There is absolutely no relationship between cannibals and hedgehogs. Or so it would seem. After picking these two words completely out of the air, I discover there are 14,500 results when I google them together.
The first result points out that in fact Indian hedgehogs behave at times like cannibals, in that those who are sick and infirm fall prey to those healthy country club hedgehogs. Who would have thought it?
The second result references a book called Liberals and Cannibals: The Implications of Diversity, by Stephen Lukes, which embarks upon an interesting typology of hedgehogs (i.e., those who adhere to a single, central, coherent vision): positivist hedgehogs, uniformitarian hedgehogs, and so on. To characterize hedgehogs as monolithic in their mode of thinking is perhaps to make a leap of faith. Still it is comforting to reflect that there may be in nature a species with a unified consciousness. It is certainly not the human being...unless, of course, we turn to the saints and mystics of the race, most of whom live in caves, and so may be said to constitute a type of the earth-dwelling hedgehog. They would not, however, ordinarily be found among the cannibal sects, which seem mostly confined to places like Washington, D.C.
The point of this is that there no two words can exist without there being inherent connections between them. Perhaps these connections are only inherent in the mind. Still, they are real enough. Do not let your thoughts burrow too far into the rooty conspiratorial mass of potential associations or you will find they will eat their own young, and in the process, you.