Endless Forms, quaich

Endless Forms most beautiful. by Sean Carroll
- fascinating book, maybe not as revolutionary as Carroll claims.

The most amazing claim he makes is that repetitive patterns are not made by one organising principle:

"The genes expressed in stripes in the early fly embryo were some of the first to have their switches examined. One of the most surprising discoveries made in taking these genetic switches apart was that individual stripes of multistripe patterns are encoded by separate switches. For example, even though the seven stripes of some tool kit patterns appear very similar and evenly spaced, each stripe is drawn by a different switch that integrates different combinations of longitudinal inputs.
...
mathematicians.. influenced by a 1952 paper by the genius Alan Turing .. "The chemical basis of morphogenesis" many theoreticians sought to explain how periodic patterns could be organised across entire large structures. While the math and models are beautiful, none of this theory has been borne out by the discoveries of the last twenty years.."

(emphsis added) I find this very hard to accept. A python with 'hundreds of thoracic vertebrae' must surely have a generator to make each (somite?) vertebra similar.
It is clear that particular segments must be identified if they are to have particular legs etc, but I predict that a prior uniformly regular generator will be found.
I read another fly-stripe book around 2001 which had some great stuff on how the stripes get crisp. Sadly I cant recall the title, nor find it on my shelves... anyway the beautiful immuno-flourescant pictures in EFMB are not the first.


Interesting that Onychophora are now held to have all 10 Hox genes that arthropods have.
The rule now seems to be: duplicate some genes first, use them later.
SC claims that the 'hopeful monster' idea is now dead, but some of the changes he instances are extremely saltational, eg mice have twice doubled the flies set of Hox. Each doubling must have been quite an event, even if not monstrous.
I recall in NZ around 1967 finding a peripatus in a crumbly log in Manawatu. I didnt realise its significance.

One symmetry breaking that SC does not discuss much is the left-right distinction. Front-back & Top bottom can be 'random' but information is required to choose right. A famous wrong choice was by Gregory Bateson - he guessed that some spiral structure on the oocyte surface would dictate polarity. It is now believed that the choice is molecular. Cilia are chiral because Amino acids are chiefly L. Cilia all turn clockwise, and churn some molecule to one side.
SC does mention "situs inversus" where the liver can be on the left, etc.

Recent imaging studies of the brains of situs inversus individuals reveal that the left-right asymmetries in the frontal lobe and planum temporale are also reversed. However these individuals still have left-hemisphere dominance in speech production and are generally right handed

- if this is true, and I take most brain imaging cum grano salis, then a lot of handwaving about speech, humans over apes etc is challenged. Brocas region without significance?
I would love to get Behe to shake (whichever) hand of a situs inversus sufferer, and offer congratulations on surviving with defective cilia, those unchangeable devils.

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I am pleased to see June Pallot memorialised by ... the 'JUNE PALLOT PRIZE' for the Best Conference Paper will be presented with an engraved quaich (A QUAICH is a special kind of shallow two-handled drinking cup/bowl in Scotland.)
Endless Forms quaich