The evolution of humankind is by now fairly well known to us. Science has worked wonders
in recent years and decades, to piece together exactly how it was that we came to be. And yet,
there are still some blank spots that remain at the very beginning of the timeline;
in the earliest instances of life on Earth. Now,
though, any remaining queries might also, finally, have been solved.
This is Unveiled, and today we’re answering the extraordinary question;
did scientists just discover the true origin of life?
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Broadly, the appearance of life on Earth is known as abiogenesis. This is the seemingly
sudden emergence of something out of nothing. Of living things out of non-living matter.
It’s the arrival of the most basic, cellular organisms, at the very beginning of the chain of
life on our planet. Up to a point, it’s wholly accepted, too, with most timelines eventually
winding all the way back to the very first cells sprouting in (or close to) hydrothermal vents,
more than four billion years ago. These vents are cracks and punctures in the deep seafloor,
ejecting out water that’s heated from the Earth within… and scientists believe
that it’s here where the first breeding grounds for life may have been established.
However, as compelling as all of that is, there is still a certain degree of
the unknown if we head even further back. The vents are often put forward as prime
locations for early evolution because they will have provided what are commonly
referred to as the building blocks for life. But what does that actually mean?
To some degree, you might call the basic elements that make us the “building blocks” of us,
such as hydrogen, carbon, nitrogen and oxygen. More typically, however, we’re referring to a
more complex stage, and to proteins… which are the key ingredients inside our bodies for a range
of crucial tasks, all of which might reasonably fall under the umbrella term of biological upkeep.
Proteins are what maintain our cellular structure; they can issue repairs when things go wrong;
they drive vital bodily functions, like muscle contraction and digestion. Some proteins double
up as messengers, or hormones, to further regulate our bodies. Others are charged with
fighting infection, to ensure you stay healthy. Ultimately, life is teeming with these incredible,
complex molecules, with all the endless different types of protein providing something that’s
fundamentally important to how we work. Take them away, and we simply wouldn’t be here.
We can go one rung deeper than proteins, however, in the search for life’s first building blocks,
to amino acids. All proteins are made of amino acids, which are simpler, organic compounds. As
such, it’s held that life cannot emerge unless amino acids are present at the very beginning.
Present and ready to form proteins; which then can combine into and power cells; which can then
continually join together into increasingly sophisticated multicellular organisms.
For some years now, and despite many abiogenesis lines leading to those hot vents at the bottom
of the ocean, we’ve also known that crucial amino acids can be found in space. In general,
this is perhaps to be expected. The very first basic elements form in
stars - hydrogen and helium - before fusing into other elements, like (again) carbon, nitrogen,
et cetera. We know that our sun and the solar system first formed out of the massive collapse of
a once-vast molecular cloud, so there was always the likelihood that amino acids would form here,
from a time before even the sun itself had taken shape. But there are still some patterns at play
that have traditionally been difficult to explain… although those difficulties could now be lifted.
In April 2023, fresh research was published by a team working at the Pheasant Memorial
Laboratory at Okayama University, in Japan. The work centers on the question; How were amino acids
formed before the origin of life on Earth? And it focuses on the near-Earth Apollo asteroid, known
as Ryugu. On June 27th, 2018, JAXA (the Japanese Aerospace Exploration Agency) successfully landed
on Ryugu with its Hayabusa2 spacecraft, which then spent more than a year navigating the rock
before leaving on November 12th, 2019. As part of the mission (which is still ongoing) samples
from Ryugu were ferried back to Earth, arriving on December 5th, 2020 - and it’s these samples
that the team at Okayama University have worked from, to establish the origins of amino acids.
To set the scene, the study’s authors explain that most amino acids come in two forms,
that are seeming mirror images of one another, “similar to human hands”... with these forms
then often referred to as “right-handed or left-handed optical isomers”. It’s
further explained that “one interesting characteristic of life on Earth” is that
it uses the left-handed type to form its proteins. In some ways, this means that when searching for
the origins of life anywhere, scientists have already narrowed it down by half.
With this in mind, the team analyzed two distinct particles from Ryugu. Amino acids (in general)
were clearly present in both, leading more weight to the broad idea that life’s building
blocks do come from space. However, it was also found that there were differences between both
particles which could yet explain how, when, and why certain amino acids form. Most notably,
one particle was found to have much higher levels of the amino acid dimethylglycine,
or DMG. Further chemical analysis then tracked the DMG back to that particular
particle at one time experiencing an abundance of water, in its ancient past. When the earliest
ices melted in the young planetesimals and shards of rock in the solar system,
it resulted in the formation of a wider range of minerals - a vital stage known as aqueous
alteration. Seemingly, though, DMG was much more likely to show up as a result of this, as well.
We certainly know that liquid water was carried inside some asteroids that had
originally formed further out from the sun, in the early days of the solar system before
the likes of Earth or Mars had evolved enough to host water themselves. We also, of course,
know that various asteroids have impacted with Earth over the course of its history. It’s
long been suggested that these monumental events could’ve brought with them the origins of life,
but this study provides a very specific example of that in action - tracing the formation of DMG
all the way back to its cosmic roots, but showing that water was still seemingly the key ingredient.
Above all else, though, this study perhaps serves to highlight the incredible balance (and run of
existential fortune) that’s required to make life possible. The catch-all term of “life’s
building blocks” can make it feel as though what’s needed for life isn’t that difficult to get a hold
of… but this study shows that those blocks can be literally billions of years in the making,
before they’re suitable for inclusion within any kind of cellular beings. For just DMG,
everything has to be just right - the materials, the timing, the chance events,
and so on. The team at Okayama University draw on this realization further, writing that;
“the findings of the study indicate that slight differences… during aqueous
alteration… can have big effects on the end abundances of amino acids”.
Concluding that, as some amino acids are destroyed while others are created,
“this in turn will affect the availability of amino acids at the origin of life on Earth”.
Finally, another takeaway here is that, fundamentally, we really are all a part
of the universe. Living out our daily lives in our towns, cities and homes on the ground, with
the unending sky above us… there’s good reason to be philosophical about the meaning of life; about
where we came from, and where we’re going to. But, in a practical sense, we do know why we’re here.
While studies do differ, those hydrothermal vents in the ocean appear a very strong candidate for
hosting the chemical equations that make us here on Earth, specifically… but Earth didn’t always
exist. And, in the time before, the solar system was swimming with infant worlds of rock and ice.
Even then, though, the very first parts of biology were being brewed. Those infant worlds
were packed with the potential for something much more complex. It would just take countless,
intricate natural processes, unlikely collisions, and plain lucky breaks…
plus multi-billions of years to allow it all to happen. But, nevertheless,
that’s why today scientists have discovered (and are still discovering) the true origin of life.
What do you think? Is there anything we missed? Let us know in the comments, check out these other
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