According to a paper about artificial life systems, the following four conditions have to be fulfilled for "open-ended evolution":

  • Condition 1: A rule should be enforced that individuals must meet some minimal criterion (MC) before they can reproduce, and that criterion must be nontrivial
  • Condition 2: The evolution of new individuals should create novel opportunities for satisfying the MC
  • Condition 3: Decisions about how and where individuals interact with the world should be made by the individuals themselves
  • Condition 4: The potential size and complexity of the individuals’ phenotypes should be (in principle) unbounded

My question
Must these conditions be met for open-ended evolution to occur? If so, do we have evidence that all of these conditions fulfilled in nature? If not, could you give examples where one or more conditions are violated?

  • $\begingroup$ Could you clarify point 2 for me please, individuals don't evolve. Do you mean that mutations/immigrants is allowed to affect variation in fitness? $\endgroup$
    – rg255
    Jan 10, 2016 at 11:11
  • $\begingroup$ Also on point 1, in principle open ended evolution can occur without a minimal criterion. If all individuals within a population contributed the same number of offspring to the next generation then there would be no minimal criterion (no variance in reproductive output through i.e. no drit or selection) but evolution could still occur by mutation. $\endgroup$
    – rg255
    Jan 10, 2016 at 11:15
  • $\begingroup$ @rg255: I don't want to unnecessarily inflate this post but you can find a clarification in the linked paper on page 3 where condition 2 is explained in a short paragraph on the left hand side. The example given therein is about giraffes. $\endgroup$
    – vonjd
    Jan 10, 2016 at 11:17
  • 2
    $\begingroup$ Even reading that paper I can't figure out what they mean with condition 3. Do they mean the individual is completely free to interact with all of its environment? $\endgroup$
    – YviDe
    Jan 10, 2016 at 15:01
  • 2
    $\begingroup$ @vonjd Please read Why is voting important?, especially the last paragraph. Additionally, mouse over the vote buttons on both questions and answers and read the tooltips that pop up. Voters are under absolutely no obligation whatsoever to explain their votes if they don't want to, instead relying on the tooltips to do the explaining for them. They may also comment and/or edit with improvements, if such a thing is possible and they have the volition. Demanding explanations for every downvote is not a generally-accepted practice. $\endgroup$
    – MattDMo
    Jan 10, 2016 at 16:20

1 Answer 1


In principle open-ended evolution can occur with condition one violated. Because evolution is simply a change from one generation to the next (see answers here, here, and here), the is no requisite for a "non-trivial minimal criterion". Such a minimal criterion (e.g. survival to sexual maturuity) would imply that evolution is occurring by drift or selection, because being non-trivial implies that some members of the evolving population will fail to reproduce. However, evolution also occurs by mutation (and migration).

For example, we can have a population at generation $1$, and each individual within that population produces one offspring, present in the next generation. This means no variation in reproduction exists. If generation $2$, the offspring of generation $1$, carry new mutations then the characteristics of generation $1$ and $2$ can differ, and the descendant generation has evolved from the ancestral state. This can be seen in mutation accumulation lines as an example:

"In a typical mutation accumulation experiment a single inbred and highly homozygous line is replicated. Each of the replicated lines is maintained at a very small population size (usually brother sister mating, or in plants, selfing). These lines are maintained for many generations. During that time mutations accumulate, and the lines generally decline in fitness, and the variance among lines increases." - UVM Blog

So the answer to your question, these conditions are not necessarily met in nature. However, that doesn't mean evolution can't be open ended - the conditions outlined in the paper are flawed when trying to compare to nature. Evolution can occur when the "minimal criterion" is trivial (when all individuals are capable of meeting the criteria). The existence of a non-trivial MC only implies drift (e.g. some don't reach survival to sexual maturity by bad luck) or selection (e.g. some don't reach sexual maturity because they carry a genetic disease which kills them first). A trivial MC says that there is no drift or selection, but says nothing of mutation. I have since spoken with one of the authors who describes a non-trivial MC as the same thing:

"Regarding nontriviality, it should at least be possible that some individuals do not meet the MC"

Note: I have only focussed on condition 1, because this condition is not necessarily met in nature, thus your question is answered (are all conditions satisfied in nature)

  • $\begingroup$ I am now in touch with the authors of the paper. A big problem seems to be that there are different definitions and approaches in the biology and the Alife community. So I guess from a biological point of view (so to speak) your answer makes absolute sense and therefore I undownvoted it and upvoted/accepted it. The authors gave me another paper which might also be interesting for you to understand their point of view a little better: eplex.cs.ucf.edu/papers/lehman_alife14.pdf $\endgroup$
    – vonjd
    Jan 14, 2016 at 15:31
  • $\begingroup$ @vonjd I also reached out to the authors for clarification of their non-trivial MC - see edits $\endgroup$
    – rg255
    Jan 19, 2016 at 14:36

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