The most recent and most precise study aimed at calculating the total number of all species living on Earth estimates there are about 8.7 million species.
It’s estimated that only 1.2 million species are currently described and cataloged by taxonomists. This means that around 86.2% of marine and terrestrial species have yet to be identified.
In the Amazon rainforest alone, a discovery of animal and plant species is made every other day. In fact, life on Earth is so diverse that scientists identify between 15,000-20,000 new animal and plant species every year.
Even with all the cutting-edge tech like AI and drones now available to scientists in their classification of new species, we may perhaps never know the exact number of all species dwelling on Earth. In fact, many could go extinct before we even catch glimpses of them.
But, there’s another longstanding and intriguing question, which we have yet to find a definitive answer.
When did Earth see the beginning of life?
When did Life’s “Big Bang” Begin?
In the geological time scale, humans appeared very recently.
Homo sapiens are thought to have appeared some 200,000 years ago. Recently, however, new scientific evidence suggested that humans maybe 115,000 years older. This puts the number for the beginning of life for humans at around 315,000 years ago.
However, in the grand scheme of things, that doesn’t change much. If Earth’s existence were to be viewed as a single day, humans would have only appeared in the last 5 minutes.
So much happened on Earth before we came to call it home.
As far as we know, humans are the only sentient beings who can ponder the question of the beginning of life.
Read More: Everything You Need to Know About the Theory of Everything
We’re eager to know whether humanity is the only technologically-advanced civilization in the universe. But, as a life form, we live on a planet that’s abuzz with living beings, even in its most extreme environments.
Over its 4.5 billion years of existence, Earth has hosted an extraordinary variety of living beings. Millions of animal and plant species have appeared and lived before disappearing to give way to other living species to reign.
However, it wasn’t always sunshine and rainbows. During the early stages of Earth’s formation, also known as the Hadean period, Earth’s hellish environment wasn’t conducive to life.
Eventually, the Earth’s primordial soup cooled and gathered the elements and conditions necessary to spark the beginning of life on Earth.
In a similar way to how the Big Bang started the cosmos, early Earth was lifeless. Then, in a short amount of time (geologically speaking), something kick-started life’s dazzling explosion that we, humans, are part of, and now asking about it.
Liquid water and life are thought to have appeared during the Hadean time. This, technically, is not a geological era per se, as rocks were still forming on our planet.
The age of the Earth has been a bone of contention for millennia. In recent times, the theory for the birthdate of the universe we continuously being pushed back as discoveries and technological tools came along the way.
From 540 million years in the 1950s, now the old range of life on Earth is between 3.8 and 3.95 billion years. Then again, it could have all been created last Thursday.
Recent discoveries seem to substantiate these estimates. Scientists at UCLA and the University of Wisconsin–Madison recently confirmed that the microfossils they unearthed in Australia represent the earliest direct evidence of life on Earth.
Found in a 3.5 billion-year-old rock, the fossilized microbial filaments are biological and suggest that life could probably have started even earlier than previously thought.
How did it all Begin? The Secret to the Beginning of Life
If bacterial and microbial lifeforms seem to be the oldest inhabitants of Earth, their origin is perhaps a bigger puzzle.
Many theories have been purported to try to explain the origin of these early unicellular organisms from which more complex life forms have developed.
Now, let’s get down to brass tacks. Here’s a rundown of the most prominent theories of the origin of life, from a historical, philosophical, religious, and scientific perspective
Spontaneous Generation: The Beginning of Life is but a Happy Accident
Aristotle was one of the earliest proponents of the theory of spontaneous generation. He propounded that life can spontaneously arise out of inanimate matter if it contains “vital heat.”
Under the spontaneous generation theory, there are two hypotheses:
Abiogenesis, which is the spontaneous production of biological life from non-living inorganic matter.
Heterogenesis, on the other hand, is the derivation of lifeforms from different living or dead lifeforms, such as flies from dung or rotten meat.
The spontaneous generation body of the thought is now considered to be obsolete by the scientific community.
The Clay Lattice: Religion and Science Reconciled?
The sacred texts of the three monotheistic religions all evoke the vital role of clay in the process of creation. There are also mentions of clay in religious transcripts of ancient civilizations.
What if religions were true and clay provided a template for organic life to form?
After proposing it in 1966, Scottish chemist Graham Cairns-Smith published in 1985 a hypothesis promoting the role of clay crystals in the development of prebiotic organic molecules.
Smith has spent his career trying to prove that mineral crystals, and not organic structures, are the first source of life.
In a more recent scientific effort (2013), biological engineers at Cornell University report that clay might indeed have been the cradle of organic life.
Using a simulation of ancient water, Cornell researchers found that clay formed a hydrogel that provided a confinement structure for chemical processes to take place until living cells developed their membranes.
Some believe in an “Intelligent Design,” which is backed by multiple religions, all of who deny evolution and believe that God created every living being as is, including humans, and sent them to Earth.
However, science has yet to find evidence that supports such beliefs. At the moment, to believe it, you have to believe in it.
Panspermia, Cosmic Dust: Life is Originally Extraterrestrial
First formulated in the 1970s, panspermia is a theory suggesting that life didn’t begin on Earth and that the earliest living microorganisms came from space. Usually, these theories postulate that asteroids and comets bombarding early Earth carried these organisms.
Some think that it’s on Mars, which comes first in humanity’s roadmap to space colonization, that life on Earth has originated from.
The hypothesis that life isn’t indigenous to Earth and has extraterrestrial origins gained some new traction, with hot streams of cosmic dust proposed as carriers of life’s building blocks.
However, this idea does have its detractors. Some argue that these early living organisms, or seeds of life, hanging on the side of rocks could not survive the harsh trip in interstellar space.
Yet, morning glory seeds have been shown to survive extreme levels of ultraviolet radiation found in outer space. Though that’s by no means direct evidence of life’s extraterrestrial origin, it does give the idea some grounding.
Read More: Who Will Have the First Successful Manned Mission to Mars?
Warm Ponds: The Beginning of Life in a Big Splash
Some scientists think that RNA molecules should be considered as the earliest life forms, mainly due to their self-replicating ability.
A new study provides further support to the theory that meteorites splashing in hot ponds could have delivered RNA molecules here on Earth, the essential ingredients for the beginning of life.
RNA molecules probably arose earlier than 4.17 billion years ago, says the study (published in PNAS), conducted by researchers at McMaster University (Canada) and the Max Planck Institute for Astronomy (Germany).
Was Charles Darwin right? In 1871, Darwin sent a letter to J. D. Hooker, a botanist and a close friend of his, where he claimed that life could have originated from chemical reactions “in some warm little pond.”
A chemical recipe for life has been the subject of research with different approaches from scientists in their effort to formulate it.
In another recent study, chemists at the Scripps Research Institute focused on the chemical reactions within the citric acid cycle (CAC).
Scripps researchers found that the elements necessary for CAC reactions could have been available on early Earth as far back as four billion years ago.
The team also found that the unavailability of some essential ingredients doesn’t prevent the life cycle from taking place. They also identified two non-biological periods that could have enabled the chemical reactions of the first citric acid cycle.
I am rather surprised at the glaring omission in this of what is now by far the best contender for the cradle of “life”, the transition to biology from simpler chemistries.
This transition is usually called abiogenesis. Some of the earlier models of abiogenesis were plagued by extreme improbabilities. None of the DNA first, RNA first, protein first or cell membrane first models that are, even now, still bandied about are truly compatible with established laws of chemistry and physics. Robert Shapiro’s important book “Origins, a Skeptic’s Guide to the Creation of Life on Earth” way back in 1987 gave an exhaustive and definitive explanation of why this is the case. It is a “must read”for anyone interested in the subject. Please do so!
However, in these exciting times it is becoming more widely recognized that the early notion that the first identifiable instances of biology were naked self replicating molecules (strands of DNA, RNA or protein) or “empty” lipid bubbles, is deeply flawed. It is unevidenced and, furthermore, cannot even be given a sound heuristic basis. It is one of those myths which has insidiously crept into scientific circles without serious challenge. Along with the equally impractical notions involving panspermia. Not to mention the feeble minded cop-out that “God did it”
Today, a far more plausible model that is consistent with known principles of physics and chemistry derives from the investigation in recent decades of the deep-sea alkaline hydrothermal vents.
These at last give a basis for a model which provides for the co-evolution of enzymes, nucleotides and, most importantly, that oft overlooked but absolutely crucial component, a cell membrane equipped with means of selective influx of nutrients and efflux of wastes.
The plumes generated by the vents provide vast matrices of catalytic cell-sized cavities, complete with suitable chemical precursors, flow, and favorable energetics that at last bring the probabilities within reasonable bounds.This scenario is explored at length in chapter 9 of my recent book “The Intricacy Generator: Pushing Chemistry and Geometry Uphill”.
Only God could create DNA, the most complex information system in the universe, life as a metabolically stable, reproducibly viable entity, human consciousness and inbred with a moral law.
Hydrothermal vents are an intellectually insulting desperate naturalistic speculation. There is not naturalistic way to manage elemental colocation, coincidence, contamination mitigation, concentration and convergence in the precise exacting manner required for organism assembly. This is not to mention the homochirality of pentose sugars and all required amino acids or the assembly of RNA and ribosomes..
There is no model for co-evolution of enzymes because modified ones are destroyed by the cell. The properly functioning cell membrane is impossible for naturalistic processes.
Chemical evolution is a myth like Darwin’s “warm little ponds” and Oparin-Haldane prebiotic soup. Hydrothermal vents are susceptible to unregulated energy input, ph variations, pressure and salt contamination making them unsuitable for any serious consideration for OoL.
Is it possible that the first self – replicator was electromagnetic in nature and was programmed by the versatile, random terrain of Earth’s crust because of the geomagnetic polarity of the crust; was laid along the crust’s surface like train tracks; or something?
Or, that there is some complex process we haven’t yet thought of like of like the newest doughnut shaped earth theory on the origin of the moon?
Interesting conjecture, but the fundamental problem is the mitigation of contamination, the concentrations, and the colocation and coincidence of the critical elements. Electromagnetic energy as an energy source is not regulated or exclusively applicable to the essential elements necessary for the origin of life.
There are no naturalistic processes capable of abiotic, inorganic, or biochemical assembly more complex than the amino acids, sugars, methane or formaldehyde that has been found, donuts included.
Thanks for the summary reprise of futile naturalistic speculation on the origin of life. None of them have any scientific viability and are really intellectually insulting.
Thank you for your thoughtful insight. Your insight is really an intellectually insulting… God bless you…
No “thoughtful insight,” just facts. Not sure what you consider intellectually insulting.
While all of the hypotheses and theories reported on have an historical basis, and while it is the nature of science to investigate the wide diversity of even the most remote possibilities of physical reality, once they are exposed as unworkable, they should die an infamous death, not perpetuate into ideology mythology.
Without time or room to expose all of the naturalistically nonsensical conjectures covered, please pick one of the wild speculations and I will give you the facts, not the naturalistic ideology: which one? Panspermia, RNA World, Darwin’s “warm little ponds.” Clay lattice and spontaneous generation are hardly worth the effort.
Thank you for the blessing, God has blessed me all my life, the same to you.
You are definitely welcome… regarding to facts; few particular samples/examples/theories/mechanisms make no mach sense to discuss here besides (may be) a very general point: probability for life to happen by chance is not a total zero therefore it is doomed to exist
with 100% certainty. All the most probable lifeless arrangements may not yield the observer so it is irrelevant how infinitely more probable lifeless arrangements are, observer is doomed to witness only life-accommodating arrangements… my existence is self-evident proof of that (as you may see no assumptions or/and restrictions are needed at all). Sure you are free to complicate the picture by introduction of creator and in fact it definitely could be the case but apparently it just postpones/moves-away the question of origin unless God is not capable to formulate the predicate about its own existence ;o)
“Introduction of a creator” in no way complicates the picture. God is the simplest explanation and only valid one to explain what naturalism can never explain. Life does not come from non-life, God is life and responsible for its creation, parsimonious, rational, explanatory truth. God is not of this universe and not subject to the creation limitations of everything in the universe. If this is an issue, you seriously need to reassess your assumptions.
Apparently I was not talking about “this” universe, my point is more general, “arrangements” include the “low of physics” of “this” universe as well as infinite number of all others actualization… Also, you’ve missed the most funny predicate part ;o)
Sorry, I am struggling to discern the expressed meaning of your comments. With respect, God does not require and is not an “assumption.” He is the reality from which everything else follows.