text: Around the time introns were discovered, Senapathy was asking how genes themselves could have originated. He surmised that for any gene to come into being, genetic sequences (RNA or DNA) must have been present in the prebiotic environment. A basic question he asked was how protein-coding sequences could have originated from primordial DNA sequences at the origin of the first cells.
  To answer this, he made two basic assumptions:
  * before a self-replicating cell could come into existence, DNA molecules were synthesized in the primordial soup by random addition of the 4 nucleotides without the help of templates and 
  * the nucleotide sequences that code for proteins were selected from these preexisting random DNA sequences in the primordial soup, and not by construction from shorter coding sequences.
  He also surmised that codons must have been established prior to the origin of the first genes. If primordial DNA did contain random nucleotide sequences, he asked: Was there an upper limit in coding-sequence lengths, and, if so, did this limit play a crucial role in the formation of the structural features of genes at the origin of genes?
  His logic was the following. The average length of proteins in living organisms, including the eukaryotic and bacterial organisms, was ~400 amino acids. However, much longer proteins existed, even longer than 10,000-30,000 amino acids in both eukaryotes and bacteria. Thus, the coding sequence of thousands of bases existed in a single stretch in bacterial genes. In contrast, the coding sequence of eukaryotes existed only in short segments of exons of ~120 bases regardless of the length of the protein. If the coding sequence ORF lengths in random DNA sequences were as long as those in bacterial organisms, then long, contiguous coding genes were possible in random DNA. This was not known, as the distribution of ORF lengths in a random DNA sequence had never been studied.
  As random DNA sequences could be generated in the computer, Senapathy thought that he could ask these questions and conduct his experiments in silico. Furthermore, when he began studying this question, sufficient DNA and protein sequence information existed in the National Biomedical Research Foundation (NBRF) database in the early 1980s.