Scientific American, Volume 239

adaptation air showers alleles amino acid animals atoms bees behavior birds brain called camera carbon cells chemical ChronTrol color cortex cosmic rays cubes cyanobacteria developed earth efficiency electric electron electron volts energy engine environment enzyme eukaryotes evolution evolutionary example Fermat's last theorem field film flow fossil fraction function gas flares genes genetic heat hominid human hypothalamus increase isotope kiwi light mathematics mechanism membrane ment metabolic meteorite million missiles molecules natural selection neurons nuclear nuclei organisms oxygen particles percent plant player population possible problem prokaryotes protein protons quark radiation ratites result Scientific American solar solution species speed spin star strategy supernova surface tektites temperature theorem tion tive tomatoes ture University