In a quiet but consequential step, scientists have crossed a boundary that once seemed fixed — teaching leafy plants to manufacture myoglobin, the protein at the heart of meat's color, flavor, and iron. Using gene guns and the protein-making machinery already humming inside plant chloroplasts, researchers have demonstrated that the line between plant and animal food need not be drawn where we assumed. The work is incomplete, the kitchen untested, but the question it raises is ancient: what, exactly, makes meat what it is?