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I've been dreaming up what I would consider to be an "ideal" sentient being and there have been a variety of fantastic responses to some of my other questions that got me re-examining my design.

First, let me give you a very brief description:

Reptilian/avian in basic external and internal biological structure.
About the size of an armadillo, stands upright with a tail for support and balance, opposable thumbs, three other fingers. And, much like an armadillo it would have an exterior shell, however more like a segmented turtle shell that it can escape into.
Cuttlefish-like eyes that allow for seeing polarized light.
Densely packed neural clusters in the brain like parrots, so in an animal the size as described above, about the same intelligence as a human.. just much older.
Naturally occurring anti-freeze agent in the blood stream, much like the leopard frog, and the ability to slow down their metabolism like a painted turtle to a point of using almost no oxygen for long periods of time (months, potentially longer).

Anyway, all of these things could potentially come about naturally in the right kind of environment (long periods of darkness/cold followed by long periods of light/heat, unsophisticated predators, etc,).

My problem is, at what point of an intelligent species evolution do the rigors of the terrestrial living no longer apply and begin to revert?

Take humans for example. We are relatively hairless, have very poor teeth for killing prey, etc. We have hands to catch food with, and can build shelters so we are by and large weak compared to other animals that still rely on their speed/camo/shells/eyesight/etc. to survive.

Could my invented species exists in the form described, or is it more likely that due to the time and evolution of their species after mastering the use of their hands they would begin to devolve?

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    $\begingroup$ "Revert" is entirely the wrong way to think about this sort of thing. E.g. human hairlessness is (probably) a POSITIVE adaptation to running in a hot climate - humans being about the best hot climate long-distance runners around. Teeth are an adaptation to an omnivorous diet, human eyes have better color & distance vision than many mammals as adaptations to eating fruit and living in open savanna... $\endgroup$ – jamesqf Feb 3 '17 at 18:06
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    $\begingroup$ So long as these traits increase your chance to reproduce in any way, they will remain, and if they don't hinder your chances of producing offspring, they will linger for many generations (why do we still have an appendix? nails?). So long as your creatures hunted some camouflaged prey that could easily be spotted with polarized vision, and had to survive harsh winters and dumb, fast predators until a few hundred generations ago, they'll still have these traits. $\endgroup$ – Swier Feb 3 '17 at 18:20
  • $\begingroup$ For the record the ability to allow one to 'freeze' themselves, or even drastically lower their metabolism, doesn't really fit with sapience. To be able to survive freezing the creature must be cold blooded to begin with. however, a cold blooded species that responds to shortages by hibernating/freezing is one that conserves energy wherever possible. Intellect has a very high resource cost. Evolutionary traits all built around conservation of energy don't seem to fit well with a species that 'wastes' resources on intellect, their kind of the opposite approach for addressing limited resourc $\endgroup$ – dsollen Feb 3 '17 at 22:14
  • $\begingroup$ I don't think the question is bad, but rather worded wrongly. As people pointed out you don't revert you just simply change and adapt to the new environment. We may lose intelligence or skills in some areas because machines and computers do that for us now, but we pick up knew knowledge and ability to operate those machines and computers and pick up new traits. $\endgroup$ – ggiaquin16 Feb 3 '17 at 22:43
  • $\begingroup$ @dsollen: I dunno. Bears are pretty smart, yet they hibernate. FTM, humans - even smart ones! - tend to spend about a third of their lives in a state of lowered metabolism. $\endgroup$ – jamesqf Feb 3 '17 at 22:45
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There is no "devolving" in science. Everything just drifts in the general direction of being better fit for the environment. And the environment changes all the time. You can imagine this as eternal dance.

So, after what time intelligence would start to be hindrance instead of a bonus? We only know one species that for sure is intelligent - us. That's horribly small sample. There also were Homo neanderthalensis, and other Homo species, but wasn't here long enough.

For us, with our tools and our intelligence, we transform our environment. Pressures that made us smart are long gone. But we seem to keep our intelligence, gain more of it, even. Why? Because we create our own evolutionary pressures. Humans have to be successful, tricky or something to find a mate and have children. And to make children's life good enough for them to survive.

There is no reason for other intelligent species not to be able to change their environment and create evolutionary pressure for intelligence. It is safe to assume that they will be quite similar in that aspect.

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    $\begingroup$ @Mrkvička my answer to that and will always be, remove the warning labels. If you are dumb enough to try it whether to sue or not, you probably shouldn't make babies... but that aside I disagree with you on some points. We may lose intelligence in some areas but we gain it in other areas. Take a look at jobs for example. More and more manual labor jobs are being replaced by tech jobs or jobs that oversee robots doing their old jobs. So we adapt from manual labor to managerial/tech jobs. The key is, are we losing intelligence in aspects of life that we still need. $\endgroup$ – ggiaquin16 Feb 3 '17 at 22:37
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    $\begingroup$ @Mrkvička from generation to generation, IQ tests give higher results. Somehow, it's still working, for some reasons. $\endgroup$ – Mołot Feb 4 '17 at 7:53
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    $\begingroup$ @ggiaquin Well, emotionally we may be weaker. I don't know, and I think it's out of the scope of this question. $\endgroup$ – Mołot Feb 4 '17 at 7:54
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    $\begingroup$ @Mrkvička shrinking brain isn't always a bad thing. A brain after all is just a muscle. Take a look at body building vs sport athletes. One can argue that a body builder is useless because they have too much muscle and cant do basic things like wiping their butts. While they are certainly big and strong, the overall bulk is excessive. A sports athlete by comparison is slimmer a lot less muscle but in many ways just as strong and a lot more practical to many areas besides weight lifting $\endgroup$ – ggiaquin16 Feb 4 '17 at 13:34
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    $\begingroup$ @ggiaquin That is a good point, and I sure hope that we're honing our brains rather than just losing grey mass. We will know in a few generations from now where we're actually headed; should it turn out that we are indeed losing too much brain for the best of our species, then I guess (hope) we can fix it manually through genetic modifications by then. $\endgroup$ – Mrkvička Feb 4 '17 at 19:40
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Unless there is a vast DISADVANTAGE to the shells or any of the other characteristics, they will still have them. OR if they interfere in any way with a ADVANTAGEOUS trait.

For example, the jaw bite strength of the great apes is better than ours. You would not think that that is connected to brain capacity, but it is.

I can see the anti-freeze blood, system shut down being one of the things to go, because I can't see higher brain function being preserved in the low-oxygen state. (I'd give them a lesser form of it. Human beings still have jaw strength, it just doesn't compare to their cousins'.)

Look at their characteristics and ask yourself how any of those could be a DISADVANTAGE and how any of them might get in the way of the ADVANTAGE of higher intelligence and a different environment.

Therefore, they might not be able to get their heads in the shells anymore, at least not well--if they evolved to have a higher brain capacity than their less evolved counterparts (even if they have special neurons and what not. space is space.)

Also, tails. Once an animal is largely walking upright, the tail goes. If they are on all fours more often, then they keep it. You can see this with the apes (our closest relative which has a more upright posture than monkeys). The upright posture and the skeletal structure means that a tail actually doesn't help with balance once they stand up.

Human eyesight, by the way, is actually very good in the animal kingdom. It's geared for daylight, mainly, but we actually see more colors than most predators, which served us well for the berry picking, determining ripeness and if something was poison. You might say cats have better vision--and they do, when it comes to movement and night vision. But during the day, we see better than they do, and in colors that they can't see. By that measure, we have the better vision.

The eyes of your armadillos will likely remain the same or pretty close, if we are using humans as the model.

Dichromats may be better at "breaking the camouflage of predators and prey," but trichromacy is advantageous for gathering. (There's actually a difference between human men and women--more men are colorblind than women, more women can tell the subtle difference between colors. Females, by and large are better equipped to gather, and men to hunt).

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    $\begingroup$ I'd also think the shell would go. If you have a big enough brain to recognize and avoid danger, why spend a bunch of energy forming a hard protective shell? Every biological system "costs" something to grow or maintain, and biology is lazy (ok, some would say super efficient). If it takes energy to make/grow/create, evolution will find a cheaper way (or a way that doesn't require eating so much) to do the least possible. $\endgroup$ – Tim Feb 3 '17 at 20:29
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    $\begingroup$ @Tim Yes, I would think the shell would be =fur on humans. We still have hair, but we don't have fur anymore. So mayhap it wouldn't be there in the full form, just partially. It might not offer as much protection. Also, shell and upright posture--I am going to say it would be tough to have both. $\endgroup$ – Erin Thursby Feb 4 '17 at 6:46
  • $\begingroup$ @Tim - I suspect you have it backwards. With a good shell, there is less advantage to developing intelligence (as we define it). Combined with antifreeze, for instance, there is little reason to invent fire. Come darkness and cold weather, you just pull into the shell and wait it out. $\endgroup$ – WhatRoughBeast Jul 28 '17 at 11:25
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    $\begingroup$ @WhatRoughBeast Not backwards, just different. If the shell is the thing that offers the best survival advantage for the least energy, it would stay (possibly at teh expense of the brain). If the brain requires fewer resources to build and maintain than a shell, it would stay (possibly at the expense of a shell). Nature doesn't prefer brains over shells. Nature prefers efficiency. Nature is all Function over Form. Even if the Form appears disadvantageous (think peacocks), it aids survival (cuz big feathers get more tail). Maybe the OPs males get more nooky if they have brains and shells! ;) $\endgroup$ – Tim Jul 28 '17 at 12:34
  • $\begingroup$ @Tim Great point that I didn't think of.. selective breeding to maintain all desired traits. Kind of like the breeding program in the Dune book series. $\endgroup$ – mkinson Jul 28 '17 at 15:45
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So, as someone said, there's no such thing as devolving, just a better fit for the environment. The idea that something is "more highly evolved" is a bugbear of biologists. Just ask one of them and they'll rant at you. Lots. Bacteria, for example, have more generations, so they've probably gone through more evolution than we ever will. We are more complex, but not more highly evolved than bacteria.

Environments can be full of changes that encourage complexity or not, and plenty of animals have gone "backwards" in complexity terms. Yet, sometimes, not all is lost. For example, fish versus aquatic mammals like dolphins and whales, in which mammals keep a lot of their complexity on the inside, while on the outside being pretty identical (functionally) to fish. Sometimes going backwards rom a more complex place can help you solve problems better.

This also leads into the phase space adjacent. So, the path through the space of all possible types of creatures (the phase space, in science), matters a lot to where you end up. Evolution can't really jump, it can only move towards phase spaces adjacent, so as long as you can trace an evolutionary path that makes sense (i.e. your species doesn't suffer from having something, but a while ago, it was vitally important), you'll never see a loss of that complexity. This point was made by things we have that are pointless but never got rid of, like our appendixes.

Also, sometimes useless or niche things turn into suddenly useful things. So, there's the belief that birds came to be because feathers were used for display and maybe insulation, while some dinosaurs learned to glide between trees. These bridged the gap between not flying and flying.

So, for your species, you probably want to have a bunch of things that have happened or are happening that would cause them to develop like you wish. For some traits that are historical (e.g. fish have vertical tails, aquatic mammals have flat tails), these will persist for a long time, since it really doesn't matter and the evolutionary difference is small, but other traits need constant selection. So, it's worth identifying any that are one or the other and, for those, making sure that the environment provides the constant stimulation they need.

I think with yours, most of the traits would be prone to constant change, with maybe an exception of polarisation and shells. Anyway, here's some stuff I thought might work as an example:

Anti-freeze and hibernation - any environment with extremes of temperature or water would give rise to this, so you're probably looking at a planet with some really weird variable stuff going on (high eccentricity, maybe, high inclination), to keep this level of complexity in the gene-pool for everything. It would be unlikely to have your species evolve from one of the more extreme environments, but if all animals are similarly disadvantaged, it's not a problem. (Also, the book Three Body Problem comes to mind, there's a planetary environment that's extreme enough to cause issues that force all life to hibernate)

Polarised light - As long as there's a situation where they developed the polarised light as a defense mechanism or hunting mechanism, this would also stay in the gene pool. So, polarised light is meant to be good at glare, so that might be a helpful mechanism in dealing with a planet with extremes of sunlight. Alternately, there may be something (e.g. dust, water vapour) which polarisation helps to cut out, or it was super-useful to their immediate ancestors.

Shells- if you have an extreme environment, these might still be quite useful. If there are intense radiation flares or sudden extreme rains due to temperature variations (e.g. sudden hail) then most animals would have shells for a very long time.

Size - if the extremes can also favour small animals and put a ceiling on size, you'd likely prevent human-scale.

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I think you are thinking about evolution in the wrong way. Evolution is the passing on of traits and the mutation of genes. The reason it seems to be adapting is that beneficial traits allow things to out compete those that get negative traits. And when you get out competed in the wild, you usually don't pass on your lower quality genetics.

So if the trait is attractive to other members of the species, it should get passed on. It actually doesn't matter how useful/not useful the traits are, if they are surviving to a breeding age(and actually breeding), the trait will be passed on.

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  • $\begingroup$ I agree with your analysis, but as written, it's not directly connected to this question. How does this answer the question of "How long before evolutionary traits revert or change?" Please edit additional information into your answer to address that question. $\endgroup$ – Brythan Jul 28 '17 at 0:39

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