Just Thinking

The following is an exact copy of a message that I posted in a flickr group called Renaissance Man (or Woman). The photos are all clickable to view larger versions and additional comments in flickr.

While I was intending to start a discussion on Fibonacci / Phi ratio in plants already, I decided to include intelligent design in the one topic as a result of Cryptia's remarks in this photo:

I made a couple of comments there, but want to expand here as it didn't seem right to do a great discourse in her photo comments. As well as the subject raised by Cryptia of the "clever" dispersal mechanism of the dandelion seeds, I would add the "clever" arrangement of them so as to fill the space around the seed head evenly.

I use the word "clever" as a loaded word, suggestive of design. Equally, it might be stated to be "effective", a word that would suggest that it worked well but not suggesting any motive in it being that way. These are two very different ways of looking at things, and people may be predisposed towards one or the other way of seeing the world. Before Darwin, only one of these ways was at all common.

Darwin's insight was to see that small variations did occur in species during his travels and to think about the consequences of this over huge periods of time. A new way of looking at things emerged, one in which design played no part, but which still got a result that was effective.

I fancy that I can possibly see fibonacci spirals in Cryptia's photo, but they are clearer in a pinecone...

... or a palm tree trunk ...

The nature of these spirals and how they increase in number while never being other than Fibonacci numbers is dealt with in this thread:

www.flickr.com/groups/emergence/discuss/72157600010225959/

But back to the arrangement itself. Mathematically it is true that if a tree branch grows leaves at some regular angle from the previous one (as seen looking down the stem) then there is one and only one angle that has a very special result, and that angle is 360 degrees times 0.618034.. (or phi) or the reverse of that. The special property is that every leaf is put in the largest remaining space (angle wise) which is clearly an advantage when we think about the "purpose" or "function" of a leaf which is to catch sunlight. So the fact that very many plants use this angle shows that nature has by design or accident found the best solution.

If a plant was able to make a consistent angle, then natural selection would eventually lead to the angle that most plants use.

See also Fibonacci Spirals.