Metabolism is the biochemical network that supplies the energy and building blocks for all cells on Earth. The collective metabolism of all cells in turn mediates the global biogeochemical cycles, which regulate Earth's climate. Reconstructing metabolic evolution provides a powerful lens for linking evolutionary dynamics across levels of biological organization and for understanding the chemical co-evolution of Earth and the biosphere.

Rogier Braakman will illustrate these ideas using globally abundant oceanic phytoplankton and co-occurring bacteria as a model system. He will argue that the macroevolution of this system drew down nutrients in the surface oceans, thereby increasing total ecosystem biomass, while also increasing levels of dissolved organic carbon.

Braakman will further argue that this evolutionary dynamic produced a collective mutualism in oceanic microbial ecosystems that is highly similar to that of organelles within plant cells.

Finally he will argue that the evolutionary self-organization of oceanic microbial ecosystems contributed to the oxygenation of Earth and, more generally, that the rise of atmospheric oxygen reflects an increasing metabolic rate of the biosphere.

About the Speaker
Like many people, Rogier Braakman had been fascinated since his childhood with the questions What are we? How did we come to be? He holds a Master of Science in chemistry from the University of Amsterdam and a Ph.D. in chemical physics from California Institute of Technology. He has held postdoctoral positions at the Santa Fe Institute and Massachusetts Instituite of Technology.

Braakman's journey into science originally led him to astrochemistry. He hoped that studying networks of organic chemistry occurring during star formation and planet formation would lead to general insights about how complex chemical organization emerges from the properties of molecules and reactions. In particular, he hoped to gain insights about how life emerged on Earth.

From astrochemistry, he was led to biology and began studying the evolution of metabolism. Braakman is now studying evolutionary and ecological theory, systems biology, microbiology, oceanography, geochemistry, and Earth history.

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