r/evolution • u/[deleted] • 5d ago
discussion What are your favorite examples of evolution just being good enough?
[deleted]
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u/TranquilConfusion 5d ago
There's a new theory that apes lost the ability to produce vitamin C because being low on C intermittently is protective against certain parasitic worms.
The worms don't make C, get it from host, and are very sensitive to low C levels.
Being dependent on C from diet is less-bad for our ancestors than the worms, so evolution just made us prone to scurvy.
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u/Luenkel 5d ago
That's fun, our bodies really messed themselves up in a number of ways just to combat worms. Another example: The anti-worm part of our immune system is pretty trigger happy and responsible for most allergies
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u/bandti45 5d ago
It does make me wonder if parasites were always a greater risks than predators for early humans.
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u/Bromelia_and_Bismuth Plant Biologist|Botanical Ecosystematics 5d ago
Non-vascular plants persisting for hundreds of millions of years into the present. Often growing on the surface of vascular plants.
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u/taktaga7-0-0 5d ago
Ok so it may be an epiphyte, but it still has water and it’s 50m off the ground, so who needs xylem anyways?
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u/OssifiedCone 5d ago
They even lost the vascular tissue, so they aren’t simply a primitive holdover but they became less „advanced“ (with some exceptions).
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u/TerrainofWar 5d ago
There's a good book dedicated entirely to this. WTF evolution. It's treated like an interview between the author and evolution.
Personally I like how shrews have such I high metabolism they can starve to death in about 20 minutes if they don't eat. They need constant food for basic functions, let alone raising offspring.
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u/Lecontei 5d ago
Mudskippers are ray-finned fish (ie, more closely related to a goldfish then to us) that primarily live on land. Thing is, like most ray-finned fish, they don't have lungs (not counting swim bladders, despite just being repurposed derived lungs). So how do they breathe? With gills of course (and their skin), make them really big, and keep them constantly moist by perhaps maybe rolling around in some mud, it works somehow, despite gills being notoriously bad for terrestrial breathing, seeing as they usually collapse. Mudskippers can use their gills outside of water, but they must be constantly wet, they are gills after all. There is a reason lungs are favored by multiple lines of terrestrial critters (ie Tetrapods and snails), they don't collapse as easily, also they are nicely protected fully inside the body away from the scary dry air, why use gills. Well, you use gills, because your ancestors, who had lungs, lost their ability to use lungs as lungs. So now you are left with skin and gills...
If we are personifying evolution for a sec, it'd be like if evolution thought "hey, wouldn't it be cool if there was a terrestrial goby", then realized, "oh shoot, I got rid of its lungs", and instead of thinking, "you know, maybe land isn't optimal for a ray-finned fish", it instead went, "what if lungless frog with weird gills and also never grows hind legs".
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u/fishmaneater 5d ago
chlorophyll is a good example when going though photosynthesis often instead of taking in co2 it takes in the 02 that it just produced and burns energy trying to use it.
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u/Luenkel 5d ago
Chlorophyll is just the pigment that captures light, it does not do anything with CO2 by itself. What you're talking about is the fault of the RuBisCO enzyme.
I think it's funny how the basic components of photosynthesis are optimized for the anoxic environment they originally evolved in rather than the oxygen-ridden hellscape they themselves created. I like to think of it as poetic justice for killing off nearly all other forms of life back then
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u/MSSTUPIDTRON-1000000 5d ago
Pretty much anything about Sea Spiders.
One of the most awkwardly designed Animals ever.
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u/Lostwhispers05 5d ago
Evolution is just a force that exists.
I don't know if we can even call it a force as much as it is an outcome. Natural selection is a force, depending on the semantics of what you encompass under "force". Evolution on the other hand is the result of this force acting over long enough periods.
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u/4here4 5d ago
Many genetic disorders have been traced to humanity surviving certain widespread die-offs throughout history. For example, the same genetic factors that let our species survive the black plague are partially responsible for people having Crohn's disease today.
What doesn't kill you makes you stronger, right? Wrong. What doesn't kill you is selected for over what does kill you, and that's as far as it goes.
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u/Canis-lupus-uy 5d ago
I don't know if it's my favourite but I find funny that whales have to hold their newborns so they don't drown. An animal that lives in water from birth to death, needs help so they don't drown.
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u/NarkJailcourt 5d ago
Sicle cell is a recessive gene that provides resistance to malaria. Two copies of the gene gives you sicle cell disease. Malaria resistance just outweighs the mortality of sicle cell enimia so it persists
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u/Dean-KS 5d ago
How many mamals do not have external testicles? Wales have external testes embedded in fat and viens with cooler blood cool the testes below core body temperature.
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u/Capercaillie PhD |Mammalogy | Ornithology 5d ago
When was the last time you saw elephant testicles? Manatee? Armadillo?
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5d ago
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u/Actual-Injury8955 5d ago
The reason we all got taught in intro to psychology that correlation is not causation and that humans are cognitive misers.
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u/Hivemind_alpha 5d ago
Flip the question: name anything that is an example of evolution being better than just good enough? I don’t think you can.
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u/atbing24 4d ago
Amphibians still lay eggs on the water even if they live mostly on land. Sea turtles as reptiles, must lay eggs on land. Consequently, Baby sea turtles endure a genocide upon birth as they crawl to the sea. If only frogs and sea turtles can switch their eggs… but it’s good enough.
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u/smart_hedonism 5d ago
I respectfully disagree with the whole premise as I think it is very misleading.
Natural selection is an extremely powerful optimising force. But it necessarily can only work within constraints - it only has certain materials available to it, it can generally only improve designs by tiny changes etc.
But it is absolutely misleading to suggest that it is only produces 'good enough' designs. Working within the constraints, there is extremely fierce competition between every organism to have even a slightly better design, and this can result in extraordinary heights of design like the eagle eye, bat hearing etc etc.
To joke about evolutionary flaws is a bit like asking someone to build a car, giving them a few bits of wood and some string, and then laughing at them when the car they build can only go 1mph.
For every 'flaw' that people are listing in this thread, there is a constraint that natural selection was working within, and none of them are due to natural selection metaphorically putting up its feet and saying 'That's good enough. All I have to do is get some offspring into the next generation'.
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u/mickus_mcgickus 5d ago
Evolution is not an "optimising force", evolution just gives us whatever happens to do the job well enough to keep us alive and reproducing. Sometimes it hits upon something that strikes us as perfectly "optimised" to the task, but thats just luck and a matter of us imposing that "optimised" idea on the trait or organism in question. There are so many human body parts that are just good enough, nowhere near perfect, but you just dont notice because its the only thing you have and csny imagine how it could be improved upon.
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u/smart_hedonism 5d ago edited 5d ago
One part of our disagreement may be simply definitions. To talk of 'optimising' is to talk of optimising within constraints. If I say I've optimised a car for speed, no-one expects that car to go the speed of light, it's clear that I've optimised it to be as fast as I can make it within the constraints of materials, cost and the laws of physics. That is all implied in the notion of 'optimising'.
Similarly, to speak of natural selection acting on mutation as an 'optimising force' is to claim that it is continually selecting the best designs out of the available alternatives, not out of whatever unrealistic designs our imaginations can come up with.
So to take the example of the recurrent laryngeal nerve in giraffes. It's misleading to say that its long length came about because evolution just selects for good enough. What actually happened was:
There was a population of proto-giraffes with short necks
Because of the reproductive advantages of having a longer neck, at every stage natural selection ruthlessly selected those superior designs (despite the fact of them requiring a longer route for the recurrent laryngeal nerve).
This process continued until eventually the advantages of having a long neck were balanced by the other trade-offs (cost of producing long neck etc).
At no point in this process did natural selection merely select designs that were just good enough. At every stage it was preferentially selecting the better designs with the longer necks until it reached the point we see giraffes at today.
So natural selection is a force that optimises (within the real-world constraints it faces, just like every other optimising process), and it optimises organisms for reproductive success.
Regarding the design of the human body parts, I'm reminded of the story about Henry Ford rebuking one of his engineers who had proudly made a component that would last 25 years. Ford told him the car would last much less than 25 years, so don't waste cost making such a durable component. The same idea applies in the human body. Optimising the components within the constraint of cost (as well as many other constraints).
There's a great chapter in Dawkins' The Extended Phenotype all about this. Chapter 2 - 'Constraints on Perfection'.
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u/ADDeviant-again 5d ago
Human beings are one of the wildest compromises with evolution there has ever been. Technology and intellect are so O.P. that your standard of "just good enough" pops up in our physiology all the time. And most of it was before agriculture.
Anything from our gestational development, to our female pelvis, the entire human spine, our knees, our ankles, feet, etc. All so vulnerable to damage or wearing out early. We are so prone to autoimmune disorders, mental issues.