What Is Life?

While talking about the search for extraterrestrial life, you may notice the difficulty in drawing a line between the living and nonliving. Bacteria are considered life forms, but viruses are not. Artificial Intelligence is able to do a lot of things that human beings can do, but it is not viewed as life by the general public…so what is life after all?

Bacteria VS Virus (from: Act For Libraries)

According to our textbook, there are six key properties for life: order, reproduction, energy utilization, response to the environment, and evolutionary adaptation. Examining those properties, we can easily rule out some suspicious candidates: viruses don’t have orderly arranged molecules; Artificial Intelligence also do not have cell structures.

However, as biologists regard evolutionary adaptation as the most fundamental property, the definition of life can be simplified as “something that can reproduce and evolve through natural selection.” Under this definition, all physical entities that have self-sustaining processes can be called life. For example, Artificial Intelligence, which has been a popular topic in recent years, might be considered as “artificial life” that can reproduce and evolve in the form of codes.

Artificial Intelligence (from: Center for Generational Kinetics)

Now that the definition of life has become more generalized, can we view AI as an advanced life form that has never appeared on Earth before? If we take this different point of view, is cell-based life only a part of the spectrum of life? Maybe we are just in a phase of Earth’s history that life with cell structures are dominant. Then, in the search for extraterrestrial life, what are we really looking for?


5 thoughts on “What Is Life?

  1. How does AI fit into “something that can reproduce and evolve through natural selection?” Reproduction is defined as either asexual or sexual reproduction, requiring cells and/or gametes. If we do meet extraterrestrial life and it doesn’t fit into our current biological definition of life, can we assume this artificial form of life was created by natural life?


    1. Whether AI fits into the definition depends on how you define “reproduce and evolve”: in a sense, AI can “produce offsprings” by programming (although AI is not able to create actual, production-worthy code right now, it is possible that in the future robots obsolete programmers and humans in general!). And I really like your last question cuz that’s also what I’ve been thinking about! Let’s think about this: are the life forms on Earth (based on which we have our current biological definition of life) all that mother nature (opposed to natural life like us) can create?


  2. This makes me think of the joke that Mars as we know it is a completely robot-populated planet. I think “keeps me up at night” question is about molecular structure of potential non-earth life. Like, what would a DNA analog be made of? What would be their version of carbon be? If we are so complex that even one base code shift can alter life irreparably, is there anything that could match the specificity of protein synthesis?


  3. Interesting concept about the nature of life. Another subject that I think is worth considering is the current race toward developing an Artificial Super intelligence during our lifetime. When thinking about different forms of life and the ability to adapt and replicate, the possibilities associated with a technological breakthrough of this scale could absolutely be considered another form of life. Our current path of the perpetual cycle of innovation and breakthrough leads me to believe that sooner rather than later we are going to see astonishing breakthroughs in technology that begin to intrude on our traditional views of life and human consciousness.


  4. From a TA: Definitely interesting subject matter! It’s a great question on whether or not to consider an AI system with means of production as a life form. Maybe I should start talking nicer to my computer…


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