Life deep in the Earth

more from this episode Balancing science and spirituality H2O How ancient life created the air we breathe How the Amazon pumps water into the atmosphere Life deep in the Earth Looking Up Photosynthesis Precis of episode two of the TV series Red balloons over the Rainforest Richard Saykally on unravelling the mystery of water The building blocks of life The quest to save a holy river The Snowdome glacier: remote, serene... polluted The wonder of nature from a Biblical perspective

One of the themes of The Sacred Balance is that we humans still have a lot to learn about the natural world. In Episode One of the TV Series, David Suzuki travels to a South African gold mine, goes three miles beneath the surface with biologist Tullis Onstott, and finds life forms that, until very recently, no one knew existed. This is an environment of scorching temperatures and crushing pressure, devoid of sunlight and oxygen, one that most scientists had long assumed could never harbour life. But Tullis Onstott shows David thriving communities of microbes. His discoveries have forced scientists to re-examine their assumptions of the basic requirements of life. In addition to the broadcast portions of David's interview, here is more of what Tullis Onstott had to say: Tullis Onstott on the volume and diversity of microscopic life deep within the Earth: "I think our studies in South Africa will show it's probably ... a substantial fraction of the total living biomass of our planet, but it may not be equal to the surface biomass. It may actually cover a greater amount of diversity than is present on the surface of the planet. It's hard to conceive that because, you know, whales are so different from trees, are different from people, are different from worms. But genetically speaking, even though they look the same, they're so different from each other, as different as they are from us, that there's probably more variety encompassed in subsurface life than is present on the surface." Tullis Onstott on the unique nature of life deep underground: "What we've found in the South African mines is that two kingdoms of microorganisms, bacteria and archaea, are present in the deep subsurface. There are a large number of DNA signatures that we find that don't closely correlate with anything that's ever been found on the surface. So here we're standing essentially with new branches to the tree of life, some of them that are quite distinct from anything that's ever been discovered before." Tullis Onstott on where subsurface life is found, and not found: "There are plenty of rocks where we don't find any bacteria, [but] in the rocks where we do find the bacteria there has to be sufficient pore throat size to allow a bacterium to basically slither through those pore throats. So if the pore throat size is, say, half a micron then it's potentially possible for the bacteria to migrate within to the interior. So in these deep rocks they would move fairly rapidly through fractures and may deposit themselves on the outside of a fracture." Tullis Onstott on whether the life forms he is finding are residues of an earlier epoch, when there was no oxygen in the atmosphere, and on the possible role of these organisms in the evolution of all life on this planet: "Three and a half billion years ago, or two point seven billion years ago, presumably the surface of the Earth was dominated by methanogens and maybe later on sulphate-reducing organisms came in. Prior to photosynthesis it was essentially an anaerobic environment. Then the cyanobacteria kick in, and these cold beasties retreat back into anaerobic niches initially in the surface and then eventually into the deep subsurface or they are always present in the deep subsurface. And in fact, their relationship is intimately tied to the origins of life in this respect: three point eight billion years ago, the surface of our planet is getting the holy bejeezus pounded out of it by these huge impact, huge, enormous impacts, things that were ten times the size of the Cretaceous-Tertiary extinction. And the effects of these impacts would be to completely evaporate the oceans and essentially sterilize the surface of the earth down to a depth of a several hundred metres. This concept of heavy bombardment, impact frustration of life, makes you recognize that the subsurface may have played a vital role in the evolution of life on our planet. The subsurface may have been a haven for life during these atrocious epochs where the surface was getting sterilized and then, following that, as the surface cooled, these organisms would come back up and recolonize." Tullis Onstott on what we still don't know about subsurface life and its origins on this and other planets: "I think there are still a lot of risks in this business, simply because there's still so much that we don't know, and it's so easy to draw conclusions which in the end may turn out to be erroneous. There are still profound questions to be answered as to whether or not life has originated in the subsurface or is capable of originating in a subsurface environment on any planet, whether or not life can survive for tens of thousands of years, or even [whether] a single cellular organism can live that long in these environments and can be transported by meteorites from one planet to the next." biography Tullis Onstott Related moment in the TV series: episode 2 - time 18:30 Search "Google" for information on anaerobic life.