This is true of very complex animals, but much less so when looking at
things like bacteria (and arguably, any current sw project is closer to
bacteria in complexity than anything mammalian).
In bacteria (and viruses), duplication of DNA/RNA is a big cost of living
in general, and as a result there is *much* less junk DNA. So in an
evolutionary sense, it's much closer to what the kernel should have (with
occasional duplication of code and interfaces to allow new functionality,
but rather aggressive pruning of the excess baggage).
In other words, all of these choices are a matter of "balance". In some
areas, excess code is not a sufficient downside, and we keep even broken
source code around with no actual function, "just because" (or rather,
because the cost of carrying it around is so small that nobody cares).
That's true in the kernel as in biology: check out not just deprecated
code, but the drivers and other odds-and-ends that are explicitly marked
as non-coding DNA (we just happen to call them BROKEN in our Kconfig).
Linus
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