RNA
2040s: RNA formed the basis for life each of the five known times it arose on the early Earth.
2040s: RNA formed the basis for life each of the five known times it arose on the early Earth.
This is a comic about how our understanding of DNA and RNA has evolved over time as we've done more research into how they figure into cellular and viral processes. In the 1960s, we had just started to understand the role of DNA; as the years progressed, we realized RNA played a part, initially as an intermediary; and it turned 'weird' as we learned that RNA's role is potentially as complex as DNA's, if not more so. People now believe that life as we know it developed as RNA, and then evolved proteins and DNA later; this is called the "RNA World" theory.
- The first panel (1960s) shows the simplified (though incorrect) version of the central dogma, saying that RNA's sole function is to carry information from DNA to produce proteins.
- The second panel (1980s) shows the discovery that RNA itself can also catalyze reactions, like in ribozymes.
- The third panel (2000s) shows the more recent discovery of many different types of RNA that have numerous functions, like siRNA which acts in the RNA interference pathway, miRNA which causes regulation of transcript expression, piRNA which regulates transposons and other genetic elements, and more.
- The fourth panel (2020s) explains that RNA seems to be the primary actor in life, and it merely uses DNA for permanent storage of information. In particular, DNA contains the genetic information that's copied when cells divide and when ova and sperm combine. This seems to be a reference to the RNA-based evolution theory, which claims that RNA is the primary driver of evolution. It's similar to the idea that a hen is only an egg's way of making another egg.
- The title text (2040s) extrapolates the increasing significance of RNA to life. Specifically, that by the 2040s humans would discover that life evolved on Earth 5 distinct times, each with RNA forming its basis, essentially making RNA central to not just our tree of life, but the development of life in general. All types of life we know of today (or have evidence of having existed) seem highly likely to have arisen from the last universal common ancestor. However, detection of past or present shadow biospheres could eventually provide evidence of alternative instances of the development of life on Earth.
RNA has been mentioned previously in 2425: mRNA Vaccine, where the COVID-19 vaccine is explained, and 3002: RNAWorld, in which Disney decides to capitalize on the success of RNA.