alt Hacker NewsThis is not a good analogy, because both kidneys do the same thing and we don't need both of them to live.
Whereas the left and right brain hemispheres do different things that enable our species to be what it now is; which is more similar to what the article calls hind and fore/front brains, which again do different things that we wouldn't be us without. We would still be human if we had only one kidney the way we have only one bladder or one pancreas.
Kidneys are more like say lungs, gonads, breasts, or nostrils in that we have +1 extra; but the benefit created by multiplicity is ~doubling or capacity and resilience to local disease and random injury-- not a profound functionality. (Like is created by the second eye or second leg.) Of these, the second breast is radically more useful than the second kidney, and is probably a special case as it changes how we live so evolved.
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The right and left hemispheres do different things… unless you had a hemispherectomy as an infant and then one half is able to mostly perform the duties of both.
I wonder if we would have been capable of endurance hunting without both lungs. I suspect that changing that would have very drastically changed human development.
I see the point, and understood it when I wrote my comment. However, as far as I know (and I could be wrong), there is no characteristic of either cerebral hemisphere determined at the embryonic stage that differentiates one from the other. As such the two hemispheres become functionally distinct but are not functionally distinct in principle or by virtue of being left or right.
Also, as others point out, hemispherotomies and -ectomies and to a lesser extent corpus callosotomies show that neither hemisphere nor their intercommunicative ability are strictly necessary for brain function. Yes, for ideal function, but that can be said of kidneys too.
Do add to this if you can argue against it.