Changes

==The evolution of photosynthesis==

==The evolution of photosynthesis==

The ability to convert light energy to chemical energy confers a significant [[Natural selection|evolutionary advantage]] to living organisms. Early photosynthetic systems, such as those from [[Green sulfur bacteria|green]] and [[Purple sulfur bacteria|purple sulfur]] and [[Chloroflexi|green]] and [[purple

The ability to convert light energy to chemical energy confers a significant [[Natural selection|evolutionary advantage]] to living organisms. Early photosynthetic systems, such as those from [[Green sulfur bacteria|green]] and [[Purple sulfur bacteria|purple sulfur]] and [[Chloroflexi|green]] and [[purple bacteria|purple non-sulfur bacteria]], are thought to have been anoxygenic, using various molecules as [[electron donor]]s. Green and purple sulfur bacteria are thought to have used [[hydrogen]] and [[sulfur]] as an electron donor. Green nonsulfur bacteria used various [[amino acid|amino]] and other [[organic acid]]s. Purple nonsulfur bacteria used a variety of non-specific organic molecules. The use of these molecules is consistent with the geological evidence that the atmosphere was highly [[Reducing environment|reduced]] at [[History of Earth#The Hadean|that time]]. {{Fact|date=February 2007}}

bacteria|purple non-sulfur bacteria]], are thought to have been anoxygenic, using various molecules as [[electron donor]]s. Green and purple sulfur bacteria are thought to have used [[hydrogen]] and [[sulfur]] as an electron donor. Green nonsulfur bacteria used various [[amino acid|amino]] and other [[organic acid]]s. Purple nonsulfur bacteria used a variety of non-specific organic molecules. The use of these molecules is consistent with the geological evidence that the atmosphere was highly [[Reducing environment|reduced]] at [[History of Earth#The Hadean|that time]]. {{Fact|date=February 2007}}

Fossils have been found of what are thought to be filamentous photosynthetic organisms dating from 3.4 billion years ago ([http://www.newscientist.com/article/mg19125654.200.html ''New Scientist'', 19 Aug., 2006]).

Fossils have been found of what are thought to be filamentous photosynthetic organisms dating from 3.4 billion years ago ([http://www.newscientist.com/article/mg19125654.200.html ''New Scientist'', 19 Aug., 2006]).