r/NoStupidQuestions • u/Frosty-Influence988 • 3d ago
Why are Mammals?
The Mammalia Class always stood out to me because it devoted considerable amount of energy into its brain. Everything from Brainstem to Cerebrum. My question is, this does not result in an immediate advantage, so why did this type of trait, especially in primates, select for reproducibility?
Humans for example, have sacrificed motion range for exclusive bipedalism, which is pretty bad for knee joints as some 80% of all humans will experience that, so that we might have a more efficient brain. That is a very high short term loss for a long term gain. How and why did this happen?
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u/VersionFine85 3d ago
Evolution isn't intentional. It doesn't select for the best, it selects for good enough. If the mutation doesn't hurt the mammals ability to reproduce and the mammal is reproducing it'll pass on genes that don't affect its survival one way or the other.
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u/Frosty-Influence988 3d ago
I understand that, my question is why and how did higher IPC selectively managed to successfully reproduce compared to brute strength? The former is advantageous in the long term, but not short term. The latter is. You can be the most intelligent person in the world and fail at reproduction if you are punched to death by a gorilla.
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u/BoredWahahaMSWater 3d ago
Brute strength requires LOTS of resources. So it costs a lot before it pays off. If you can achieve the same with less investment of calories since you use your brain instead of your muscles it leads to higher chances of survival and reproduction.
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u/Frosty-Influence988 3d ago
Brute strength requires LOTS of resources.
But it also immediately pays off. If you are the biggest animal, you are the apex predator. That is why many higher trophic predators invest in size.
This isn't true for a brain though, at least not in short term. So why did Mammals, especially primates develop this high level of cognition?
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u/kitsnet 3d ago
But it also immediately pays off. If you are the biggest animal, you are the apex predator.
Absolutely not necessarily.
It is also possible that when you are the biggest animal, you need additional brain in your ass, because otherwise your nerves are too slow to fight the smaller but faster predators.
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u/Frosty-Influence988 3d ago
you need additional brain in your ass,
First, I am laughing my ass off.
Secondly, yes it is true that you might need additional brains, but those are less like ours and more like central nervous system hubs that autonomously coordinate parts of body further away from CNS. It is like our brainstem, but extended in very large animals.
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u/No_Logins_Required 2d ago
Having a lot of muscles also drastically increases brain size. Social hunters like humans can multiply their strength by coordinating, and that coordinating is strongly helped by a more calorie-hungry brain. But there are solo hunters like the octopus and the archerfish that use big brains to hunt and not raw strength, and many birds like crows and parrots spend a lot of their calories on a clever brain instead of increased strength.
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u/BoredWahahaMSWater 3d ago
You first have to become strong. That costs a lot. That's why we don't have more Apex predators. At one point it's just to inefficient and you would starve regardless of your strength.
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u/Fwahm 3d ago
Why don't you think higher intelligence is useful in the short term? You don't need to survive getting punched by a gorilla if your higher intelligence lets you avoid getting punched by a gorilla.
Regarding the original post, joint problems that primarily arise after reproductive age isn't really a concern for evolution.
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u/Frosty-Influence988 3d ago
Why don't you think higher intelligence is useful in the short term?
Well because strategy really does not help in raw fights. It is why most animals historically never invested much towards brain as they did towards size, from Anomalocarididae to Eurypterid to Tyrannosauridae to now Ursidae (yes, even among Mammals we selected for size to become Apex Predators)
Regarding the original post, joint problems that primarily arise after reproductive age isn't really a concern for evolution.
My point was that bipedalism has traded long term mobility in humans for brain. Now i understand socialization is one of the most powerful things humans have done, but selectively it still puts the individual at a disadvantage.
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u/BoredWahahaMSWater 3d ago
Tell that the huge boxer loosing against the armed, small and weak opponent. It DOES help in raw fights. You are thinking of a a very unrealistic situation where two opponents are standing in a ring only relying on one strength. Don't forget about levers, tactics and groups working together.
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u/VersionFine85 3d ago
You keep saying investment like evolution is making active decisions. It's not... It literally is stuff passed on before the parents died. All the stuff regardless. If there's nothing around to punch the humans to death then they're passing on their genes
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u/Frosty-Influence988 2d ago
I apologize if that came across like that, what I am saying that evolution selects for most energy efficient AND most successfully reproducible. Organisms not meeting this criteria can do it as well, but they would be in a very hard spot.
Take an example of marathon runners. Sure you CAN tack on a 30lb cooling vest that will keep your body temperature lower and in the long term, may make you win the race because you are sweating less and producing less heat, but the initial requirements themselves are so high that most would not. So how did Humans, primates and mammals in general not just go with the small decentralized CNS route many reptiles have, with little to no offspring investment.
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u/Fwahm 3d ago
Raw fights are not very relevant if you have higher intelligence. You can make a spear to kill gorillas with, you can use your intelligence to avoid raw fights by having higher social intelligence or by being sneakier, and you can use your intelligence to team up and ambush enemies you normally would lose against.
Humans are social creatures, an evolutionary adaptation doesn't need to benefit a singular loner (even if in this case it does) if it helps reproductive capability for groups as a whole.
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u/BrushNo8178 3d ago
Well because strategy really does not help in raw fights.
10 humans throwing stones will chase away or kill any land animal except the big five (lion, leopard, rhinoceros, elephant and buffalo).
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u/alvysinger0412 2d ago
Strategy is usually more about avoiding fights altogether. Animals in general actually don't truly fight unless they have to. It risks injury, which can be deadly (a cheetah with a broken ankle can starve to death) and doesn't often accomplish enough as a reward. That's why the majority of brute force leads to posturing and assertion of strength that isn't direct battles to the death. Strategically, intelligent animals would avoid those faceoffs, and because there's not much reward for winning said faceoff beyond maintaining territory or food, that's fine.
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u/BrushNo8178 3d ago
Also knee problems don’t prevent grandparents from watching their grandchildren and keep the fire burning wile the mom collects roots and the dad hunts.
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u/VersionFine85 3d ago
The only thing that matters is reproduction. As long as the human reproduced before being punched to death by gorilla being then it doesn't matter if you got punched to death by a gorilla
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u/Morag_Ladair 3d ago
Brains are really fucking useful. They allow you to remember, to deduce, to reason, to think, to imagine, communicate and work together, to think of long term goals and evaluate risk, to create and explore.
The bigger your brain the better you are at all these things. If you’re better at those things you are more likely to survive and be able to reproduce.
Bipedalism might not be great for your knees but it’s really good at freeing up your hands to do really cool things like use tools.
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u/BellerophonM 3d ago
Humanity's development of extremely large brains and very high intelligence is a great example of how that intelligence was so advantagious that we took on a great deal of evolutionary 'baggage' due to our rapid evolutionary shift to tool-using bipeds, the changes occurring so rapidly that our joints aren't particularly well-functioning and our birth is a bit of a nightmare compared to most mammals, and it was still worth it because of how immediately those smarts paid off in survival and hunting.
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u/Exact_Avocado5545 3d ago
Your assumption that it doesn't result in an immediate advantage is wrong. It did. All things in evolution have to give an immediate average, otherwise they don't emerge
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u/EverydaySexyPhotog 3d ago
Human bipedalism allowed our hands and arms to specialize for making tools and throwing things.
Other great apes can fling something in your general direction from 5 meters away. A human can throw a spear into your vital organs from 50 meters.
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u/Frosty-Influence988 3d ago
Hmm, is it that it allowed our hands to specialize (thus indicating a pre-selective bias to do so) or doing that over and over again selected for those who were more efficient at it?
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u/pasrachilli 3d ago
Dinosaurs also developed bipedalism, and basically conquered the planet, so I assume there's a huge advantage. Just speculating, of course.
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u/Lumpy-Notice8945 3d ago
A brain is the most powerfull tool any animal can have. No mater an animals strength or how sharp its claws are if you poke it with a spear, shoot it with a bow or trap it, that does not matter anymore. And that requires a brain.
But thats not specific to mamals, our unique feature is not brain power its tits...
Mamals birth teir children early and nurse them at start, thats again a bit downside with an even bigger benefit. We dont need to give birth to fully capable humans anymore but can let them develop and grow after birth.
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u/deefstes 3d ago
I'm not sure that it is a short term loss for a long term gain. I think it might rather be a loss that developed after thousands of years because of the shorter term gain.
What I mean is that the larger brain brought some more immediate advantages. One of those were the species' ability to live much longer lives and, unlike almost all other species, well beyond sexual maturity.
A long term result of living so much longer was that knee and hip problems became more of a thing in old age. But when our ancestors were still quadripedal, they didn't live nearly long enough for knee and hip problems to be a problem.
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u/13lostsoul13 3d ago
Well my understanding bipedalism is because it freed are hands and are hands and thumb are also just important as brain. Also Seem to remember something about running is more energy efficient so we are endurance hunters. WE may not been has fast or quick but we can follow you until animal is resting.
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u/Cinnabun6 3d ago
If it works it works. Despite knee problems humans have taken over the planet. Other mammals such as rats are hugely successful as well
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u/BoredWahahaMSWater 3d ago
One could argue insects are more successful. Humans have just been really successful in their ecological niche and environment.
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u/Cinnabun6 3d ago
Yes, insects are hugely successful as well. Just like it would require a mass extinction to completely get rid of ants or roaches, it would be the same for humans
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u/BoredWahahaMSWater 3d ago
I agree, just wanted to throw in another perspective. We always say how successful humans and mammals are and to some extend this is true. However, we are relatively "new" in this world. So whether we will persist to exist is another question. Maybe jellyfish are the true successors :)
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u/Cinnabun6 3d ago
That's true, and given enough time we probably will be extinct or at least morphed into something else, like other species that dominated the planet before past extinction events
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u/BoredWahahaMSWater 3d ago
It increases chances of survival of you and your offspring if you are smart. So as long as the resources invested in the brain don't lead to a lack of such other wise it will be positively selected.
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u/Frosty-Influence988 3d ago
It increases chances of survival of you and your offspring if you are smart.
Right, that's my question. Why?
Take a human baby, very insecure, completely helpless and dependent. For the first 10-15 years, you as a parent has to invest your own energy and time to take care of your child.
This does not exist in say reptiles, and they successfully reproduce as well. It makes sense for reptiles, their reproduction and lifecycle seem to be very efficient, Mammals' isn't, yet we still reproduce successfully. A reptile infant will out of the egg, be instinctually ready to be evasive, have developed motor controls and will even start hunting. This wouldn't occur in Mammals for years.
How and why?
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u/BoredWahahaMSWater 3d ago
We cannot all follow the same path since we all compete for resources. We save huge lots of energy by being able to cook our food and hunt in a coordinated manner which is more or less unique to mammals.
Also, f.e. walking is incredibly energy saving since our tendons reuse the energy similar to a kangaroo jumping (quite fascinating).
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u/Alarmed_Bad4048 3d ago
Evolution happens incrementally on a long time scale, "immediate advantage" does not come into it.
Once upon a time a mammal was born with ever so slightly bigger brain than standard. For whatever reason this helped the mammal stay alive long enough to reproduce.
Hundreds or thousands of generations later our big brain mammal has become average brain. Then a mammal is born with a slightly bigger brain...
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u/Frosty-Influence988 3d ago
Evolution happens incrementally on a long time scale, "immediate advantage" does not come into it.
One thing it immediately selects for is reproducibility. If you cannot reproduce, you are out of the game.
For whatever reason this helped the mammal stay alive long enough to reproduce.
Right, why?
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u/Alarmed_Bad4048 3d ago
Fair enough, i did gloss over the why.
Its because the mutation
a) made them more likely to survive to the age of reproduction
b) attracted mates to reproduce with
To answer why a bigger brain helped with either, i dont know, i wasnt there at the time.
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u/dilly_bar18 3d ago
Everything just works differently for its environment in order to live long enough to reproduce. Walking upright is beneficial for humans bc it allows our brains the tools (arms, hands, and fingers— fine motor skills) to use its intelligence more efficiently. To hold our babies which differ from most primates as they’re kinda useless when born. Also ä sacrifice given in exchange for the brain. Humans r pretty underdeveloped at birth compared to… honestly most other living things. W an extremely long development period to hone the brain.
The body didn’t cause the brain to change or the brain to change the body they def changed and worked together over time. So mutual feedback probably and what works works n we ended up here. Our brains grow when we explore n engage our environment. U can do that more if u have mobile arms and hands. Humans like eye contact for some reason like it’s good for u n socially beneficial for bonding as a species. Standing eye to eye, or being able to hold and look at ur babys face and them see urs directly is beneficial.
A lot of shit we don’t even think or know about is also just collateral and side effects too. And there’s no perfect reason. Having 6 fingers a hand is dominant. Obviously we’re fine w 5. Idk y the diff would have ever mattered given u have a pointer finger and thumb. Idk y we largely only have 5 except insular communities where it becomes more prevalent. There r illnesses that r dominant. The universe is not perfectly orchestrated at all times. Sometimes illogical stuff happens like the random mutation of blue eyes in highly hot and sunny places (independently from Europe which makes more sense ig). Y? Idk. It b like that. Y do we need redheads? We don’t (love u tho). Y do we need to b so thoughtful w such intricate minds to the point ppl commit suicide? We don’t. But it’s a side effect of the brain being so developed.
But u don’t need mass to win life. If u have the ability to imagine and create, and the body fit for turning it into material useable stuff or tools to make even more… to be able to VERY long term plan and strategize to a level a bear cannot then. It works. Having the brain to imagine, create, and finely use tools and multi step approaches means u can shoot the lion from a distance. U don’t need to b buff. It does bc it can’t do anything but that. We even have the mind to build shit like cars and tanks to make ourselves big. If it works it works.
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u/Andeol57 Good at google 3d ago
> This does not result in an immediate advantage
Depends what you call immediate. For example, mammals typically take care of their offspring, making sure they are protected and fed until they reach adulthood. That's a massive advantage. It's not unique to mammals, but it's still a pretty major characteristic of that family, that is tied to the extra intelligence.
> Humans for example, ... so that we might have a more efficient brain
Bipedalism isn't really about having a more efficient brain (Ostriches and Emus are pretty dumb). It's more useful for endurance and long-distance travel. Granted, those characteristics in turn work pretty well to get the most out of a big brain.
Where do you see a short-term loss for long term gain in that?
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u/Cool_Percentage_4867 3d ago
Mammals are a huge class of animals and humans make a very poor example of what an efficient mammal looks like. Most aren't bipedal.
But I do think theres merit to the question.
At some point we had a working Vomeronasal organ, just like the vast majority of animals, that would have allowed us to constantly be aware of our own health, the health sex identification of anyone nearby just based on pheromones. The first prehuman born without a VNO would have been at a huge disadvantage, wouldn't have been able to have sense predators threats or mates and weve had that disadvantage ever since.
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u/bdog143 3d ago edited 3d ago
The number one factor influencing selection for reproducibility is survival. The brain ultimately has two functions as an organ in an evolutionary sense. One is to keep the gonads alive from birth until reproduction, and the other is to keep your offspring and relatives alive so they can reproduce. Fulfilling those functions includes keeping you (and your gonads, and your family) fed, watered, in one piece, and finding someone to reproduce with. Given how many mammals there are, it would appear that better brains have led to improved survival and improved reproductive success. Having the cognitive wherewithall to make sure there's food on the table and spot danger and avoid it/outsmart it is a very big and very immediate advantage.
Re humans' shift to bipedal movement, that also has a lot of advantages. It allows for very energy efficient movement, we have more reach and visibility to get food/spot predators, we have hands free to carry food/babies/weapons. Bad knees are something that comes well after reproductive age in an evolutionary sense, so isn't a problem - starving to death or getting eaten by something at age 10 is a significantly stronger selection pressure than dodgy knees at age 40.
Also worth noting that we haven't sacrificed range of motion for bipedalism, we sacrificed strength and range of motion for fine motor control. A chimp can quite happily rip your arm off and hit you over the head with it, we can accurately throw a spear and catch dinner. There's a few hundred thousand chimps and more than 8 billion of us, so that looks to have been a decent evolutionary advantage.
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u/BellerophonM 3d ago
Increased intelligence and brain size does often provide immediate advantages.
It's more that it's particularly prevalent in mammals to have large intelligent brains because the much longer gestational periods of mammals, during which the foetus has an effectively unlimited supply of nutrients, easily allows for a lot more foetal brain development. Non-mammals are comparatively very restricted on how much foetal stage development is possible.
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u/LookOverall 2d ago
It’s about cooperation, I think. A strong correlation exists between brain size and troop size. The big human brain allows us to know about 150 people.
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u/Random_182f2565 3d ago
Because it just works