These cultures were sufficiently isolated from each other as to make it highly unlikely that they copied each other.
Therefore cultures throughout history have independently come to the conclusion that ritually slaughtering someone in order to appease the gods is a good idea.
Therefore humans have an innate tendency to consider human sacrifice to be a good thing.
So human sacrifice is a natural human response to deal with challenging conditions.
With the credit crunch and all that we are enduring challenging conditions.
Therefore we should consider ceremonially killing someone in order to satiate the thirst of an angry god.