flamming_python Sun Jan 04, 2015 12:37 pm
kvs wrote: flamming_python wrote: kvs wrote: flamming_python wrote: GarryB wrote:Considering the size and age of the universe there should be lots of life out there in the universe... statistically speaking...
The problem is we don't know how likely life is to occur. If there are 100 billion, billion planets with the potential to support life; but the chance of life evolving at any one place is 1 in 100 billion, billion, billion; then that means the chance of there being other life in the universe is 1 in a billion.
It's like waking up to find yourself in a zombie apocalypse as a lone survivor - and trying to extrapolate the probability of there being another human in a 1 km range, or even if they're any at all. It's impossible; there's not enough information to make any sort of assessment. If however you went around for a few hundred meters and saw two people at different places; then from that you can roughly estimate the mean density of humans in the region and make a guess as to how many others there might be.
It could also be that single-celled life, or even primitive multicellular life - is not uncommon, but what's vanishingly rare is the development of intelligence as well as the conditions that will allow intelligent life to progress technologically (dolphins might have done it - if there was fire, tool-making, etc... under the sea).
From a physics perspective the difference between a mouse and a human is token. Once you have the mouse, human intelligence is not that far away
so I do not buy the vanishingly small argument. It is the formation of single-celled life based on DNA that is the real "entry barrier".
Human intelligence, as far as we know - has only evolved once over the last billion years of complex multicellular life on Earth - which is itself almost 1/14th of the age of the universe.
And it only evolved within the last 50,000-100,000 years in fact. Before then - there was nothing like it - it took however many tens of extinction events to wipe out the majority of complex multicellular life on earth; before mammals took prominence, eventually, and then went on to evolve into primates - one of the species of which has proven to be the only one; out of all the hundreds of thousands among all the genus, families, kingdoms, domains, etc... to both evolve intelligence and have the capacity to take advantage of it and develop technology.
For all we know, it could have taken another billion to develop intelligence or more; who's to say we didn't get real lucky?
So far we have an actual data point: intelligent life on a life-supporting planet. Most of the other life supporting planets are just as old as the
Earth. A proper inference is that there is a very high likelihood of intelligent life on those other planets and not a low likelihood. Some
of them may have more intelligent lifeforms and some of them may have less intelligent lifeforms. But to assume a vanishingly small probability
of any intelligence is simply nonsense. It's more of the humans are the center of the universe hubris. The key here is that we have many other
animals on this planet that have brains that are over 90% as complex as ours. Perhaps if we were the only species with a complex
brain and the rest were insects then this vanishingly small probability argument would have some basis. But that is not the case on Earth.
Nope, the fact that we ourselves are intelligent is not enough to say anything - other than that life & intelligence is possible.
For if there was intelligent life out there anywhere in the universe, someone (i.e. us) would exist to observe it - but just because you exist to observe it; it doesn't mean that you can conclude that your own evolution was likely, or an incredibly unlikely fluke, or anything. You just cannot know.
Going back to my zombie apocalypse analogy. If you wake up in a ruined, zombie-infested city from a coma or something. How exactly are you supposed to know that you're not the only one left alive?
Intelligence is pushed by evolutionary pressure. It is not an anomaly.
Evolution is just a series of anomalies, some of which become popular because they give an advantage; this is evolutionary pressure.
Although some characteristics pop up more than once independently throughout the evolutionary timeline and in different species; so one can say that at least with earth-like conditions, they are reasonably likely to evolve.
Human-level intelligence has only appeared once, and only after many millions of years. Although lesser forms of intelligence have popped up too - but only really in mammals; the same root as us.
You're wrong to automatically assume that intelligence is necessarily such an evolutionary advantage. Perhaps its only an advantage under very specific conditions. Dinosaurs ruled the earth for dozens of millions of years; and they were all dumb as a rock.
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