[translations idioma=”ES” url=”https://archives.rgnn.org/2013/10/18/el-primer-sintoma-de-vida-mas-alla-de-la-tierra-podria-ser-un-virus”]

U.S.A. What does it mean for something to be alive? Why are we so fascinated by the idea of life on other planets? These two questions are closely related because to find life on other planets, we have to understand at what point something is considered to be alive. As of now, we can only study life here on Earth. However, this includes organisms as diverse as those that survive on oxygen, carbon dioxide or methane to those that survive off other living organisms to viruses, which are not even considered to be alive.

In 2011, Jeff Marlow gave a TEDtalk on how we have to keep exploring here on Earth and outer space to push our boundaries and challenge what we think we already know. We were lucky enough to get the chance to interview him and discuss some of his ideas. Here, he talks about how life survives in extreme conditions, explains what astrovirology is and how all of this might be able to help us in our daily lives.

What made you so interested in subjects as distant as the deep sea and Mars?

Both Mars and the deep sea are at the limits of exploration; increasingly advanced robots go to Mars, and submersibles take scientists to the bottom of the ocean. These sites also represent frontiers of biology – places very foreign to those of us living here on the surface of Earth, and yet life has found a way. Some of the capabilities that have allowed microbes to survive in the deep sea could help similar organisms survive on Mars – cold temperatures, or certain types of metabolisms, like “breathing” iron, or eating methane. Remarkably, life persists in just about every corner of planet Earth that we’ve been able to look at, but life on Mars would be the biggest test of this trend. Either way, studying life, or the absence of life, in both of these settings tells us a lot about the fundamental limits of biology, and that can have big implications in an number of fields more applicable to everyday life, like alternative fuels or medicine.

What are the requirements for something to be considered life?

Defining life in a biological sense is surprisingly complicated. It’s easy to propose definitions that exclude things that are alive (like donkeys, if the ability to reproduce is a part of your definition), or include things that aren’t (like a computer program, if you consider learning, evolution, and growth to be essential). To me, it comes down to a cell’s ability to maintain disequilibrium in an environment that otherwise pushes everything toward disorder. If an unbalanced state is maintained for a long time, then some sort of energy needs to be making that happen, resisting the inevitable move toward balance. This is essentially the definition that the physicist Erwin Shrodinger proposed in 1944.

In your TEDtalk, you discussed how the more we learn about life on Earth, the more we can learn about possibilities in outer space. You referenced places that mimic some of the more inhospitable conditions of outer space, including the Rio Tinto in Spain, ice caves in Iceland, and methane vents at the bottom of the ocean. What is it about places like these that help us understand life?

From a scientific perspective, you don’t really know much about something until you can describe its limits, and that’s exactly what the study of extreme life forms is all about. We’ve known for a long time that life can make food out of sunlight through photosynthesis, or that particular microbes and animals can survive in the oceans, but only in the last few decades are we really getting a sense of the incredible versatility of biology. When we see organisms that can handle temperatures over 100 C, or below -12 C, or acidity levels similar to battery acid, or huge doses of radiation, it challenges all of the assumptions we’ve previously made about what life can handle and what it really need to survive. Extremophiles really demonstrate just how adaptable life is, and we’re still just scratching the surface of biological capabilities.

What is synthetic biology and how is it being used today?

Synthetic biology is the modern-day incarnation of our constant drive to shape nature for our purposes. This has happened for centuries through selective breeding, for example, as farmers might only plant seeds from high-yield varieties of crops. But now we have the tools to alter biology on a much more fundamental level, by going in to the genetic code to reformat metabolic pathways, to produce desired products like biofuels or new drugs. It’s possible to push evolution in a certain direction, and by editing genes and developing quick output tests, the rate of changes we can impose is higher than the natural process. Scientists are also getting close to being able to make an operational cell from scratch, which is really pretty remarkable considering how many billions of molecular interactions go into a functional biological system.

Again, like the study of extremophiles, synthetic biology is really about understanding how biology works in some fundamental ways. Being able to describe biology is one thing, but being able to construct it suggests a deeper understanding of the intricate processes at play.

Of course, there are a lot of things we don’t understand about how altered genes interact and affect other unforeseen aspects of biology, so we’ve got to be cautious in applying these tools, but being able to edit the text of biology is a very exciting opportunity.

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