Aren't (some) viruses RNA life?
I am surprised that nobody has mentioned ALH84001 yet. There is still debate about whether the meteorite contains biogenic fossils or not. In my opinion, some of the evidence is very hard to explain by non-biological means. So it's quite possible that we already have fossil Martian life in our hands.
Aren't (some) viruses RNA life? Even on that scale, life forms that are able to interact and take what they need to survive from life forms that dominate the planet, would have a huge competitive advantage over alternative RNA life that would have to compete without being able to profit from that dominant life form.Or alternatively, such life would fill up a niche where it can survive because it does not have to interact with us to survive, so by definition it would not be found anywhere near our kind of life. And it would have an evolutionary benefit in keeping 'us' away, so it's probably quite toxic to us.Think about it: something in a location harder to find, less likely to be habitable (to our preconceptions) and very likely less identifiable as life than snotites. We wouldn't even know where to start looking.
I may be mistaken, but if I understand correctly prions do not require nucleic acids to replicate. Prions are proteins that, while chemically identical to healthy proteins, are folded differently than their healthy counterparts. Their misfolded morphology becomes a template which causes healthy proteins to misfold, thus replicating the prion.
I may be mistaken, but if I understand correctly prions do not require nucleic acids to replicate.
Fundamental dogma of biology, man. DNA -> RNA -> Protein. Prions interfere with the last step to amplify their variation, but without the production machinery they have nothing to replicate from.
In my (very non-medical) thinking, I view prions as akin to a virus, in that they can't reproduce on their own. They "take over" properly folded proteins as viruses take over a normal cell's mechanisms in order to reproduce. Maybe, they are just in a class by themselves.On tests for finding RNA life--yes, IIRC Ward discusses this, and says while RNA life might have been here first, and may still be here, because of the requirement of DNA for "life as we know it," researchers look for DNA. Ward's "Life As We Do Not Know It" and his other book "Rare Earth" (co-authored with Don Brownlee, who taught one of the best classes I ever took) are very good reading indeed for folks interested in the possibility of life elsewhere. But fair warning, Rare Earth is a bit soul-crushing for those who want intelligent life to be common.
Ward's "Life As We Do Not Know It" and his other book "Rare Earth" (co-authored with Don Brownlee, who taught one of the best classes I ever took) are very good reading indeed for folks interested in the possibility of life elsewhere. But fair warning, Rare Earth is a bit soul-crushing for those who want intelligent life to be common.
Quote from: jgoldader on 09/05/2016 10:29 amWard's "Life As We Do Not Know It" and his other book "Rare Earth" (co-authored with Don Brownlee, who taught one of the best classes I ever took) are very good reading indeed for folks interested in the possibility of life elsewhere. But fair warning, Rare Earth is a bit soul-crushing for those who want intelligent life to be common.Mind you "Rare Earth" is very dated now. Something he acknowledges.
Quote from: Dalhousie on 09/06/2016 03:36 amQuote from: jgoldader on 09/05/2016 10:29 amWard's "Life As We Do Not Know It" and his other book "Rare Earth" (co-authored with Don Brownlee, who taught one of the best classes I ever took) are very good reading indeed for folks interested in the possibility of life elsewhere. But fair warning, Rare Earth is a bit soul-crushing for those who want intelligent life to be common.Mind you "Rare Earth" is very dated now. Something he acknowledges.Oh, the book is getting on in years, yes. It's a darned good read, though. I don't keep up on the geological stuff or paleobiology that much, so if that's dated, I'd not know. Their astronomy, as I recall it, is still sound. There was the follow-on book "Life and Death of Planet Earth" which might have updated the biology and geology some. It's unusual for *any* book to make me emotional, much less a science book, but both made me sad.
Quote from: jgoldader on 09/06/2016 11:18 pmQuote from: Dalhousie on 09/06/2016 03:36 amQuote from: jgoldader on 09/05/2016 10:29 amWard's "Life As We Do Not Know It" and his other book "Rare Earth" (co-authored with Don Brownlee, who taught one of the best classes I ever took) are very good reading indeed for folks interested in the possibility of life elsewhere. But fair warning, Rare Earth is a bit soul-crushing for those who want intelligent life to be common.Mind you "Rare Earth" is very dated now. Something he acknowledges.Oh, the book is getting on in years, yes. It's a darned good read, though. I don't keep up on the geological stuff or paleobiology that much, so if that's dated, I'd not know. Their astronomy, as I recall it, is still sound. There was the follow-on book "Life and Death of Planet Earth" which might have updated the biology and geology some. It's unusual for *any* book to make me emotional, much less a science book, but both made me sad. It was the astronomy part that was most dated, as it still assumed that planetary systems are rare (unfortunate given the exoplanet revolution that was already underway when it was written). if you like Ward's writing, you should try Gorgon, all about the amazing mammal-like reptiles of the Permian and the Permo-Triassic extinction.
Makes you wonder if this indicates that as soon as a planet finishes forming, that providing conditions are right life will spring up ASAP. Considering that it's now believed life could have started on Earth 4.1 billion years ago, so very early on.
I am surprised that nobody has mentioned ALH84001 yet. There is still debate about whether the meteorite contains biogenic fossils or not.
Are we saying that life on Mars never progressed beyond the RNA stage?
Quote from: high road on 09/04/2016 06:43 pmAren't (some) viruses RNA life?The kind of RNA life biologists are interested in is the kind that doesn't require enzymes made from protein. i.e., the "RNA World" hypothesis is that the enzymatic activity required for life is possible using self catalysed reactions.
Those fossil candidates seem to impress many, compared to the slow consensus of the 3.5 Ga stromatolites. So maybe we will see references to 3.8 Ga fossils soon.