Earth the only model for extraterrestrial evolution.

[Omits]

Interested in views on this idea. With the elements to hand we end up with just enough limbs to handle the physical. Just enough intelligence to survive. Society and beliefs will govern the speed of growth of technology. Are we tinkering with evolution now so polluting the model?

 

[paranoid marvin]

Human intelligence and the ability and proclivity to dominate other species is what led us to the top of the food chain. I think that humans have been evolving from when they first came into being, improving intelligence, enhancing their own abilities in certain areas (whilst diminishing in others) by using science to their advantage.

It's likely that the most dominant lifeform on any planet is likely to be the most intelligent and also the most ruthless. Which is why I think that if we ever encounter alien life it is more likely to be predatory than benevolent. Having barely the know-how to travel to our own Moon, is now really the right time to seek alien life whose technology far exceeds our own? And (judging by our current knowledge of the Universe) to advertise a bountiful world filled with rare, desirable things that are there for the taking?

 

[Robert Zwilling]

An interesting question, how do we fit into the scheme of things.

That totally depends on one's definition of dominant. But what other word could be used besides dominant. Does the term dominant include being able to protect your land against invasion? If it involves forceful taking of more than is needed without ever replenishing anything, then humans are at the top of the list. If it involves continually shaping and replenishing the planet in a way that is beneficial to everything else living on the planet with a lineage going back 3 or 4 billion years, then it would be the microbial world is the dominant power and we just hang out here.

When dinosaurs ruled the Earth, did their actions increase or decrease the biodiversity of Earth. What if our interaction with evolution is how things work. Instead of being a dominant force, we are just an extension of the main body whose diversity varies with time. There was a literary excursion into the realm of dinosaurs versus the aliens. People bring dinosaurs back to life, an accident puts the dinosaurs back on top again, then the aliens show up.

Humans need the microbial world to survive, the microbial world has never needed humans to survive. We like to think that we live in the jewel of the universe and anything flying around in space would want it. But how viable is that assumption. If one had the ability to fly anywhere in space, there could well be many other different factors that would define desirability. Maybe there are locations in the universe where things don't get hit by massive asteroids every couple of hundred million years. A pristine environment might be more desirable than one loaded up with all kinds of substances that don't promote long life for larger size creatures. Perhaps our infusion of industrial substances makes the planet the ultimate poison pill in terms of worthwhile conquest. We think in terms of what we personally like. There could be species that found sulfur to be far more important than water. In that case Venus might be more desirable than Earth.

The ratio of bacteria to human cells in a body used to be pegged at 10 to 1. Now some estimates have it closer to 1.3 to 1. But if you throw in everything microbial than the ratio could be quite higher than 2 or 3 to 1, maybe even back to 10. Imagine a world where the interaction between the microbial and large size life was so entwined that if you messed with the large size life you were also directly messing with the microbial world, that could make it a lot harder to just take whatever you wanted.

Maybe the purpose of evolution is not to make things that last, those are the exceptions. Maybe it is suppose to just keep making new creations and then cast them off, ready to make the next variation, whatever that might be.

When we are in space the biodiversity of our bodies decreases, some organs even shrink. Does long tern exposure to space travel create a less diverse pool of life? If we need a piece of life to make things work, maybe we have to integrate that life into our genetic makeup so we can carry it to wherever we go. Do space travelers become clones of the original stock becoming more and more similar to each other. Is that what is happening now? Is it Earth just one big spaceship traveling through time?

 

[paranoid marvin]

It's true that aliens may have different priorities and needs to humans. My understanding is that life on Earth originally found oxygen to be poisonous, and lifeforms had to adapt to survive in an oxygen rich atmosphere. In that case somewhere like Venus may be more amenable to alien life. It is said though that water is necessary for life. Now I'm not sure that we can confidently say that based on known science on one planet out of (almost) limitless others. But if it is true then we have plentiful supplies that are easily obtainable.

There is also an abundance of life on our planet, something we think (based on current science) isn't the case on other planet's. Whether just from natural curiosity or other nefarious purposes this could be an attractive proposition to alien lifeforms.

But for all the fact that humans dominate (at our molecular level) this planet, it is only for a fraction of its timeline; in relation to the Universe its less than an eyeblink of time. Humans have been around for 2 million years, and are extremely unlikely to last another 2 million. The dinosaurs managed 165 million. Eventually a disaster - probably natural, and probably in the form of an asteroid - will once again reset life on this planet, and some other species will get the chance. Last time it was large lizards, this time it was ape-like descendants, next time who knows?

 

[Wayne Mack]

It's likely that the most dominant lifeform on any planet is likely to be the most intelligent and also the most ruthless.

I am not sure how one determines the level of dominance, but I consider the aspects of intelligence to be the ability to manipulate the environment and the ability to recognize the consequences of doing so. I characterize ruthlessness as the lack of recognition of consequences. A civilization that survives long enough to develop long range space travel would also have had to learn to live in balance with its environment. This leads me to believe that a spacefaring race would not be ruthless.

 

[Omits]

If we find no evidence of (past or current) life on other objects in our solar system that may be evidence that Earth is unique for intelligent life.

If Aliens arrive (intentionally travelling here) they will either be in no state to do us harm or they don't need anything of us. Thus benign.

 

[paranoid marvin]

The chances are that if an alien race had the technology to reach Earth, we would be at their mercy. They may be benevolent or they may be hostile, or they may ignore humans entirely, as we might ignore a mouse or an ant.

Stephen Hawking advised caution about broadcasting our presence out into space.

Maybe most aliens out there are really friendly guys, and would love to make contact with humans, sharing the secrets of the Universe with us. Or maybe they would judge humans by their actions over the last couple of thousand years and decide that we aren't suitable neighbours. Perhaps they ignored us entirely and simply plundered our planet for its natural resources, or maybe they would demolish our planet to make way for a new interplanetary bypass.

Personally I think we are better off seeing what is out there before we start broadcasting our position, but the likelihood is that due to the massive distances and the extreme time spans involved we will never know if the Iniverse is teeming with life or is bereft of it.

 

[Omits]

We are broadcasting our presence anyway! Consider a race with greater tech then they have seen our planet likely having life w/o us having to signal them (which will take generations to reach them). We are on their books for a future visit.

 

[paranoid marvin]

We are broadcasting our presence anyway! Consider a race with greater tech then they have seen our planet likely having life w/o us having to signal them (which will take generations to reach them). We are on their books for a future visit.

Yes, we are determined to attempt contact with anyone 'out there' who will listen. It's questionable whether radio waves will ever reach another form of life that could meaningfully interpret them, but it's possible that some of the interstellar space probes may eventually be discovered by alien life.

 

[Fiberglass Cyborg]

One fact I find interesting is that not all "terrestrial" planets are similar to Earth. This could be seriously restricting our ability to imagine life elsewhere. Depending on the history and elementary composition of their home star system, planets can have drastically different ratios of magnesium, silicon and iron, affecting their geology. Levels of the chemicals used by life will vary a lot , too. Some are so rich in carbon they are though to be covered in a sludgy layer of it several kilometers deep - what would life on such a planet be like?

 

[Omits]

The universe must be homogenous in materials as well as its density and therefore elements distributed evenly as the dust particles coalesce.

 

[Fiberglass Cyborg]

It's homogenous on average, in that you can describe it as "mainly hydrogen and helium plus trace elements." But the "trace elements" turn out to be rather important for rocky planets. As the Universe ages, more and more of the heavier elements are created inside stars and by supernovas. Older stars and their planets have a lower proportion of heavy elements than younger stars and their planets.

Planets are thought to have a similar mix of heavy elements to their stars, and analysis of the light from nearby stars has shown a surprsing amount of variation in that mixture. For instance, some have a lot more carbon and a lot less oxgyen than our solar system, while others have drastically different ratios of silicon and magnesium.

 

[Swank]

Humans aren't evolving. Our special gift is the ability to adapt our environment to us, not the other way around.

We look at terrestrial type planets because we know that there is at least one example where that worked out, and provided the conditions and materials for technology. But that doesn't mean anyone believes that intelligent life can't evolve in a gas giant, under an ice-capped ocean, on the surface of a neutron star or in the electromagnetic fields of a coalescing nebula. We just don't have any good tools for looking in those other places or interacting with what we find. Just like we have no real way of interacting with the complex signaling that goes on between fungus on earth.


I don't think it is true that beings that can cross between stars are necessarily more advanced than us. We probably could have launched several star ships by now if we thought it was necessary.

It is also true that the motivation to travel between stars is not something we really understand, outside of repaying a debt to Jabba the Hut or finding a planet without corn blight. So the reason actual travelers will be interested in the trip comes down to alien motivations that we can hardly guess at, but they seem more likely to be based on curiosity than assessing threats to the Empire of the Galactic Overlord, or to establish a local Galacto Burger franchise.

Basically, our biggest fear is that life is mostly like us, and therefore probable a-holes. But even we are capable of growing up.

 

[Christine Wheelwright]

Going back to the original question; yes, the idea of evolution as Darwin presented it has been somewhat bypassed in recent human development. We clearly evolved to be intelligent as a means to improve survival and procreation. But now we have arrived at a point where we can rely upon accumulated knowledge (and I think this is unique among evolved species on Earth). I don't need to re-invent electricity in order to heat my house, for example.

The struggle for survival is something of a prerequisite for evolution of the species. Life must be hard in order for marginal genetic benefits to have any effects on survival and reproduction.

I think this discussion is, anyway, quite academic. Any real evolutionary changes would take thousands of years to become apparent. But I expect those changes - where humans are concerned - have become slower than ever.

 

[AllanR]

Any real evolutionary changes would take thousands of years to become apparent

Human selection, instead of natural selection, can speed up the process.

The silver fox domestication experiment - Evolution: Education and Outreach

For the last 59 years a team of Russian geneticists led by Lyudmila Trut have been running one of the most important biology experiments of the 20th, and now 21st, century. The experiment was the brainchild of Trut’s mentor, Dmitri Belyaev, who, in 1959, began an experiment to study the process...

evolution-outreach.biomedcentral.com

 

[Swank]

Human selection, instead of natural selection, can speed up the process.

The silver fox domestication experiment - Evolution: Education and Outreach

For the last 59 years a team of Russian geneticists led by Lyudmila Trut have been running one of the most important biology experiments of the 20th, and now 21st, century. The experiment was the brainchild of Trut’s mentor, Dmitri Belyaev, who, in 1959, began an experiment to study the process...

evolution-outreach.biomedcentral.com

We're doing that. People with more intelligence and education don't have as many children. So we are selecting for being good at watching TV.