"To quote you a number of years ago: 'Linux is evolution, not intelligent design'," noted Greg KH, quoting Linux creator Linus Torvalds. Linus expanded on the statement, "evolution often does odd (and 'suboptimal') things exactly because it does incremental changes that DO NOT BREAK at any point." He continued, "in other words, exactly *because* evolution requires 'bisectability' (any non-viable point in between is a dead end by definition) and does things incrementally, it doesn't do big flips." When alternative examples in evolution were pointed out, Linus suggested that the kernel was much simpler than a mammal and more similar to bacteria:

"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)."