Evolution: Single cell to multicellular (Introduction)

by dhw, Friday, January 07, 2011, 11:55 (4865 days ago) @ David Turell

I'm still trying to get my head round the article David has drawn our attention to, concerning the transition from unicellularity to multicellularity:-http://www.the-scientist.com/2011/1/1/38/1/-Some of the scientific details are outside my range of comprehension, but the implications of the section headed "complexity breeds cooperation" could hardly be clearer. "An incredible amount of cooperation is required for individual cells to come together and function as one, and with Natural Selection acting at the level of the individual cell, there will be significant evolutionary pressure to cheat the system and sabotage the success of the multicellular whole."-Regardless of the unknown origin of single-celled organisms, why and how did these individual cells come together in the first place? And since they took on different functions (the author compares the multicellular organism to colonies of insects), why and how did they do so? The implication seems to be that individual cells have their own intelligence as well as the ability to combine and adapt ... reminiscent of BBella's contention that intelligence is in all things. -The fact that single-celled organisms contain genes common to multicelled organisms (revolutionizing previous views of fungus/animal evolution, but surely also providing important evidence that later forms of life did evolve directly from earlier forms) is viewed by David as evidence of pre-planning by a UI. Maybe, but if the ultimate goal was humans, as you and Tony believe, why the following? "...such transitions are not always smooth, as conflict can arise when selfish mutations result in cheaters that attempt to benefit from the group without contributing their fair share." Quite apart from the wonderful parallel this presents to human society, it suggests to me that if there was pre-planning, it stopped at the stage of allowing infinite combinations. Once the mechanism for combining and adapting is in place, there seems to be a gigantic free-for-all. Hence the vast variety of species, extinctions, innovations*** ... anything is possible, and natural selection simply decides which combinations are to survive. Were humans inevitable? I don't see why. And although we're presumably going through a period of evolutionary stasis now, nor do I see why in the next billion years or so there should not be more environmental changes and mass extinctions, after which these intelligent cells may again come up with new combinations, perhaps more advanced than us humans. Though we may not be around to find out how they do it! As the article puts it: "The origins of this intriguing phenomenon remain shrouded in mystery."-*** My thanks again to David for his post (6 January at 15.10) summarizing a study which again cannot explain the mechanism for innovation. (I don't know why Natural Selection can even be considered as a source, since it doesn't originate anything.) We know that all of us animals do actually unite a variety of "intelligent" systems that function independently of our own volition (the senses, digestion, circulation, immune system etc.). So maybe the concept of intelligent cells forming new combinations can at least give us a different angle of approach from the highly unsatisfactory one of random mutations, even if it still doesn't offer an explanation.