Quote:
Originally Posted by leewong
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First, I would state it arose from a colony of cells not a single cell...a colony. We have examples living today of fungi that form simple sets of four identical cells stuck together, others that form balls of 32-64 not quite identical cells with some specialized functions, up to full-blown multicellular organisms with 50,000 highly specialized cells, including reproductive germ cells.
Here is a possible theory. It is all hypothetical but shows just how easy early animals could evolve from just a single colony of cells:
1) A species of single celled organisms began forming aggregates of cells stuck together by a glue of secreted proteins and sugars (we can see species which do this today). All it takes is a few mutations to produce this effect. These cells have an advantage over other cells in some environments.
2) It is important not to forget these cells didnt live in colonies BEFORE the mutation that started gluing them together. These single cells developed flagella BEFORE a mutation started gluing them together. Now, a mutation appears that orients the flagella in the same direction, so that most of the flagella could work together to control the swimming direction of the colony.
3) Now you have a mutli-cellular colony that is fully mobile. It is important to remember that these cells are developing multiple mutations simultaneously. It isnt just one mutation at a time. During that same period this group of cells could be also developing mutations that allow chemical signals to be sent from one cell to another or to detect light.
4) It isnt hard to imagine from here how this colony could develop into a more sophisticated one later. A little mutation here, a little mutation there, and the cells are able to become ever increasingly complex and specialized. Small steps...
One thing you also have to consider. This isnt just one colony but trillions of colonies all mutating randomly from one another. Nature then determines which will survive an which will perish after each new mutation. You may have a handful of colonies all developing the proteins that glue them together simultaneously or thousands of years apart. Some colonies may not have had flagella for instance when the gluing protein mutation arose. Some colonies wouldnt ever produce the gluing mutation. It all depends on the random mutation and the environment selecting for it.
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Once upon a time..........
Good story really it is.
Ok so that sounds simple enough I can imagine that happening honestly I can.
Now all we have to do is gather some of those cell colonies that still exhibit those properties and Boom! We have the proof.
You should ask oxford for a grant.