A mother traces her son's growth from baby to grown man, and she describes it in the language of human evolution. The "her bones" in the opening lines point to Lucy, the famous fossil hominid, whom the speaker names later. As her boy learns songs, faces, manners and rhythm, he becomes a little hominid: a juvenile stalking with sticks, then an adolescent finding his "clan."
The tone starts warm and playful, full of nursery rhymes and small discoveries. It turns quieter near the end. Her son now lives "a long walk away," and the mother-bond survives in a Sunday-night phone call. The final lines shift to something sadder. Lucy "held together," but people don't: hearts shatter, families scatter, bones come apart. The speaker seems to feel both tenderness and an ache. Children grow up and leave, and the poem suggests that this ancient pattern of separation is part of being human, though love still reaches across the distance.