Evolution of the Eye - http://youtu.be/swGFMEqZKSU
While I believe Behe has since stated that "because science has not yet discovered a process by which a nerve may become photosensitive does not mean that it is impossible via evolution", as his work, which is now twenty years old, is a common argument for intelligent design/creationism I thought I'd attempt to address this point. It's not my topic, as I've repeated, when it comes to evolution I don't know shit, I just report the news, however, could light sensitivity have come from merely sensitive?
Eyes are defined in multiple ways and many carry the meaning "organs that detect light, and convert it to electro-chemical impulses in neurons" but others define an eye as simply the organ 'of vision' or 'of sight'.
The parameters of that 'vision' only become 'set' by the meaning we allocate to the word but as 'eyes' are capable of all sorts of vision from infrared to ultraviolet, 'sight' is much more wide that we describe it.1
Also, there's no reason to believe that the current highly specialized function of the eye, is what the eye 'originally' was. Some eyes can 'see' heat - in ice cold water the detection of heat means the detection of food.
may simply be because it would be an evolutionary leap too far.
A mutation which allowed a standard nerve cell to become exodermal would provide advantage; the new exodermal cell would provide a 'signal'. The signal from an exposed tooth nerve may be agony, often one cannot tell hot or cold but one can always tell 'extremes' of temperature.
Also, biology loves symmetry even in mutation so two nerve cells erupting on opposite sides of the being is likely (e.g. snails eye stalks) and would give distinct directional signals.
Instinct would drive the being toward one or other and experience of the consequentially discovered object that was providing the 'signal' would give positive or negative feedback to the being. In simple terms - Cold = no good, warm = food possibility.
After a minimum of only three trials of following the instinct to 'go toward cold' or 'go toward warm' a result could emerge, positive enough to gamble on, as to which 'direction signal' to follow.
If the instinct was to follow cold, then two of the results could produce 'of no use' responses and only one 'useful'.
If the instinct was to follow hot, then two of the results could produce 'useful' responses and only one 'not useful'.
One result reinforces the instinct; the other teaches that the instinct was 'wrong'. Whether the initial instinct was right or wrong, the fact that knowledge is power was as true then as it is now.
I think the problem with the eye is that we think of it as the magnificent camera it is; we forget that the 'first' 'eye' need not have been able to 'see' but simply to 'give advantage'. When clear advantage becomes established, the natural process of mutation takes of over, each generation slightly different, the mutation which provides the most advantage, gains more/better food for it's owner which provides the resources to produce more offspring, the new mutation becomes the norm etc. etc.
As the organisms 'minimal' advantage allows it to become more complex, more/different enzymes/proteins are likely to be produced within the being, made from the nutrients being absorbed or imbibed from the 'better' sourcing of food from the environment.
With newer building bocks in the mix, the being's offspring will be made slightly differently, the previous advantage giving 'eye buds' benefit from the new ingredients and the being spawns offspring where the eye buds are able to discern shape or heat.
Over a creature's life its offspring forms three groups, 50% have parent's style of 'eye'.
25% have 'new' eye mutation but don't figure out how to use it and die without reproducing.
Remaining 25% have 'new' eye mutation but DO figure out how to use it and thrive. It gives a food sourcing advantage over the 'original' eye group of .0001%
Over 10000 gens the thriving 'new' eye group's reproduction rate outstrips the 'original' eye group and because of the new eye groups' success, the original eye group is squeezed into extinction via natural selection.
More on the eye here
PEACE
Crispy
Crispy
Please leave a comment - Anything will do
The best communications are often,
THREE WORDS OR LESS
OR ONE OR MORE FINGERS!
1 - Science Daily - 'Seeing' Without Eyes: Hydra Stinging Cells Respond to Light
The best communications are often,
THREE WORDS OR LESS
OR ONE OR MORE FINGERS!
1 - Science Daily - 'Seeing' Without Eyes: Hydra Stinging Cells Respond to Light
