Most of energy consumed by living species on earth stems ultimately from the sunlight harvested by photosynthetic cells. The light harvesting apparatus works like a solar cell, and optimizing its efficiency for the various habitats of life forms was a key strategy for survival of the fittest. After exploring for decades the role of individual molecules in light harvesting, chlorophylls, carotenoids, and small aggregates of these, researchers in the Theoretical Biophysics Group have now been able to put their findings together to calculate the overall efficiency and operational characteristics of a particular light harvesting system, that of purple bacteria. Based on structural biology, spectroscopy, and quantum mechanical calculations, a kinetic scheme was devised to show how evolution, like a good engineer, optimized the overall function of the system. The results are described in a recent paper, as well as in a review article .