In my story there are future humans that managed to build a time machine and for research purposes and decided to travel back in time to change past events from taking place. These future humans have a unique anatomy where they have evolved large brains with a head that is roughly around 25% (1/4) of it's own body length. On average they have a height standing about 5ft tall. What I would like to know is What type of mutations or evolutionary processes would be needed for these changes to take place and how many years would it take for these changes to occur?.

Head size proportions Future human with large head

  • $\begingroup$ Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer. $\endgroup$
    – Community Bot
    Nov 16 at 18:18
  • 1
    $\begingroup$ (a) You are allowed one and only one question per post. (b) Questions must be specific, objective, and scoped per the help center. (c) There must be a hope of a best answer. We're barely scratching the surface of evolutionary development. Thus, it would help to know why increasing intelligence, the devleopment of psionic powers, etc. (the traditional reasons for comic-book big heads) aren't justification enough for your needs? $\endgroup$
    – JBH
    Nov 17 at 2:58


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