One of the deepest and most profound questions ever to be asked: How did we get here? By "we", I mean us humans. Science has a very detailed explanation of our history through evolution but mystery still surrounds that moment where we made that transition from non-living to living. In this article, we are going to focus on actual ideas that some people believe are plausible explanations for the origin of life.
One of the biggest questions out there is: Are we alone? There are hundreds of billions of galaxies with each containing hundreds of billions of stars with each star possibly containing dozens of planets and moons…surely, there must be life somewhere out there other than on earth, right? Most people would agree that, statistically, the universe should be swarming with life, yet we have never encountered any real forms of life out there.
There are a few solutions to this problem. Either we just aren't looking far or hard enough, or…we are actually alone. Now, let's assume the second one is true for a second. This means that, out of the bilious and billions of planets out there, earth is the only one that gave rise to life. This in turn would imply that the origin of life, whatever it was, was SO improbable and rare (like, we're talking infinitesimally small chances), that we will NEVER figure out how it started. Some people propose that we will never find out the answer simply because the event was so stupefyingly rare that it is something no would could possibly think of or gather evidence for.
The Theory: Basically, it says that, if we truly are alone in the universe, then we are wasting our time trying to find out what triggered the origin of life because there was 0.00000……(keep going)…..0001% chance of it occurring.
Whatever happened, we know that it must have been some kind of incredible and rare event. Remember though: whether life started here on earth or elsewhere in the universe, it only had to happen once - after that, it's not too difficult to see the evolution up to humans. The universe is a really big place and 13.7 billion years old. These ideas may sound improbable, but a lot of shit can go down when you're given that much time and space.
5. Let There Be Light...ning!
The study of the human body has revealed that one common difference between nonliving things like rocks and living things like humans is (surprisingly) electricity! All brain activity is a series of complex interactions between neurons and electricity. When you move your body or make a conscious decision (things that only living things can do), electrical impulses are racing through your body. It's the same deal with the heart - the reason it pumps is because of periodic electric shocks.
So scientists decided to take this one step further - what if the origin of life has something to do with electricity. The details get a bit complex, but the basic building blocks to life are proteins called amino acids. All you need to get evolution going is a self replicating molecule (something that can divide and give rise to other molecules - eventually developing into cells that also continue to divide). Early in the earth's history, there were definitely many chemicals around that make up amino acids - the only problem is how did these chemicals come together to form amino acids.
This is where the Miller-Urey experiment comes in. In 1953, these guys showed that electric sparks had the energy to excite things like methane and hydrogen so that they could come together to make up amino acids. They simulated the early conditions of the earth and actually produced many organic compounds.
The Theory: All of these basic chemicals may have bee swimming around in some pond when - BAM - a bolt of lightning strikes (maybe several bolts) that give rise to amino acids. The rest would be history from then on. Note: All this theory does is suggest that it is possible that lightning could have given rise to life - it makes no other claims.
Doubts: This theory basically proposes an idea of spontaneous life - a bolt of lightning and BAM - you have life. The question that many people ask is then - why doesn't this continue to happen today? Today, there is an abundance of oxygen around us and it has been shown that oxygen actually does not allow the formation of spontaneous organic compounds…meaning this idea would not work today. It does however, work in the early earth which was actually very volatile and oxygen-poor.
4. Aliens...
Okay, maybe not aliens in the traditional sense - the idea is actually called Exobiogenisis. Some estimates indicate that life could have arisen up to around 9 billion years ago somewhere in the universe - that age is much older than the age of the earth. This has led people to hypothesize that microbial life may have landed on earth from outer space via some sort of meteorite or other rock. If true, this microbial life would be the only living thing on its environment for the first time in its life - meaning its evolution would be accelerated due to little competition for resources (imagine having the entire earth to yourself).
The Theory: Summed up, what it says is that a single cell or bacterium may have come from outer space riding on the back of a meteorite. Although this still wouldn't explain the origin of life itself, it does propose a solution for where life on earth came from.
3. Organic Molecules From Outer Space
This one is slightly different from the alien microbe theory - and more plausible as well. The alien microbe theory avoids the question of how any microbe got started, but this one gets to the point.
Okay, so organic compounds are basically any compounds with carbon. Carbon is the building block of life for humans. It also happens to be the 4th most abundant element in the universe, meaning there are a lot of organic compounds floating around in space and in the atmospheres of planets.
Getting these guys to earth (a hospitable environment compared to outer space) would have given them 1) a place to rest for a little and join forces later on (to create complex molecules) and 2) increased chances of actually meeting each other (since they'd all be in the same place).
A NASA study on a meteorite in 2011 indicated to some scientists that some of the basic blocks of DNA (like adenine and guanine) could have been created in outer space (and some would say they must have been formed in outer space). Also, in 2000, Glycolaldehyde, the first interstellar sugar molecule, was found at the centre of our galaxy. The important thing here is that Glycoldaldehyde is an important ingredient in RNA…which is ver closely related to DNA…hmmm…
The list goes on. Glycine, a fundamental part of certain amino acids, was found on a comet, other types of sugars that are important in metabolism and in genetic coding have been found in other star systems. All of this suggests that the fundamental chemicals and building blocks for life are…kind of everywhere. They would have (slowly over time) come to the earth, where they would have and the chance to come together and evolve.
The Theory: Basically, what the evidence behind this theory does is suggest that the building blocks for life probably came from other space. It sure does make it a lot easier for life to arise on earth when most of the lego pieces are provided for you and you don't have to make them from scratch. In this case, the universe, with its billions of stars, would have slowly made these blocks fro earth.
2. Snowball Earth
One common problem with a lot of origin of life theories is that the ideas they propose just seem so improbable. Take the theory about organic compounds coming together over time to form amino acids. Sure, that would make sense, but how would they ever possibly come together? What are the odds?!
The snowball earth possibly answers these criticisms. By observing the life cycles of stars, scientists have proposed that the sun (in its younger years) was much dimmer than it is today. Even a slight dimming effect would impact earth's climate and around 3 billion years ago, when life first started, it is estimated that the earth would have been so cold, that it basically would have been covered mostly in ice. The oceans would have been frozen solid with a top layer of ice measuring hundreds of feet!
So how does this help? Well, the fragile organic compounds that would have eventually given rise to amino acids would have been protected from sunlight, radiation, and other environmental threats under this ice. The compounds would have been basically preserved, allowing them time and opportunity to actually snuggle up with each other. Moreover, molecules do not break as easily in cold climates (this is why things turn liquid when you heat them). The cold temperatures under the ice would have also encouraged strong bonds between molecules.
Adding credence to this idea is the discovery that primitive life (and organic compounds) can actually survive under sheets of ice. In 1999 and again in 2012, it was found that Lake Vostok, a body of water buried under a 4000 meter deep sheet of ice contains microbes, fungi and other primitive bacteria.
1. The Anti-Theory - Maybe There Is No Answer!
There are a few solutions to this problem. Either we just aren't looking far or hard enough, or…we are actually alone. Now, let's assume the second one is true for a second. This means that, out of the bilious and billions of planets out there, earth is the only one that gave rise to life. This in turn would imply that the origin of life, whatever it was, was SO improbable and rare (like, we're talking infinitesimally small chances), that we will NEVER figure out how it started. Some people propose that we will never find out the answer simply because the event was so stupefyingly rare that it is something no would could possibly think of or gather evidence for.
The Theory: Basically, it says that, if we truly are alone in the universe, then we are wasting our time trying to find out what triggered the origin of life because there was 0.00000……(keep going)…..0001% chance of it occurring.
Whatever happened, we know that it must have been some kind of incredible and rare event. Remember though: whether life started here on earth or elsewhere in the universe, it only had to happen once - after that, it's not too difficult to see the evolution up to humans. The universe is a really big place and 13.7 billion years old. These ideas may sound improbable, but a lot of shit can go down when you're given that much time and space.
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