People like to say that we cannot witness evolution because it occurred over a timescale immensely greater than human experience. Here, we show that it is possible to witness, explain, and predict evolution by focusing on technology evolution. We review the evolution of heat transfer devices from the point of view of the constructal law of design and evolution in nature. This is a broad view of the evolution where organs (components) are not stand-alone devices but play an important role in the live' finite-size systems that incorporate them. The larger systems can be human made or natural beings in which overall organization evolved, and continues to evolve. We show that heat transfer technology evolves predictably toward compactness, heat transfer augmentation, lower friction, and lower pumping power expenditure. These features are often misunderstood as competitors' in the design process, while in fact they are collaborators' from the perspective of the whole system that moves mass over the surface of the earth. Constructal law predicts that the characteristic size of the organ shifts toward lower thermodynamic imperfection and smaller sizes. In time, complexity increases predictably as larger numbers of high-density heat flux components become interconnected in finite-size constructs. Copyright (c) 2014 John Wiley & Sons, Ltd.