Could any animal subject to the right conditions evolve human-level intelligence? Suppose that an artificial intelligence (AI) decided to artificially evolve a population of octopus (don't ask why, its for science) by restricting them to calculated environmental pressures, and over millions of years, the AI manages to produce a relative of the octopus that has a similar level of cognition to humans. Is this possible? If it is possible, what are some steps (in general) that might be required to evolve a complex animal brain (to human-level cognition or beyond)?

  • $\begingroup$ I think this question is far too broad and answers will probably be opinion-based/speculative, and have therefore voted to close. $\endgroup$ Commented May 26, 2015 at 12:55
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    $\begingroup$ @fileunderwater - I disagree. There are many factors identified that have resulted in the development of the human brain. Particularly the cerebral (neo) cortex is associated with higher cognitive skills; the subcortical structures have been very stable during evolution. No need to close this one. The formulation may be a bit awkward (OP is a computer scientist I guess, explaining the question pitch) but i see no reason for closure. $\endgroup$
    – AliceD
    Commented May 26, 2015 at 13:17
  • $\begingroup$ @AliceD Just because something is answerable in some kind of shape and form(at) doesn't mean it is a good fit for the site. This is spanning from neurobiology to evolution, natural selection and evolutionary constrains, is very speculative, and is asking if this scenario is "possible" (by definition "opinion-based"). I just think it is problematic to keep these kinds of questions open, if we aim to treat all questions in a consistent way. However, users of the site will decide if this should be kept open. $\endgroup$ Commented May 26, 2015 at 13:50
  • $\begingroup$ @fileunderwater, you might be right, I agree it is a bit of hazy question... It's just interesting stuff. Perhaps i am biased. Perhaps not. I could make a bash at re-writing this question into something more rigid, but somehow I don't like the idea of that... $\endgroup$
    – AliceD
    Commented May 26, 2015 at 13:55

1 Answer 1


Answering the question what is needed for a human brain to evolve starting from a cephalopod brain is hard. However, I can expand on what is thought to have been the driving forces behind the evolution of the humanoid brain (Hawks, 2013):

The species of the famous Lucy fossil, Australopithecus afarensis (~3-4 mln yrs ago), had skulls with internal volumes of between 400 and 550 milliliters, which is comparable to chimpanzees and gorillas. Australopithecine brains started to show subtle changes in structure and shape as compared with apes. however. For instance, the neocortex was expanding, which is an indication that the evolutionary pressure on higher functions of the brain was important.

Homo habilis, the first of our genus Homo, who appeared 1.9 million years ago, saw a modest hop in brain size, including an expansion of a language-connected part of the frontal lobe called Broca's area. The first fossil skulls of Homo erectus, 1.8 million years ago, had brains averaging a bit larger than 600 ml. This shows that language development is a likely factor that has driven evolution of the human brain.

By 500,000 years ago, the humanoid brain reached a volume of about 1,000 ml. Early Homo sapiens had brains within the range of people today, averaging 1,200 ml or more. It is thought that cultural and linguistic complexity, dietary needs and technological prowess took a significant leap forward at this stage, and that our brains grew to accommodate the changes. The shape changes we see accentuate the regions related to depth of planning, communication, problem solving and other more advanced cognitive functions.

Interestingly, in the past 10,000 years of human existence the brain actually shrank. Limited nutrition in agricultural populations may have been an important driver of this trend. Industrial societies in the past 100 years, however, have seen brain size rebound as nutrition increased and disease declined (Hawks, 2013).

Indeed, one of the driving components behind the expansion of the human brain is increased availability of fatty fish to sustain the large amounts of fat needed in a brain - survival of the fattest (Cunnane, 2006).

Although the past does not predict future evolution, a greater integration with technology may lead to further expansion of the human brain (Hawks, 2013).

- Cunnane, Med Sci (Paris) (2006); 22(6-7):659-63
- Hawks, Sci Am (2013)

  • $\begingroup$ but "what are some steps (in general) that might be required to evolve a complex animal brain"? $\endgroup$ Commented May 25, 2015 at 2:20
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    $\begingroup$ The bolded-out points in my answer are some essential human skills on which evolutionary pressure may have had its effects driving evolution (as to the question title: requirements). I have, admittedly, not directly attempted to answer the question what steps are needed. I find steps needed a vague term, and open for various interpretations (spanning molecular level to anatomical levels). Instead, I have focused on the what was important for early humanoids and how did that affect the brain. This is less opinion based from my point of view. $\endgroup$
    – AliceD
    Commented May 25, 2015 at 2:30

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