Kimbra explained the album title during a Reddit AMA:
"The words Primal and Heart both by definition trace back to origin, the essential, fundamental, the central inner most part of something. This strikes a chord with all that I want to put forth in this next stage of the journey.
These songs are an exploration into human strength, hope, resilience but also vulnerability and instinct, origin, the core emotions that connect us and drive us as humans. I'm interested in re-contextualizing the word 'primal' as a progressive term, rather than making one think of just the primitive and simple.
I love the idea that humans are connected by both our primal instincts of self-preservation and at times, fear, but also our desire to strive beyond ourselves and transcend our own cyclical nature."