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gwern comments on Brain shrinkage in humans over past ~20 000 years - what did we lose? - Less Wrong
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Except most discoveries which might confer a decent amount of fitness - enough for fixation to have a chance - are rare. For example, Tasmania had a population of thousands, yet they lacked almost all technology, and couldn't even make fire (instead relying preserving existing flames); if anywhere someone would be inventing technology to help their kins, Tasmania should have seen such secret wiles. But no.
(This is part of a general argument against individual selection for innovation: innovation is too rare, and diffuses too rapidly to unrelated or barely-related people, to be an advantage for the individual - however excellent it is for the group.)
Really? Wikipedia links to Cotton (1887) which is handwritten but says:
I did see that mentioned while reading Wikipedia, but I dismissed it. It is a third-hand report from decades (someone told someone who told me who tells you) previously about a method which may - like the Easter Island 'invention' of writing - simply have been copying foreigners either directly or indirectly and so even at face value doesn't establish the claim. I don't think such a dodgy source is enough to overcome all the reports and circumstances (eg. described cumbersome system of firekeeping seems to be less likely if knowledge of making fire had been retained).
Minor innovation. Try attaching stones to sticks for example; humbling experience; I'm pretty sure you are going to get pretty strong correlation between even such modern measure as IQ test, and how well the stone stays on the stick.
For Tasmania, the population of thousands is insufficient to preserve genetic diversity and counter the drift, as the article you linked to itself says. The niche that made us intelligent is very unique. Put us into another niche - especially, a well isolated niche with little competition - and we may well de-evolve. Bird species that come to an island that has few predators using their flight, may not need to fly any more - same for intelligent species that figure out a way to get onto an island.
The usual trend with such things is that IQ correlates with speed of learning, with a ceiling effect; the high IQ hits the ceiling faster. It's not at all clear that for simple tasks like stone on stick that the investment is worth the additional speed - what else are Tasmanian islanders going to be doing?
I think even in far limit higher IQ's stones will stay better on the sticks. It ain't easy to attach a stone to a stick well. It isn't some well controlled industrial process here that you can figure out better. One day you have one stick, other day you have other stick. We rely on modelling of reality inside our heads to make items - seeing in mind's eye how it would detach if the wrapping is in that particular place, but would stay on if its in another place.
It's also pretty hard to start fire.
Seriously, I recommend to try without looking up the precise details of techniques. Armed with the knowledge of the fire drill.
Re: tasmanians, once again, it is an island. Birds go flightless on islands just because there's some empty ground animal niche available. We can go complex-tool-less and fire-starting-less on island, too. For the fire starting skill to matter, you got to NEED the fire for survival. In some nearly tropical island, what is the great harm, exactly, in not being able to start the fire? Here you freeze to death in the first winter; there you just eat raw food which is not that much worse anyway. BIG difference in pressure. (also it is altogether possible that they were able to start fire, and it's just racist claims that they weren't)
It doesn't require 16 years of education and then a PhD to master making spears or fire, especially when there's not a whole lot else to do; even if there were no ceiling, that still doesn't justify the extremely high calorie and protein consumption of a top-notch brain.
There's no point in me looking it up; I was a Boy Scout, I knew how to make and use a fire drill.
It's not really a tropical paradise either.
Winter night temperatures are still way above freezing, though.
Which is why even the highlands don't receive snow, is that right...
Something did justify the huge brains, somewhat bigger than we have now, and bigger in relation to bodies too. And it sure wasn't the PhDs.
Very sophisticated society has taught you how to make and use a fire drill, using a process well developed to make a person able to use a fire drill. Did you make it from 100% natural materials you picked up in the forest? What is the range of humidity at which you can start fire? How well you can improvise if something you want to use isn't available?
Heh, it goes down to -30 Celsius where I live, so i may tend to call stuff tropical even if its kind of cold. The ~0 Celsius weather is not too bad without fire. Even at -30 many animals live just fine without fire.
edit: plus from what i've read i'm not even sure they didn't have fire, in the first place.
You can't just go around dispelling advantages of big brains without providing any alternative explanation why big brains evolved.
I never said they didn't have fire; please read what I wrote.
Of course I can.
And besides, it's a very simple story: if big brains improve individual reproductive fitness by enabling innovations, then there need to be innovations. Evolution can't act on genotype which is never expressed in phenotype. In Tasmania, not only are there no innovations, there's actual loss of existing innovations. If you try to argue that the population base was too small, then that's even more damning: what kind of innovation-supporting gene can be selected for by Evolution when thousands of aborigines over many generations all fail to produce anything? Even if one aborigine did, how does that make up for thousands of his relatives/ancestors burning huge amounts of calories and protein on the innovation-capacity only one of them benefited from?
Combined with the observations about innovating being a public good (and group selection being rare to non-existent), this is pretty convincing evidence that big brains were not selected for their innovation, but for something else - the Machiavellian brain hypothesis seems like a good one.