Interoperability and the Code of Life

I work on anaesthesia machines and ventilators. Since they are used in operating rooms and hospitals, there are well defined instructions on how to clean, disinfect and sterilize them. That includes the temperature at which they should be sterilized: 132˚C. That number initially caught my attention because it wasn’t a round number (130 or 135). Why that particular temperature? How could one be sure if that temperature would kill all microbes, even in the future?

 

The answer is interesting. All lifeforms on earth, or all that we have checked, from the bottom of the oceans to volcanoes to you and me, are made of the same DNA strands. And DNA strands unravel (break up) at 132˚C. In other words, the temperature for sterilization is based on the facts that (1) all life is made of DNA, and (2) 132˚C is the temperature at which DNA strands break up.

 

Which then raised another question: why is all life based on DNA?

 

In Richard Dawkins’ famous book, The Selfish Gene, he briefly mentions that there must have been multiple codes of life (not just DNA) at the beginning, but DNA was probably better in some ways (error detection? error correction? speed of replication?) and thus came to dominate the planet (survival of the fittest code). That certainly sounds possible.

 

In an earlier blog, I had talked of how genes can be transferred not just vertically (parent to child) but also horizontally (individual to any individual, not even limited by species boundaries) aka Horizontal Gene Transfer (HGT). In The Tangled Tree, David Quammen mentions that for HGT to work, the recipient should be able to read and make sense of the HGT gene. That’s only possible if the genes in both lifeforms are written in the same code. And so, if the benefits of HGT as a means to “share” solutions and ideas across lifeforms was high enough, then species that can “interoperate” would have an evolutionary advantage over species that came up with some new code.

 

If you flip this entire blog around, it would feel like the knowledge that all life shares a common code (DNA) has found a practical application via our sterilization practices! And genetic editing of cells today is truly based on our having understood parts of that common code. The biologist Carl Woese was never a fan of such “applied biology”, disparaging it as “a biology operating from an engineering perspective”. He railed that the purpose of biology is to understand the world, not to change it. But, as Quammen wrote:

“This daring new century really wasn’t his century, and he knew that.”

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