Human Baby Problem inherently not amenable to parallelization?
"Now, not all applications (or, more precisely, important operations of an application) are amenable to parallelization. True, some problems, such as compilation, are almost ideally parallelizable. But others aren’t; the usual counterexample here is that just because it takes one woman nine months to produce a baby doesn’t imply that nine women could produce one baby in one month. You’ve probably come across that analogy before. But did you notice the problem with leaving the analogy at that? Here’s the trick question to ask the next person who uses it on you: Can you conclude from this that the Human Baby Problem is inherently not amenable to parallelization? Usually people relating this analogy err in quickly concluding that it demonstrates an inherently nonparallel problem, but that’s actually not necessarily correct at all. It is indeed an inherently nonparallel problem if the goal is to produce one child. It is actually an ideally parallelizable problem if the goal is to produce many children! Knowing the real goals can make all the difference. This basic goal-oriented principle is something to keep in mind when considering whether and how to parallelize your software."
- Herb Sutter
http://www.gotw.ca/publications/concurrency-ddj.htm