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!

 

 

 

 

Wednesday Science Limerick - The Language Enigma

The Tower of Babel

We use our intelligent brain
To speak phrases – both bright and mundane
Are we really so clever
That despite all endeavour
Its real workings we’ll never explain.

When I started this blog I drew attention to the black hole in brain research and have referred to the subject on various occasions since. Now a paper How Could Language Have Evolved published at the end of August by Johan J. Bolhuis, Ian Tattersall, Noam Chomsky and Robert C. Berwick which demonstrates that, at least as far as the origins of language are concerned, they agree that there is a significant problem. Their abstract begins:

The evolution of the faculty of language largely remains an enigma. In this essay, we ask why. Language's evolutionary analysis is complicated because it has no equivalent in any nonhuman species. There is also no consensus regarding the essential nature of the language “phenotype.” 

My views on the subject suggest that they have been busy digging a very deep hole in the wrong place.  I am just getting things back together after a month's holiday entertaining a visitor from Australia but hope to have a post describing where they should have been digging by the end of the week.

How Humans invented Natural Language and why Animals don’t have it

Each species will balanced the use of resources between activities such as feeding, breeding, avoiding predators, and learning how to optimise these resources by using the brain. There are many different evolutionary strategies. For instance some fish lay millions of eggs while humans have small numbers of young and use their brain to maximise the survival of each youngster. However we can be certain that no animal evolves an organ bigger than it needs, and if conditions change an organ will shrink if it is bigger than necessary. This will apply to every organ and function and no species will not evolve a brain bigger than it needs.

Is Language the key to understanding human intelligence?

In my previous post I referred to a paper with a title that ended with the words “Modern Human SuperiorityComplex” and these words were at the back of my mind in reading the book “Louder than Words” by Benjamin Bergan. I am currently drafting a paper on my evolutionary approach to a symbolic language to explain how the brain processes information and I decided to read this book to help me clarify where my ideas fit with recent cognitive science research and where there are discordances which I need to address in my paper.

Some thoughts on the Difference between Neanderthals and Modern Humans

The recent paper Neandertal Demise: An Archaeological Analysis of the Modern Human Superiority Complex by Paola Villa and Wil Roebroeks reviews the archaeological literature and suggests that the evidence that the Neanderthals died out because they were in some way inferior to modern humans is weak. I wouldn’t claim to be any kind of expert in the assessment of the archaeology but I suspect there will be quite a lot of criticism from people who are sure we are superior.

When did language Evolve

Adam Benton recently posted "When did Language evolve" on his blog Evoanth which looks at the latest information about the evolution of the hyoid bone, which is linked to the tongue and other muscles which are involved in speech.

Clearly there is a relationship between our ability to vocalise and our use of language - but a key question is what came first.  Did early humans use imitation animal calls to help in hunting and then use a feature that already existed to communicate - or did our vocal tract evolve because we were already using a simple language and a clearer voice make things better. If we think of it in terms of information flow one thing seems obvious - our ability to makes a wide range of sounds, with clicks, whistles and a wide frequency range is far more than is needed to support our natural language. In the animal kingdom a number of birds, such as the Myna bird,are very good at imitating the sounds it hears - and also has the Fox2 gene supposed to be responsible.

However my own feeling is that natural language is almost entirely due to cultural evolution and I posted the following comment to Adam's post.

Do Prairie Dogs have a sophisticated communication language

In trying to model the neural code in human and animal brains one of the key factors to be considered is that of language and whether the biological foundations of human language are significantly different to other animals - or just an existing feature stretched to a significant extent - rather like a giraffe's neck. is a stretched version of a "normal" mammal neck. My own feeling is that virtually all our language is a product of culture - and the more rapidly a brain can absorb culture the more sophisticated the language can become  - in something akin to an autocatalysed chemical reaction.

I am therefore extremely interested in the work of Professor Con Slobodchikoff, as described in Animal Behaviorist, with video, at TheAtlantic.com. Experiment show that not only do their calls distinguish between different threats, but that the calls appear vary to convey additional information - distinguishing between, for example, between a tall human in a blue shirt and a short human in a yellow shirt. It addition there are complex "chatter" between individual prairie dogs which the researchers have no idea how to interpret, different groups of the same species living in different places have different dialects of the "same" language, while different species appear to use different vocalizations. 

Following a holiday and other distractions I am about to return to drafting my detailed notes on the evolutionary implications the ideal brain model (see From the Neuron to Human Intelligence: Developing an “Ideal Brain” Model). Research such as this, which suggests that we have underestimated the ability of animals to communicate with each other, makes it much easier to argue that our brain works in the same way as the brains of many other animals - except that ow brain has adapted to handle large quantities of cultural information. 

Babel's Dawn and the Evolution of Vocalisation

A copy of Edmund Bolles' book, Babel's Dawn, A Natural History of the Origins of Speech, has just arrived and tells a fascinating story of how humanity has developed from just being a great ape over the last six million years. He uses a series of verbal snapshots to reconstruct what life was like for the Last Common Ancestor and their descendants. At each stage he discusses the findings of recent research, the uncertainties of reconstructing the past of our species, and the many gaps that still have to be filled. For each episode there are brief notes that re-direct you to the extensive bibliography.

So far, so good, but I have two major problems with the book. Before I retired I used to review books for the New Scientist, and also was the book review editor for an online discussion forum called HICOM, which was an early UK based interactive forum discussing a very wide range of subjects relating to the way humans interacted with information and computers. This book might even have been included on the possible review list as it is about how humans came to communicate with each other.

The first question I would ask in picking up any book to review myself, or to allocate a suitable specialist to review, is “What is the market for this book?” In the case of Babel's Dawn I am not sure. The story is told as if the reader was was walking through a museum with dioramas representing different periods in the past, with a verbal commentary being given as you go. For school children and the generally interested public the book would have been far more effective if each vista had been described with an associated picture with the pre-human figure in a reconstructed view of the landscape, and the amount of more formal scientific discussion significantly reduced. On the other hand, the serious scientific reader might find the faction approach annoying and the lack of an index frustrating. However my knowledge of the modern US university student book market is very limited, and it could be a useful reader, rather than reference book, in introducing a subject which many students might find controversial because of their religious beliefs – a problem which is far less an issue in the UK.

I also had a serious problem with Edmund's treatment of vocalisation and its relevance to speech, Without vocalisation there can be no speech as we know it and in my opinion the book fails to examine the evolutionary pressures that lead to the changes in the vocal tract which makes speech possible.

To be fair there is a very real difficulty in reconstructing this aspect of mankind's part as sound is about as ephemeral as one can get, and there is no possibility of any direct fossil evidence. Even indicator evidence, such as the changes in a tiny bone in the larynx, is hard to find, as the bone is rarely found in fossil deposits. In practice all one can do is to speculate on the evolutionary pressures that might lead to the evolution of vocalisation, which in turn lead to speech.

So lets step away from the book and speculate as to how the story might have been told.

Undoubtedly a very important aspect of the evolution of the human body was the move from living in forests to living in far more open and dryer environments. As the forests dried out they would have initially fragmented, depending on soil, altitude and drainage conditions locally, leading to a series of forested “islands” that would eventually vanish entirely. Forest species trapped on these islands, including our ancestors, would either have to adapt or become extinct. Such environmental changes, temporally trapping creatures in small habitat areas which are in the process of disappearing, are powerful evolutionary workshops and if we look at the human body most of the changes make sense. Descending from the trees and walking in more open areas is an obvious driver for changes in our lower limbs. Such changes also free our forelimbs for gathering food, tool making and throwing things. As a vulnerable animal, which no longer has trees to climb to escape, and who is not agile enough to catch fast moving prey or run from the larger predators, early man would need a degree of cunning and planning which will be helped by a larger and more imaginative brain.

The relevant evolutionary pressures are not so obvious when it comes to vocalisation. The modern human has a very powerful and flexible vocal system – which can produce a wide range of noises, including whistles and clicks, with significant control over pitch, volume and timing. However a modern human language may only use about 30 phonemes to express meaning – so it would seem that our vocal system has developed to a far greater extent than is necessary to support speech.

Of course social bonding might have been a factor, as Edmund suggests, but our great ape ancestors would almost be using facial expressions, body language, grooming and gestures to communicate when they are close together, and it has been suggested that the reason that we have developed whites to our eyes is to make it easier to “read minds” by observing our social companion's eye movements. It is easy to see why, if vocalisation changed for other reason it might have been adapted for social communication but it is not obvious why, if stronger social bonding was an advantage, that this should not have been done by a cultural change affecting the existing bonding techniques, rather than the far slower method of, for example, evolving a more versatile larynx.

One must realise that when man's forebears first came down from the trees the use of sound would have had its snags. Using sound is a very public way of communicating – and while someone might be able to signal to a colleague on the other side of a valley one must remember that every prey or predator in the neighbourhood would pick up the sound and turn to look at where the sound indicating danger or food came from.

However there is one area where improved vocal ability could have a significant advantage and that is if used as a tool when hunting. After all, in evolutionary terms getting enough to eat must be the top priority after avoiding being eaten yourself. If the aim is to catch a medium-sized herbivore such as an antelope a good technique is to drive the animal towards an ambush, but this needs a number of hunters working as a team, and this involves signalling at a distance. The ambushers need to tell the drivers when they are ready while it could increase success if the drivers warn the ambushers that the prey is approaching the killing area. Initially an ape-like grunt to indicate that the ambusher is ready might be adequate – but over time evolutionary pressures on the prey would alert it to the fact that ape noises can indicate danger – so the signalling method would need to change. As the long time battle between prey and hunter continues the hunter must improve his tactics – so an innocent imitation call of an owl hooting, or the whistling call of a bird would be a far better signal. But as the hunters vocal skills develop it will become possible to lure other animals by making, for example, mating calls at the right time of year.

If we consider that the ability to mimic other animals is an advantage to the increasingly intelligent hunter we now have an evolutionary pathway that will lead to the development of a very wide range of vocalisations - which is what the human species possesses. But this also leads to a possible start for using vocal symbols to communicate. After all, using an animal call to symbolise an animal is the equivalent of using a simple picture as a symbol in the early days of writing. Perhaps, in the same way that pictorial languages simplifies to alphabetic languages using words, vocal languages developed in a similar way by using special combinations of sounds to symbolise names of individual members of the group, perhaps naming them after animals. Vocalisations might then be extended to other objects. Further moves towards the rudiments of language would involve reducing the number of phonemes needed to be accurately recognised and generated by combining groups of sounds into words.

But that is a story for another day.

The explosive evolution of langauge

Greg Laden's blog has just posed the following talk by Mark Pagel under the title "How language transformed humanity"



I am very interested in the way that language suddenly appeared on the scene, and the accelerating speed at which it has helped to transform the world in which we live. While Mark clearly recognizes the importance of cultural factors I was not happy with some of his supposed facts - and while I think that the concept of "social learning" can be useful in discussing the cultural explosion that coincides with, and is possibly driven by, the appearance of language I was not always happy with some of his examples. As a result I published the following comment on Greg Laden's blog.

Oh Dear - he really runs down the capability of our ape and early human relatives and misses the significance of fact that many of the areas where there are many languages with few speakers involve primitive societies.


I would agree that once language reaches a certain tipping point it greatly facilitates the transfer of information between generations - and also motivates further cultural development of the language itself. Basically you get what in chemistry I would call an auto-catalytic reaction. Once the tipping point is reached the each development in language skills makes further development easier - and there is an accelerating chain reaction. This will not only affect language - but also all the cultural activities and objects of the time.


The question which he does not address is what came before "language" which he does not really define, except by a crude analogy. Once the human line split off there has been a steady increase in brain size and almost certainly vocal abilities - and the majority of these changes will have been before "language" evolved.


What were the evolutionary pressures to drive these "improvements" if "language" did not exist. Humans were hunting on the African plains and needed skill and good team working to catch and kill larger animals. For instance in setting an ambush those lying in wait need to alert the drivers that they are ready. What better than sound - but if the sound is obviously human the prey will evolve to treat obviously human utterances as a danger - so what could be better than to evolve the ability to mimic other animals such as an owl hooting, etc., and to make a wide range of clicks, whistles and yodels, and to be able to change pitch


Before a proper language had developed there could well have been a simple hunting symbolic language which would involve a very wide range of phonemes - and each hunting group might use them in different way because they were hunting different prey in different environments. Recent research on attempting to date the development of language in Africa start with the assumption that the more primitive languages use a larger number of phonemes. Such an origin might also explain that the majority of languages with very small numbers of speakers involve tribes which are either still hunter gathers or were so until comparatively recent times.


Where did the tipping point come. My own guess is around the camp fire of an evening, when the hunters returned - and started to use their hunting calls to tell the story of the day. Children would learn about the methods and dangers of hunting without being exposed to them - thus acquiring a wider range of hunting skills. Once language reaches the stage of "Tell about the time you killed the lion, Daddy" the art of story telling has got underway. Legends are born and those of the Australian Aborigines go back several tens of thousands of years to the Dream Time, when some now extinct animals were alive.


An interesting feature of this model of language development is that language starts from a cultural tipping point and there may be no simple genetic factor at all. OK - more brain capacity could help handling far more concepts - and better vocal skills might make it easier - but the fact that the more advanced languages use less phonemes would suggest that a wide range of vocal skills is not essential for language.

Brain Storms - 3 - Evolutionary factors starting on the African Plains

Image the plains of Africa three or four million years ago – populated by a range of medium to large sized mammals which (for verbal convenience) we will describe in terms of modern species. There will be herds of antelope and zebras grazing on the ground plants, and animals such as giraffe who can eat foliage from high in the trees. Other herbivores will include elephant and rhinoceros. Wart hogs will have a more varied diet, and there would be the carnivores and carrion feeders such as lions and hyaenas. All have basically the same body plan, biochemistry, and genetic coding mechanisms – which have been modified by evolutionary pressures in different ways in different species. It is reasonable to assume – at least in a brain storm such as this – that the basic body plan includes the processes that allow the brain to store and process information.