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You very well may be correct. I have no way of calculating these things. But if the parent comment's DNA sample did actually match Earth-based organisms, you
by metalliqaz 6y ago
You very well may be correct. I have no way of calculating these things. But if the parent comment's DNA sample did actually match Earth-based organisms, you would have no choice but to assume contamination from human probes as the most likely explanation.
- rsynnott 6y ago> you would have no choice but to assume contamination from human probes as the most likely explanation. You would have considerable choice; it would be quite obvious whether they'd been on a separate evolutionary trajectory for billions of years or not. That's still the boring outcome, though; not related to us at all would be far more interesting.
- wolfram74 6y agoI mean, I wouldn't call support for panspermia /boring/ exactly, but I agree that a wholly separate abiogenesis event would be pretty astounding.
- eloff 6y agoIt would mean primitive life must be everywhere in the universe of it happened twice on adjacent planets independently. Very, very unlikely outcome.
- rsynnott 6y agoWell, we don't know how unlikely it is. It increasingly looks like life showed up on earth almost as soon as it was geologically possible for it to show up, which, if true, would indicate either that abiogenesis is pretty easy or that panspermia is a thing.
- eloff 6y agoIt would indicate that, but it's also somewhat expected if we're around to make that observation, which tempers how much information we can take away from it. However, happening on two adjacent planets would really affect our estimations of the likelihood of abiogenesis.
- Jweb_Guru 6y ago> It would indicate that, but it's also somewhat expected if we're around to make that observation, which tempers how much information we can take away from it. Life could have arisen on Earth much later than it did and we could still have been around to see it (or if not us, something like us) so the anthropic principle doesn't apply here. The fact that it arose so early is meaningful.
- eloff 6y agoIt is, but it's also sample size of 1. So yes, it indicates something but the confidence interval is really wide. Still, like you point out it's not meaningless as some people do try to argue.
- baja_blast 6y agoIf you take a bayesian approach to the problem it's far more likely that abiogenesis is common. This youtube video does a great job of explaining it: https://youtu.be/iLbbpRYRW5Y https://youtu.be/iLbbpRYRW5Y
- Bud 6y agoWe have basically zero data to tell us whether this outcome is "unlikely" or not. It could very easily turn out that this outcome is overwhelmingly likely.
- beders 6y agoNo need to invoke panspermia. The inner planets have exchanged material such as rocks since the beginning of their existence. I would assume it is DNA-based life. It would be a major surprise if it would be RNA-based life or something not resembling our tree of life.
- Jedd 6y agoAbsolutely - let me retrospectively adjust the panspermia 'a few billion years ago' to include potentially quite recent cross-fertilisation. In any case it makes it much less interesting, as it implies same origin. Implies but does not prove, I should add, of course.
- castis 6y agoIf they matched, another possibility is that a stable life most easily forms a specific way, or this way only. Knowing for sure wouldn't be possible until more samples are found in the universe.
- willis936 6y agoThis is about as likely as guessing a 1024 bit encrypted key. “Match” means “match”. Not “similar structure and behavior”. If it is the same DNA then the only compelling explanation is that it is from the same origin.
- deleted 6y ago[deleted]
- lawlessone 6y agoIf it's DNA at all then it would be from the same origin? How likely is it that alien life would also use DNA?
- gmuslera 6y agoEven if it is DNA, if it encodes the same proteins in the same way than the life here would a be very improbable event. Think in an alien alphabet looking like ours, but also making the same sounds and some common words and meanings with the similar looking symbols.
- willis936 6y ago“Origin” in this case would be something in the very physically close and near term. Something that excludes the possibility of serious evolutionary change. Even relatively static species undergo mutations in the long term. So if something is an exact match it is evident that they came from the same time and place (within some reasonable window). The origin would implicitly be Earth in the 1960s.
- castis 6y agoI meant match, similarly to saying curtains and carpets match.