Is there another Earth out there?

Ah, I see what you are saying. I was assuming that your were speaking of the prey/predator relationship (which I was). It appears that you were speaking of the entire behavior. Although I tend to agree with you that there are instinctive limits on behavioral patterns, these don't seem to be hard and fast limits. Each individual is different and situations arise in which patterns change.

What I was specifically addressing was the fact that many have the view that predators only kill the prey that they can eat. This is just simply not so. Predators quite often will slaughter far more than they can eat (ever seen what one weasel can do to the population of a chicken coop?). And tortuing their prey is not that uncommon (cats playing with mice and Polar Bears sucking the blubber out of still-living walruses are examples that come to mind).

You make some assumptions about life spans to show my analogy is flawed. However, your assumptions are made up out of whole cloth, since there is no way to verify them.

I am telling of our actual experience. Which is that individuals in agrarian societies tend to reproduce in an exponential fashion while individuals in highly developed societies tend to reproduce in a linear or sub-linear fashion.

However, building on your assumptions, it is reasonable to think that perhaps individuals in such civilizations may not mature until a couple of centuries. And considering that, even in our own little corner of existence, the food production world-wide is increasing 1/3 again as fast as the population, it is not unreasonable to assume that a super or supra galactic civilization would have at least the same people to food production ratio.

So I ask you, which of these assumptions is incorrect or not conservative?

In my personal view? The assumption that anyone would undertake interstellar travel - or, more accurately, colonization - with a maximum 10% luminal velocity. I further think the assumption dubious that a practical power supply could necessarily be developed to routinely provide the low-estimate 150 billion billion joules of energy required to reach even the nearest star system. Finally, the assumption that a civilization will maintain itself long enough to initiate exponential interstellar colonization strikes me as quite daring.

For one thing, there seems a general assumption that - at the very least - a civilization will see fit to undertake such a task whenever its star nears death. There's no consideration that a hyperadvanced civilization may, assuming it has persisted that long: (a) find an easier means of preventing the star's death; (b) find an easier means of surviving the star's death, without relocation; (c) have evolved into a state where the star's death is irrelevant to its survival; (d) find a means of departure which does not require the procurement of a new star system; (e - ) etc.

To answer your specific questions:

Or look at it another way. Assuming mankind does not destroy itself in the next 10,000 years (a big assumption), Do you think it unlikely that we will create a ship capable of sustaining life through deep space?

I think it would prove exceedingly difficult to create a ship capable of sustaining life with sufficient practicality and reliability to reach the nearest terrestrial planet.

And, knowing how to do that, is it unlikely the space craft would seek to create others like itself once it found sufficient resources?

Yes, probably. I think it unlikely that we would create a spacecraft with no other purpose than to seek out sufficient resources on some extrasolar system so that it may replicate itself. Moreover, I think it of relatively low probability that the initial colonization expedition would be undertaken, indeterminate whether it would succeed in locating & establishing a suitable colony, arguable whether such a colony would endure long enough to send out its own motherships, and so, and so forth.

And once several of these existed, isn't it likely that some would get good at doing this process?

The process is either doable & sustainable as a matter of course, or it is not. I do not think it will be done for no other purpose than to do it. On the off-chance that it were, I think the chances of failure at some intermediate stage of interstellar colonization are quite high.

But if ever there was an exception, would it not be inevitable that life would expand to consume all the resources of the galaxy in a very short time? So, either we are the first, or we are the only, or through the craziest of coincidences, we came along on the same universe-day as another species with our propensities.

There are numerous alternatives - as I've discussed in preceding posts as well as this one. In the course of speculation, the foremost limitation is your imagination.. Here's another previously alluded to alternative: we see the evidence of interstellar colonization all around us, but do not recognize it for what it is.

It is true, no doubt, that life takes a long time to develop. But earth has a 100% batting average at producing intelligent life. I don't think you can use Earth as an example of how intelligent life is unlikely to emerge.

I have used the Earth as an example of how there's every plausibility that life is common but that technological civilizations do not arise fairly frequently. The more meaningful statistic, in my view, is that only during some 0.00010989% of its lifespan has Earth evidenced technological civilization.

Your point, if I understand it, is that some intelligent life might have the characteristics you describe. My point is that if _ever_ there were an exception, that life form would quickly consume the galaxy.

My point is to convey a sense of how many variables must evidently fall into place for the scenario of exponential interstellar colonization to prove true. By example, an intelligent life form may very well have those personality characteristics but never reach a point of developing interstellar colonization for a variety of reasons - including that it's practically impossible, assuming that's the case.

I agree that it has yet to be established that we can long exist with advanced technology. But if we can, then you have to assume a space colony would also be able to persist even with advanced technology.

Not if we follow the assumptions that have been tossed around here. Many appear to think there's a high likelihood that interstellar colonization would not only get undertaken but have some probability of success even on a shoe-string budget, with no great guarantees of survival/arrival, and no apparent purpose aside from its own accomplishment. As such, there is every probability, in my view, that a modest interstellar expedition, during the course of its century & a half transit at 10% luminal velocity, would either encounter some mechanical or sociological disaster, or arrive at a system unsuitable for colonization (barring another century & a half transit elsewhere), or find its successor colony collapse for whatever reasons.

Why do you assume they are there?

My statement does not assume that they are there; it states that we do not know why we have not identified evidence of their being there. It may be because they are not there. Or, it may be because they are here. Or, it may be that interstellar travel is either impossible, or at least so difficult that nobody undertakes it because it is not worth the effort. Or, it may be because you are a bug-eyed, tentacled creature hallucinating in the insane asylum of some interstellar ark.

My statement encompasses all these possibilities.

And tortuing their prey is not that uncommon (cats playing with mice and Polar Bears sucking the blubber out of still-living walruses are examples that come to mind).

And humans have similar propensities, largely directed toward our own species--it wouldn't surprise me to learn the the answer to the question "Where are they?" is that we are sequestered off by the civilized beings in the universe until our manners improve.

The point that's interesting to me is not that predators are well-mannered--it is that predators are just well-enough armed to do their job, and no better. You could take it that, viewed as a long term relationship, prey-predator relationships are co-dependencies. Darwinian relationships in reasonably stable conditions dictate that bears don't get much faster then moose, and vice-versa.

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