4 ms·

(a) is exactly what is described in a paper he linked- the exterior, and more important, gray matter is pretty much all there. The vast majority of what is miss

(a) is exactly what is described in a paper he linked- the exterior, and more important, gray matter is pretty much all there. The vast majority of what is missing is white matter. http://blogs.discovermagazine.com/neuroskeptic/2015/07/26/is-your-brain-really-necessary-revisited/ http://blogs.discovermagazine.com/neuroskeptic/2015/07/26/is... Not as exciting when you look at it like that.

emn13 11y ago
Also, it's fairly reasonable to assume that IQ doesn't scale nearly linearly with brain mass (data on male/female differences clearly shows that a 10% size difference doesn't translate to much of anything on average). But let's pretend mass difference does simplistically affect neurological computational throughput. Even then, physically larger brain will need longer, more expensive signalling pathways, which can't be entirely free. Also, the larger the animal, the lower the metabolic rate - and translated to a brain with lots of dead weight, that may mean that mass gained via density is at least partially offset by a lower metabolic rate of the tissue (i.e. such a damaged brain may be burning more calories per gram of brain matter left, and that might even be less efficient overal - but in todays society, I think it's safe to say that some hypothetical extra calorie needs wouldn't need to be a problem...) If you look at it computationally, it's reasonable to assume that many of the "algorithms" the brain uses scale supra-linearly. If you had twice the computing power, the accuracy of the resulting solutions wouldn't be twice as good or arrived at twice as quickly, but some amount much lower than that. To take the classic example of chess; twice the computing power only lets you look ahead a fraction of a move more, not twice as many moves. Furthermore, the brain is a ridiculously parallel computation device. At that scale, it's conceivable that even considerably fewer neurons that operate slightly more quickly (due to a higher metabolic rate and shorter signaling pathways) might perform just as well or even better on certain tasks. All in all, it doesn't surprise me that a considerable difference in brain mass don't necessarily translate to an easily measurable IQ difference. There's going to be some effect surely, but how large would the mass difference need to be before it's noticeable? I have no idea. And those dramatic images seem to be from http://www.thelancet.com/journals/lancet/article/PIIS0140-6736%2807%2961127-1/fulltext http://www.thelancet.com/journals/lancet/article/PIIS0140-67..., that describe a patient with IQ 75 - perhaps still impressive, but also clearly below average.

emn13 11y ago

Also, it's fairly reasonable to assume that IQ doesn't scale nearly linearly with brain mass (data on male/female differences clearly shows that a 10% size difference doesn't translate to much of anything on average). But let's pretend mass difference does simplistically affect neurological computational throughput. Even then, physically larger brain will need longer, more expensive signalling pathways, which can't be entirely free. Also, the larger the animal, the lower the metabolic rate - and translated to a brain with lots of dead weight, that may mean that mass gained via density is at least partially offset by a lower metabolic rate of the tissue (i.e. such a damaged brain may be burning more calories per gram of brain matter left, and that might even be less efficient overal - but in todays society, I think it's safe to say that some hypothetical extra calorie needs wouldn't need to be a problem...) If you look at it computationally, it's reasonable to assume that many of the "algorithms" the brain uses scale supra-linearly. If you had twice the computing power, the accuracy of the resulting solutions wouldn't be twice as good or arrived at twice as quickly, but some amount much lower than that. To take the classic example of chess; twice the computing power only lets you look ahead a fraction of a move more, not twice as many moves. Furthermore, the brain is a ridiculously parallel computation device. At that scale, it's conceivable that even considerably fewer neurons that operate slightly more quickly (due to a higher metabolic rate and shorter signaling pathways) might perform just as well or even better on certain tasks. All in all, it doesn't surprise me that a considerable difference in brain mass don't necessarily translate to an easily measurable IQ difference. There's going to be some effect surely, but how large would the mass difference need to be before it's noticeable? I have no idea. And those dramatic images seem to be from http://www.thelancet.com/journals/lancet/article/PIIS0140-6736%2807%2961127-1/fulltext http://www.thelancet.com/journals/lancet/article/PIIS0140-67..., that describe a patient with IQ 75 - perhaps still impressive, but also clearly below average.