Most of the news that gets covered here is related to new discoveries and good events happening around the world, but sometimes we need to take a step back from those discoveries and think deeper about what it all means. Recently NASA launched its most ambitious mission to Mars and they hope to find evidence of life.

But what is life?

Philosophers for hundreds of years have tried to answer this question and depending on who you ask we are closer or no closer than we were when humanity first asked such a question. Some people rely on old writings or established mythos for defining life, but those generally don’t old up when looking for something truly alien to us. Which leads us to something relatively new to the world of science and that is figuring out a sound and comprehensive definition for life for the purposes of scientific research.

Defining life poses a challenge that’s downright philosophical. There’s no ambiguity in looking for water, because we have a clear definition of it. That definition is the same whether you’re on Earth, on Mars, or in intergalactic space. It is the same whether you’re dealing with water as ice, liquid, or vapor. But there is no definition of life that’s universally agreed upon. When Portland State University biologist Radu Popa was working on a book about defining life, he decided to count up all the definitions that scientists have published in books and scientific journals. Some scientists define life as something capable of metabolism. Others make the capacity to evolve the key distinction. Popa gave up counting after about 300 definitions.

Things haven’t gotten much better in the years since Popa published Between Necessity and Probability: Searching for the Definition and Origin of Life in 2004. Scientists have unveiled even more definitions, yet none of them have been widely embraced. But now Edward Trifonov, a biologist at the University of Haifa in Israel, has come forward with a new attempt at defining life, based on a new strategy. Rather than add on yet another definition to the pile, he’s investigating the language that previous scientists have used when they talk about life.

Edward Trifonov: Life is self-reproduction with variations.

Trifonov acknowledges that each definition of life is different, but there’s an underlying similarity to all of them. “Common sense suggests that, probably, one could arrive to a consensus, if only the authors, some two centuries apart from one another, could be brought together,” he writes in a recent issue of the Journal of Biomolecular Structures and Dynamics (article PDF).

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