In most cases, the odds that a
protein can evolve are simply 1 in 2(molecular knowledge), or in this case, 1
in 2127, but this technique may not apply to insulin. Insulin binds to a
protein called the insulin receptor. This receptor senses insulin, and through a few more
steps signals cells to absorb sugar from the bloodstream.
This receptor is very specific to the insulin hormone. The original
receptor may have been much less specific. So while today insulin requires 189 bits of
information and 127 bits of knowledge, a precursor that might have existed 500 million
years ago may have required much less. One could certainly envision a very different
insulin receptor. Perhaps this receptor signaled the cell to absorb sugar when it detected
any protein greater than 20 amino acids. In this case, the first insulin molecules would
have required almost no molecular knowledge, and figure 4.7 might look like figure 4.8.
Figure 4.8: Molecular knowledge in Insulin
If figure 4.8 is accurate then there is a very clear path for Darwinian
evolution to work just like Darwin theorized. All of the steps are small; thus, the
scientist can easily climb to the top.
Because the structure and specificity of the first insulin receptor is
unknown, there is no way to choose between figure 4.7 and 4.8; therefore, the molecular
knowledge in insulin cannot be used to reliably infer design. There is no way to choose
between figure 4.7 and figure 4.8. Insulin was chosen because it is a very small protein.
This makes it easy to manually calculate the information and hence the knowledge. Insulin
was not chosen because it implies design. It is merely a convenient learning tool.
Insulin is unique in that its required molecular knowledge depends on
its receptor. This allows insulin to co-evolve with its receptor. Most proteins do not
have this option.
next: A
Review of Information Theory
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