A new theory on how humans evolved their large brains

Originally published at: A new theory on how humans evolved their large brains | Boing Boing


I’m sure this grossly simplifies this, but it seems to me that this theory means that instead of natural selection gradually acting on normal variation in brain size, human large brain size occurred by discontinuous random mutation, which was then selected for.

Even the “normal variation” (of genetically derived traits) is a “discontinuous random mutation”, yet in this case the lack of recovered more gradual evolutionary transitions supports that an embiggened human brain was an especially large ‘discontinuous mutation’. (probably can jettison the “random” in front of mutation, since they are random by definition, at least random allowing for structural constraints). The other popular accepted example of a large discontinuous mutation gave raise to wings on insects. (one semi-fanciful theory going that a bit of exoskeleton was a nice ‘come hither’ mating buzzer and then managed to allow for lift-off!)
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That giant obelisk didn’t hurt either.



that make the human species distinct from other species–suggest that the genes for large brain size emerged from random mutations

as far as I remember, this is not a “new” theroy at all; sounds more like this study just partly confirms this “new” theory…

(is it maybe finally possible to distinguish between “thesis” and “theory”? please? or does the title implies “new” theory as in “new study proves old thesis therefore new theory”??? Im so fucking confused…)




Not a “new theory”. It’s a report about a study that collates additional evidence to support a rather old theory. “Additional Evidence Described in Study Supports Theory About How Humans Evolved Their Large Brains” would be a clunkier but more accurate headline.


A new theory on how some humans evolved their large brains


Others clearly did not.


Came here to make the same point regarding mutation being the driver of all variation, regardless of “size”.

The insect wings example made me smile. Can you imagine the astonishment of the potential mates responding to the mating rasp only to see their paramour lift off into the sky? Wonder what the insect version of wtf is.


I am smart enough to say I don’t understand - but not so smart as to understand how it wasn’t already assumed to be random.

If it wasn’t random mutations, then it was… God?

Of it was random mutation then it was… god?


When there are various genes that lead to larger brains floating around the gene pool, over time, they meet and “team up” if they’re pro-survival, where individuals will tend to inherit more of them.


I am reminded of Stephen Jay Gould and how he pointed out that evolution is stutters and bursts, almost never a smooth slope. So something triggered a bunch of mutations, and somehow the one with the larger brain managed to use that larger brain to make lots of kids, who themselves had lots of kids.

In other words, I don’t think the bigger brain had to be as much of a survival trait as it was a reproduction trait. Live longe enough to have sex, and to somehow have more sex than others. Which, when it’s so oversimplified, looks like I’m talking about eugenics. Er.


Check Out The Big Brain On Brad GIFs | Tenor


I thought that we evolved large brains so that we could compile scientific papers explaining how we evolved large brains?


punctuated evolution is what he called it. i’m not sure if it’s accepted as “the” mechanism or not, but it makes a lot of sense

he also raised the very interesting conundrum: what makes evolution so stable?

if its gradual, we should really see a continual drift in all species and we don’t. if it’s punctuated, why does it occur when it occurs?


…We do see continual drifts in all species as their environments change though. Right now the biggest changes are from us, and you can find all sorts of reports of populations changing a bit in size or color or behavior or so on as a result.


So that’s how we evolved the colon; and the semicolon?


I think it’s the opposite It was probably not just “making kids”. A literal neanderthal could do that. So can rabbits.

It’s probably more to do with food gathering, storing, and the ability to survive extended harsh conditions. The community who could both reproduce AND keep everyone alive is the one that would grow and continue to evolve.

The ones that only made kids with out being able to plan for the future died at the first extended drought or overly hard winter.


i think part of the question is whether those are deep genetic changes. you’re right, there’s some amount of built in flexibility to accommodate changes, but it’s not enough that it tends to create brand new species ( even for as fuzzy a term as that word is. )

over long periods of time, we can identify a lot of stability and significant change. the tyrannosaurus rex existed for more than two or three million years, that’s around the length of time from australopithecus to us. what kept the trex trex so long?

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maybe you’re thinking of the appendix? there’s quite a few references in the literature but it takes sometime to digest