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
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
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 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 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
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.
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
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
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
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
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
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.
Evolution
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
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
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 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 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
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.
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
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
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
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
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
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.