DNA not Essence of Life

For a long time, and way before the discovery of its structure, DNA has been considered “essence of life”, the molecule that defines every organism including humans and that links ancestors with descendants over generations. Associations between DNA and heredity as well as between DNA and various hereditary traits have only enforced this view. Genetic code similarity between humans and other organisms seems to substantiate the tree of life and the story of evolution since we’re 99% chimps, 69% rats and 50% bananas according to the DNA. Recent computer developments lead us to the analogy between the DNA code and programming.

Is DNA essence of life? Are our development, appearance, behavior, and diseases pre-programmed in our DNA? Many connections have certainly been observed, but DNA is far from organism determinism. The information carried by the 3 billion base pairs of DNA nucleotides – each containing 2 bits of information (ACGT) – in the human genome amounts to only 6 G-bit of data which is less than 1 G-Byte (fits easily on a thumb drive). This is hardly enough to capture the complete manufacturing specifications for the simplest products around us like a pencil or a tire. Moderately complex systems like cars and airplane require a lot more data than available in a genome, and even that information is for high level recipes rather than complete (from atoms and simple molecules) instruction manuals.

A bit is a bit is a bit whether magnetic, silicone or DNA nucleotide. Some bits may certainly carry more important information than others, but only to the extent they link (index) to other information. “Fetch the human” can be encoded in a single bit if the only alternative is “fetch the chimp”. “Assemble or Fix a human” as in “transplant into a dying patient a cadaver hart” on the other hand requires a lot more information if this is to be carried out by a transplant surgeon in training – in fact this is the kind of information that may require on the order of Gigabytes in teaching materials. “Make a human” as “…from one zygote and the available atoms and molecules” is the type of request that demands an unknown number of bits, for certainly exceeding by many times the 1 GB of data available in the zygote’s DNA.

Does anyone believe that the differences between humans and chimps can be fully described in 8 MB of data? Scientific presentations that don’t even begin to scratch the surface of this topic take more than that computer storage space. Furthermore, 0.5% of our genome separates us from other humans while 1.2% separate us from bonobos and chimps. The implication is that our differences are more than skin-deep and cannot be explained by our similar genotype. The co-evolution story of chimps and humans that, given our similar genome, seemed plausible for a while, becomes much harder to accept if the genome is far less important than thought.

If not in DNA, then where exactly is the actual human blueprint? We do not have any strong leads, but we do know that even genetic twins are somewhat different, that epigenetics play a role, that some information is encoded chemically (as in redox reactions and DNA PCR), and that environment and the maternal womb are critical. None of these is a sufficient explanation however. Chemistry is common to all organisms, the environment can vary drastically without affecting the outcome that much (homeostasis), and the maternal womb is itself an outcome of a previous development.

What are the implications of ‘DNA not essence of life’? Most important (as discussed) is that “human just another ape” needs to be reevaluated, and that we need to seriously begin searching for this ‘essence of life’ somewhere else. Of smaller importance, revival of extinct species might be much harder than currently expected as would be chimera hybridization, and abiogenesis attempts currently focused on DNA and RNA might be futile.

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