Does Technology affect the size of our brains?

On the Futurelearn Course Introduction to Psychology I made the distinction between genetic development of the brain (how big it is) and the cultural development - where the culture is always changing generation by generation.

DB asked  I am guessing that the evolution of technology may also relate to our brains' size?

If you think about it modern technology means that we don’t have to use our brains so intensely as in the past. I was brought up “under the counter” in a newsagent and tobacconist’s shop and as a child enjoyed serving customers – and all sales were done in your head in old £sd money, no bar codes and computer tills to help. In fact the work of the average shop assistant has been significantly deskilled in my lifetime. 

Where modern technology
replaces the human brain

When I learnt to drive I had to plan out routes from a map and remember details – while now one simply types the post code of where you want to go – and get a commentary telling you what to do at every road junction. Many jobs are also being deskilled – we are in the process of buying a stair-lift and the salesman simply takes the relevant measurements and a computer will work out the exact dimensions of the components to be manufactured to fit.

Our individual brains are not actually shrinking – but what matters to evolution is that it is not so important to have a very good brain in order to reach adulthood and have children. As a result, over hundreds of generations, average sized human brains could well start to get smaller as computer technology takes over more of the thinking for us.

Video including ayoung chimp
learning to crack nut

In the past brain size has moved in the other direction. Our early ancestors were probably like modern chimpanzees who sometimes use stick as cudgels, or to build sleeping platforms in trees, and break open hard nuts with a stone as a hammer. The problem is that if an early hominid developed a new technology (and I include things such as hunting techniques as tools) it would only be significant if his descendants could reliably copy it. But trial and error copying takes time and uses memory – so because those who could make more tools has a better chance of survival there was evolutionary pressure to develop larger brains.

Old Stone Age Tools

But genetic evolution is very slow so early human brains slowly got bigger over a period of 4 or 5 million years, and at the same time tool making very slowly improved – with an early design of the stone hand axe remaining virtually unchanged for nearly a million years.

Middle Stone Age Tool

About 250,000 years ago there were at least 3 Homo species, our own species (with its large brain) lived in Africa, Neanderthals (with an even larger brain) were in Europe and Asia, and the Denisovans (brain size not known) in Asia.

Some New Stone Age Tools

Then came the New Stone Age with a far wider range of crafted stone tools, and at about the same time our species started to spread out of Africa and replaced, and in some places breed with, the Neanderthals and Denisovans. From this point on technology advances at an ever increasing pace, with agriculture coming some 10,000 tears ago, followed by the development of large towns and cities and goods being moved around on wheeled vehicles and ships. By 2000 years ago the Romans were living in well-built house with underfloor central heating. And now we are sending robots to explore the other planets in the solar system. 

There is an immediate puzzle. For about 4-5 million years our use of technology increased slowly in line with the increase in brain size - and then - suddenly our technology started to increase in every larger leaps and bounds - while there was no increase in brain size - and even a very small decrease. Why?

The answer is almost certainly that language developed to a point where it was the best wau of teaching about tools. As a result:

(1) Teaching about tools was far quicker than trial and error copying so more tools could be taught in a given time

(2) If a tool was taught by language it required less memory - so more tools could be learnt without the brain getting bigger

(3) The previous two points means that language allows more elaborate tools to be taught.

(4) But language is a tool - so each generation can introduce improvements in language so it becomes possible to teach tools even more efficiently

(5) Language makes it possible to share knowledge with different individuals specializing in different tools - so a single brain no longer has to learn everything needed to survive

(6) Tools such as writing, printing, and now the world Wide Web, make information more accessible - so your brain doesn't need to remember the details - simply to know where the details can be found.

I won't go into details in this post, but the neural net model I am working on shows how there are some critical tipping points, where language allows us to learn more about making tools more efficiently, and how we share that knowledge with others. For this reason the brain we evolved over the previous 4-5 million years is actually bigger than we need to survive - but we can use the "spare capacity" to carry out other activities - creative activities.