Systems Thinking is, simply, thinking about the world and its problematic situations as made-up from open interacting systems, so thinking in a "joined-up" way, but at the same time, "getting to the heart of the matter"— whatever that matter might be.
Systems Thinking Presentation—Methods and Methodologies
'N-squared' Chart, showing nuclear Hunter/Gatherer family relationships/interactions. Is this why grandmothers tend to live longer, even today?