Is there a significant difference between the way human and animal brains work?

 

The following essay was written as a follow up to an article by Micheal Marshall quoted in the Futurelearn Course "Introducing Humanism"

"Ultimately, the human brain is capable of some remarkable achievements; it is also capable of a quite remarkable level of self deception. By questioning even the facts we want to be true, by striving to look for the bigger picture, and by making use of methods like tests and trials to remove as much of our bias and motivated reasoning as we can, we can find out what’s really going on. "

Michael Marshall

So let us question a deeply held belief and see where the questioning leads.

 

Surely everyone knows that we are more intelligent than animals. Universities all round the world have scientists studying different aspects of the human brain with more and more powerful tools to try and find out what it is - perhaps a very unusual gene - which is the source of our great intelligence. Even Michael Marshall seems to support the idea that there is something special when he says that "the human brain is capable of some remarkable achievements."

 

Why our brains are shrinking

A letter in the current New Scientist (April 22) asks the question "But why have we never filled up a brain?" and wonders why we appear to have evolved brains with spare capacity. I have just posted the following reply:

There are good evolutionary reasons why our brains are bigger than we need to survive. About 100,000 years ago the rate at which we invented new tools started to increase and as our tool-making knowledge increased we might have expected a significant increase in brain size. The opposite is happening and our brains are now slightly smaller than our immediate ancestors.

An ongoing re-assessment of an unconventional research language called CODIL suggests the reason. The original research looked at how humans and computers might work together on complex tasks and the current analysis suggests a direct relationship between the brain’s neural nets, language and intelligence. Animal (and early human) brain size is clearly limited by the time spent on trial-and-error learning in a single lifetime. However, once a self-modifying language has been invented (no need for a change in brain size or structure) a major tipping point is reached. One generation can now pass information to the next generation as abstract concepts, reducing trial-and-error learning times.  High level generalizations learnt in this way also need less neuron storage space and the savings increase as language became more sophisticated over the millennia.  In addition modern civilization allows us to call on shared knowledge (other people, books, etc), and so we no longer need brains as big as those of our pre-language ancestors in order to survive, and are actually left with some spare capacity to enjoy science, the arts, and the world around us.

Of course one is limited in what one can say in a short letter (New Scientist letters are rarely more than 250 words long) and it is worth saying a few words here to expand the above point.

 

Bottom up learning by neural net is an expensive business and brains cost a lot to run, and have to compete for resources with the other organs of the body in the evolutionary struggle to survive. But normally everything an animal learns in its lifetime is lost when it dies, so there is a practical limit on how much time an animal spends learning useful patterns rather than eating, breeding and evading predators. Different species have adopted different strategies and one, adopted by the primates is to concentrate on a small number of infants, and protective parents, to maximise learning time.

 

Early humans found simple tools helps survival and needed to pass on their tool-making skills to their children. So a slightly longer learning time helped and over some five million years our ancestors brains very slowly grew bigger allowing them to make somewhat more sophisticated tools. However the more steps it takes to make a tool the harder it becomes to learn how to make it by trial and error copying.

 

This is where CODIL comes in. CODIL was designed to allow humans to "teach" computers in a way that can be related to neural nets - and can be considered as a model for early human language as a means of making tools, with language itself being a taught tool, which can morph from processing patterns (normal animal learning) into set processing (handling abstract ideas and generalizations) and on to rule building (instructions for making tools).

 

What appear to have happened is that until about one and two hundred thousand years ago humans brains could be considered as little more that animal pattern recognising systems which learnt by trial and error - including trial and error copying of their parents using a simple language. Then language developed to a point where it allowed more complex tools. This meant that having language allowed each generation to make more powerful tools, including a more powerful language, which in turn enabled even more powerful tools to develop. A tipping point was reached which as equivalent to an auto-catalysed chemical reaction which, once it has started, proceeds at an every increasing rate.

 

The process also means making more and more powerful generalizations, which can be stored more efficiently in the neural network of the brain. (For instance learning about "mammals" and their key differences uses less memory than learning about a large number of species bottom up.) As long as our ancestors still lived in family-sized hunter gatherer groups most of the brain would still have been needed for survival. However once people started living in larger communities specialization would have started - and survival would depend on the skill mix of the community rather than individual skills. In fact the more we depend on others, including knowledge in books, etc., the less general survival skills we each need - and this allows our brains  - which evolved to learn as quickly as possible - to spend time on creative mental activities which have no obvious survival value!

 

 

 

 

Trapped on Flores - Why did the Hobbit have such a small brain?

I have currently be doing a short online course Homo floresiensis uncovered, run by the University of Wollongong. This hominin was only about one metre high and had a disproportionally small brain. In terms of my own interest in the evolution of human intelligence  this raises the interesting question of whether a smaller brain means less intelligence.

Homo floresiensis

First some of the background. Flores is an island in the Indonesian chain east of Bali and the Wallace line which separates the Asian fauna and flora from the Australian fauna and flora. As such it lacked, (until Homo sapiens arrived about 50,000 years ago, on his was to Australia) any Asian carnivores, herbivores or primates - with the exception of a pigmy elephant, Stegodon. and the diminutive Homo floresiensis. The only native carnivore which could threaten the hominin was a Komodo dragon.

Is Civilization making us (and our leaders) stupid?

I was most interested to see the article in The Atlantic with the title Is Goole making Students stupid? It suggests that the use of modern computer aids means that people are not having to be as imaginative as they would otherwise be . This would make their behaviour less intelligent when faced with unexpected and difficult problems.

But perhap the problem is far deeper that that, as there is some evidence that the human brain may have got smaller over the last few tens of thousands of years and I suspect that this is due to the similar effects cause by the whole process of civilization.

When all humans lived in small hunter-gatherer groups everyone needed to learn a whole raft of skills to keep themselves, and their family group, alive and well. However people started to develop specilist skills and trade so that for example, a skilled maker of early metal tools of bronze or later iron would not have to learn to hunt because he could get the food he needed by trading. As civilization advanced more and more people have become specialist, to the point where everyone has some very specialised skills (which depend on a stable society to be useful) and few general survival skills. The overall effect is, of course, that the collective knowledge and intelligence of society has increased enormously but, particularly on the most highly developed countries, everyone is dependant on the skills of thousands of other people simply to survive. Using all one's brain to lean to survive is no longer important and we have plenty of "spare capacity" to enjoy activities which have no real survival value - such as enjoying the works of Shakespeare or Mendelson, or even writing blogs.

This could have an evolutionary toll as there is no loner any evolutionary pressure to weed out people with minor disadvantageous brain mutations, and there would be a tendency for the brain's capacity to shrink very slowly over the generation because it is now "more powerful"  than is necessary to simply survive in a modern civilized society. After all the world population has exploded because the natural thinning out pressures of "evolution in the raw" no longer apply. We are likely to become even more dependent on "climbing on the shoulders of giants" and ever less able to look outside the establishment boxes set by our society mores and our leaders dictats.

So as civilization advances its members become more "domesticated" and more prone to practice "follow my leader" behaviours. But in the long run society can only survive if we have leaders with enough imagination and intelligence to tackle any challenges that may emerge - such as the effects of climate change. If we look at our current leaders and prospective leaders (I am particularly thinking of the coming UK general election) we see only unimaginative self interest and unintelligent short-termism. With our choice being restricted to such uninspiring prospective leaders the future looks bleak indeed.