dhw: Again you state this as if it were a fact, but it's a belief. An alternative is that as environments change, and cell communities combine, they accumulate and exchange more and more information. > >david: Bluntly cell do not exchange information, only chemical reactions. Transfer of DNA is done between species. Cells have the same DNA with different funtions by differential expression of genees.-I thought this an interesting lecture (Lecture 6 in a series). -How do cells talk to each other and what do they say?-http://www.sysbio.org/resources/tutorials/2003series/biolecture5.pdf-Page 31 says this:-"Cells make different decisions depending on the input" -Seems as though cells do exchange information with each other. They may not speak in our language but through cell signals, etc., they do exchange information and make decisions accordingly.