29 August 2011

Prof. Lynn Margulis: "I want to stay as close as possible to nature looking at the lives of cells in very different environments"

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Lynn Margulis is Distinguished University Professor in the Department of Geosciences at the University of Massachusetts, Amherst. She co-developed the Gaia theory, the view that Earths’ biosphere is a living superorganism capable of self-regulation

Nevertheless Margulis is best known for her theory of symbiogenesis, which challenges a central tenet of neodarwinism. She argues that inherited variations significant in evolution come from the merging of two separate and different organisms to form a single and completely new organism .

Could you explain this concept?
The point is that from the two organisms which merge, a completely new organism is formed and that these mergers are able to handle different environments, for example one lives in the water and the other lives on land and the recombinant can do both. Another example involves organisms that use different energy sources, one photosynthesizes, which uses light, and the other consumes food; the recombinant can gain energy from either source. Traits of obvious selective advantage are called semes. The ability to make a seed over winter conditions, to breath oxygen in a world that has fluctuating amounts of oxygen and the ability to fly are all semes. Semes are genetically determined traits that evolutionists but not geneticists have always used for analyses. The problem with the geneticists, the embryologists and the evolutionists is that they are talking at different scales, with different languages and they do not talk to each other.
Any of the traits that have traditionally been used to trace evolutionary pathways in live organisms are semes, characteristics that can be identified and that confer selective advantage in given environments. Semes involve many genes. It is very easy to become blind from a single mutation, but you will never acquire an eye with single mutation.
The geneticists measure Mendelian traits that are inherited in a predictive fashion, like people’s hair and attached earlobes. From the very beginning embryologists said that the Mendelian geneticists studied trivial traits that are of no advantage whatsoever for selection and it is true. I am not interested in those. All the traits I am interested in are semes; novel features of great importance for survival.

Could you give another example of where and how symbiogenesis takes place?
Organisms that eat and do not digest what becomes the chloroplast is the biggest and most obvious case of symbiogenesis. Hungry animals or protoctists along translucent, light-filled shoreline ingest algae but digestion is inhibited. The little green algae that have been eaten attempts to inhibit digestion so they are not destroyed. Over time green snails or green worms that bask in the sunlight all day evolve. The animals photosynthesize since they have not digested or destroyed what in the past was their food. They are body farmers that are they grow food inside their translucent bodies. The acquisition of chloroplasts became a permanent part of the animal or protoctists life history. Greenness in animals is reproduced in future generations. The photosynthetic process is one of the most valuable semes. Its acquisition produces a complete change from an animal that has to run around to acquire food to one that lies in the sun and make its own food.

If symbiogenesis has the role of creating what does natural selection do?
The number of offspring of any single-parent or double parents organism can be expressed as the biotic potential, that is the number of offspring per unit-time under optimized conditions. That number is characteristic of every organism in the world that can be measured. Darwin’s favorite example was that a pair of elephants could have enough offsprings to cover the entire earth. Nevertheless that number is only very occasionally reached and that is what natural selection is, the failure of the biotic potential to be reached. No one disagrees with the continuous presence and unstoppable power of natural selection to eliminate.

What are in your opinion the reasons why the theory of symbiogenesis encountered so much resistance from the scientific community at first?
The scientific community and the entire world in those years were communist versus non-communist. You had the English American tradition with the concept of independence and capitalist success measured in money and on the other side you had Eastern Europe with the communist way of life. Never does science transcend the cultural context in which it exists. Symbiosis seemed to be communist and Neo-Darwinism –that is an exaggeration of what Darwin said- competition, survivor of the fittest were seen as western. So you had a huge political split that was reflected in science and I was just a victim of that.

Do you think the symbiogenesis theory is related to the concept of collaboration?
I think that it was taken to me. Symbiogenesis is a scientific word and collaboration is a word for sports and people, it is completely social and not science in any way since it is unmeasurable. The word collaboration has always contaminated the symbiogenesis literature but I have never used it since those who collaborate are people, not cells. The same happened with Darwin. What he did was to describe nature while the idea that his theory is competitive is post-Darwin and comes from the English speaking cultures and from choosing only the parts of his work that could support this idea and this cultural prejudice.

Another controversial concept of yours is that of bacterial intelligence. What do you mean by that?
The ability to sense wet-dry, to be attracted to or repelled by chemicals, poisons or food, the sensitivity to gravity, every property that we consider sensitivity to the environment and capable of affecting responses for the environment is already present in live beings and the minimal live beings are bacterial cells.

Nowadays many of your ideas, such as the fact that chloroplasts began as cyanobacteria and that mitochondria arose from oxygen respiring bacteria are accepted. There is still one part which needs to be proven and it is what you are working on: the origin of the eukaryotic cell from an archeabacterial and eubacterial merger, which you propose is connected to the origin of eukaryotic motility.
In my opinion it is already scientifically proven as much as anything can be scientifically proven that involves scientific information derived from more than one single field. What I have done is show that the same processes as those hypothesized in the history of evolution take place today. However, they do in places people don’t study, like the intestine of termites, where many different kinds of spirochetes (long, slender, swimming eubacteria) live. Never is movement seen inside bacteria cells. Yet in all eukaryotic cells, those of animals, fungi, plants and protoctists, with a microscope, one can see perfectly that movement takes place inside the cell. What I argue is that this intracellular movement is due to structures that belong to the eukaryote's "cytoskeletal system." The movement comes from ancient swimming bacteria, spirochetes, which originally lived outside.

Why is it important?
The cytoskeleton that I believe integrated by spirochete bacteria is absolutely fundamental for the activities that need movement inside the cell, including ingestion, digestion and mitotic cell division.
A very few kinds of spirochetes are infectious agents of syphilis (Treponema pallidum) and Lyme disease (Borrelia burgdorferi). However spirochetes are ubiquitous and far more diverse. Right now you have hundreds of different kinds in your mouth! When people talk about "killing germs," that is suicide! There are more bacterial cells in the human body than animal cells and you cannot function without their presence.

Besides being a researcher you are a scientific communicator with a lot of publications and you participate in hands-on teaching activities with middle and high graduate students. What brought you to science communication?
I suppose being around siblings, children, students without stop. My whole life I have been cooking for them! I am saying, the frightening level of ignorance... Science is a way of learning, of finding out about the world, not a dogma or a set of doctrines. It has been transformed into a dogma with a lot of rules but science itself is not the making of bombs, it is a way of examining the world to satisfy curiosity, something that is present in all the young people who are healthy until the school, the parents, the church and so on knocks it out of them. So fundamentally your answer is being childish.

You co-developed the Gaia theory but you criticize the fact of calling the whole Earth a superorganism. Why?
Lovelock calls the Earth superorganism because he says that if people believe it is an organism they will respect it and treat it well. I tell him not to call it like that because no single organism can cycle its own waste, breath in its spent gasses and survive. I would replace the word ‘organism’ or ‘superorganism’ with ‘ecosystem’, which is much broader.

You have co-written several books with your son Dorion. How has this collaboration started and how is it to work with your own son?
We have been working together since he was 18 years old. He was looking at a manuscript of mine and told me there was a mistake, because text didn’t match with the notes, and he was right! In that moment I felt our professional collaboration was going to have a bright future! We learned never to work in the same place, at the same manuscript and at the same time and now we have a great protocol. He is much more of a journalist and a philosophy reader and I am much more of a pure scientist, so one edits the other until we are both satisfied.

Which are the goals that you still would like to achieve both at a personal and professional level?
Right now I am writing the fourth edition to my book ‘Symbiosis in Cell Evolution: Microbial communities in the Archean and Proterozoic eons’ but now I use a new word, Simbiogenetics, for the analysis of simbiogenesis. I want to finish it most of all to explain what no one but some of my students seems to understand, that is the whole history of millions of years that took to form the eukariotic cell. I want to finish it not to convince others but to show this evidence. I want to stay as close as possible to nature as I have been doing so far, looking at the lives of cells in very different environments. Every morning I spend time close to nature and swim in the lake when the weather permits, looking at nature with my own eyes and following the experience of many people who have done documentaries on the behaviour, growth and metabolism of living beings. For me this is the way of receiving information directly from life and it is what Darwin did in his trips. You could say I am a naturalist and it is true. Reconstructing the past of nature during a thousand million of years using evidences from all the possible direct sources is still both my professional and personal goal and it is a big enough one in my opinion!
 

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