, or slithering)

      • Where and how it lived (habitat and behaviors)

      • Social behavior (whether it lived alone or in groups)

      • Diet and digestion (from fossilized feces, called coprolites)

    • Both types of fossils help scientists reconstruct past ecosystems and understand how life evolved over millions of years.

  • Fossil Evidence: Dating

    • The ability to determine the age of a fossil is important to understanding its role in evolution

    • It is relatively easy to determine the relative age of a fossil (which is older and which is younger) while the absolute age (in years) is much more complex to determine

    • The absolute age of a fossil is determined based on the rate of decomposition of an isotope incorporated into the organism while it was alive or environmental cues (like volcanic ash)

    • Based on how much the isotope has decayed and how fast the rate of decay occurs the age in years can be determined

    • Absolute age can be determined with carbon dating, carbon is incorporated into living things during their lifetime and then after they die it slowly decomposes into N-14

    • The number of years it takes for half of the C-14 to decay into N-14 is called the half-life and it is 5730 years, so we determine how many half-lives have gone by and then multiply that number by 5730 to determine the age of the fossil.





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Evolution

The Big Bang Theory

  • The origins of the universe are one of the great mysteries of our world

  • While we have no first-hand evidence of the formation of the universe, we do have substantial secondary data

  • These various forms of evidence have led to the formation of the Big Bang Theory

  • Key stages to consider in the formation of our universe include:

    1.) The Big Bang (13.8 billion years ago)

    • The universe began as a hot, dense point

    • Space, time, and matter were created

    2.) Inflation (Fractions of a second after the Big Bang)

    • The universe expanded faster than the speed of light for a very short time

    • This made the universe smooth and uniform

    3.) Formation of Fundamental Particles (First few seconds)

    • Energy turned into quarks, electrons, and neutrinos

    • Quarks combine to form protons and neutrons.

    4.) Nucleosynthesis (3-20 minutes after the Big Bang)

    • Protons and neutrons fused to create hydrogen, helium, and lithium nuclei

    • The universe was too hot for atoms to form yet

    5.) Recombination (380,000) years later - Formation of Atoms

    • Electrons joined with nuclei to form neutral atoms

    • The light was finally able to travel freely, creating the Cosmin Microwave Background (CMB)

    6.) The Dark Ages (After recombination - a few hundred million years)

    • The universe was mostly dark and filled with gas

    • No stars or galaxies existed yet.

    7.) Formation of Stars and Galaxies (A few hundred million years later)

    • Gravity pulled hydrogen and helium together to form the first stars

    • Stars grouped into galaxies, including the Milky Way

    8.) Formation of Our Solar System (4.6 billion years ago)

    • A giant cloud of gas and dust that collapsed, forming the sun

    • the leftover material formed planets, moons, and asteroids

    9.) Present-Day Universe

    • The universe continues to expand

    • Stars are born and die, forming new elements

    • scientists study dark matter and dark energy to understand the future of the universe

The Formation of Chemical Elements

  • Chemical elements are substances that ordinary chemical processes cannot decompose into simpler substances.

    • The number of protons in their nucleus makes them different from one another

    • Some of the most common elements in living things include: Carbon, Hydrogen, Oxygen, Nitrogen, and Phosphorus.

  • The first elements to form were also the simplest: Hydrogen and Helium were the first to form and are key to the fusion reactions occurring within stars.

    • One of the main sources of energy in the universe (and therefore on Earth) is solar energy

  • The name of the theory which best explains the formation of the solar system is called the Solar Nebula Theory

    • About 4.6 billion years ago, a huge cloud of gas and dust floated in space

    • It began to spin, and the high-density high-pressure core became a protostar, and eventually, the sun

  • Evidence for solar nebula theory includes:

    • The placement of the rocky planets, then the gas giants both with the debris that never became a planet between them

    • All planets orbit in the same direction

    • Some meteorites are 4.6 billion years old, the same age as the sun and planets

The Conditions of Early Earth

  • 4.6 billion years ago

    • The atmosphere was toxic: CH4, H2, H2O, N2, NH3)

    • There was substantial volcanic activity

    • Meteorite impacts were a regular occurrence

    • Temperature changes were extreme (due to the lack of ozone & those factors listed above)

Key events in Early Earth

  • Key events in the formation of Early Earth:

    • Formation of Earth (4.6 billion years ago)

    • First life (prokaryotic bacteria, 3.5 billion years ago)

    • Photosynthesis evolved (2.5 billion years ago)

    • Oxygen revolution (2.4 billion years ago)

    • First multicellular organisms (600 million years ago)

    • First land plants and animals (500 million years ago)

    • First mammals and dinosaurs (230 million years ago)

    • First humans (200,000 years ago)

The Evolution of Photosynthesis

  • The jump from single-celled life to complex multicellular life:

    • The jump from simple life to complex life begins 2.4 million billion years ago

      • Photosynthesis: A ‘mistake’ mutation

        • using sunlight to turn into food

      • Cyanobacteria - the first bug to use photosynthesis

      • The cyanobacteria thrive, but the waste product is oxygen, which accumulates in the atmosphere, leading to significant changes in Earth's environment and paving the way for aerobic life forms.

    • Most of life on earth is killed off by oxygen, leading to the evolution of new species that adapted to utilize oxygen for respiration, ultimately resulting in a diverse array of aerobic organisms.

      • As oxygen was released, it changed the entire chemistry of the planet

      • it reacted with the earth’s atmosphere, turning the planet very cold - a snowball planet (lasts for 200 million years)

      • After volcanos rewarm the earth, multicellular organisms thrive and they use oxygen to survive.

  • What is photosynthesis

    • The process by which plants and other autotrophs can convert solar energy into chemical energy

    • The first organisms to evolve the ability to do photosynthesis were bacteria, specifically cyanobacteria

    • One of the waste products of photosynthesis is oxygen, which over millions of years changed the composition of the Earth’s atmosphere.

      • Organisms that can exist in the presence of oxygen are called aerobes while those that cannot are anaerobes

The Rate of Speciation

  • Speciation is the process through which new species form

  • It has been a critical process over the billions of years during which life has evolved on our planet

    • It occurs through natural selection

    • The rate of speciation has been inconsistent over our planet’s history

  • The primary influencing factor on changes in speciation rate is environmental conditions

    • Under some conditions, selection occurs quickly or radically

    • Consider a species of snails that had been living with the same basic form for many thousands of years, layers of their fossils would appear similar for a long time.

    • When a change in the environment takes place, such as a drop in the water level, a small number of organisms are separated from the rest in a brief period

    • , essentially forming one large and one tiny population, the tiny population faces new environmental conditions

    • Because its gene pool quickly became so small, any variation that surfaces and that aids in surviving the new conditions becomes the predominant form.

What is Evolution

  • Evolution is the change in the heritable characteristics of biological populations over successive generations

  • A population is a group of individuals of the same species living in the same place at the same time which can interbreed

    • Individuals cannot evolve in the biological sense

  • Before Darwin:

    • Jean-Baptiste Lamarck: Organisms adapt to their environment

    • Georges Cuvier: organisms change over time (fossil evidence)

    • Charles Lyell: the Earth is billions of years old (geological changes)

    • Thomas Malthus: overproduction (economic models)

    • Charles Darwin: Natural Selection

Who was Charles Darwin

  • Charles Darwin was born in 1809, the son of a wealthy English society doctor, he began to formulate his theory in the 1830s and spent almost 20 years perfecting it before he published his book On the Origin of Species

  • Alfred Wallace was born in 1823, the son of an English mother and Scottish father who struggled financially

  • Both men were naturalists, they studied patterns in nature and were eager to explore the world to study more new species.

  • In 1858, just one year before Darwin published his book both men presented their ideas to the Linnaean Society and both men’s ideas were very simillar

What is Natural Selection

  • Natural selection occurs through the following mechanism:

    • 1.) Variation: Within a population of one species, there is genetic diversity, which is called variation

    • 2.) Adaptation: Due to natural variation, some individuals will be fitter than others

    • 3.) Overproduction: Fitter individuals have an advantage and will reproduce more successfully than individuals who are less fit.

    • 4.) Descent with modification: The offspring of fitter individuals may inherit the genes that give that advantage

Differing Selection Pressures

  • A selection pressure is an evolutionary force that causes a particular phenotype to be more favorable in certain environmental conditions

  • A trait that gives only small benefits to survival and/or reproduction has a low selecting pressure (such as slightly better food gathering)

  • A traut that gives significant benefits to survival and/or reproduction has a high selection pressure (such as antibiotics and bacteria)

  • Many pests have evolved resistance to pesticides over time

    • Pesticides are chemicals that are designed to kill pests such as insects that eat crops

Sources of Variation

  • sexual reproduction is one of the most significant ways in which genetic variation enters a population

    • When two parents combine their haploid gametes this significantly increases the variation in their offspring and the more chromosomes the species have (n) the more possible combinations there are.

    • 2^n = possible combinations where “n” is the haploid number of a species

    • Sexual reproduction requires considerably more work, more risk, and more energy consuming than asexual reproduction.

  • Throughout the process of meiosis and sexual reproduction, there are several other ways in which variation is increased.

  • 1.) Independent Assortment of chromosomes in Metaphase I and II or meiosis

  • 2.) Crossing over of non-sister chromatids on homologous chromosomes during Prophase I or meiosis

  • 3.) Occurs during interphase and is completely random: Mutations

    • They can be harmful, beneficial, or neutral

Evidence for Evolution

  • A theory is a well-substantiated explanation of an aspect of the natural world that can incorporate laws, hypotheses, and facts

    • To substantiate the theory of evolution we require evidence, there are several types which we will discuss

  • What is a fossil?

    • Fossils can be formed in many ways and may be considered trace fossils or body fossils

    • Trace fossils are fossils of footprints, trails, burrows, feces, or other trace of an animal rather than of the animal itself.

    • Body fossils are the remains of plants, animals, and microorganisms preserved in a geologic context and are what most people think of when they think of a fossil

  • Fossil Evidence: types

    • From Body fossils (preserved bones, teeth, shells, etc.):

      • What the organism looked like (size, shape, structure)

      • How species have changed over time (evidence for evolution)

      • What the organism ate (from teeth shape and stomach contents)

      • Relationships between species (comparing fossils to modern organisms)

    • From Trace fossils (Footprints, burrows, feces, etc.)

      • How the organism moved (walking running, or slithering)

      • Where and how it lived (habitat and behaviors)

      • Social behavior (whether it lived alone or in groups)

      • Diet and digestion (from fossilized feces, called coprolites)

    • Both types of fossils help scientists reconstruct past ecosystems and understand how life evolved over millions of years.

  • Fossil Evidence: Dating

    • The ability to determine the age of a fossil is important to understanding its role in evolution

    • It is relatively easy to determine the relative age of a fossil (which is older and which is younger) while the absolute age (in years) is much more complex to determine

    • The absolute age of a fossil is determined based on the rate of decomposition of an isotope incorporated into the organism while it was alive or environmental cues (like volcanic ash)

    • Based on how much the isotope has decayed and how fast the rate of decay occurs the age in years can be determined

    • Absolute age can be determined with carbon dating, carbon is incorporated into living things during their lifetime and then after they die it slowly decomposes into N-14

    • The number of years it takes for half of the C-14 to decay into N-14 is called the half-life and it is 5730 years, so we determine how many half-lives have gone by and then multiply that number by 5730 to determine the age of the fossil.