Thanksgiving is essentially a celebration of what makes us human

[youtube=http://www.youtube.com/watch?v=oHv6vTKD6lg&w=600&h=315]

First off, that's not to say a nation that doesn't celebrate Thanksgiving also doesn't contain humans. It's more a discussion of the core elements of Thanksgiving -- thankfulness and gratitude -- being far more than sentiment.  Evolutionary biologists and philosophers use the term reciproca…