Human nature for blaming

Here is an analogy to the blame game between problems that occur in IT and when terrible natural disaster like Katrina or Mumbai monsoon rains occur. During natural disasters people start blaming various government departments or even specific individuals for long ignoring upgrades. Similarly when a bug is found in production, who's to blame? Is it the tester for letting the defect slip through? Is it the developer for introducing the bug into the code into the first place? Is it the analyst who neglected to anticipate the myriad ways in which the system could be used? Or is it the project manager who did not allocate enough time for testing? Clearly there is an element of accountability on behalf of the entire team, but this fact is too often obscured by the need to find fault. I guess it is just human nature to try to place blame. Imagine the productivity improvements we can get if people do NOT focus on the blame game, but if the blame analysis efforts can be channeled through to better avoid future problems from occurring.