When I studied psychology at university I was always amazed at the willingness of people to ascribe things to instinctive behaviour. I tended much more towards the nurture side of the "nature versus nurture" debate. That is, I believed that just about all behaviour was learnt.
However, I gradually realized that there was more to it, and finally came to the conclusion that there are not two but three forces that shape an individual, which is part of the source of the confusion in the the first place. I call these genetic, environmental and extra-genetic.
When we talk about "nature versus nurture", nature basically refers to genetics, and nurture refers an individual's particular environment. What I call "extra-genetic" is information passed from parent to child but not genetically. I guess you could think of it as something like culture and hence the debate could instead be decribed as "nature versus nurture versus culture".
This extra-genetic information is in many ways like genetic information and in other ways environmental which is why the whole debate is so difficult to resolve. I think I need to explain this in more depth.
Behaviour
In the first primitive organisms all behavior was passed genetically. This is called instinctive behavior. Of course, though the amount of genetic information that can be passed to an offspring is large it is limited. Hence, there is a limit to the amount of instinctive behavior.
As organisms became more advanced they developed larger brains for various reasons. One reason was that a large brain presented a way to bypass the limit on the amount of genetic information. Parents teach their children things, so that information is passed from generation to generation. The limit on the amount of information is now the size of the brain and the amount of time required to transfer it. Genes are still involved, of course, to endow the child with a large enough brain and the predisposition to learn from their parents.
Humans
Humans really have taken this to extremes. They have very large brains and it take many years after birth before they can even begin to function as a fully-fledged person. This is why children have to be involved and learning from their parents from day one. Their genetic programming means they are continually learning and processing information. They have a very strong inclination, especially at a young age, to try to copy their parents' behaviour.
This was brought home to me watching my nephew Alex on my brother's farm. He must have been about one year old at the time as he was barely walking and not yet talking. My brother had been using various hand tools and Alex had been watching. During a break in proceedings he gave a very impressive display of emulating his father using a hammer (though he could barely lift it) and other tools.
This whole process of passing extra-genetic information has been really muddied by humans. Since human societies are incredibly cooperative information is often not passed from an individual's genetic parents but from many other sources. With the advent of writing information can even be communicated from someone you have never met or who is long dead.
I will note at this point, though, that you can't learn everything from a book (or a blog). Many behaviours are only learnt by watching and copying. This is why young humans, to develop properly, need "role models", preferably their genetic parents.
This has all been evolving (in humans and other animals) and feeding back into itself over millions of years. Behaviours that were previously instinctive may have changed in some species to being learnt, freeing up genes for other purposes.
Is All Human Behaviour Learnt?
So, I return to my original thoughts. I still believe that most behaviour in humans is or can be learnt. However, I now believe that heredity plays a very important part. I believe genes give people a predisposition to some types of behaviour but that does not mean that if brought up in an atypical environment they will not behave in a completely different way. I'm trying to think of an example...
I would imagine that people of western European descent would find it easier to learn languages from western Europe than say an Australian aboriginal dialect. Conversely, an Australian aboriginal would find it harder to learn English than a local dialect. Obviously, this does not mean it is impossible, just that thousands of years of evolution mean that brains have evolved to be better at using local dialects.
So your genes do not determine your behaviour, which mainly depends on your upbringing, but they do give a tendency towards some types of behaviour. And I guess the stronger this tendency is the more likely it is to be called instinctive.
This gives rise to the question: Is any human behaviour truly instinctive? I would have to say yes. There are some things under the control of the brain that are almost impossible to override - for example, breathing. But the fact that people can feel so strongly about something to go on a hunger-strike and die from starvation, means that some of even the most basic behaviours can be "unlearnt".
Monday 10 October 2011
Thursday 6 October 2011
Neutrinos, Photons and Z-bosons
I mentioned last week that I would not be surprised if neutrinos do travel faster than photons (as suggested by the recent highly-publicised OPERA experiment). But this definitely does not mean that I think Einstein's theory of relativity is wrong or any of the other nonsense that was printed in the papers. If anything, I think Einstein's mistake was calling the maximum speed the "speed of light".
Are Neutrinos Tachyons?
The newspapers have spouted all sorts of nonsense, that if the result is correct it means that neutrinos are tachyons, sending messages back in time would be possible, extra dimensions, etc. Let's look at these first.
It is a common misconception that Einstein said that if you can send a message faster than the maximum speed you can send it backwards in time. I do not believe you can send a message faster than this but if you could the maths does not say that the progress of time becomes negative but in fact it becomes "imaginary" (ie involves the square root of negative numbers). I believe anything that involves imaginary numbers does not exist in the real world.
Another idea is that there are extra spatial dimensions and neutrinos are somehow taking a shortcut. Extra dimensions are often used in theories (eg string theory) but people should remember what Einstein himself said - "keep it as simple as possible, but no simpler". Adding extra dimensions, which we have no proof of, just makes things much more complex.
When people first looked at Einstein's equations they thought that it was possible for particles with special properties to travel faster than the maximum speed and they were called tachyons. However, I don't believe tachyons exist. If you look at the mathematics then again the existence of tachyons relies on use of "imaginary" numbers.
My first thought after reading about the OPERA experiment is if neutrinos are tachyons why don't they travel twice as fast or a million times as fast or 10^300 times as fast. The results of the experiment (if correct) shows they only travel at a tiny fraction more than the speed of photons. This immediately implies to me that photons travel at less than C, rather than neutrinos travel at more than C.
Problems
In any case, I think a lot of our thinking is clouded by nomenclature. People equate the maximum speed "C" with the "speed of light" (really meaning the "speed of electromagnetic radiation in a vacuum"). There are other particles, apart from photons, that are also supposed to travel at the maximum speed, among them neutrinos and Z bosons. To avoid confusion I think we should call the maximum speed simply "C", and distinguish it from the speed of neutrinos, Z bosons, photons in a vacuum, etc, which may possibly be different.
From my understanding there are already problems in this area with current thinking. Neutrinos are believed to travel at C, but recent experiments have shown that neutrinos must have a rest-mass. If something has rest-mass then it takes an infinite amount of energy to accelerate it to C (and like "imaginary" numbers I don't think "infinite" numbers have any basis in reality).
The only conclusion is that neutrinos travel at less than C (even if by a very small amount). If neutrinos travel at less than C I can't see why photons might not also. Nobody has ever found that photons have a rest mass but this may just mean it is too small to yet be measured.
Another reason I think photons have rest-mass is that they are affected by gravity. It will be argued that anything that moves through space must be affected by gravity since gravity bends space. My reply to this would then be that anything that moves through space must have mass. One day we will understand what it really means to have "mass".
Z-Bosons
The latest reason proposed (by Cohen and Glashow) that there is something wrong with the OPERA experiment results is this: If neutrinos were travelling faster than light they would emit particles until they lost energy causing them to slow down. This is similar to the way that electrons emit photons (called Cherenkov radiation) when traveling faster than the speed of light in water.
I will explain my understanding of this, in case you have never heard of Cherenkov radiation. Photons travelling through a medium such as water or glass travel at a significant fraction less than their speed in a vacuum. (The difference in the speed of light in glass and air is why lenses work.) If electrons travel through a medium faster than photons would travel through the same medium (but still less than C, of course) then they emit some of their energy as photons till they slow down. You can think of this as a "sonic boom" but for the speed of light not for the speed of sound.
Electrons only do this because electrons have an electrical charge and photons are electromagnetic particles. Neutrinos will not do this because they have no electrical (or magnetic) charge. However, neutrinos do have a "weak force" charge and the weak force equivalent of a photon is a Z-boson. (I know this is not strictly the full story.)
I think the Cohen & Glashow response does not preclude the OPERA results being valid. It is only relevant if neutrinos travel faster than Z-bosons. But I don't think the neutrinos are travelling faster than Z-bosons only faster than photons. So if the speed of Z-bosons is faster than the speed of light then the neutrinos still do not have to slow down to the speed of light.
I don't believe the speed of Z-bosons has been measured, or at least measured anywhere near as accurately as the speed of light. My belief is that neutrinos travel slightly faster than light but slower than Z-bosons. (Again I remind the reader that nothing travels faster than C.)
Are Neutrinos Tachyons?
The newspapers have spouted all sorts of nonsense, that if the result is correct it means that neutrinos are tachyons, sending messages back in time would be possible, extra dimensions, etc. Let's look at these first.
It is a common misconception that Einstein said that if you can send a message faster than the maximum speed you can send it backwards in time. I do not believe you can send a message faster than this but if you could the maths does not say that the progress of time becomes negative but in fact it becomes "imaginary" (ie involves the square root of negative numbers). I believe anything that involves imaginary numbers does not exist in the real world.
Another idea is that there are extra spatial dimensions and neutrinos are somehow taking a shortcut. Extra dimensions are often used in theories (eg string theory) but people should remember what Einstein himself said - "keep it as simple as possible, but no simpler". Adding extra dimensions, which we have no proof of, just makes things much more complex.
When people first looked at Einstein's equations they thought that it was possible for particles with special properties to travel faster than the maximum speed and they were called tachyons. However, I don't believe tachyons exist. If you look at the mathematics then again the existence of tachyons relies on use of "imaginary" numbers.
My first thought after reading about the OPERA experiment is if neutrinos are tachyons why don't they travel twice as fast or a million times as fast or 10^300 times as fast. The results of the experiment (if correct) shows they only travel at a tiny fraction more than the speed of photons. This immediately implies to me that photons travel at less than C, rather than neutrinos travel at more than C.
Problems
In any case, I think a lot of our thinking is clouded by nomenclature. People equate the maximum speed "C" with the "speed of light" (really meaning the "speed of electromagnetic radiation in a vacuum"). There are other particles, apart from photons, that are also supposed to travel at the maximum speed, among them neutrinos and Z bosons. To avoid confusion I think we should call the maximum speed simply "C", and distinguish it from the speed of neutrinos, Z bosons, photons in a vacuum, etc, which may possibly be different.
From my understanding there are already problems in this area with current thinking. Neutrinos are believed to travel at C, but recent experiments have shown that neutrinos must have a rest-mass. If something has rest-mass then it takes an infinite amount of energy to accelerate it to C (and like "imaginary" numbers I don't think "infinite" numbers have any basis in reality).
The only conclusion is that neutrinos travel at less than C (even if by a very small amount). If neutrinos travel at less than C I can't see why photons might not also. Nobody has ever found that photons have a rest mass but this may just mean it is too small to yet be measured.
Another reason I think photons have rest-mass is that they are affected by gravity. It will be argued that anything that moves through space must be affected by gravity since gravity bends space. My reply to this would then be that anything that moves through space must have mass. One day we will understand what it really means to have "mass".
Z-Bosons
The latest reason proposed (by Cohen and Glashow) that there is something wrong with the OPERA experiment results is this: If neutrinos were travelling faster than light they would emit particles until they lost energy causing them to slow down. This is similar to the way that electrons emit photons (called Cherenkov radiation) when traveling faster than the speed of light in water.
I will explain my understanding of this, in case you have never heard of Cherenkov radiation. Photons travelling through a medium such as water or glass travel at a significant fraction less than their speed in a vacuum. (The difference in the speed of light in glass and air is why lenses work.) If electrons travel through a medium faster than photons would travel through the same medium (but still less than C, of course) then they emit some of their energy as photons till they slow down. You can think of this as a "sonic boom" but for the speed of light not for the speed of sound.
Electrons only do this because electrons have an electrical charge and photons are electromagnetic particles. Neutrinos will not do this because they have no electrical (or magnetic) charge. However, neutrinos do have a "weak force" charge and the weak force equivalent of a photon is a Z-boson. (I know this is not strictly the full story.)
I think the Cohen & Glashow response does not preclude the OPERA results being valid. It is only relevant if neutrinos travel faster than Z-bosons. But I don't think the neutrinos are travelling faster than Z-bosons only faster than photons. So if the speed of Z-bosons is faster than the speed of light then the neutrinos still do not have to slow down to the speed of light.
I don't believe the speed of Z-bosons has been measured, or at least measured anywhere near as accurately as the speed of light. My belief is that neutrinos travel slightly faster than light but slower than Z-bosons. (Again I remind the reader that nothing travels faster than C.)
Wednesday 5 October 2011
Cicadas and Prime Numbers
Australian summers are usually filled with the deafening sound of cicadas but there are the occasional years where there seem to be no cicadas. I remember one summer (1967?) when I was a child there were huge numbers of cicadas. One weekend, along with two friends (Jimmy and Peter), we collected over one hundred of at least four different varieties. (Kids had given names to the different types based on their colour, like Black Prince, Green Grocer, etc.) Not only was this a fun time for kids but the birds were enjoying a feast too. Many times each day you would hear the monotonous sound of the cicadas interrupted by the intermittent and panicked sound of a cicada that had been caught by a bird.
Someone told me at the time that every seven years there are a lot of cicadas but I do not recall ever having seen so many in any year since. Several summers later I noticed that were no cicadas at all that year. This started me thinking about the variation in cicada numbers from year to year and I came across some information on the life-cycle of cicadas.
Life-Cycle of Cicadas
Apparently, the different varieties we had found were different species most of which had different life spans. (If you don't know, cicadas spend many years underground sucking on the sap from tree roots before emerging and mating for a few months before dying.) The life span of various species varies from 3 years to as long as 17 years. I had just learnt of prime numbers at that time and it occurred to me that the life span (in years) of any particular species was always a prime number. The most common varieties spend seven years in the ground but others spend 3, 5, 11, 13 and even 17 years underground.
Now it was obvious why some years there were few or even no cicadas and very occasionally there were a huge number. Obviously the numbers of each variety varied from year to year either through some form of collusion or due to different environment factors (weather conditions, prevalence of predators, etc) in certain years. If a variety has a life-cycle of seven years then the peaks and troughs in their numbers would tend to follow a seven year cycle, though I guess there could be several peaks in one cycle.
Why Prime?
Since different varieties have different cycles then only occasionally would the peaks coincide. I believe the "year of the cicada" I experienced happened when the peaks of at least three types coincided or at least came close to coinciding. This probably happens only once, or a few times, every 105 (3 x 5 x 7) years. By my calculations there may be another peak in 2019 and/or 2020 (1967 + 52/53), though this may be localised to the Lower Blue Mountains area.
But why would the life cycle of cicadas always be a prime number? I believe cicadas have evolved to have these life spans for the very reason that it makes their numbers unpredictable from year to year. If there were always the same number of cicadas each year, birds would come to depend on this and the number of birds that hunted cicadas would increase. The fact that different varieties have different life spans is the key to this strategy working. I believe that this is an example of inter-species cooperation. (Inter-species cooperation is something you never hear of and I believe it is far more common than biologists are currently aware.)
Clarification (Oct 11): I should clarify my last comment. Obviously, symbiotic relationships between species have been extensively studied. I simply meant that I feel there is a lot of more subtle inter-species cooperation that is yet to be discovered.
Someone told me at the time that every seven years there are a lot of cicadas but I do not recall ever having seen so many in any year since. Several summers later I noticed that were no cicadas at all that year. This started me thinking about the variation in cicada numbers from year to year and I came across some information on the life-cycle of cicadas.
Life-Cycle of Cicadas
Apparently, the different varieties we had found were different species most of which had different life spans. (If you don't know, cicadas spend many years underground sucking on the sap from tree roots before emerging and mating for a few months before dying.) The life span of various species varies from 3 years to as long as 17 years. I had just learnt of prime numbers at that time and it occurred to me that the life span (in years) of any particular species was always a prime number. The most common varieties spend seven years in the ground but others spend 3, 5, 11, 13 and even 17 years underground.
Now it was obvious why some years there were few or even no cicadas and very occasionally there were a huge number. Obviously the numbers of each variety varied from year to year either through some form of collusion or due to different environment factors (weather conditions, prevalence of predators, etc) in certain years. If a variety has a life-cycle of seven years then the peaks and troughs in their numbers would tend to follow a seven year cycle, though I guess there could be several peaks in one cycle.
Why Prime?
Since different varieties have different cycles then only occasionally would the peaks coincide. I believe the "year of the cicada" I experienced happened when the peaks of at least three types coincided or at least came close to coinciding. This probably happens only once, or a few times, every 105 (3 x 5 x 7) years. By my calculations there may be another peak in 2019 and/or 2020 (1967 + 52/53), though this may be localised to the Lower Blue Mountains area.
But why would the life cycle of cicadas always be a prime number? I believe cicadas have evolved to have these life spans for the very reason that it makes their numbers unpredictable from year to year. If there were always the same number of cicadas each year, birds would come to depend on this and the number of birds that hunted cicadas would increase. The fact that different varieties have different life spans is the key to this strategy working. I believe that this is an example of inter-species cooperation. (Inter-species cooperation is something you never hear of and I believe it is far more common than biologists are currently aware.)
Clarification (Oct 11): I should clarify my last comment. Obviously, symbiotic relationships between species have been extensively studied. I simply meant that I feel there is a lot of more subtle inter-species cooperation that is yet to be discovered.
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