Monday, 14 May 2018

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."
But we must be careful for it is easy to fool ourselves unless we make it clear what we mean by intelligence. As yet no-one has published a theory which explains exactly how the chemical and electrical activities in the neurons produce the intelligence needed by Shakespeare to write plays, Beethoven to compose music, or modern scientists to send rovers to explore Mars. The harder we look the more magical our intelligence seems to be.

But in trying to prove we were something special humans have been wrong before. When we believed we were at the centre of the universe the scientists of the day used mathematics to devise elaborate epicycles to explain the apparent motion of the lights in the sky called planets, As scientific instruments got better the epicycles got more and more complicated - until a logically much simpler answer was discovered. We are not at the centre of the universe. The Earth is just one of a number of planets going round the Sun, The Sun is just one of billions of stars in the Milky Way, which in turn is just one of billions of galaxies in a universe - which itself may not be unique.

There is a similar story involving large numbers with  evolution. Different cultures had mutually exclusive supernatural explanations for the number of different species while Darwin came up with one simple solution involving minute changes, in vast numbers of living organisms, over countless millions of generations.  The problem with both these cases is that they involve very large numbers in a way that the human mind finds difficult to understand.

So perhaps we are wrong in looking for some special gene which somehow makes our brain intelligent. Perhaps the reason we do no understand the relationship between the neurons in our brain and what we use it for is because we are search for a Philosopher's stone of intelligence to explain why we are “So special” and able to do many things other animals can't do. Perhaps there is a simpler solution which also involves very large numbers.

But first we must be careful what we are talking about - and exactly what we mean by "Intelligence."

We could simply define "intelligence" in terms of those things our brain can do which animals cannot do.  But we already know the limits of such an approach if we try to explain limitations in our knowledge in terms of a "God of the Gaps."  As we discover more and more the gaps become smaller and smaller and there become less and less need to postulate the need for a God at all. In recent years research into animals as different as chimpanzees, dolphins, crows and even octopuses are revealing surprising aspects on animal intelligence.

Of course we have bigger brains, and perhaps a bigger brain allow us to learn more things, but we must be careful not to confuse quality with quantity. Would a squirrel which could hide and later find a million nuts be more intelligent than one that can only hide thousand nuts? Of course not. No animal needs a brain that holds more information than it could possibly use in a lifetime and no squirrel could every eat anything like a million nuts. In evolutionary terms brains are expensive organs which have to compete with resources such as feeding and breeding and avoiding predators. Some species make having more offspring a priority over a sophisticated brain and are not worried about how many of the offspring die. Just think how many eggs a codfish lays. Other species have a small number of offspring but use a bigger and more active brain to ensure more of their offspring survive.

I think we can all agree that humans come at the extreme end of the "less offspring, bigger brain" spectrum, and of course our brain will have "stretched" using the same evolutionary mechanisms that have stretched the organs of other species - such as the neck of the giraffe or the hands of a bat. Of course such changes will have affected some of the genes - but the fundamental structures remain despite the differences in outward appearance.

So lets get down to details.

If we look at the evidence for human evolution over the last 5 million years or so the pattern is what we might expect. The early humans were just beginning to make simple tools, just like modern chimpanzees. Simple tools increased the chances of survival and a slightly bigger brain meant it was easier to learn how to make tools and pass the skill to the next generation. Biological evolution works very slowly and so over hundreds of thousands of years our brains slowly got bigger, other changes - such as changes to the new-born skull, the female hips, and the length of childhood - occurred - and this allowed us to make even more simple tools. But the process was so slow that the ways in which we made some stone tools were virtually unchanged over a period of a million years.

What we need to understand is what happened about 100,000 years ago. At the time there were several different human species in different parts of the world. The Neanderthals were in Europe and had the biggest brains, the Denisovans and others were in Asia, and the African there were several species including our own species, Homo sapiens. In a short space of time, in geological terms, the archaeological evidence showed that we started making more and more different kinds of tool, and the rate of new tool making has increase exponentially ever since. Just think of the number of new tools the human race has invented in your lifetime.

What one might expect is that when we started making more and more tools there would be more to learn and so our brains would have started getting bigger to absorb all the extra knowledge. In fact the opposite is happening and our brains are fractionally smaller than those of our hunter gather ancestors 100,000 years ago. So isn't it obvious some happened to the human brain which makes us extra special …

But in the quotation at the head of this essay Michael Marchall said "By questioning even the facts we want to be true … we can find out what’s really going on." We know that in the past humans have assumed that we are something special and we should be careful not to make the same mistake again. So let us assume that nothing biological happened to the human brain 100,000 years ago and that our brain still works in the same way as any other higher animal.

So if the brain hasn't changed what has? In reading this you are using a computer as a tool to help you learn - and computers are a very modern invention, This demonstrates that we can make tools that help the brain learn. A hundred thousand years ago we had tools which help us to kill animals for food, to make clothes to keep us warm, and make fires to render food more nutritious. So could these early humans have invented tools to help the brain to work more efficiently. Three types of tools could have made it possible to “suddenly” start inventing new tools:-
  • A tool which help us to invent new tools
  • A speed-learning tool which made learning about the new tools faster and more efficient
  • A tool which allowed information about the new tools to be passed between generations - so that knowledge of how to make the tool was not lost when its inventor died
Looked at in this way it is very easy to recognise the tool we developed - and we call it "natural language."  For perhaps as many as 5000 generations  each generation has developed language further and the combined body of cultural knowledge passed between the generations has grown exponentially. In effect our intelligence is due to our admittedly larger than average animal brain using language to process the cultural knowledge passed on to us by our parents and other teachers.
 Many (if not most) people will find it difficult to accept that apart from being bigger, our brain works in the same way as our nearest animal relatives. However the proof of any scientific theory is the accuracy of its predictions and it is appropriate to ask how our mental capabilities would be affected if this idea was true. I have been researching the evolution of human intelligence and I find that following features can be directly related to its animal origins:
  • We have a very small "short term memory" which limits the complexity of any problem that we can easily understand.
  •  We have an unreliable long term memory (although we like to pretend we never get things wrong).
  • We suffer from confirmation bias - which means that we tend to accept ideas we agree with, and reject ideas which do not support our views.
In addition there is a particular problem with "speed learning" which is relevant to other parts of this course. Once an infant has learnt to use language they become a sponge anxious to adsorb new information and even when adult we are anxious to learn what the most charismatic “teachers” have to say. For instance I suspect many of us love David Attenborough’s wild life programs because they tell us so much about the natural world. The problem is that using the most charismatic figure as a source of reliable information is a good survival strategy if you are a member of a large family group or a small tribe. However speed learning is a dangerous trap when scaled up to the national level, especially when coupled with confirmation bias. After all many Germans thought Hitler was a charismatic figure and believed what he said with dire consequences – and some of us may be worried about some of the present day leaders on the world stage. As Humanists we becomes more skeptical when people follow the alleged sayings of supernatural charismatic leaders, as the supposed source of what is claimed to be reliable information cannot be questioned.
 To conclude: What I have tried here to do is to suggest that a belief that our brains are fundamentally different to those of animals is misguided and that if we look for a simpler answer one possibility is that our apparent superior intelligence arises from the cultural knowledge bank we have accumulated over many thousands of years. But as a skeptical scientist I know I could be mistaken – so I very much welcome your views on the matter. 

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