Zoom: A History of Everything

Created by the students of History 238 (Zoom: A History of Everything) at the University of Michigan // Color coding: Magenta = Astronomy; Blue = Geoscience; Black = Chemistry; Green = Evolutionary Biology and Paleontology; Red = Anthropology and Archaeology

A History of Everything

Era of Nucleosynthesis & Nuclei

13,700,000,000 BCE

"The first elements are formed, including hydrogen, helium, lithium, boron, and beryllium. The universe is then ionized and the nuclei recombine with matter to form atoms."

Formation of First Hydrogen Atoms

13,700,000,000 BCE

"The formation of atoms in the universe was extremely important in Big History, because atoms compose the foundation of all matter in the universe. Hydrogen atoms, along with helium and trace amounts of lithium atoms, formed molecular clouds in the universe, which condensed into stars. Stars, which burn hydrogen atoms in nuclear fusion for energy, eventually burst in supernova and scattered elements throughout the universe, forming planets such as our Earth over long periods of time. Everything we know is composed of matter, and without the formation of atoms in the universe, especially hydrogen, we would not exist."

The Big Bang

13,700,000,000 BCE

"The specified time range includes the earliest, initial eras of the universe, that all began and ended within the first fraction of a second. The Big Bang itself is when all of the matter and energy of the universe began expanding outwards from a single point. Energy separated from space and time during the Planck Era, which is the smallest unit of time with physical meaning. After the initial Big Bang, the expanding universe began to cool, inducing phase changes."

Era of Atoms, the Dark Ages

13,699,620,000 BCE - 13,200,000,000 BCE

"The heat and light produced by the Big Bang has faded, so for many years atoms exist in dark space, colliding with one another and collecting together into ever larger combinations, which will provide the basis for the formation of stars, planets, and galaxies."

Galaxies Begin to Form

13,200,000,000 BCE

"Hypothesized to be the result of quantum fluctuations creating a gravitation pull, galaxies began to form when matter and gas clumped together. Scientists today are able to correlate the current distribution of the galaxies with the likely arrangement of the early universe."

Birth Of First Stars

12,900,000,000 BCE

"The birth of the first stars in the universe was a miraculous transformation, as molecular gas clouds with mostly hydrogen and helium atoms in the universe condensed by a factor of two million into extremely hot, dense stars. Powered by fusion, these stars not only fueled themselves but created a wide spectrum of elements through further fusion. By the time stars can no longer maintain themselves, they explode in supernovae, where a star explodes at hundreds of billions of degrees and creates all of the chemistry elements we know today. Stars represent a vital chemistry concept in big history, as all the elements owe their origins to stars, and without them there would be no chemistry."

Formation of our Solar System

4,600,000,000 BCE

"Our sun, earth, and entire solar system emerged from a proto-planetary disk surrounding a young star. The planets began to form through a process of condensation, accretion, differentiation, and fractionation of the matter in the proto-planetary disk."

Formation of the Earth

4,560,000,000 BCE

"Gravitational attraction pulls clumps of space debris together, and through the process of accretion of planetesimals the Earth formed."

Hadean Era

4,560,000,000 BCE - 3,800,000,000 BCE

"The period of time after Earth's formation until the development of the crust. During this time Earth was constantly bombarded by meteorites and the surface was essentially molten lava."

Formation of Earth

4,500,000,000 BCE

"The approximate age of the Earth, which is much older than the traditional age of 10,000 years as claimed in Genesis."

Formation of the Earth

4,500,000,000 BCE

"Our planet developed with a conversion of the kinetic energy from bombardments into heat. As Earth grew, its gravity compressed its core until it was molten and the layers of the Earth that we can observe today formed during the differentiation of the early liquid planet."

Early Atmosphere Formation on Earth

4,500,000,000 BCE - 4,000,000,000 BCE

"The early Earth (Hadean period) underwent a process of differentiation involving heavier metals sinking towards the core of the planet and gases such as hydrogen, helium, methane, water vapor, nitrogen, ammonia, and hydrogen sulfide rising towards the top. Before the Earth's gravitational pull was great enough to trap gases, no atmosphere existed. Once the Earth was large enough to maintain an atmosphere, much of the methane and hydrogen sulfide converted into carbon dioxide which (hypothetically) was the dominant component of the early atmosphere."

First Signs of Life

3,800,000,000 BCE

"Age of the first evidence of simple, single-celled fossilized life: archaebacteria. Life is speculated to have come to existence less than a billion years after the formation of the earth itself. The first life forms most likely thrived off of chemical energy and could survive in extreme conditions, and slowly evolved into more complex organisms over very long spans of time."

Life Emerges - Prokaryotes Form

3,800,000,000 BCE

"Prokaryotes are cells without a nucleus. Prokaryotes represent what are now recognized as the first living organisms by biologists today. They are significant because they represent the genesis of life as we know it, and all the life we see today evolved from prokaryotes."

First Life

3,800,000,000 BCE

"After the formation and stabilization of the Earth the first life quickly forms in the form of simple, single-celled organisms called prokaryotes, cells without nuclei. These organisms survived by extracting energy from inorganic chemicals. The organisms lived away from the surface because they required a stable environment, which the Earth's surface could not yet provide."

First Sign of Photosynthesis

3,500,000,000 BCE

"Cells that were nurtured via the process of photosynthesis (cyanobacteria) first came to being at the surface of the ocean around this time. These cells contributed to evolution in that their respiration processes created the ozone layer, shielding the surface environment from harmful UV rays, allowing for other organisms to survive in the atmosphere on Earth's surface."

Volcanic Infancy

3,200,000,000 BCE

"Volcanic activity that resembles activity currently observable today would have begun in this time period. With the creation of Earth's crust, internal pressures and tectonic activity would have resulted in the need for the out-gassing of elements."

Increase in the amount of Oxygen in Earth's atmosphere

3,000,000,000 BCE - 1,500,000,000 BCE

"Fossil stromatolites from 3 billion years ago and the process of photosynthesis that these organisms (cyanobacteria) undergo gives evidence that these organisms helped contribute to the formation of oxygen in the atmosphere. This slow build up of oxygen overtime would be essential for complexity in early life to evolve, enough so that the first eukaryotic organisms evolve approximately 1.5 billion years ago."

Earth's Ozone Layer is Formed

2,700,000,000 BCE

"The Earth's ozone layer formed and reduced the amount of UV radiation in the atmosphere, which enabled the evolution of life on Earth."

Great Oxygenation Event

2,400,000,000 BCE

"This event marks the availability of free oxygen in the Earth's atmosphere, due to photosynthesis of early organisms. Before this event, oxygen was already present in small amounts, but this event reflects the saturation of oxygen in the environment. This had produced an abundance of banded-iron formations, a rock made up of iron layers. Furthermore, the abundance of oxygen enabled the formation of the ozone layer."

Eukaryotes Form

1,700,000,000 BCE

"Eukaryotes are cells with membrane bound structures. Eukaryotes developed after prokaryotes, and all complex organisms on Earth are eukaryotes. The formation of eukaryotes is significant because it represents one of the first steps towards complexity for life on Earth."

Erosion of Grand Canyon

1700000000 BCE - 2011

"The roots of the grand canyon formed 1.7 billion years ago and have been eroding ever since. Erosion is a chemical process - rocks dissolve and break down the sides of a cliff. This is the same process that erodes limestone structures and shapes the earth geologically. The introduction of particulates into the atmosphere through pollution causes acid rain, which exaggerates these effects."

Cambrian Explosion

600,000,000 BCE - 530,000,000 BCE

"The Cambrian explosion is a time when, after the evolution of eukaryote, the "relatively sudden proliferation of larger, more complex, and more energetic life-forms" began from much simpler ones, which occurred around 530-600 million years ago. This sudden increase in morphological complexity lasted only 10-15 million years, which is lightning fast compared to both geological and evolutionary time scales. In this relatively short time span, every single major body plan that exists today was formed."

First Sign of Bilaterians

580,000,000 BCE

"Speculated time frame of when the first simple bilaterians came into existence. Bilaterians constitute most multi-cellular life forms; they have left-right symmetry, and a gut, anus, and mouth. The simplest, most ancient bilateral life forms represent a step in complexity between to more intricate animals in Evolutionary Biology."

Mammals Evolve

220,000,000 BCE - 2011

"Mammals are characterized by having fur, being warm blooded, giving birth to live young, and producing milk for their young. Mammalian evolution exploded filling Dinosaur's niches who died out in the Permian-Triassic extinction. This is significant because humans are mammals, and mammals have come to be the dominate class of terrestrial animals."

Ardi Specimen's Lifetime

4,400,000 BCE

"The Ardi specimen of Ardipithecus ramidus lived at this time. The Ardi specimen was earlier and more complete than the Lucy specimen of Australopithecus afarensis."

Lucy Specimen's Lifetime

3,200,000 BCE

"The Lucy specimen of Australopithecus afarensis is believed to have lived during this time. This was, for its time, the most complete early hominin discovered, until the discovery of the Ardi specimen."

Oldowan Stone Tools

2,600,010 BCE - 1,700,000 BCE

"Earliest known formal tools, used by human ancestors in Africa. Tool usage demonstrates the growing cognitive capabilities of the genus homo."

Homo erectus Lived

1,800,000 BCE - 1,300,000 BCE

"This hominid was the first to expand well beyond Africa, into Asia and Europe. It is also the first hominid believed to have used fire as a tool."

Emergence of Hunter-Gatherer Lifestyle

1,800,000 BCE

"For nearly the entire time that human societies (including Homo erectus) have existed on earth, they have survived as a hunter-gatherers."

Earliest Appearance of Modern Humans

200,000 BCE

"Suggested beginning date for the appearance of modern humans, with the capability for collective learning and, eventually, language. These modern humans appeared first in Africa and then migrated from the continent."

Earliest Evidence for Human Migration Out of Africa

97,990 BCE

"Skulls in the Middle East demonstrate the beginnings of human migration out of Africa, about 100,000 years before the present."

Homo floresiensis Lived

94,000 BCE - 12,000 BCE

"Homo floresiensis, sometimes referred to as the Hobbit, lived on the island of Java during this time. These are the last hominins besides human beings to exist."

Proposed Date for the Beginning of Human Language

50,000 BCE

"Estimated date for behavioral changes and collective learning in humans suggestive of human language."

Origins of Agriculture

10,000 BCE

"The domestication of plants was a very important event for the sedentary lifestyle that many modern human societies adopted."

Genesis Creation of Earth

10,000 BCE

"According to Genesis, this is the traditionally accepted date for when God created the Earth, the universe, and all life. However, this date is far too recent to be accurate, for carbon dating and the fossil record show otherwise."

End of the Last Ice Age

7,990 BCE

"By the end of the last ice age, humans occupied all habitable parts of Earth, with the exception of some Pacific islands, thus showing the success of their migration."

Writing Invented in Mesopotamia

4,000 BCE

"Estimated date for the invention of writing in ancient Sumer, allowing for a written record to be a part of historical and archaeological evidence."

Mesopotamian Scripts Capable of Writing Syllables (Cuneiform)

2,700 BCE

"Estimated date for the rise of syllabic writing, allowing for the cultural transmission of multiple languages, literature, abstractions, modal verbs (such as should, would, could, must, may) and negations (writing what should not happen), greatly increasing the development of language."

Egyptian Pyramids at Giza Built

2580 BCE - 2560 BCE

"The Egyptian Pyramids are a clear indication of human civilization, organization, and cooperation. They also are an example of hierarchy of labor and distinctive culture."

Recording of Genesis

1440 BCE

"Traditional date of when the Genesis Creationist theory emerged. Authorship is attributed to Moses, however, many also believe it was an oral legend written by many scribes throughout hundreds of years at around this time."

Geber (Jabir-Ibn-Hayyan)

721 - 815

"Considered the "Father of Chemistry" by many, Geber brought about innovations and tackled chemistry as a science by practical means through experimentation. Geber practiced alchemy and his findings aid us to this day in differentiating between metals and non-metals. His application of chemical principles to manufacturing brought about the process of steel making and rust prevention as well. The chemical apparatus and techniques used by Geber during his time are still relevant in our world today as they seem to be immensely effective in obtaining results, thereby showing how brilliant Geber's ideas were during his time."

Baghdad Academy

800 - 1200

"The Baghdad Academy, established around 800 AD, was the first true academy devoted to the study of the sciences and arts. The Baghdad Academy provided a solid foundation for the development of chemistry and transformed the way scientists for centuries to come approached the science and medicine. The academy established a clear distinction between science and religion. This enabled science to branch out and develop in many ways that would have previously been impossible."

"On the Revolution of Heavenly Spheres" Published

March 1543

"In this month, Nicholas Copernicus published his work, "On the Revolution of the Heavenly Spheres." This book was the first to model a heliocentric theory of the universe."

Kentmann's Ark


"In 1565, there is the first recorded publication of a an illustration of a collection of "fossil objects." Assembled by Johann Kentmann, it housed many unique objects, including minerals, elements, and fossils (called "stones in animals" and "various marine objects"). This collection led to the greater preservation of fossilized objects, a major point in the science of paleontology."

"Dialogue Concerning the Two Chief World Systems" Published


"This date marks when Galileo published his "Dialogue Concerning the Two Chief World Systems--Ptolemaic and Copernician," where he argued that the sun revolves around the Earth in plain Italian. This work aroused the wrath of the Pope of the time, leading to Galileo's subsequent trial and house arrest."

Nicholas Steno Explains Fossils Scientifically


"A shark's head was sent to Nicolas Steno in late 1666. After dissecting it, Steno realized that shark's teeth bore a resemblance to fossilized objects that were otherwise called "tongue stones." These objects were, before Steno, explained largely supernaturally- some thought they had fallen from the sky or the moon. Steno published his findings in 1667."

Nicholas Steno Develops the Concept of Stratigraphy

1667 - 1669

"In 1667 Steno writes Canis Carchariae, followed by Prodromus in 1669. He determined that the layers of the earth are strata of ancient, layered sediment deposits. This is the formation of basic stratigraphy, developing his principles of superposition, initial horizontality, and strata continuity."

The "Principia" Published


"In this year, Sir Isaac Newton published the first edition of "Principia," a book that laid out his laws of motion. The "Principia" also described the effects of gravity for the first time, providing an excellent view on the mechanics of our universe."


1800 - 1850

"Vitalism, the idea that life cannot be explained simply by science, has existed for thousands of years. The idea that a "vital force" is needed to create life is significant in that it helps us to understand how early people viewed the life question. Additionally, the theory itself shows that there still remains a great deal of information that we need in order to truly understand the difference between those things that are alive and those that are not."

Louis Pasteur

1822 - 1895

"Louis Pasteur, a French biologist, remains significant because of his broth experiment which finally disproved the idea of spontaneous generation, one that had been around for thousands of years. Pasteur's broths, sterilized soups made of organic materials to kill all life, remain without life even today. While this still does not answer the question of how exactly life began, it does rid scientists of a theory that was wrong."

Questions about Isomers Begins


"Liebig and Wohler, two German chemists, both became confused about how two chemicals, silver fulminate and silver cyanate, had the same molecular components but very different properties. Although these men could not fully solve the enigma of compounds being "the same and not the same," this began the inquiry into understanding isomers. It wasn't until the 20th century that scientists could fully understand how isomers worked."

Artificial Synthesis of Urea


"Friedrich Wohler's synthesis of the organic compound urea without aid from the kidneys of an animal partially disproved Vitalism (organic compounds could not be produced from inorganic ones because they lacked a "vital force" only present in living organisms). It additionally helped make the sub-discipline of organic chemistry possible, adding complexity to the field and opening new avenues of discovery in medicine and biology. The use of experimentation to systematically assess a theory's validity -- in other words, the scientific method -- was also novel, consequently replacing pure reason as science's core philosophy."

World's First Chemical Journal Founded


"The founding of the Annalen der Chemie by Justus Liebig and Friedrich Wohler greatly helped expand and legitimize the science of chemistry. The journal's instructive articles provided a text for teaching future chemists everywhere, helping standardize the field. An intellectual consensus in chemistry, in turn, aided discovery by constructing an authoritative knowledge base that chemists could consult and build upon in the course of their experiments. The journal also eased the process of uncovering scientific errors by becoming a kind of international forum for debate on new theories and findings."

Darwin Visits to the Galapagos Islands


"Charles Darwin's visit to the Galapagos Islands aboard the H.M.S. Beagle was very important to the development of his theories of evolution and natural selection. During Darwin's stay on the islands, he discovered a variety of finches that had slightly different beaks depending on what type of food was most readily available on each island. These observations helped Darwin develop the idea that animals evolved through natural selection."

The Invention of Plastic


"Plastic was first invented by scientist Alexander Parkes in 1855. Parkes's original attempt was to create synthetic ivory but instead, he accidentally give birth to the first artificial material - plastic. Parkes's invention was immediately adopted in industries and constantly improved by the scientist following his great discovery."

First Neanderthal Discovered


"Schaaffhausen discovers the first Neanderthal in Germany and partly due to his colleagues' prejudices against evolution, grossly misinterprets it."

Disproval of Spontaneous Generation


"Louis Pasteur performed an experiment that disproved the "spontaneous generation" of microscopic animals by boiling and storing broth in an open-necked container. The broth has remained sterile to this day, despite that it has been exposed to the supposed-religious "life force" found in the air, proving life only comes from life."

"On the Origin of Species" Published


"The book described his theory of natural selection, which is the process by which beneficial heritable traits make it more likely for an organism to survive and reproduce. This theory is crucial to the theory of evolution."

Charles Darwin publishes "On the Origin of Species"


"Scientific publication considered to be the first formal presentation of evolution by means of natural selection. The book was initially extremely controversial, especially for implying a shared ancestor between humans and apes. Darwin's presentation of evidence launched further study by other scientists, and later had social implications based on the natural selection idea of "survival of the fittest.""

"Experiments on Plant Hybridization" Published


"Gregor Mendel publishes his work on basic genetics. Breeding pea plants through selective and controlled cross-pollination, he was able to develop universal principles on how physical traits are passed down from parent to offspring. His laboratory discoveries support both Darwin's theories of evolution and natural selection with scientific evidence because he was able to artificially select which traits he desired through controlled breeding."

James Mark Baldwin Develops Theory of Baldwinian Evolution


"Baldwinian evolution posits that behavior can introduce new sexual selection pressures, thereby affecting evolution."

Age of the Earth - Radioactivity

1896 - 1903

"Building upon Henri Becquerel's discovery of radioactivity in 1896 and Curie/Lamborde's discovery that radioactive decay produces heat, John Joly proposed (correctly) in 1903 that radioactive elements generate heat inside of the earth. This discounted Kelvin's age of the planet (about 20 million years old), as it revealed that a heat source inside the earth would make the earth seem much younger than its actual age. Therefore, it was discovered that the earth was actually much older than previously supposed. This helped give credence to Darwin's theories, which assumed an earth much older than Kelvin's estimates."

Special Theory of Relativity Developed


"In this year Albert Einstein published his special theory of relativity. By claiming that the speed of light is constant, this theory eliminated the need for an invisible ether for light to travel on, which scientists had not been able to find. It also laid the groundwork for Einstein's theory of General Relativity."

General Theory of Relativity Developed


"In 1915, Albert Einstein published his general theory of relativity which, among other things, provided a foundation to model the universe. This gave astrophysicists and cosmologists the ability to model whether the universe was expanding, contracting or staying still."

Discovery of Australopithecus africanus


"Raymond Dart discovered a human ancestor in Africa, as predicted by Darwin's theory of evolution. This discovery was one of the first to give evidence that humans and apes had a common ancestor, and it began a wave of anthropological digs to Africa over the next several decades."

First Australopith Fossil found


"While in South Africa, Professor Raymond Dart and some of his students discovered a series of fossils that Dart asserted fell between apes and modern humans. He called this new species 'Australopithecus Africanus.' The fossils showed evidence of walking upright and had human-like teeth. This fossil is an important link to our understanding of human origins and evolution."

Scopes "Monkey" Trial


"Tennessee teacher John T. Scopes taught his students about Darwinian evolution, breaking the law as stated by the Butler Act, which prohibited such lessons in the public classroom. After a very famous and heated trial, involving famous attorneys Clarence Darrow as the defense and William Jennings Bryan as the prosecutor, Scopes was found guilty. However, many people view the trial as a victory of science, rationale, and evolution over traditional theology."

Radiocarbon Dating Invented


"Willard Libby invents a method of radiocarbon dating at The University of Chicago in 1949."

Urey and Miller Experiment


"Harold Urey and Stanley Miller conducted a simple laboratory experiment by simulating the atmosphere of the early Earth to discover whether or not life could have been created through natural chemical reactions. After blasting glass tubes filled with water, ammonia, methane, and hydrogen with lightning-like sparks, 22 amino acids (the building blocks of proteins) were found in the resultant sludge. Though life itself was not created, basic components of it were."

Miller-Urey Experiment


"The Miller-Urey Experiment was performed by passing free energy through what was believed to be a recreation of Hadean earth. Despite its flaws, the experiment proved extremely significant to the progress of chemistry because it showed scientists that the creation of the building blocks of life on early earth to be fairly simple. This discovery ultimately became important to understanding the possible preconditions of life."

Theory of Plate Tectonics Accepted by Scientific Community

1955 - 1969

"Plate Tectonics explains the shifting of the lithosphere, which causes seafloor spreading and explains how continents can have moved."

Thalidomide Controversy

1957 - 1962

"Thalidomide was a drug created to treat nausea in pregnant women. The process of manufacturing the medicine created two different isomers; one treated nausea and the other was thought to be an inert by-product. It turns out that the "inert" product actually caused severe birth defects. This showed the world how sensitive the body was to specific isomers of chemicals."

The Concept of Nanotechnology is Introduced


"The concept of "nano-technology" was first introduced by physicist Richard Feynman at the American Physical Society meeting on December 1, 1959. This advant-garde lecture named "There is Plenty of Room at the Bottom" explored the idea that the properties of materials at the microscopic level act differently and has its potential in developing new materials. Scientists later on then build on Feynman's idea and make exponential progress on the advancement of nanotechnology as the modern technology allows scientists to scrutinize materials in microscopic level."

Modern Materials Science becomes a Discipline

1961 - 1969

"Even though the study of materials such as metals has existed since the beginnings of human civilization, it is not until the 1960s that the word "Materials Science" becomes the term for the study of materials on atomic and molecular levels."

Discovery of the Cosmic Microwave Background Radiation


"In this year, Arnold Penzias and Robert Wilson discovered the cosmic microwave background radiation of the universe. This radiation of about 2.7 degrees kelvin provided proof in favor of the big bang theory of the universe against the steady state theory."

Repeal of Butler Act


"Evolution could lawfully be taught in schools in Tennessee through the repeal of the Butler Act. Evolution is currently widely accepted as the factual origin of modern species today, but this date shows how recently theories of creationism were still mainstream belief."

Lucy Fossil Discovered


"Lucy, an australopithecus afarensis fossil, was discovered. It was the most complete human ancestor fossil that had ever been discovered at the time."

Discovery of Hox Genes


"The discovery of the hox gene (known as the homeobox or homeotic gene) was important evidence for evolution. Hox genes control the the location and development of the different parts of the body. They are also shared among all animals. For example, if the hox gene for a fruit fly eye was switched with the hox gene for a mouse eye, each animal would still develop their proper eye. This is strong evidence for Darwin's theory that all living organisms share a common ancestor."

Ardi Specimen Discovered


"The Ardi specimen was discovered in Aramis region of Ethiopia"

Discovery of an Accelerating Universe


"The discovery that the universe is accelerating was proved by two competing research groups in 1998. This data displays our lack of understanding of the universe, as now theory predicts only 4% of the universe's contents to be human matter."

"Sue" Exhibition Opens at the Field Museum in Chicago


"Sue was unveiled in May of 2000, ten years after her discovery. She is the largest, most complex, and best-preserved Tyrannosaurus Rex ever discovered and constructed. She is forty feet long and twelve feet tall. Her reconstruction is important to the study of evolutionary biology and paleontology because she shows the power of fossils in allowing us to visualize the past."

Discovery of Sahelanthropus tchadensis


"Finding of a fossil that, according to discoverer Michel Brunet, may be the oldest human ancestor on record (7 million years old, about the time estimated that humans and apes diverged evolutionarily)."

Discovery of Earliest Bilaterians


"Researchers uncover remains of organisms exhibiting bilateral symmetry in the Doushanto Formation of China. The soft tissue of the fossils were preserved in lagerstatten, and were found to be between 580-600 million years old- almost 50 million years older than previously supposed. This earlier date for the emergence of bilaterians indicated that internal complexity of organisms evolved before an increase in size."

Discovery of First Embryonic Fossils


"A group of 15 scientists discover the first Embryonic fossils from 550 MYA. In doing so, they observed (through x-ray imaging) evidence of cell differentiation in said fossils. This discovery is very significant because it marks the first time scientists were able to use concrete evidence to support the hypothesis that internal complexity came first before a larger body size and possibly explain the processes and changes that occured during the Cambrian Explosion."