The evolution of P/F vs T/K raises important questions

[Jorge_Stolfi]

 f p characters need to be written with two horizontal lines whereas  k t just need one. So they need to be written taller and need more top room. Within a paragraph of packed text there might not be enough top room and this might explain why they don’t seem to appear often there. Paragraph first lines seem to be their preferred location.

Inded, the extra space both invites and allows the use of large fancified glyphs. Including exaggerated forms, like those on You are not allowed to view links. Register or Login to view. and f42v.  (Could that fancy initial be a play on the plant's name, if it is indeed the belladonna?)

So perhaps there is no linguistic or evolutionary explanation for their frequency. It might just be a product of language B pages have longer lines, bigger paragraphs, tight writing, and language A pages having more free space to accommodate the plant drawings.

More generally, the decision to use a puff versus its ordinary version seem to have been arbitrary. In that case it may depend on the mood of the Scribe.  

Like, as time went on, he developed increasing dislike for the job, so he used fewer and fewer puffs.  But then he got a raise from 50 cents per page to 60 cents, and is use of puffs jumped back up, together with his mood...

It would be interesting to see a graph of  f p counts plotted against their paragraph word size. A flat graph would show the 'top room' effect to be true.

More interesting may be a plot of parags as dots with (count of puffs on the head line) vs (total glyphs on head line) as coordinates, color-coded by section.   The "nothing interesting" hypothesis would have all the dots on the same straight line, except for sampling error.  Anything else would be interesting...

All the best, --stolfi