Biomass-burning emissions impact almost all of the radiative forcing terms considered by the IPCC, yet little is known about smoke aerosol aging in nature beyond a few days. The marine southeast Atlantic free-troposphere is a natural testbed for examining aging through photolysis/oxidation of African continental fire emissions advected westward. In-situ measurements primarily from September, 2016 indicate highly-oxidized aerosol with minimal primary source signatures after 4-9 model-predicted days since emission. Aerosol loses approximately one-half of its organic aerosol over the ocean. The organic aerosol to black carbon mass ratios decrease from 14 to 10, significantly lower than many model predictions. This mass loss, combined with stability in black carbon, supports an observed 20% increase in solar absorptivity. The decreased single scattering albedos, reaching 0.83 at 9 days, arguably represent the lowest values measured globally. The relationship of the aerosol properties to model-derived time since emission suggests a useful new modeling constraint.