The Origin of Life on Earth

Based on many years of data and observations, scientists approximate the Earth to be around 4.5 billion years old. The earliest evidence of life that has been found exists in Greenland, and consists of fossilized remains of cyanobacteria, otherwise known as stromatolites. These fossils date back to 3.7 billion years ago, and even still, scientists believe that life may have gone back even further, due to rocks in Australia that contain high levels of carbon--an element that is majorly involved in most biological processes. This evidence raises the question of how life actually formed all those years back, and many different scientists propose different theories. Some of these include life coming from outer space, finding its way to Earth by means of an asteroid or comet. Others believe that there are several origins of life, and that life formed on Earth through a series of chemical reactions. These reactions are hypothesized to have led to the creation of self-sufficient systems that formed organisms. Whether one theory is correct or not, scientists still do not know for sure. However, by looking at the existing evidence, such as the cyanobacteria that is still around today, and by examining RNA and DNA qualities, they have a better idea of what very well might have been.

Scientists have widely accepted the idea that the primary molecule for life was RNA, a molecule made up of nucleotides that aids in protein synthesis and works as an on/off switch for many genes. However, upon the emergence of DNA, RNA was replaced due to the more stable and better performing nature of DNA. Since DNA is the basis of all life in organisms today, we can study it and gain multitudes of knowledge from studying its structure and functions. Perhaps we will never know the exact origins of life on Earth, but by continuing research on these molecules that we know have been around since the start, there is a much better chance at getting there. I think that the fact that we do not know the exact origin of life on Earth is very interesting because there are so many different explanations that can account for it. However, the fact that we know that RNA was the primary molecule is a step in the right direction because we have a lot of knowledge about it, and continue to study it nowadays. Perhaps one day we will make a discovery that answers how exactly life began on Earth, but until then we can only wonder.


Link: http://www.livescience.com/1804-greatest-mysteries-life-arise-earth.html

Complex Life's First Milestone

Hydrothermal vent at the bottom of the ocean

     In regards to the origins of complex life forms, one theory is globally accepted. This is the theory that RNA strands were being continuously formed in the mixing pot that was the prehistoric ocean. These strands would grow and reproduce until longer, more complex chains formed actual life-forms such as early amoebas and worms. Scientists have now discovered how it may have been possible that complex RNA strands out-competed simple, shorter ones.

     Technically speaking, shorter RNA strands can reproduce more efficiently because, although they are more primitive, with less material to copy the process is quicker. However, an article in Science Magazine claims that pores in the rocks surrounding hydrothermal vents in the oceans floor may have created the perfect breeding ground for the complex RNA strands, that eventually lead to us. The superheated water that emerges from these fissures is highly enriched with nutrients. Through a physical effect known as thermophoresis, “charged molecules in a solution accumulate in colder water, and the longer chains, having more charge, would do this more often than shorter chains”. Add this save haven, porous environment, together with the flow of nutrients and temperature changes from hydrothermal vents, and the result is much more efficient reproduction.

     This theory was recreated in a laboratory experiment that resulted in the longer strands reproducing much better inside the pores, leading to larger and more stable populations. The new findings may have opened a door to better understanding the evolution and origins of complex life, and the environments that made it possible.  

DNA From Outer Space

     Sitting with a few beers at a campfire on a warm summer night, i can only imagine that many people ponder how life came to this planet.  What else would there be to talk about? Well a team of Swiss and German scientists have completed studies that produce clues that it could have been possible for the first DNA to come from outer space.  Early in the Earth's history, meteorites and asteroids hit the planet.  The popular thought until now was that anything that entered our atmosphere reached extreme temperatures and could not survive. 

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The scientists dotted a rocket with DNA fragments inside the exterior grooves.  Once the flight of the rocket was concluded, they tested the stability of the genetic material.  The flight consisted of a 13 minute round trip with exit and reentry into the atmosphere.  They found that the DNA that could create life survived the trip intact. The scientists did note that the experiment could not fully replicate the speed and temperature of a meteorite colliding with earth.  It does prove that a civilization could be contaminated with DNA on the outside of a spaceship.  Bacteria was already known to survive certain similar conditions.This of course does not prove or disprove any evidence of how life was started on earth or anywhere else if there is life on other planets.

http://www.scientificamerican.com/article/dna-can-survive-reentry-from-space/

http://www.ibtimes.com/nasa-dna-found-meteorites-indicates-life-may-have-originated-space-828233

DNA survives critical entry into Earth's atmosphere

          A team of scientists from UZH discovered that DNA can survive a flight through space and re-enter Earth's atmosphere during an experiment on the TEXUS-49 research rocket mission. The DNA was applied to the outer shell of the payload section of a rocket using pipettes and flew into space from Earth and back again. After the mission, the DNA was still found on the application points of the rocket and was still able to transfer genetic information to cells, proving DNA is able to survive in extreme conditions. 

        

        The scientists got the idea to put DNA on the rocket from studying the role of gravity in the regulation of gene expression in human cells using remote-controlled hardware inside the rocket's payload. During preparations for this experiment, researchers began to wonder if the outer structure of the rocket might be suitable for stability tests on biosignatures. 

       Quickly improvised, the experiment was supposed to merely be a pretest to check the stability of biomarkers during space flight and re-entry into Earth's atmosphere. Scientists were surprised to find the DNA completely intact and functioning, proving DNA can survive in very harsh conditions. 

      This experiment is interesting not only because of its spontaneity, but because of the results produced. The fact that DNA can survive in space proves the greatness of the molecule and opens the door to possible life on other planets.

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