In a certain sense, science may be viewed as a religion:
1. Science has its venerated saints, Charles Darwin and Stephen Hawking for example.
2. Science holds certain truths as being sacred: All life on Earth shares a common ancestor known as the last universal common ancestor.
3. Science has developed what amounts to a sacred narrative: it may be called “The Evolutionary History of Life on Earth”. This “writing” or writings, is said to be true by its followers.
4. Science’s sacred narrative explains the origin of life and the Universe.
5. The truthfulness of scientific writings is supported by testable explanations and predictions about its subject matter. However, when it comes to the science of evolution, as in other religions, science has to fall back on faith in order to uphold it truths.
Most of my professional life I have worked as a geologist, mainly in industry. Although I have authored and co-authored scientific papers, I am by no means an academic. However I do have a good grounding in the fundamentals of the science, an insatiable curiosity about our origins and how geology can be reconciled with religion, and specifically Torah Judaism.
This essay in many ways is a simplistic excursion through 3.25 billion years of Earth’s history from the first recorded appearance of a life form to first appearance a real animal. Along the way the scientific community (including evolutionary biologists, paleontologists and geologists) have had to use what amounts to leaps of faith in order to connect the dots in unraveling this difficult puzzle.
The Earth is believed to have formed 4.5 billion years ago (Ga). There is good evidence for life beginning at least 3.8 billion years (Ga) ago. The scientific community does not know how life began. That is, they do not know how on the planet Earth we went from chemistry to biology. But indeed life did begin, and here we are today.
Let’s back up a bit, actually more than a bit. The universe originated about 14.5 billion years ago, 10 billion years earlier than the formation of the Earth, in what is called the”Big Bang”. Simplistically the Big Bang is when Energy somehow happened to become Matter, basically nothing became something…and this coincidentally tracks with the Book of Brereishis.
The earliest life forms were microbes or bacteria. The atmosphere was different back then. There was next to no oxygen. The early atmosphere contained hydrogen sulfide and methane (CH4) and huge amounts of carbon dioxide. The earliest life forms did not need oxygen as a source of energy. They used hydrogen or hydrogen sulfide or methane as a source of energy to convert carbon dioxide or methane and nutrients into organic matter
Although scientists do not how it happened, another form of life called cyanobacteria appeared as early as 2.7 billion years ago. Cyanobacteria differed from their cousins that used hydrogen or hydrogen sulfide or methane as a source of energy .Cyanobacteria utilized energy from the Sun, sunlight in a process called photosynthesis.
Cyanobacteria are believed to be the first microbes to produce oxygen by photosynthesis. And so they did. Incidentally, oxygen is a waste product of photosynthesis. As the population of cyanobacteria increased so did the amount of oxygen they produced by photosynthesis. By 2.7 billion years, the amount of oxygen in the atmosphere rose to as much as 0.01%. That ain’t much, but you have to start somewhere.
But what may sound good for us oxygen breathers, 2.7 billion years ago it was a disaster for life forms that utilized methane and the like for an energy source. Oxygen was toxic for these creatures. For them it was an Oxygen Holocaust, an Oxygen Catastrophe, an Oxygen Naqba. And even at this extreme low oxygen level, Cyanobacteria became responsible for one of the most significant extinction events in Earth's history.
Oxygen levels continued to rise, exceeding 0.02%. Oxygen began escaping into the atmosphere. Oxygen in the atmosphere combined with methane, producing carbon dioxide and water. Carbon dioxide is a powerful greenhouse gas. It prevents sunlight from reaching the Earth. Added to the fact that the Sun was much weaker then what it is today, the Earth began to cool.
By 2.4 Ga the Earth was covered by glacial ice. Ice extended from the poles to the Equator. The temperature at the Equator was minus 20 degrees Centigrade. This is the temperature today at the poles. This event is referred to as Snowball Earth. The ice age lasted until 2.1 Ga, one of the longest ice age in Earth’s history. Somewhere between 2.1 Ga and 1.9 Ga a new and more complex life form emerged, not that you should regard cyanobacteria as simple, not in the least.
Cyanobacteria belong to that group of life forms called prokaryotes. Cyanobacteria and all of its prokaryotes relatives are single cell creations, and like all organisms are made up of cells. They have a cell wall, but inside the cell there is a mish-mash of substances that are responsible for carrying on the life processes need for the cell to live. Instead of a nucleus, the prokaryote cell has what is called a nucleoid, almost a nucleus, but not quite.
The new and more complex life forms that emerged after the Snowball Earth Ice Age are called eukaryotes. These single cell life forms are the ancestor of every living organism today. Structurally, they are more organized than their prokaryote precursors, no more mish-mash of substances that are responsible for carrying out life processes and they definitely contain a nucleus. Eukaryotes probably had prokaryotes for breakfast. Early eukaryotes that we are familiar with are red algae, amoebas and yeast and mold. Although mostly single cell organisms, some live in colonies and others developed long streaming filaments as seen in some sea weeds. Step back a little and think about the statement “the ancestor of every living organism today”. Maybe it is my human ego, but I have difficulty in acknowledging human ascent from a life form that from time to time has to be scraped off the inside glass of an aquarium.
For the next billion years or so, things are relatively quiet on the planet Earth. As best as we can tell from the fossil record there were no catastrophes or upheavals. It was a period of stasis, for what reason I do not know. This period of time is often referred to as the “boring billion”.
Emerging evidence suggests that the Earth underwent three major global ice ages during the period from about 780 Ma (million years) to about 635 Ma.
The most severe of these worldwide glaciation events lasted from approximately 650 to 635 million years ago. During this time the Earth suffered the most severe ice ages in its history. Glaciers extended and contracted in a series of rhythmic pulses, possibly reaching as far as the equator. It was another case of Snowball Earth.
When the glacial ice receded, a new life form emerged, the Ediacaran. This period of Ediacaran life spans 94 million years from about 635 million years ago to the beginning of what is called the Cambrian Period 541 Mya. The fossil record of Ediacaran is sparse; hard-shelled animals had yet to evolve. Ediacaran biota include the oldest definite multi-cellular organisms. the most common types of which resemble segmented worms, fronds, disks. Ediacaran biota bear little resemblance to modern lifeforms, and their relationship is rather difficult to interpret. I am thinking that Ediacaran biota represent a failed experiment. In southern China there is a rock formation call the Doushantuo (Stratigraphic range: 635–551 Mya). In one of its rocks layers, in addition to Ediacaran biota, sponges have been found. Sponges are multi-cellular. This then is the first evidence of a real animal on our planet. As a human being, the connection between me and a sponge is a bit more than tenuous. But for those folks who are said to have a mind like a sponge, maybe it is easier to take.
From that time on (that is, the Cambrian at 541 Mya), life forms on Earth’s were marked by a history of catastrophes that result in worldwide mass extinctions. Then when the extinctions cease, the life forms enter a period of utopia. By utopia, I mean that the community of life forms or the biotic society comes to possess traits that are highly desirable or nearly perfect for its inhabitants to prosper and spread out, to fill the Earth so to speak. The causes responsible for these mass extinctions are several and I would need another essay to describe them.
Thus far and the point of this essay is that in order to reach this juncture the scientist has had to make several leaps of faith. Among these are the leaps of faith that necessary to address the following questions:
1. What existed prior to the big bang?
2. What prompted the Big Ban to initiate?
3. What is the probability that the Earth possessed the conditions necessary for the creation of life?
4. How do we go from chemistry to biology in the process of creating life?
5. Why were the first life forms prokaryotes?
6. How do you go from being a prokaryote to being a eukaryote?
7. Are the Ediacaran life forms a failed experiment?
8. Am I an advanced sponge life form?
Leaps of faith are required because in order to ascertain the “truth”, Science either does not flat outright know or does not have testable explanations and predictions about the subject matter. Science has to fall back on faith in order to uphold it truths. No big deal, if I can do it, so can they.