The origin of life on earth is a fundamental mystery that has eluded scientists for ages but
new evidence found within several meteorites may hold the key to figuring out how it all started
are we the offspring of some ancient cosmic alien biology
welcome back to Factnomenal today we're unraveling the mysteries of the origins of life
and looking at how the building blocks for it were brought here on the backs of meteorites
scientists have had a hunch for a while that the building blocks for life may have been brought
to earth from outer space some components that make up dna that helix-shaped source code for all
organic life on earth were discovered in several meteorites over 50 years ago these components
are called nucleobases in dna there are four of them adenine guanine cytosine and thymine rna
dna's close cousin is made up of the same bases except instead of thymine it has uracil
these nucleobases bind with sugars and phosphates to create nucleotides which then combine to create
dna and rna which interact with proteins and fatty acids to build life as we know it
we've known for some time that many meteorites have brought adenine and guanine with them
when they crash to earth these meteorites have also carried alien amino acids which
are the building blocks of proteins and sugars which are also fundamental to life
but new techniques for analyzing samples have now revealed conclusive traces of
all five nucleobases on three meteorites from the u.s australia and canada it now seems that nearly
all the components for life could have been brought to earth from outer space
but how could they have formed there remains a mystery the answer may lie in space dust
the theory that life originated in outer space is called panspermia but to figure out how these
building blocks ended up on meteorites that ended up seeding our own planet
we have to go way back to the beginnings of the universe itself stars began forming in our
universe about 100 million years after the big bang some 13 billion years ago
they were created in clouds of cosmic gas and dust called molecular clouds
which are nicknamed stellar nurseries because that's where stars are born and develop
these clouds eventually condensed and collapsed under their own gravitational pressure
heating up in the center to create a dense ball of energy a star was born this process repeated
and repeated until entire galaxies formed then crashed into each other and created
more galaxies as the universe expanded outward all the while whatever matter wasn't sucked into stars
or black holes after the stars collapsed kept floating around as interstellar dust
our milky way galaxy formed through this process an estimated 14 billion years ago
9.4 billion years later our own sun condensed into existence and with it our solar system was born
there's a lot we still don't know about this whole process but scientists now think that these clouds
contain three of the four nuclear bases required for the formation of dna they also probably
contain the other essentials for life including sugars amino acids and phosphates an experiment
in 2019 mimic the conditions we think can be found within the molecular cloud that birthed our sun
a team of researchers in japan filled a vacuum chamber up with a gassy mixture of water
ammonia and carbon monoxide and then super cooled it to negative 263 degrees celsius then they aimed
ultraviolet lamps at the chamber which kicked off a chemical reaction and created an icy film on the
surface of the dust inside when they brought the whole thing back up to room temperature
the three nucleobases and several amino acids had been born are we literally made of stardust
it's a fascinating theory and what we think happened right after our son was born makes the
whole thing that much more compelling first of all don't know when exactly life began on earth the
earliest records we have are 3.7 billion year old fossilized microorganisms found near deep's events
but some estimates put the origin of life at 4.4 billion years ago
just 100 million years after earth's oceans formed when our own solar system was created
a couple hundred million years before that there was rock and dust flying everywhere huge masses
were hurling into each other and fusing together our earth according to one widely accepted theory
crashed into a protoplanet called thea early on in this process which created our moon
in fact two chunks of thea may still be launched deep in earth's outer crust could thea have seeded
earth with the right stuff to help kick-start it towards the world we know now or was it hundreds
of millions of years of bombardment with dna and amino acid-infused space rocks into earth's
developing body that did the trick or did it happen even later after the oceans developed
the truth is we don't really know when it started but what about how it started
dna has allowed us to map out the history and evolution of life on earth
down to the very beginning by looking at the information stored within its helixing strands
but once we get to the very beginning we hit a wall dna is great for storing and transferring
information but cells also need proteins which are kind of like molecular mechanics that keep cells
alive and running smoothly there is an inherent paradox in the process that jump-started life
dna needs proteins in order to form yet protein formation requires dna
we're left with a chicken or egg scenario that has puzzled scientists for decades
the answer might be found in rna rna can do stuff that both proteins and dna can do like dna it can
store information and like proteins it can perform maintenance that keeps cells alive
rna world theory proposes that rna molecules came first before dna or proteins billions of years ago
a self-replicating strand of rna formed then kept replicating and replicating until there was enough
data to create more complex things the initial burst of self-replication is called autocatalysis
basically rna strands were able to catalyze themselves and produce molecular reactions
that led to more of themselves which then led to the rest of well life a kind of big bang for
organic matter we normally think of this process as a series of interactions between proteins
dna and rna as information is stored maintained and moved as cells form and divide but if rna
came first and had the ability to auto catalyze it could then create the proteins needed to build the
super highway of genetic information known as dna and power the replication engine that is life as
we know it you can think of a chain of rna kind of like a ladder cut in half from top to bottom
the strand has four nucleobases adenine guanine cytosine and uracil these nucleobases are
connected to each other along backbone atoms which create nucleotides nucleotides can be
arranged in any order along the chain creating strands with all kinds of different combinations
along the strand the different nucleobases attract one another like magnets in a process
called base pairing adenine attracts uracil and cytosine attracts guanine eventually enough bases
are paired so that the latter zips back up and you're left with a complimentary strand which is
the exact inverse of the original strand when temperatures heat up these strands lose their
grip on each other and the ladder splits apart again the process repeats and repeats mutations
slip in and the strands evolve eventually some strands base pair with themselves because there
aren't enough other free nucleotides around this creates what are called ribozymes as
ribozymes grow more complex they form all kinds of different shapes and can actually begin building
nucleotides and putting together other molecules like little factories they start functioning
almost like living things as they evolve and begin influencing their environment
molecular organisms that perhaps existed before the formation of living cells
was this how it all started maybe maybe not this process of rna self-replication has only
been produced in labs using special enzymes and techniques that help the original base
pairs in an rna strand bind together it's still a mystery how this originally occurred in nature
the true answer may be that there were some proto-rna ancestors we haven't discovered yet
that have special properties that create the initial auto catalytic reaction
if this is indeed part of the explanation for how life began the next question is where it began
self-replicating single-celled organisms maybe could have made their way to earth from outer
space cooked up in a cosmic dust and ready to go however they would have needed to be super
cells extremophiles able to withstand huge blasts of cosmic radiation as they travel through space
we at least now know that most of the building blocks for these cells did come from space so
let's check out what earthly processes could have taken these cosmic ingredients and cooked up life
as we know it one theory involves lightning in the 1950s a scientist named stanley miller carried out
a series of experiments really similar to the team of japanese researchers mentioned earlier
except instead of radiation he used electricity he used the same basic gases ammonia hydrogen methane
and sealed them in a flask with water added some electricity and voila amino acids had formed the
building blocks of protein we're left with a vision of early earth buzzing with lightning
storms and volcanic eruptions churning inorganic matter into an amino acid sludge
but there was a problem even if these were the right conditions for life on earth
the presence of amino acids alone couldn't explain how life began
as we've just seen life also needs dna and rna to act as replicators to make copies of themselves
and drive the self-sustaining process of life dna and rna need to be spurred into action by
an enormous amount of concentrated energy energy that wouldn't exist in a soupy early
earth sludge pond that was only marginally energized by lightning and surface volcanism
the best evidence we have for the terrestrial origins of life on earth
can be found at the bottom of the oceans in deep sea vents these underwater volcanic
towers spew superheated water and gases concentrating them in rocky structures
that have intricate labyrinths where molecules are forced together forming mineral catalysts
for the critical reactions that create dna rna and the amino acid building blocks for proteins
and remember thea that early planet that blasted into earth and created the moon the fact remains
that scientists think two massive chunks of this planet are buried deep in the earth's core
chunks that could quite possibly have contained amino acids and the building blocks for dna and
rna the possibility of panspermia combining with volcanism deep underwater to create life is a
tantalizing possibility the more we understand our universe what it's made of and how it all came to
be the more we'll understand the origins of life we're coming to realize that the building blocks
of life didn't just magically appear on earth but were part of the same cosmic madness that created
earth in the first place the question remains though does life exist elsewhere in the universe
if all the ingredients for it are already out there then why shouldn't it on the other hand
maybe some forces unique to our pale blue dot help stir these ingredients in just the right way
there are quite a few theories we didn't touch upon in this video
and what do you think are there any other theories that could explain the origins of life
let us know in the comments and don't forget to like and subscribe for more stellar space content