It is often stated that the human brain is the most complex object in the universe, but is it more complex than, say, Earth鈥檚 biosphere? And how can this complexity be measured?
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Herman D鈥橦ondt Sydney, Australia
As the biosphere contains, at last count, more than 7.9 billion human brains, we can confidently state that the biosphere as an object is at least 7.9 billion times more complex than a brain.
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Garry Trethewey Cherryville, South Australia
This claim has occasionally been made in articles and letters in 麻豆传媒. A reader, Guy Cox, pointed out that a human body containing a brain must be a more complex object than just a brain.
This suggested the possibility of some sort of density component when measuring complexity. For example, is a pair of computers more complex than a single one, because of the number of parts present, or is it the same because the number of parts per computer is the same?
Is the complexity of a biosphere a function of the number of parts, such as human brains, birds鈥� feet or tree leaves, or does that have to be divided by, perhaps, volume, or the number of entities?
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Hillary Shaw Newport, Shropshire, UK
The complexity of a system might be measured by the minimum incompressible information needed to describe it. However, perhaps we should also divide by space occupied, so complexity is now minimum information compressed per cubic centimetre, so 鈥渕inimum information content per unit of space鈥�.
The London road network is surely more complex than the much sparser British road network, even though London roads are a subset of British roads. Without dividing by the space occupied, the biosphere must be more complex than the human brain, as the latter is a tiny part of the former. However, the biosphere is probably a lot more repetitive in content than the human brain is, so its descriptive information could be compressed a lot.
Some elements of the human brain do repeat, for example glial cells, but I鈥檇 still go for the human brain on this information/space basis.
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Mike Follows Sutton Coldfield, West Midlands, UK
The notion that the human brain is the most complex object in the universe smacks of anthropocentrism. Surely the brain is less complex than the body that accommodates it. Besides, other animals, like blue whales, have bigger brains than ours.
A brain is certainly more complex than a digital computer. The CPU (central processing unit) chip in a computer typically has 2 billion gates. Each gate can be set to just one of two values (0 or 1) and connected to only a handful of other gates.
In contrast, the human brain has neurons instead of gates and about 40 times as many of them. They are interconnected in myriad ways and each one acts like an analogue device that can be set to a wide range of values. But surely the human brain meets its match with the internet, or will in the future.
Complexity can be defined as an emergent property of systems that follow simple rules. An example of this can be seen in a starling murmuration or schooling fish. Each creature is 鈥減rogrammed鈥� to avoid a collision by maintaining a minimum distance from its neighbours, yet this simple rule leads to startling patterns.
The universe began with the big bang, and has certainly developed to become ever more complex. However, the brain is the only object known to have produced self-awareness and this might be what sets it apart from other objects.
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Martin Murray Telford, Shropshire, UK
I have long found this statement annoying. It sounds sciencey, but is totally meaningless. An object is a mental construct that exists only in the brain. It is how we divide the universe into bite-sized chunks so that it is digestible.
We can define the human brain as an object and come up with a measurement of complexity. The whole human being can also be an object and obviously more complex. A collection of humans could be an object (parliament, Congress, UN general assembly) and the whole planet of several billion brains can be an object.
If you take out the random mental constructs, the universe is entirely composed of subatomic particles interacting with all the other particles according to the same physical laws and thus everything is equally complex.
Statements like 鈥渢he brain is the most complex known object in the universe鈥� might be useful for grabbing a headline and landing a bit of research funding, but I don鈥檛 think they are much use otherwise. I don鈥檛 think nature plays Top Trumps.
A more relevant question would be: is the human brain complex enough to avoid self-extinction, or are all evolved apex intelligences doomed to wipe themselves out? That one isn鈥檛 looking good for the human brain right now.
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