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Dmytry comments on Brain shrinkage in humans over past ~20 000 years - what did we lose? - Less Wrong Discussion

15 Post author: Dmytry 18 February 2012 10:17PM

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Comment author: Dmytry 19 February 2012 04:42:48PM * 0 points [-]

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.

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.

There's no point in me looking it up; I was a Boy Scout, I knew how to make and use a fire drill.

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?

It's not really a tropical paradise either.

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.

Comment author: gwern 19 February 2012 05:14:32PM * 8 points [-]

edit: plus from what i've read i'm not even sure they didn't have fire, in the first place.

I never said they didn't have fire; please read what I wrote.

You can't just go around dispelling advantages of big brains without providing any alternative explanation why big brains evolved.

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.

Comment author: Dmytry comment score below threshold [+] (7 children)

Comment author: [deleted] 05 March 2012 05:36:02PM 1 point [-]

They all died out, remember? Here's your reproductive fitness.

They had a bit of help with that: http://en.wikipedia.org/wiki/Black_War

Comment author: gwern 20 February 2012 03:09:14PM 1 point [-]

They all died out, remember? Here's your reproductive fitness.

Only if you want to appeal to group selection. Otherwise, this demonstrate the point: even with the total group shrinking and ever more reproductive fitness possible, innovations still did not materialize and still did not give any individuals fitness.

What more evidence could one possibly ask for?

Comment author: Dmytry 20 February 2012 03:23:18PM * 2 points [-]

What more evidence could one possibly ask for?

Some argument that is not equally applicable to reproductive uselessness of flight, based on Dodo. I don't see yet anything that you said about intelligence and invention and Tasmanians, which wouldn't be equally applicable to wings and flight and Dodo.

The flight may fail to materialize for a zillion of reasons that have nothing to do with it's usefulness, or possibility of achieving flight using wings. Ditto for the innovation.

Comment author: gwern 20 February 2012 03:38:05PM 1 point [-]

Flight is not even comparable. Flight is incrementally useful, for gliding or flying occasionally to full life airborne. It is directly useful, and all benefits are internalized - I can't watch you fly and then somehow instantly gain the ability to fly myself; flight is obviously not a public good, and that alone disqualifies it as a comparison.

Comment author: Dmytry 21 February 2012 08:04:08AM * 3 points [-]

The point is that even the birds give up the flight on islands despite as you too understand it being so advantageous and internalized and such.

That makes entirely void by counter example your logic chain that if animal (humans) gave up innovation on island (Tasmania), then the innovation must not be very reproductively advantageous in general.

Because regardless of whenever something is or isn't reproductively advantageous on mainland, it can be given up on islands. Islands have empty niches. Bird gets there, bird may fill a niche usually filled by mammal. Human can get there, and fill a niche of a small bear.

If you want to argue that innovation is not selected for sufficiently because it's a public good or not incrementally useful or something (I disagree), then do so without invoking Tasmanians as support (and I won't refer to Dodo).

Comment author: gwern 21 February 2012 03:53:49PM 0 points [-]

The point is that even the birds give up the flight on islands despite as you too understand it being so advantageous and internalized and such.

Continue that line of thought. Why were the birds able to give up their wings?

Because no predators.

Is that true for Tasmanians? Was it a socialist paradise, was it somehow homo homini lupus non est? Was there no pressure for innovation among the groups?

I deny the legitimacy of the comparison; it is as dead and useful as a dodo.

Comment author: Dmytry 21 February 2012 05:03:48PM * 0 points [-]

The very (alleged) fact that Tasmanians have lost their technology, yet other groups did not, got to be a fairly good indication that Tasmanians were under less pressure to keep it than other groups. The people that came to far north back during ice age, if they lose their technology there, they promptly die. And on a big continent there's large number of other people that'll swiftly get rid of ya if you lose technology.

Also, look at predators: bears, wolf packs, tigers, etc. Vs tasmanian devil and tasmanian 'tiger' which sounds scary but is the size of a dog and doesn't hunt in packs. I'd guess on Mauritius the Dodo coexisted with similar 'predators' that can't eat the Dodo.

Ohh, and the rhetorical questions: hello to the black n white world, where I'd have to prove zero selective pressure in Tasmania. Not interested. It suffices that the pressure is lower and costs aren't. Humans are very unique animals that evolved under immense external pressure. We barely made it. Homo homini lupus est does not cut it for evolving intelligence, or we'd have the original lupus evolving the intelligence. Every predatory species and it's granma are pressuring themselves, and not progressing nearly as fast as humans did, under external pressure, having been forced off trees.

Dmytry comments on Brain shrinkage in humans over past ~20 000 years - what did we lose? - Less Wrong Discussion

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