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Scientists Offer 'Overwhelming' Evidence Terran Life Began in Space
An anonymous reader writes "Using data from recent comet-probing space missions, British scientists are reporting today that the odds of life starting on Earth rather than inside a comet are one trillion trillion (10 to the power of 24) to one against. That is, we're not originally from around here. Radiation in comets could keep water in liquid form for millions of years, they say, which along with the clay and organic molecules found on-board would provide an ideal incubator. 'Professor Wickramasinghe said: "The findings of the comet missions, which surprised many, strengthen the argument for panspermia. We now have a mechanism for how it could have happened. All the necessary elements - clay, organic molecules and water - are there. The longer time scale and the greater mass of comets make it overwhelmingly more likely that life began in space than on earth."'" jamie points out that the author of this paper has many 'fringe' theories. Your mileage may vary.
Also in the news this week is the opposite result: that life cannot exist in comets because of the radiation. So... it's not obvious (to me) that there is any scientific consensus on this topic.
For those interested in why the tornado in a junkyard assembling a 747 is a useless analogy for the process of evolution, the simple explanation is that evolution works by a ratcheting effect: improvements are made one tiny step at a time, in sequence, for a cumulative effect of complexity. The selection process by which those steps are made - i.e. mutations that constitute an improvement in fitness survive and others die out - is simple and nonrandom. The tornado analogy implies instant emergence of full complexity, which is nothing at all like what actually happens.
A-Bomb
Except that when life first evolved on Earth, there was no free oxygen in the atmosphere. In fact, the introduction of oxygen from cyanobacteria lead to the so-called oxygen catastrophe.
The world's burning. Moped Jesus spotted on I50. Details at 11.
You're not. Adams himself regretting writing it and said its grim tone reflected a grim period in his life. He said he wanted to end the series on a more upbeat note. Unfortunately, exercise killed him before he could finish it.
End of lesson. You may press the button.
The simplest thing we have that is theorized to be capable of evolving is a bacterium
Nonsense. Any replicator subjected to differential survival pressure is capable of evolving, and there are simpler replicators than bacteria.
We can start with the fact that macro-evolution (as defined by biologists, and not creationists) has been observed (that is to say, evolution beyond the species level).
There is a fairly (and far beyond me to explain) statistical aspect to evolutionary biology, but the main thing to keep in mind is that modern evolutionary theory predicts that all life, extant or extinct, will fit into a nested hieararchy. The bonus of the Modern Synthesis and of the last thirty or forty years of genetic research has given us a twin-nested hiearchy; not only do the fossils give us a pretty good notion of the faunal succession, but the genetic data, by and large, confirms and extends those observations.
This is the root of why evolution is a well-supported scientific theory. It's nice to have a single line of data, but when you get to evidentiary lines that fit together as well as the fossil and genetic data does, I don't think it's any great leap of any kind to state "Here is evidence for common descent".
Let's remember the flip side of all of this, and that's falsification. For common descent to be falsified, one need only provide some examples of organisms that fall outside of the twin-nested hieararchy, or of fossils that violate the faunal succession. So, if you can produce some bacteria that uses an entirely different genetic scheme that is not related in any way to the way life as we know it does, then common descent has been falsified (though, you'll note, evolution has not). As to the faunal succession, if you pull a rabbit fossil out of strata, say, 3 billion years ago, where bacterial colonies represented the most complex organisms around, then we have a very serious problem.
Now, how do we falsify a common Creationist retort; that God (or the Designer(s) or whatever) used a common toolkit, and that's why all life uses the same basic nucleotide system, or genetic language if you will. On the face of it, it seems a reasonable retort, until your factor in that said Designer likely could use any genetic he/she/it/they pleased, and there's every reason to expect that there might be a half a dozen, or a hundred or any number you like (and can expect to be likely to be useful for inheritance) such systems as there is just one. In short, any and all observations are essentially compatible with the claim "God did it" (or whatever formulation of God/designer/alien scientist/etc. you want to invoke).
The reason Creationists are picked on for their "million to one, 747 out of a scrapyard" arguments is because those arguments do not in fact address anything that modern evolutionary theory or Common Descent states, but rather knock down oversimplified and rather silly strawmen of what those theories claim happened. There's nothing positive in their claims, simply just fallaciously-formulated arguments against everything from the Big Bang to the formation of the first cell.
If one observers that all extant organisms fit into a hieararchy, then I don't think it's an inference too far to state that that relationship is more than just happenstance. If that observation fits within the predictive nature of a specific theory, then is it unreasonable to state that that observation is in fact a piece of evidence for that theory?
The world's burning. Moped Jesus spotted on I50. Details at 11.
In the absence of pre-existing organic life, none of those things are self-replicating. Ideas evolve as well, even simple ones, but that is again not helpful in determining the simplest thing which can (without help from another organism) replicate. To my knowledge, bacteria, or the bacteria-like organisms thought to precede them, are the simplest such things currently known, or in any meaningful way theorized. It's been speculated that maybe there was an RNA-based life form that was simpler, but I don't believe any actual model for such has ever been suggested.