Some researchers are urging us to broaden our definition of life, which may have an impact on the search for life on exoplanets.

In a new paper, published in the Journal of Molecular Evolution, Santa Fe Institute researchers Chris Kempes and David Krakauer argue that in order to recognize life’s full range of forms, we must develop a new theoretical frame.

Santa Fe Institute, ” New theory of life’s multiple origins” at ScienceDaily

Although there are many definitions of life, they all assume a strict separation between life and non-life — and that is what the researchers challenge:

Culture, computation, and forests are all forms of life in this frame. As Kempes explains, “human culture lives on the material of minds, much like multicellular organisms live on the material of single-celled organisms.”

Santa Fe Institute, New theory of life’s multiple origins” at ScienceDaily

Their broader definition of life includes the idea that life has multiple origins; all life did not begin with a single cell; it may not even require cells. Viruses would certainly be considered alive in their scheme.

When researchers focus on the life traits of single organisms, they often neglect the extent to which organisms’ lives depend upon entire ecosystems as their fundamental material, and also ignore the ways that a life system may be more or less living. Within the Kempes-Krakauer framework, by contrast, another implication appears: life becomes a continuum rather than a binary phenomenon. In this vein, the authors point to a variety of recent efforts that quantitatively place life on a spectrum.

Santa Fe Institute, “New theory of life’s multiple origins” at ScienceDaily

On one hand, this broader approach might make it easier to envision, thus look for, extraterrestrial life. We would not insist that it be like life on Earth.

The idea is not entirely new. Astronomer Fred Hoyle (1915–2001) wrote a science fiction novel, The Black Cloud (1957) in which the extraterrestrials turn out to be a dark, gaseous cloud, much more intelligent than humans. The cloud is creating havoc by accidentally blocking the sun but, being so informed, it expresses surprise that there are life forms that are actually solids.

On the other hand, there is a danger is losing a grip on what makes life on Earth unique. Culture, for example, originates as ideas, which are immaterial in character. That makes culture quite different from cells. And, while forests are full of life forms, the concept of a “forest” is an idea in the human mind.

Similarly, however powerful computers may become, insisting that they are “life” could only have the effect of diminishing the importance of biological life. If all computers “went extinct,” the effect on the environment would be negligible compared to what would happen if most pollinators did.

Kempes and Krakauer’s approach sounds like one of those ideas that is better explored in a conference workshop than used for definitions or enacted into law.

The paper is open access.

You may also wish to read: Scientists try to understand how one-celled life forms learn. Artificial intelligence may offer a model for learning without a brain.