For instance, a car is thought of as an engine, transmission, wheels, chassis and bodywork.
The engine is a self-contained part. I live on a narrowboat, and its engine is actually a diesel engine designed for a van.
So independent is the engine from the rest of the van that it can be used as a component in a different vehicle entirely.
The engine itself has distinct independent transferable components. Identical pistons can be used in several different types of engines, and the same is true for many other parts.
The engine parts themselves have components, like screws and washers, that are interchangeable with screws and washers in many other types of machinery.
This hierarchical principle is even more pronounced in the design of computer programs.
The history of programming, and computer systems in general, is the history of abstraction and combination.
Abstraction is the breaking of complex ideas and difficult techniques into simple reusable components which are understandable on their own.
Combination is used to make ever more complex and useful structures out of the simple pieces.
It is thought that this 'hierarchical design' is psychological. It makes things easier to understand if they can be understood piece by piece.
But the same hierarchies are evident in animals and plants.
I have a heart, which is interchangeable with other human and animal hearts.
There have been experiments where the hearts of pigs have been exchanged with the hearts of humans.
Arms, legs, eyes, lungs, fingers, fingernails, bones, skin have distinct functions, are transferable and independently understandable as pieces.
But evolution has no mind.
So this apparent hierarchy cannot be psychological.
What is its cause?
It is possible that the hierarchical design in nature is illusionary, and that we are, with our hierarchical minds, perceiving a structure that is not there.
I do not believe this.
I suspect there is a mathematical answer, that causes mindless evolutionary processes to produce hierarchical designs.
And I further suspect that that answer might explain why our minds like to make hierarchies.
But I do not know what the answer is, or even how properly to ask the question, and I do not know whether anyone has asked or tried to answer the question before.
I liked your carefully reasoned explanation of abstraction and assembly. Given that the human mind is good at finding "rules" where they are none as the recent controversy over mathematics is veering towards anit-Platoism.
ReplyDeleteI'm inclined to think that this universe is like a fractal. There a bunch of laws of physics, etc and the rest progresses from there. Of course, for this grand experiment to have any purpose, there would have to be an intelligent proscribing of those rules. Very much like how you might write a program to calculate and display Madelbrot fractals and then observe how they evolve at varying degrees of zoom.
On that basis intelligent design and evolution are compatible concepts. And we are living in a fractal holographic universe.
It doesn't: it looks like stupid design. Compare the human retina to the octopus retina. WHY DOES THE HUMAN RETINA HAVE A BLIND SPOT?
ReplyDeleteOr why doesn't the human eye have ten blind spots?
DeleteAnon #2, that would be an excellent and relevant response if our host were arguing for any sort of creationism. The designs of living things contain tactical mistakes that a deity, or even a moderately smart human engineer, would be unlikely to make. But he isn't (unless he's engaged in some sort of outright deceit, which I think very unlikely) arguing for the involvement of a deity. He's arguing that the hierarchical structure of living things is something that needs explaining.
ReplyDeleteHere are two suggestions of where to look for an explanation. (1) Evo-devo. Living things grow gradually from (necessarily) very simply-structured beginnings. So you (inevitably?) get a process of growth-with-refinement, like writing a piece of software top-down, which produces hierarchies. (2) An organism design is more "evolvable" (i.e., better suited to *future* evolution) if its genes perform somewhat orthogonal functions, so that changing one doesn't screw up others. So in situations where mutability down the generations is an advantage (e.g., rapidly changing environments, parasites) organisms with more-orthogonal genes will have more descendants, and if (as I think may be true) most living things have plenty of such situations in our evolutionary history, we should expect somewhat-orthogonal genes everywhere. But this, again, encourages hierarchies, and again for reasons similar to those of human engineers: hierarchical designs can have their bits more readily decoupled from one another.
Transplantation of hearts and other organs is a very messy and uncertain procedure, I believe. Things in nature tend to be highly integrated, although they can appear modular to us.
ReplyDeleteI wouldn't call this "hierarchical design" illusionary. It's there for we perceive it. Nonetheless abstraction is something our mind does. We recognize patterns and restructure our thinking (and our language) after them.
(How they came to be in the first place is a mystery to me. Maybe they just are there. There must be enclaves of structure in chaos. Just a thought...)
When we design and build something, we apply known patterns to it right from the start. It's like digestion, but with patterns.
Maybe you like that novel:
http://www.signandsight.com/features/1758.html
The answer is:
ReplyDeleteThe cost of having specialised bits and bobs is lower in multicellular organisms than having unspecialised bits and bobs. ( http://www.evolutionofcomputing.org/Multicellular/Specialization.html )
You can put a pig's heart in a human because pigs and humans have common ancestry.
See also: convergent and parallel evolution.