Yeerk Evolution

[MoppingBear]

This one confuses me a lot more than andalite evolution.  How did a species evolve to be intelligent with virtually no sense.  Even if you grant convergent evolution on all planets leading to most species being infestable, how did the ability evolve in the first place?  IIRC the gedds are the only infestable species on the homeworld, and they are clumsy and not very physically capable, so it would not have been too evolutionary advantageous.  They are also described as not being intelligent, even at present, so they are not a likely source for yeerk intelligence.

[Bustercloud]

They'd have to involve some form of intelligence and cooperation for them to really grow as a species. They'd need to be at least semi intelligent to get into the head of a creature that stands a few feet above them, and as a race in general the more cooperative ones would spread faster into hosts.

[voodooqueen126]

Well if you think about it evolution is all about efficiency: a species becomes parasitic for food or for reproduction, why would you become parasitic for eyes.

[voodooqueen126]

at the beginning of Hork-Bajir Chronicles, Esplin makes pretty clear that he was born after the yeerks left the homeworld. they left Yeerk homeworld in 1966 and arrived on HB homeworld around 1968, which makes Esplin around 2 earth years old at the beginning of the yeerk war. but he makes pretty clear that he is an adult and has full intellectual capacity. one could say that this is a result of different levels of maturity for yeerks-that they reach intellectual maturity at 2. but this doesn't make sense: intellectual maturity doesn't just automatically happen as we age at least in sentient species.

When I was younger I always said that next year I will do well at school and grow up, but it never did: each year I was as hopeless as I had been the year before. Because maturity don't just happen as a result of age, though ageing plays a role as your emotions (which are based on hormones) become less intense with age, it is not the sole cause of intellectual maturity.  The real causes of maturity are experience and education which must be gained over time. This has been observed by anthropologists who note that primitive people have a 'child like' way of thinking (politically incorrect as it is say so these PC times) a more tragic example would be Jaycee Dugard, who hasn't had any experience except trauma or education since the age of 11. Her step father noted that she said on the phone 'I have babies!" when her children were in their teens. her lack of experience and education has trapped her intellect at childhood. So how are Yeerks (like Esplin) able to grow up in such a short period of time.

[Homiegee]

IIRC the gedds are the only infestable species on the homeworld, and they are clumsy and not very physically capable, so it would not have been too evolutionary advantageous.

Perhaps at one point in the Yeerks' evolution, which could be assumed to occur over millions upon millions of years, there were more types of species suitable for infestation on the Yeerk homeworld. Species which may have been more intelligent or physically capable than the Gedds. Then later on, some form of mass extinction wiped most of these other species out save for the Gedds, but the Yeerks still retained the ability to infest hosts.

As for the source of Yeerk intelligence, perhaps it evolved in competition. As Yeerks are useless in their natural states, their intelligence rather than their physical fitness is what enabled them to be competitive with other Yeerks, so it was a trait which was chosen for.

[MoppingBear]

except there is no reason for it. intelligence takes energy to maintain. the yeerks are "photosyntehtic" and spend their natural lives in a yeerk pool just soaking up rays floating around. since they have no real means to experience the world, barely any motion capability, and no need to find food, they dont really have a need for intelligence.

[Jess]

And yet they are.

Which has made all the difference.

[voodooqueen126]

Well they don't need intelligence, intelligence is high maintanaince and if you don't need it you won't evolve it. the reason smart people are stereotyped (Not necessarily accurately) as being weak on Earth is that intelligence fulfills the purpose of physical strength in industrilised societies in that it should enable you to earn more and have more children... if you're life is basically photosynthesising and swimming why evolve a brain?

[Azguard]

 What i wonder is how the ability to infest occurred in the first place. Its not like Gedds, or some other animals, or just lying down in the pools by the masses, long enough for generations of Yeerks to start retaining that trait...

[DinosaurNothlit]

How I look at Yeerk evolution is by noting that, between Gedds and Yeerks, the relationship is actually not a parasitic one.  They have a true symbiotic relationship, beneficial for both species.  The Yeerks get the Gedd's body, the Gedds get the benefit of the Yeerk's intelligence.  Win-win.

What i wonder is how the ability to infest occurred in the first place. Its not like Gedds, or some other animals, or just lying down in the pools by the masses, long enough for generations of Yeerks to start retaining that trait...

Actually, they probably did exactly that.  As I said above, it would actually be to the Gedds' benefit to be infested by Yeerks, since they're barely even self-aware otherwise.  Thus, the Gedds that happened to fall down near Yeerk pools and get Yeerks in their ears would have an evolutionary advantage over ones that did not.  Ergo, that trait would be selected for, and pretty soon you have a species that actively seeks out Yeerks.

Well they don't need intelligence, intelligence is high maintanaince and if you don't need it you won't evolve it. the reason smart people are stereotyped (Not necessarily accurately) as being weak on Earth is that intelligence fulfills the purpose of physical strength in industrilised societies in that it should enable you to earn more and have more children... if you're life is basically photosynthesising and swimming why evolve a brain?

By that same token, though; why not?  It's true that intelligence is an expensive trait, yes.  And it wouldn't be evolved for no reason.  But the fact that Yeerks photosynthesize their energy means that they would be able to maintain the energy needed for their intelligence much more easily than a species that had to find and eat their food.  And, FYI, Yeerks did not spend all their lives swimming.  They spent their lives inside Gedds, so their intelligence was hardly wasted.

You simply cannot look at the Yeerks' evolution and the Gedds' evolution separately.  As separate species, neither of them would have ever evolved.  Just as flowers and bees would never have evolved if the other didn't exist.  It's the pairing between them that made both species possible.  Yeerks, because they don't have to spend energy on finding food or developing a physical body, can devote all their energy to their intelligence.  And Gedds, because they did not have to devote any energy to intelligence, could easily find food and develop their physical bodies.

Perhaps at one point in the Yeerks' evolution, which could be assumed to occur over millions upon millions of years, there were more types of species suitable for infestation on the Yeerk homeworld. Species which may have been more intelligent or physically capable than the Gedds. Then later on, some form of mass extinction wiped most of these other species out save for the Gedds, but the Yeerks still retained the ability to infest hosts.

That sounds very plausible.  And that would explain why Yeerks can infest the wide range of species that they are able to infest.

[Visser Phi]

That's a pretty good analysis, DinosaurNothlit, of what's in it for the Gedds. You're right that an infested Gedd would have more reproductive success than an non-infested one, and it's easy enough to see why.

I'm curious about your thoughts regarding what the benefit was to the Yeerks, though. Only traits that encourage successful reproduction are passed down, and Yeerks reproduce through some kind of fusion in the Yeerk pool. Surely it would be easier for them to reproduce if they, well, stayed in the Yeerk pool, rather than infesting Gedds and wandering away from it? There's also no obvious reason why intelligent Yeerks would reproduce more successfully than non-intelligent Yeerks, unless Yeerks were prey for some creature that they had to continually outsmart. Even if that were the case it's unclear what the Gedds had to do with any of it.

One possible solution I came up with is that Yeerk reproductive hormones are environmentally dependent, and only kick in when the population density is low enough. When the population density of a Yeerk pool is too high, having babies would be a drain on the already taxed resources, so in crowded pools Yeerks simply don't reproduce. This is where the benefit (to the Yeerk) of being able to infest a Gedd comes in. Yeerks who can infest Gedds can use them to migrate across land to different, less-crowded pools, and reproduce there instead. Or they can use Gedds to escape a pool that's stagnating for one reason or other, or is suffering from nutrient shortage, or is afflicted by some pandemic, etc.

[DinosaurNothlit]

Good points, Visser Phi, but I would think of it not just in terms of reproduction, but also of survival.  Any creature as helpless as a Yeerk is would be EXTREMELY vulnerable to any kind of predator.  Remember the Yeerkbane from book #2?  It was said to be a predator from the Yeerk homeworld that sucks Yeerks right out of their hosts.  Now, for a predator to go to such extreme lengths to eat Yeerks, I'd draw the conclusion that Yeerks are really, really, really tasty.  And they're probably full of all kinds of nutrients, considering that they spend all day literally soaking in their food.  A pool full of helpless slimy delicious wads of nutrients would be any predator's dream come true.  Being in a Gedd gives a Yeerk protection from predators.  Yeerk pools, full of unhosted Yeerks, are practically all-you-can-eat buffets.

And you also made the point that being in a Gedd would allow Yeerks to be more mobile, and that's probably true, too.

[MoppingBear]

pretty good points.  it would even explain why gedds evolved with 1 leg shorter than the other, specifically to make them less stable and more likely to fall into the yeerk pool.  perhaps at that point, the yeerks couldnt really control hosts, they were just along for the ride, but those that could control were more reproductively successful because they were able to move out to other pools.

[voodooqueen126]

Nate the Ape made the argument that being infested by the yeerks caused the Gedd's to De-evolve.

[DinosaurNothlit]

pretty good points.  it would even explain why gedds evolved with 1 leg shorter than the other, specifically to make them less stable and more likely to fall into the yeerk pool.  perhaps at that point, the yeerks couldnt really control hosts, they were just along for the ride, but those that could control were more reproductively successful because they were able to move out to other pools.

I was just thinking about that.  And actually, that's probably only why Gedds started evolving that way.  After they 'learned' to seek out Yeerk pools, their instincts would eventually evolve so that they would lay down next to the pools, and have no more need to fall over.  And, in fact, a Gedd-controller who still fell over all the time would be pretty maladaptive.  I think it's probably more likely that they evolved that way so that they could support themselves with one arm, and manipulate objects with the other.  Really, when you think about it, sentient creatures only really need one hand, anyway.

And having a hand to manipulate objects is, of course, extremely adaptive.  Yeerks, intelligent as they are, once they evolved hands, would be able to build defenses around their Yeerk pools to protect their fellow, unhosted Yeerks from predators.  They would need their hands to dig trenches, erect torches, or whatever it is they do to deter predators.  And that's probably how the Yeerk pools are not just constantly attacked by hungry predators, because they're guarded by Gedd sentries.  Which is, of course, yet another reason why taking hosts is adaptive to the Yeerk population.

Voodooqueen, that's probably somewhat true.  I mean, look at humans.  We became intelligent, and then promptly lost any physical features that might be adaptive.  Fur, claws, sharp teeth . . . anyway, the Gedds probably did the same thing when they became 'intelligent' via Yeerks.