How a Mass Extinction Changed Our Brains

Check out Brilliant! brilliant.org/Eons/
During one of the most pivotal moments in our evolutionary story our brains actually shrank relative to our bodies.
Thanks to Ceri Thomas for the excellent Cenozoic mammal reconstructions! nixillustration.com/
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Produced by Complexly for PBS Digital Studios
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References: docs.google.com/document/d/1_...

[@geekyprojects1353]

Everybody who worked in customer service can confirm that shrinking brains can be observed even without a mass extinction.

[@davidt3563]

And then watching those people drive.

[@lorrygoth]

It has actually be documented that brain sizes have started to diminish.

[@ZedaZ80]

We're currently in the Holocene extinction >_>

[@Kroggnagch]

A-mothafuckin-men

[@mad_max21]

"haha, people but not me are subhumans, so funny"

[@thepeff]

"The human brain is the greatest wonder in the natural world." -The Human Brain

[@RichardWilkin]

I suspect that thinking of yourself as being special is more likely to promote survival behaviours than self-deprecation.

[@Iku00]

It's the only organ in the world advanced enough to name itself

[@arthurvice503]

@@Iku00 deep down we are just brains communication with eachother

[@thepolloelectrico1117]

It's the only thing in the universe able to aknowledge and proclaim it's own existence, no small feat.

[@JubioHDX]

@@thepolloelectrico1117 Pretty biased words coming from another human brain 😂 im not saying youre wrong, but we also only know what other humans are thinking. As of right now its impossible to confirm how true that statement is, especially considering we have no feasible way to prove we are the only planet with life in the universe anyway even though we're the only life we know about

[@ZQRDS2W]

"Having to fuel a big brain can reduce the organism's ability to reproduce." You didn't have to rub it in.

[@anyoneofus9948]

69 Heh heh yeah cool!

[@ladyjatheist2763]

as well as its DESIRE to reproduce OR OVER-reproduce.

[@airborneranger-ret]

lol

[@jbri1]

​@@filipbelciug i think Tinder is to blame for declining birth rates

[@Abra_Dabra]

@@jbri1 declining birth rates aren't a bad thing though, human populations are way too high

[@RorikH]

I don't know if you take requests, but could you do something on why land animals that returned to the ocean (like icthyosaurs and whales) often become so successful? Is it something like Lungs being better at breathing than Gills even if gills let you breathe underwater?

[@Dankleberrrrg]

Or is that those species that are not able to adapt quickly enough to be very successful die off very quickly?

[@macgonzo]

They've done an episode on when whales transitioned into the sea. As for your question, I'm not sure it's something that can be answered, because it's a relative question... Would they have been less successful if they hadn't transferred into marine ecosystems? Probably not. If they had been less successful, they'd have gone extinct before they even evolved into the forms you mention. I'm sorry, but it's not something that has an answer you'd find satisfying. That said, they mention in the video that whales, at least, developed larger brains Vs body size, which can potentially explain some of their success.

[@Bowie_E]

I appreciate this question and macgonzo's response 🤗

[@Jossandoval]

Another important thing, is that you said here "why land animals that returned to the ocean (like icthyosaurs and whales) often become so successful?", and, sorry if I sound unpleasant, but... How do you know that? I mean, how many lineages failed trying that path? How many went extinct, and how many went back to be land-lubbers? Maybe is not that often, and we have just the confirmation bias of knowing only the successful ones. I honestly have no idea.

[@Great_Olaf5]

The lungs almost certainly play a role, as you suspected, more efficient respiration will allow for larger body sizes even if you need to hold your breath, and filtering oxygen out of the water just isn't very efficient compared to air. There's a series that deals very heavily with the principles of evolution, though it is speculative biology rather than real, on the channel Biblaridion.

[@picolete]

Corvids and parrots are extremely intelligent for their brain size, we really don't know how smart or dumb dinosaurs were

[@LimeyLassen]

It's possible the reason mammals didn't get smarter right away is because birds already had that niche cornered.

[@rhael42]

octopi are also smart af

[@w0tch]

We know the non avian had (for most) small encephelization

[@danilooliveira6580]

@@LimeyLassen "smartness" is not a niche though, its a characteristics that can help with survival.

[@Zaxares]

Octopi too are incredibly intelligent (they're one of the few non-mammalian species that can figure out how to open twist jars) despite not having brains similar to ours.

[@AceSpadeThePikachu]

I know this is more of a topic for PBS Space Time, but this is one potential answer to the Fermi Paradox. It could be that while the circumstances for simple life to get started are easy to come by, intelligence may require a lot of VERY specific things to happen on a planet in just the right way to get to a point where one species begins building radio transmitters and spacecraft. We may be living in a galaxy teeming with life, just most of it very "dumb" life.

[@11thNite]

Hippo hardware running stoat software is nearly unimaginable, but hilarious. More seriously, a smell-focused, relatively low encephalized, but physically large species reminds me a lot of rhinos

[@Superwelder0]

Instantly one of my top 3 Eons videos to date! Would love a followup episode specifically on how this "Encephalization Arms Race" manifested among extant mammal species. For instance, increased meat consumption in human ancestors. Or how it could have affected social development in mammals(the dogs, horses, us, etc listed in this video).

[@sasshole8121]

what are the other two?

[@Superwelder0]

@@sasshole8121 She lists some standout species at around 8:25

[@ccvcharger]

@@Superwelder0 I think Sass Hole was asking what are your other 2 top Eons videos.

[@sasshole8121]

@@Superwelder0 As ccvcharger stated, I was referring to your top 3 Eon videos.

[@douglasharley2440]

extremely interesting!...it seems that when competing for new niches, against other species, size is most important; when competing against same species, for niche optimization, intelligence is most important. *makes sense!*

[@SomeThingOrMaybeAnother]

It might not have even been a competition, as much as rapid evolutionary radiation to fill all the niches left behind by the extinction event. Intelligence isn't necessary, when most of the niches are open.

[@icollectstories5702]

I don't think it's that simple. Niche specialization often includes body features such as beaks or teeth. I think intelligence is more useful for a generalist rather than a specialist who thrives when every day is lived like every other day.

[@w0tch]

I think the opposition is more on empty vs full niches

[@Ezullof]

@@icollectstories5702 It's certainly not that simple. In fact, the opposite seems true. Most smart animals are generalist and opportunist, not specialist. Crows, humans, octopodes. Even dolphins are generalists. Meanwhile, new niches seem to be simply occupied by the most successful groups that were already there, with intense diversification. Overall it simply seems that animals that have to deal with a variety of situation to survive tend to be smarter. It's more about the lifestyle than anything else. And even then, it doesn't explain everything. Elephants have pretty simple lifestyles but are still smart.

[@filipbelciug]

​@@Ezullof I'm curious, you said most smart animals are generalists and you proceeded to give crows and octopodes as examples, along with humans. But how are crows and octopods generalists? What's a specialist then?

[@artistroman8204]

It definitely didn’t change the brain of my neighbors.

[@M167A1]

That's what they said about you 🤠

[@drewharrison6433]

Yes. Cause that's how evolution works... lol

[@josephrion3514]

I can't believe the top comment is such a great dig at someone. Surprising, humorous even.

[@AnMaPa]

@@M167A1 are you his neighbor?

[@JohnDrummondPhoto]

"... And that's something we should always *bear* in mind", she says as an image of Ursavus plays. We see what you did there!

[@astick5249]

Also the fact they said mind

[@thierryploum5923]

A great episode! Judging by some of the comments, I am glad to see we the public also don't have to be fed eye candy of a new fossil to enjoy some great analysis. I feel like a kid again, at school, being instructed in mind blowing discoveries all about making sense of our world and marvelling at how incredible it is, both in and of itself and that our brain, to pull this episode in the comment, has the capacity to make connections between all kinds of facts and deduce new ones and that they have nothing to do with our immediate survival, when that is usually what the brain is required to do. You have a great bunch of people doing this work and presenting it.

[@MyOwnNameWasTaken]

I like the territorial acknowledgment

[@AllenCrawford3]

It took our level of intelligence to realize that intelligence isn't a great long-term survival strategy.

[@burnte]

I’d rather lose the violent streak before the intelligence.

[@svennoren9047]

The video said exactly the opposite. When there was lots of empty space and not much competition bigger bodies won out. Eventually though, the bigger brains won out over big muscles.

[@martijn9568]

​@Sven Norén Unless the competition goes away for some reason. Then large brains become an unessecarry energy cost.

[@icollectstories5702]

I think it's rather insolent for a species around for less than a million years to opine on long-term survival.😜😜😜

[@Gildedmuse]

​@@martijn9568 Isn't that basically evolution? "Traits are successful until they are not.*

[@downsidebrian]

This, I think, is something people should understand a lot better. Hardship does not make you smarter. Intelligence can only be improved when basic survival is relatively easy to ensure.

[@phkhzaw]

Did you even watch the video? They got dumber when it got too easy. Only when things got harder that they got smarter. WTF

[@kyrab7914]

Maslow's hierarchy of needs is smthn I feel should be taught more

[@downsidebrian]

@@kyrab7914 the problem is, it's too easy to misconstrue, especially when doing so confirms your biases, and especially when using it at the individual level.

[@creiglamb6036]

that's kind of the opposite point made in this video. greater intelligence was born out of increasing competition, ecological pressure and well... danger. Or as you could put it - hardship.

[@phkhzaw]

@@creiglamb6036 that's what I said, they had to evolve because their basic needs can no longer be met with a small brain

[@m0j0rising]

Another quality video from PBS. Thanks for the "thought provoking" topic!

[@jennyanydots2389]

If you watch it again you'll notice that this video is actually about pet sexual assualt.

[@swammies]

Thanks! Will be using this to study for my mammalogy midterm :)

[@origaminosferatu3357]

This is a super interesting episode. I´ve never seen most of those older Palaeocene mammals before, I´d love to learn more about those big chunky boys.

[@blandp11]

Truly a joy to watch. I had not previously heard of this evolutionary history and it is very exciting! Thanks so much!

[@Summer-xe6in]

Incredible story, episode, information, pictures... Excellent. Well done everyone

[@gabrielzinho3230]

Brain size depends, like many innovations in evolution, on the availability of resources. Part of what had mammals get large brains was occupying niches that belonged to the dinosaurs. I think that's beautiful!

[@laylahame]

the little snippets at the end is really fun to watch too after all the facts in the video, really showcases everyone's personalities love it !~

[@MacysMoment]

Love you PBS EONS!!!

[@yinnyari]

"Think on their feet, paws" - I'd have great difficulty in resisting the phrase "paws for thought"

[@Primarch359]

Since rodents were not included in the list of groups that experienced increased encephalopization, when did rats get so smart? Was that entirely during the Anthropocene?

[@LimeyLassen]

Early rodents and primates were related.

[@icollectstories5702]

Rats are very social. This means they have to be able to forever recall who did what to whom.

[@jamesdriscoll_tmp1515]

@@LimeyLassen through the common ancestor Eutherians

[@danielled8665]

​@I Collect Stories it's actually really interesting how often social survival strategy overlaps with intelligence. Corvids, rats, dolphins, primates...

[@MaureenLycaon]

@@danielled8665 Yep. Being social makes heavy cognitive demands on a mammal, to process all those interactions, determine how you should respond, and remember all that data. So being social almost forces a species to evolve a bigger neocortex.

[@sunspot42]

One interesting thing that I read about - might have even seen it here - is that during the age of dinosaurs our tiny mammalian ancestors generally lived underground or in trees or caves and didn’t come out much in broad daylight. Many were only active at dawn or dusk or were fully nocturnal. This might have been part of what saved mammals after the big smack - their habitats were better-protected - but the way their nocturnal brains had come to be organized over a hundred plus million years might have also been what put them on course to become so smart (eventually) after the dinosaur competition was eliminated. Essentially their brains were designed to help them make do with less information - especially visual information - than was available to their dinosaur competitors. They had to extrapolate more. When those structures eventually scaled up millions of years post-dinosaur, it gave the mammals abilities the dinosaurs never evolved during their reign.

[@hassansyed4135]

I'm not so sure, because birds (which are a living descendants of...) also followed the trend to intelligence, so there is a bit more to a trend to intelligence than just being a mammalian feature.

[@CB-eo6xo]

@@hassansyed4135 Than one has to wonder why birds never even got the chance to reach the levels of intelligence on par with primates and even humans, aside from a few certain ones like crows and parrots that are highly intelligent in their own right that come pretty close to rival most primates.

[@sunspot42]

@@hassansyed4135 I suspect birds may have been forced toward intelligence via competition with mammals. Mammals in general really do seem to do it more effectively - and more pervasively - than birds though. I think that’s more the point - mammals broadly got these bloated brains as competition between them increased once they took over all the niches non-avian dinosaurs held. They also displaced avian competitors from a bunch of niches they initially held after the big smack. Like the “terror birds” which seem to have all been wiped out by competition with mammals. This “big brain” strategy never took off when dinosaurs were competing with each other. And it doesn’t seem to have taken off among birds until after mammals leveled up.

[@DonnaBarrHerself]

Watch birds in a storm - they head for every little chink in cliffs. The asteroid just took out whatever was big. And formerly most successful. Brains had nothing to do with it.

[@sunspot42]

@@DonnaBarrHerself I’m not sure a chink in a cliff would be a great shelter. I think most of the aves that survived were aquatic at the time.

[@czitrom42]

"And that's something we should always bear in mind." Nice pun! I love it.

[@joonzville]

Excellent video on new discoveries. Thanks, I love this channel!

[@cameronjim2983]

Mammals basically as they outwitted their other mammalian predecessors: “Congratulations, you’ve played yourself.”

[@theobozikis8225]

Another awesome video!!! Thank you all for this very informative one!

[@r.d.whitaker5787]

This is my favorite episode so far. The lady explained it really well.

[@remmont3984]

Much better than the scruffy bearded dude.

[@AndrewBlucher]

Michelle

[@AndrewBlucher]

​@@remmont3984 Do you mean Blake?

[@ambergris5705]

Thanks for this one! I would have loved to know more about why while this happened mostly to placental mammals, the marsupials stayed, for a lack of a better word, stoopid.

[@discgolfcasaus]

I always love when this one hosts the show. She's so genuine and real. All of us humans have capabilities we could never imagine. It's the elasticity of the mind that gives us true power. Whatever your dream is, your actions can make it come true. If you have a goal, never let anyone misdirect it. Never be held down, we can all fly, eventually...

[@suzycanfly]

Thanks for this ❤👍

[@luminyam6145]

That was fascinating, thank you.

[@SamTheUndying]

Thanks for making such informative videos, its always a treat to watch them

[@the_luggage]

"Encephalization", that's a new word for me; thank you, very interesting!

[@naturalstench]

I love these videos! Thanks for making them ❤

[@jennyanydots2389]

You're welcome son. How about floatin' a little cash my way boy?

[@naturalstench]

@@jennyanydots2389 if I wasn’t unemployed I would

[@jennyanydots2389]

@@naturalstench Time to open up that bee whole for money son. Truck stop solicitation is a booming market right now. You need to get out there and start earning some cash for me boy.

[@ZOGGYDOGGY]

Thanks. Your work is enlightening.

[@curiousworld7912]

This was really, very interesting. Thanks. :)

[@nathanielhellerstein5871]

The voice from the UFO cried, "To the smartest we'll give a free ride!" Several men volunteered But the ship disappeared With a whale and two dolphins inside.

[@nobodysbaby5048]

☺️

[@JatPhenshllem]

☺

[@grimmoris]

Michelle I'm your fan, thanks for existing

[@harrystone3527]

Absolutely love your nails

[@coconutsmarties7916]

That bit right at the end is funny and endearing

[@cudi313]

WHOEVER IS IN CHARGE OF THE MUSIC. THANK YOU.

[@leovalenzuela8368]

Great episode

[@dersitzpinkler2027]

Serving looks and science in this one 🔥

[@d36williams]

love that synth music and bass

[@Bager_Wisdoms]

Scientists: It's not just the size of the brain that matters, it's the neurons and connections and all that. Scientists in every documentary and article: Lets talk about big brains.

[@martijn9568]

Probably because all stats matter. Not just one, but it is often needed to dumb down a complicated topic as the general public isn't always seen as the brightest kind of people. And you know what, sometimes they're right.

[@ccvcharger]

@@martijn9568 let's be honest, humanity really is just a bunch of hairless apes propped up by the achievements of the few bright ones.

[@JubioHDX]

@@martijn9568 honestly, theyre pretty much always right lol. when you try to look at it objectively, the average person has no idea of the nuances that go into the topic (because why would they? it takes years of study and not everyone is interested in that path, so not knocking anything, im probably average too just with different interests despite what im about to say. anyways:) and then you need to consider that roughly just below half of all people are "dumber"(or at least more ignorant) than average, just due to how averages work. combine that with the majority of people being average and the majority of those people having no idea the specifics of the topic, and you end up with a vast majority of all people being pretty darn stupid. (or again, maybe just more ignorant, but when you add in human stubbornness it basically ends up being the same)

[@simonbut8062]

It’s easy to make fun of science if you leave out all the context, subtext, details, and co- factors

[@doom_371blahblah5]

Humans have a eternal affinity for comparing sizes 😉

[@morgothainur9389]

This video is so interesting and relaxing.

[@bokchoiman]

What an amazing story. thanks for telling it.

[@marquistf1996]

Ty for the vid

[@sincodabuera]

Very nice, Thank You for this.

[@johndoh5182]

One word I think most likely sums all this up, predators. After the extinction of the dinosaurs along with a large percentage of most all life on earth, mammals that were non-predators had little to worry about, but once populations became healthy again so did the predation, and that requires more thought. And it's that competition between prey and predator that grows brains.

[@chriswatson7965]

I'll have to disagree. Predators are not the only driver of evolutionary development, and are amongst the least likely to drive brain development. Intra-species competition for resources and offspring are a stronger driver of brain development. The message from this story is that, from an evolutionary perspective, it is much easier for genes to modify physical characteristics than cognitive ones, but that there are a greater number of cognitive niches than there are physical ones, especially in intra-species competition. Our admiration for intelligence is inherited and even the belief that the trait of intelligence exists is inherited, and they are both driven solely by intra-species competition.

[@buraklale6210]

Thanks!

[@edwardcamp3376]

8:12 Love the fence posts and farm house.

[@ivytarablair]

hangin' out in Missoula so's your chai can be in equilibrium with the environment - that's some homeostasis commitment! 😂😂😂😂😂 This ep reminded me of a weird scifi book in which the advantage/disadvantage of *sentience* is the main tension of the plot. It was fascinating to consider that sentience might actually be an evolutionary disadvantage 🧐 It makes complete sense that the little shrew-sized mammals went through a "we need to get bigger and grab hold of a LOT of ecological niches asap!" stretch of time, before a complex enough ecology started to present an advantage to the big thinkers. Very cool ep, thank you!

[@amelade]

its 2023: my fashion inspiration comes from PBS Eons hosts. i learn about style and mass extinctions at the same time

[@objetivista686]

For re/populating new niches, the R-strategy is more efficient and tends to correlate with shorter development and then little brains.

[@Verwunscht]

Famous five music in the background. Nice 😄

[@Vantyler66]

Would love to see a video on the evolution of activity patterns (e.g. nocturnality)

[@WAMTAT]

Fueling my brain while watching this

[@donnierussellii4659]

Have you considered doing a video about the Axial Twist Hypothesis? It tries to explain why the vertebrate brain hemispheres are connected to opposite sides of the body, and why the optic nerves cross.

[@hoeyao]

Very engaging title for the video

[@rosetownstumpcity]

this is a very interesting video 🙂

[@asherperkinsmusic2767]

Excellent

[@memyself3510]

4:47 ok whatever that thing is it’s freaking adorable

[@emarti3853]

There is a power point error @7:45. The slide does not highlight the time period "56 million years ago" but it does make the sound effect.

[@kb7662]

Thank you for acknowledging The First Peoples.

[@valerievankerckhove9325]

Oh wow, so that coincided with the paleocene-eocene thermal maximum that I had just watched about in the previous video I watched by you.

[@jesipohl6717]

smell is the foundation of memory consolidation and learning in terms of neural evolution.

[@surrealfarm]

When you list the most intelligent beings on the planet, don't forget the octopus.

[@takenname8053]

Super Nice

[@MrPink-qe1rm]

Our brain developement is linked with our naturalbiological evolution of course. Thats just 1 part of the three sciences involved. You also need to explain neurons firing in relation to radiation emitted from the sun and our earths core; also the chemistry involved in the creation of life from comets/natural earth surface elements as well as elements brought tothe surbace by extinction events. This episode is only telling 1 chapter of a 3 chapter story......pretty vague but i suppose this is for children?

[@JVHShack]

The study of evolution is constantly evolving.

[@DomyTheMad420]

7:50 that would have been the perfect time to show a graph of 'time v relative brain sizes'.

[@zimmy1958]

This episode pleases me. ;-)

[@sarahlynn4798]

That last pic tho.. "& that's something we should all dog-bear in mine"

[@carsonsullivan3452]

PLEASE MAKE A VIDEO ON THE EVOLUTION OF OCTOPUSES

[@ozien2]

''The Age of Mammals' - 0:36 - Ostrich begs to differ 😁

[@peterkavanagh64]

Walking for allthis wnormailaies the ideas if what or where I am in life

[@MrCraigEric]

"Having to fuel a big brain can reduce an organism's ability to survive, and reproduce." ...tell me about it 😂😭

[@skybattler2624]

When the End of Cretaceous Patch is literally a balance update to buff and nerf stuff by the Devs of Earth.

[@aips0]

Who dislikes a video like this and why?

[@daem0nfaust]

Isn't optimization also the reduction of size but increase of efficiency and functionality?

[@petefluffy7420]

I have had the sane one all my life. Did I miss out on the new model update ?

[@lh3540]

I'm picturing that mammal acting like a capybara and just chilling all day.

[@SuperLoops]

something its probably impossible to infer from fossil evidence is the evolution of energy efficiency in brain tissue, but it must have been a hugely significant factor when you have evolved an organ like a mammalian brain that has such huge energy requirements but is also fundamental to the organisms survival strategy. like, there must be as much or more selective pressure for better processing power per calorie, which isnt going to be apparent in a comparison of fossil skulls

[@paraceratherium255]

Can you do a video about megafauna in general.

[@pollytiks3885]

Whenever I watch these videos I wonder what kind of evolution is taking place now and would we recognize ourselves in a million years. 🤔

[@The_Jovian]

A million years is a long time but if we stay alive that long then we probably won't change much. genotypically, anyway. Natural selection doesn't play much into our genetics anymore as we can modify our environment instead.

[@AndrewBlucher]

​@@The_Jovian And that stops evolution ... how?

[@zogar8526]

@AndrewBlucher it doesnt directly stop evolution. But the fact natural selection doesnt really play a roll for us chages it, including how long it will take. Evolution already takes a long time in normal circumstances. Now consider we dont worry about aurvival in the same way. We keep many who would orherwise die off alive and they pass on their genes. And that populations are no longer separated, mixing our genes even more. And the process slows down to basically nothing. We will still evolve and change. But it will likely be more on the inside. Changing genetics for things like residence to dieases and other stuff that doesnt show as much on the outside. That is of course assuming things stay mostly as they are. Add us going in to space, a new evironment and now separated populations. Or some disaster that wrecks civilation and things could end up different.

[@The_Jovian]

@@AndrewBlucher the driving force of evolution is natural selection. Individuals that are most fit to create offspring are more likely to pass on their genes. Individuals that are less fit tend to die or fail to attract mates. These forces very rarely affect modern humans in a meaningful way so the rate of evolution will be incredibly slow.

[@AndrewBlucher]

@@The_Jovian A nice theory. The one that humans are not subject to evolution, that we are special. If course humanity is evolving. As you should know very well after surviving a pandemic.

[@Shnoerkle]

10:20 "bear in mind" while showing some bear lol

[@mojrimibnharb4584]

Encephalization has always struck me as a crock. There is a limited number of neurons that must be devoted to sensory motor and internal physiologic functions, and it doesn't vary directly with body mass. What we call intellect appears to be a function of connections between neurons of the brain, perhaps related to the number of axon terminals. This could probably be approximated by measuring surface area; the amount of folds and crevices being crucial. Our big trick was evolving n-dimensional geometry to fit this many connections into these tiny skulls.

[@peterkavanagh64]

My interpretation of a evolved bipedal that makes a great help to the earth is the ballance brain a Brian not specialising in sight lifting or war the rounded head some neaetheerland some convergence walking a lot amd seeing hearing talking nit waiting to talk . Etc it works . So the afirvan had access to fruit and nearthelanad lost this so meat become its defined

[@LothairApoclyane]

Have any periods of encephalization ever been hypothesized to occur in non-mammal species such as birds or cephalapods? And, is there a future for further brain adaptation en masse?

[@Anne-gs7ym]

Loving the background music, is there a source for it?

[@Zarcondeegrissom]

if needing to fuel a larger brain wasn't advantageous during the Paleocene, makes me wonder just how scarce food was to favor smaller brains that would allow animals to live longer between meals. Maybe that also spurred the evolution of doing more with less brain mass, so when brains did start getting bigger again, the intelligence factor was more profound for the larger volume of nerve cells, maybe. just a thought.

[@andredepadua8799]

A Hamster-brained Pony-bodied animal is both utterly terrifying and adorable

[@unknownentity4620]

Love the brain earrings

[@shaydowsith348]

As far as Mammals "ruling" a case can be made that insects have prospered more.

[@terrydailey8589]

Quick question when is there going to be new episodes of mysteries of deep time?

[@NemoA90]

evolution is basically the best evidence we have that if it works it aint stupid