What's the meaning of the sentence “the code never became shared among all organisms - a number of distinct codes remained in use”?

Question

... the code never became shared among all organisms - a number of distinct codes remained in use no matter how long the team ran their simulations...

While I know the meaning of each words I don't understand the meaning of the sentence. I think there is a contrast(or relatoinship) between "became shared" and "remained in use" but I am not able to understand it.

Does "shared" mean " divided" here?

Could you please explain it to me?

The fuller text is here:

Starting with a random initial population of codes being used by different organisms - all using the same DNA bases but with different associations of codons and amino acids - they first explored how the code might evolve in ordinary Darwinian evolution. While the ability of the code to withstand errors improves with time, they found that the results were inconsistent with the pattern we actually see in two ways. First, the code never became shared among all organisms - a number of distinct codes remained in use no matter how long the team ran their simulations. Second, in none of their runs did any of the codes evolve to reach the optimal structure of the actual code. "With vertical, Darwinian evolution," says Goldenfeld, "we found that the code evolution gets stuck and does not find the true optimum."

https://www.jwz.org/blog/2010/01/darwins-bootloader/

Answer 1

Shared in this case does not mean divided. It means common or duplicated.

The quoted sentence basically says the same thing in two different ways separated by a dash, and you are correct that there is a contrast between them. However, the contrast is not between "shared"/"in use"; instead, it is between "shared among all"/"distinct". "A number of distinct codes" means that there is more than one code, and stresses that they are different.

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As a specific example, below is a population with the code AACCG at location 3 "shared among all" organisms:

0 1 2 3 4 5 6 7 8 9
. . . A A C C G . .
. . . A A C C G . .
. . . A A C C G . .

Below is a population with "a number of distinct codes" at location 3. In this example, the number of distinct codes is 2:

0 1 2 3 4 5 6 7 8 9
. . . A A C C G . .
. . . T A C A C . .
. . . A A C C G . .