Gratitude is a complex notion, which bears upon both well-being and significant contemporary discussions in philosophy. In this article, I consider what may be contributed to our understanding of gratitude by examining it in terms of biological roots. In doing so, I will refer to forms of reward and recognition found across nature in biological mutualism. One can situate human gratitude within this matrix, whatever else might also be said in addition. Speaking about such roots can be undertaken in a considered way. Judgement and assessment in this territory, however, are strongly shaped by deeply held metaphysical and metaethical dispositions and assumptions. For some, the ethical and distinctively human only begins when the natural is left behind; for others, the ethical and distinctly human is rooted in the natural, even if it also goes beyond it. What we make of attention to the roots of gratitude will therefore likely be shaped, possibly quite profoundly, by underlying convictions.