This is another question about my aliens who have both reptilian and mammalian characteristics.

Now, I'm not talking about developing intelligence on evolutionary time scales but rather within something like 20 years.

Now if it is possible to develop intelligence on a small time scale here is what I figured for the size and intelligence level over time:

A hatchling would be about the size of an adult crested gecko(8 inches long) and not very mobile. Its brain would be mostly auditory right after hatching because so much processing goes on in the auditory center. Besides that, most of the brain triggers reflexes. No worries about heat because even though they are cold-blooded, they don't have to bask until later on, they get their heat from their mom. So they wake up after the mom has basked in the heat.

At 3 months, when it is about 10 inches long(about the size of an adult leopard gecko) and has decided which nipple to suckle from, it is still not very mobile but the brain development has really started

At 6 months, when it is 24 inches long(about the size of a bearded dragon, it has become more mobile and can walk on all fours. It is about as intelligent as a mouse(that is to say, not very intelligent). This is when they start having to bask.

At 2 years, when it gets to the size of an iguana, 3 feet long, it has an intelligence level similar to that of a cat. This is when the legs start to get a growth spurt and it gradually goes from obligate quadriped to facultative quadriped and then finally to obligate biped

At 6 years, when it gets to the size of a monitor lizard, 4 feet, it has an intelligence level similar to that of a dog.

And then over the next 14 years, intelligence level grows way faster than the size of the alien and it reaches the intelligence level of humans.

But is this plausible for a creature to go from almost no intelligence to the intelligence level of humans in 20 years? How would being cold-blooded(which they are) affect intelligence?

  • 1
    $\begingroup$ Are you talking about intelligence development in species or in an individual? Your timeline is not very different from how human child is developing. $\endgroup$
    – Alexander
    Jul 10, 2018 at 22:24
  • $\begingroup$ I mean in an individual. I thought that was already clear with me having the timeline and saying that the intelligence development was in 20 years and not evolutionary timescales. $\endgroup$
    – Caters
    Jul 10, 2018 at 22:32
  • $\begingroup$ Then this is already working in humans - why do you think it won't work in reptiles? $\endgroup$
    – Alexander
    Jul 10, 2018 at 22:40
  • $\begingroup$ Well, I'm just wondering if it is possible for a reptile to go from almost no intelligence to human-level intelligence. I thought that maybe being cold-blooded would be strongly against developing intelligence given that metabolism would only be relatively fast when at a certain temperature and in a cool environment the metabolism would gradually slow down. After all, metabolism is the source of heat in warm-blooded creatures like humans. Wouldn't slow metabolism and being cold-blooded stop intelligence level from gradually going from almost none to human level intelligence? $\endgroup$
    – Caters
    Jul 10, 2018 at 23:02
  • $\begingroup$ So, your scenario is that parent generation has no intelligence, but children (all children?) suddenly develop human-level intelligence? $\endgroup$
    – Alexander
    Jul 10, 2018 at 23:08

1 Answer 1


Yes it is plausible. Although geckos aren't necessarily creatures with no intelligence. While they certainly couldn't pass an IQ test, that doesn't make them dumb. (Yes, that was a joke.)

As an example, humans have to increase the size of their brains post utero, basically because we're overendowed in the brain department, and if we were born with fully developed the mothers wouldn't survive child birth. This is a broad generalization, but it will suffice.

There is no reason why a species couldn't evolve where brain development increases radically over the growing up phases of the organism's life in its development from, effectively, infant to adult phase. There is no need to comment on the environment where the requisite natural selection pressures result in such a creature. But it is biologically plausible.

There is one caveat. Such a creature will need to consume a lot of food to grow its brain, but considering its body size is also increasing radically as well this is not implausible. In fact, it makes sense. Big brained creatures need a lot of metabolic energy to maintain brain function. As adults they will need to eat lots.

It is noted your aliens are poikilotherms (that is, in common parlance, cold-blooded) during their early stages of development. This will mean their metabolic activity will rise and fall with temperature. This will impact on their levels of brain function too. They might function better if they acquired homothermy (that is, hot-blooded) during their adult stages. There's no point them becoming slow-witted when the temperature. Not unless you want to use this concept as part of your story.

Being homotherms will also increase their need for additional food for the energy to maintain a stable body temperature.

  • $\begingroup$ But how could a reptile go from being cold blooded to being warm blooded as it develops? That seems like an impossibility. $\endgroup$
    – Caters
    Jul 11, 2018 at 14:37
  • $\begingroup$ @Caters Not impossible. An organism that was initially cold-blooded could develop, as it grew, in relation to this example, to its adult stages, the regulatory mechanisms necessary for it to become a functionally hot-blooded. It may sound remarkable, but it is merely a matter of an organism following the requisite developmental path. It may be improbable, but that doesn't make it impossible. $\endgroup$
    – a4android
    Jul 12, 2018 at 7:28

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