What came first? the Chicken or the egg

There has been a long-standing debate on which came first, the chicken or the egg? You need a chicken to lay an egg, but you need an egg to make a chicken. Similarly, for decades, scientists have wondered what came first regarding genetic materials needed to make a living organism.

The Central Dogma explains the flow of genetic information in a biological system that controls all functions needed for life to be viable, allow for diversity and evolution. The Central Dogma states that DNA (carrier of genetic information) is transcribed to RNA (material essential in coding and expression of genes), and then RNA is translated into protein. You would assume that DNA is the origin of life since it is first in this sequence, but it is not. In the process of cell division, mitosis or meiosis, DNA is replicated. However, the replication process requires proteins like polymerases or helicase, thus DNA cannot be replicated and a cell cannot divide without proteins proving that DNA did not come first.

To figure out how life was formed, scientists mixed methane, water, ammonia, and hydrogen to mimic the atmosphere of the Earth in the beginning of life formation. After adding electric sparks to mimic lightening, they were able to produce amino acids, the building block of proteins. Thus, many assumed that protein came first. However, in 2009, British scientist John Southland found that nucleotides, the building block of DNA and RNA, was present in early Earth, even before the formation of proteins. They found that the nucleotides were made through chemical reactions on the surface of minerals. This metabolism-first scenario suggests that the high pressures and high temperatures of early Earth, provided the optimal environmental conditions to drive catalytic reactions by minerals and give rise to organic compounds.  

RNA World hypothesis may have the answer, where RNA came before protein or DNA. Why? Protein and RNA hold that ability for chemical reactions. RNA, like DNA, is also advantageous in being able to store genetic information. It is ability to do both is why it is suggested to play a crucial role in creating life. So, a suggested series of events may be, based on RNA World theory, that RNA was made auto-catalytically with chemicals and minerals interacting in the environment. Then the RNA developed proteins for additional functions. Later, since DNA needs proteins to replicate, DNA was the last thing in the central dogma to be formed to store information in a stable manner.

So what came first, the chicken or egg? Sometimes the answer may be something in between and has the quality of both, just like RNA.