The origin of life on Earth has been a mystery ever since the first organisms were discovered. One hundred years ago, it was thought that life began in the sea and then eventually seeped up onto dry land. This theory was later abandoned with the invention of plate tectonics and the realization that there are pools where chemicals necessary for life exist deep within our planet’s crust.
In recent years, scientists have proposed an alternative theory: Life could have begun on Earth rather than being delivered to us by some external source like comets or meteors. Life may have originated on Earth, but it could have had to rely on an ancient form of genetic material called RNA and other natural catalysts.
RNA is a molecule that has many structural similarities to DNA, the hereditary material in our cells, and all other living organisms. However, there are significant differences between the two molecules. The last universal common ancestor (LUCA) of all life forms must have possessed genes and proteins capable of producing RNA. Later on, RNA was combined with self-replicating protein molecules called ribozymes to create transfer RNA (tRNA); tRNA allowed bacteria to break down and recreate RNAs as needed. RNA is created by enzyme molecules called ribozymes, designed to bind to specific sites in DNA and cut off the block of bases by copying itself. Ribozymes are proteins with a base-pairing site at the bottom of their structure which can be altered to bind with another tRNA molecule. These enzymes can also catalyze reactions in the cell itself by cutting bonds between amino acids.
So far, scientists have only been able to isolate RNA from a few microbes and viruses, but they have made significant progress over the last decade or so. The first naturally occurring genetic material was isolated from a soil bacterium in 2001, but it had a very short lifespan as it could only live for an hour before degrading. A new species of RNA-like material called P4 was found in 2010 and was capable of self-replication for up to a few hours. This breakthrough in research has led scientists to believe that a natural copy of RNA could be hidden away somewhere deep beneath the surface of our planet, just waiting for another organism to develop it into life.
Some researchers have suggested that the RNA used by living things today is an ancient form that DNA replaced, but this theory doesn’t answer some important questions about the origin of life. RNA is better at carrying out biological functions because it has more structural connections than DNA; a single strand can perform many more tasks than a single strand of DNA. This characteristic of RNA explains why RNA can perform such a variety of roles in living things. Also, DNA is very vulnerable to damage and oxidation. This means that it must be protected from these sources to ensure the longevity of cells. RNA breaks down eventually, making it an ideal candidate for life, as it doesn’t need any protection from external sources like proteins and ribozymes do.
Researchers are now looking for ancient life forms in geologic environments where the Earth is extremely hot, with temperatures of up to 1700C or 3000F, which would have been perfect for bacteria-like microbes capable of replicating themselves. These environments include parts of Australia, Antarctica, and other places on or around the Earth’s surface. If life did originate on Earth, it could have continued to evolve as a result of thermophilic bacteria accumulating in these conditions.
There is also debate over whether RNA was actually the first life form. Tony Capra, a professor at the University of Utah, argues that it’s unreasonable to believe that RNA came before DNA as we know it. Some researchers take this point of view; others believe that RNA evolved within other forms of pre-existing chemical compounds, which were later folded into DNA-like molecules. This is similar to the theory proposed by Erwin Schrödinger in 1944, which shows that anything could be either a substance or a wave. According to this theory, RNA could have existed as any one of five states but later became fully DNA-like.
RNA is thought to be the element of the cell responsible for making proteins and carrying out other essential functions.
