A common definition of life, including the one in Biology SE Life requires physical entitites to have the capability of being able to reproduce.

A process defining organisms that grow and adapt to stimuli while maintaining a state of organization and energy production and being capable of reproduction.

Under this definition one could think that a specialized cell like a bone cell or a skin cell doesnt have life. But also, a common definition of cell, including the one here in Biology SE says a cell is

the smallest unit of life.

So, my question is, are specialized cells which dont reproduce supposed to have life? This question came up to me thinking of other living organisms which have tissues which seems to be inert and survive hundreds or thousands of years (ie, wood, bones, etc.)

  • $\begingroup$ I'm not sure if this belongs here and hence it might get closed, but 'life' has several meanings and 'a life' usually refers to an entire organism most notably humans, while cells are 'living' things or 'lifeforms', but it's not common to use 'a life'. $\endgroup$
    – user40950
    Commented Sep 30, 2020 at 20:54
  • $\begingroup$ Note that your first quote used the word "organisms," while your second one used the term "life." Are specialized cells in the body alive? Yes, by most definitions they are living. Would a culture of skin cells in a petri dish be considered a viable organism? Probably not. But definitions in biology can sometimes get fuzzy around the edges. The Philosophy stack is probably a more suitable place if you're looking for an in-depth discussion of this question. $\endgroup$
    – MikeyC
    Commented Sep 30, 2020 at 21:45
  • $\begingroup$ It has to belong here, because if Biology deals with life, you can't do science over something that doesnt have a definition. The requirement for doing science over something is to be able to test it, and to be able to test it you need a definition $\endgroup$
    – Pablo
    Commented Oct 1, 2020 at 11:32

2 Answers 2


Life is defined in many ways.

Common definitions are usually simplified definitions. Under some definitions it would be "life" under others it would not be. But it doesn't matter. The problem you are having is thinking definitions of life are anything more than artificial categorization. Really there is no difference between living things and the rest of chemistry, or at least there is a smooth gradient connecting them, but we humans can't easily think that way, so we create descriptive but imperfect definitions to help our thought processes. There is a lot of gray area for any definition of life, and you have found one.

  • $\begingroup$ If we use definitions to identify similar properties and the common nature of entities, and be able to build knowledge over it, how is it that it doesnt matter? For example, can I expect a wood cell to biological age? How about a skin cell? How about Taxonomy? There are 103 million entries in Google talking about this branch of Biology, it doesnt seem it doesnt matter to classify living things. I think there should be more discussion on the definition of life if some unidentified definitions are being used to build knowledge in Biology $\endgroup$
    – Pablo
    Commented Oct 5, 2020 at 11:58
  • $\begingroup$ All of those things can be asked without ever deciding whether the thing is "life" many living things do not age and many do. The difference between life and non-life are arbitrary, a hold over from when we though life was special. Its only useful at the most simple level but once you are talking about biology in any detail the definitions become counterproductive, as can be seen in your original question. $\endgroup$
    – John
    Commented Nov 4, 2020 at 5:26

The short answer is that Yes, specialized cells are considered to have life, as are sterile ants that serve the colony but do not themselves reproduce. The definitions that are given for life are attempts to characterize a phenomenon that people are already capable of recognizing. Specialized cells arose out of a reproductive process and they do other life-y things like metabolizing. So they are alive.

If the definition given in a book seems to imply that specialized cells aren't alive, then the definition is ill-formulated, misunderstood, or both.


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