What strikes me about the article is that a gratitude journal is recommended because of its effect, with no real discussion of the cause of the increased happin

What strikes me about the article is that a gratitude journal is recommended because of its effect, with no real discussion of the cause of the increased happiness. What could possibly explain a strong, common desire regardless of life-circumstances to thank an external source for the good things in our lives? If we're merely products of genetic mutation, this seems like a very bizarre psychological phenomenon.