Having just finished “Sapiens” by Yuval Harari, I watched a lecture which he presented at the RSA. [https://www.youtube.com/watch?v=2Vllgib842g] In it, he commented on the significance of the recent shrinking of the human brain. Recent, that is, as in evolutionary time. He noted that once we ourselves had become domesticated, we no longer needed the range and depth of knowledge to survive which is found in humans as hunter-gatherers. [The life-cycle of the sea-squirt is usually cited here…] By implication, we have (as it were) outsourced such knowledge – or perhaps expressed better as having ‘externalised’ it. I have not needed to learn how to find and identify edible berries; instead, I learn where to shop.

This externalisation, as has been observed, allows knowledge to be transferred across generations. And more: it can be modified and improved. This would probably fit well with Dawkins’ memes, or indeed with his ‘extended phenotype’. Sadly, I read that over ten years past, and my memory does not work so well. I also tried to locate another fading memory of something read long ago. In Stewart and Cohen’s ‘Figments of Reality’ [Ch. 8, ‘What is it like to be human?‘ at around p220 in my 1997 copy], they note that animals in laboratory settings show different, and arguably smarter, behaviour than anticipated; it seems that they are responsive to the context. Indeed, that they adapt idiosyncratically to the local environment. It also reminded me that Stewart and Cohen proposed a similar concept for this externalisation: ‘extelligence’. Still, looking into this now has brought to my attention ‘The Domesticated Brain’ by Bruce Hood, whose prefatory chapter is available here:


So that book will now be added to my reading list.

I note also how Harari uses the same device as Dawkins: he reverses the common perception that we domesticated wheat, into the way wheat has domesticated us. Just as for Dawkins, it’s the genes that manage us, not they who are our passive passengers. There are mutually reinforcing feedback cycles here; but that is for later consideration. [Note to self: cp ‘Order out of Chaos’ by Prigogine and Stengers.]

But this transfer of information also occurs in cells themselves, at least in eukaryotic cells. I understand that (again in evolutionary time-scales) mitochondrial genes have migrated to nuclear DNA. [See Mark Ridley, ‘Mendel’s Demon’, chapter 6 – the section ‘the snark was a boojum’.] So, even at that level, information is promiscuous; it is hard to say where it must belong.

But my musings took a different turn.

We are aware that there is a strong case to be made for certain diseases being a consequence of civilisation, or more simply settlement and farming. For example, our problems with obesity appear to be exacerbated by our inbuilt, ancient, need to seek out once rare sources of sugar and fats. Sensible in a world where such foods are scarce; regrettable where they are in surfeit.

Humans learned to cook; fire proved a great asset. Prepared food required less time to eat or to digest; shorter guts, less digestion needed, more time available. [The topic of increased available time also merits deeper consideration.] Cooking killed many pathogens; unfortunately, it may also have increased the presence of carcinogens. These, however, took much longer to hurt us; cancer is mainly a disease of old age, and often occurs well past breeding-time. Likewise the heart-attacks, and type-2 diabetes from the sugars and fats. Well, we do live longer, but have perhaps newer forms of death. All this is also giving us more time to be social animals, to share knowledge and culture.

Back to the shrinking brain.

Allowing that the evolutionary shrinkage may not be uniform, and the inherent complexity may yet be retained or enhanced, is it possible that the increase in dementias – Alzheimer’s, etc – is promoted by our having externalised many earlier functions of our brains? Perhaps we should look at what elements are believed to delay, or even protect from, the onset of these dreaded diseases; perhaps they seem reminiscent of that hunter-gatherer life. More exercise? New skills? But that is probably too simplistic.

Broadly, given that our brains have shrunk, might they have lost some resilience?

New posting prompted by being asked for a lost link to the blog [Althea], and feeling quite embarrassed that I have written almost nothing…