Mirror, Mirror...Everywhere

One biology fact that, until last week, that I never had to worry about is why life on earth not just is all DNA-based but also all share the same chirality. E.g., all life we know about has DNA with a right-handed double helix, uses right-handed sugar molecules, but builds proteins with left-handed amino acids. That’s just how life is, right?

DNA's mirror image could be scary. Credit: Bing Image Creator

But it turns out that life’s chirality is not a law of nature, and that scientists believe that “mirror life” is not only theoretically feasible but plausible within the next ten years. And, many of them believe, that is something we should be very worried about.

Last week, a group of scientists released a lengthy Technical Report on Mirror Bacteria: Feasibility and Risks, along with an accompanying commentary in Science: Confronting risks of mirror life. Long story short, this is a mirror into which we should look very cautiously – if at all.

The report explains the fundamentals:

In a mirror bacterium, all of the chiral molecules of existing bacteria—proteins, nucleic acids, and metabolites—are replaced by their mirror images. Mirror bacteria could not evolve from existing life, but their creation will become increasingly feasible as science advances.

Credit: Adamala, et. alia

That’s the kind of progress science makes, for better and, sometimes, for worse. The problem, as the report also points out, is:

Interactions between organisms often depend on chirality, and so interactions between natural organisms and mirror bacteria would be profoundly different from those between natural organisms. Most importantly, immune defenses and predation typically rely on interactions between chiral molecules that could often fail to detect or kill mirror bacteria due to their reversed chirality. It therefore appears plausible, even likely, that sufficiently robust mirror bacteria could spread through the environment unchecked by natural biological controls and act as dangerous opportunistic pathogens in an unprecedentedly wide range of other multicellular organisms, including humans.

“The threat we’re talking about is unprecedented,” co-author Prof Vaughn Cooper, an evolutionary biologist at the University of Pittsburgh, told The Guardian. “The consequences could be globally disastrous,” another co-author, Jack W. Szostak, chemist at the University of Chicago, agreed in The New York Times. 

OK, that does sound bad.

Michael Kay, MD, PhD, professor of biochemistry at the University of Utah and one of the contributors to the report & commentary, warns:

If these bacteria are able to grow at all—and there is evidence that they probably would be able to grow, at least to some extent, in our natural world—maybe, over time, they could evolve the ability to eat our food and convert it to mirror food. If that happened, that would release a brake on their growth, and then all these other controlling mechanisms, as far as we can tell, would not be effective against these mirror bacteria.

I was especially chilled by this statement from Professor Kay: “There is a real possibility that mirror bacteria would struggle to find enough food to eat in order to grow, but we are humble in the face of evolution.”

As we should be. Evolution tells us that life finds a way (or did you not see Jurassic Park?).

Credit: Adamala, et. alia

The authors believe this is a time for caution. They urge:

However, in the absence of compelling evidence for reassurance, our view is that mirror bacteria and other mirror organisms should not be created…In light of our initial findings, we believe that it is important to begin a conversation on how the risks can be mitigated, and we call for collaboration among scientists, governments, funders, and other stakeholders to consider an appropriate path forward.

The people involved in the report and commentary are not alarmists. They are scientists who have been working in the field. “It’s inherently incredibly cool,” co-author Kate Adamala, a synthetic biologist at the University of Minnesota, told The New York Times. “If we made a mirror cell, we would have made a second tree of life.”

Cool indeed. But when they started talking about risks, they grew more concerned. “We’ve all done our best to shoot it down,” Professor Cooper admitted to The New York Times. “And we failed.”

Not everyone is so worried. Andrew Ellington, a molecular biologist at the University of Texas at Austin, told Scientific American:  “I’d argue a mirror-image bacteria would be at a gross competitive disadvantage and isn’t going to survive well.” He is dismissive of efforts to curb research: “This is like banning the transistor because you're worried about cybercrime 30 years down the road. I’m not particularly worried about a mostly unknown threat 30 years from now versus the good that can be done now.”

For example, one of the uses researchers were investigating mirror life for was for prescription drugs. Professor Kay explains: “they have the potential to last for a much longer period of time and to open up a whole new class of therapeutics that would allow us to treat a variety of diseases that are currently challenging.” A moratorium on research could hamper progress in drug development, such as for H.I.V. or Alzheimer’s.

The authors conclude their commentary with a very reasoned plan: “To facilitate greater understanding of the risks associated with mirror life and further progress on governance, we plan to convene discussions on these topics in 2025. We are hopeful that scientists and society at large will take a responsible approach to managing a technology that might pose unprecedented risks.”

Yeah, well, that’s not going to happen. As with AI, nuclear weapons, or any other transformative technologies, we’re more likely to plunge ahead regardless of risks, afraid that other scientists/companies/countries will get a jump on us if we slow up.

I wish we were more thoughtful; I wish we were better at anticipating risks versus benefits. I’m proud of these scientists for their innovative work, and for being brave enough to advocate caution about it, but I’m not optimistic that their plea will be heeded. Someone is going to make mirror cells, and probably sooner than we expect.

Then, Professor Kay predicts: “Once a mirror cell is made, it's going to be incredibly difficult to try to put that genie back in the bottle.”