Tom_McCabe2 comments on Natural Selection's Speed Limit and Complexity Bound - Less Wrong

4 Post author: Eliezer_Yudkowsky 04 November 2007 04:54PM

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Comment author: Tom_McCabe2 05 November 2007 04:29:25AM 0 points [-]

"But mammals have many ways of weeding out harmful variations, from antler fights to spermatozoa competition. And that's just if they have the four children. The provided 1 bit/generation figure isn't an upper bound, either."

Read a biology textbook, darn it. The DNA contents of a sperm have negligible impact on the sperm's ability to penetrate the egg. As for antler fights, it doesn't *matter* how individuals are removed from the gene pool. They can only be removed at a certain rate or else the species population goes to zero. Note than nonreproduction = death as far as evolution is concerned.

"Life spends a lot of time in non-equilibrium states as well, and those are the states in which evolution can operate most quickly."

Yes, but they must be balanced by states where it operates more slowly. You can certainly have a situation where 1.5 bits are added in odd years and .5 bits in even years, but it's a wash: you still get 1 bit/year long term.

"1. A lot -- I mean a _lot_ -- of crazy assumptions are made without any hard evidence to back them up. (E.g., the "mammals produce on average ~4 offspring, and when they produce more, it's compensated for by selection's inefficiencies.")"

The bit rate is O(log(offspring)), not O(offspring), so even if you produced 16 offspring, that's only three bits/generation. How many offspring do you think we have? 8,589,934,592? (= 32 bits/generation)? Selection *will* have inefficiencies, so these are upper bounds.

"This kind of redundancy, along with many other factors, makes me wonder if we need to change the 1 bit by some scaling factor..."

The factor due to redundant coding sequences is 1.36 (1.4 bits/base instead of 2.0). This *does* increase the amount of storable information, because it makes the degenerative pressure (mutation) work less efficiently. Then again, it's only a factor of 35%, so the conclusion is still basically the same.