Multiple Extinctions

[Nam]

I was taking a quiz where it mentioned that the Earth goes into an extinction period every 26 million years. The problem I had with it was it was written factually (granted, it was a quiz answer/question), and, though I've heard of the idea, that's what I always thought it was: an idea, or rather an hypothesis. So, I went to http://scientificamerican.com to see if they had anything on it, and they did, and they stated it was a hypothesis, I believe. The article said that there was no evidence therefore the whole idea is in limbo.

Then I thought if the Earth is estimated at 4.5 billion years, is it possible--by rate of decay, and other factors--that a similar humanoid (not necessarily "human") species could have existed? Not stating to the general degree or level in which we are at but just a generalisation of one?

Which, in turn, had me think that a few more extinctions (or more) could totally wipe out humans ever being here. I mean, the Earth has, I believe, about 2 billion more years, or something...and I once saw a documentary a few years back on how if no one's here to attend all man-made structures that eventually they will decay away, in time. Leaving little to absolutely no trace we were ever here (except perhaps the preservations of our fossils).

Likewise, in some future arena, could not another similar species exist?

Just late nite thoughts.

-Nam

[Fiji]

It'll be quite some time before all trace of our existance is wiped away.
Plastics and bronze statues will last a VERY long time ... hundreds of thousands of years at least. Things like Chernobyl, Fukushima and Nova Zembla will also be dead giveaways. And when this new species starts drilling/digging for stuff, they'll find way too little oil and occasionally some rather nasty barrels. But, suppose the Spanish flu had done us in, then the only clues would be a lack of coal and the occasional statue/bell/canon. Now, if the bronze age equivalent of this new species figures out they can smelt those statues, most of em will be gone by the time they start to really investigate and record stuff.

[wheels5894]

Mmmm, interesting! I'd think it unlikely that there has been a species like us on the earth before. Evolution works but needs vast amounts of time and there hasn't been enough in the last 4.5 billion years when one takes only the time when the place was habitable, after the vast amounts of molten rock and lava finally cooled enough. It's far more likely that we ate currently the first species like us.

We have 5 billion years left on earth before the sun turns into a red giant and engulfs the planets. it is quite possible we will become extinct and possibly that there will be another species like us take over. On the other hand, if the earth is hit by a big enough piece of space rock, lfe might end up as solely bacteria and single celled forms.I expect, though, that well before then we will have found a way to settle a new planet and what the human race has become by then will continue under a different star.

[Mrjason]

Likewise, in some future arena, could not another similar species exist?

I don't see why not, it's happened once already. I suppose it would depend on when the extinction event occurs.

If it happens at a point before we are able to stop it but too late for other species to evolve to our level then that could be it for intelligent life on earth.

There will be evidence of us for the foreseeable future, along with the detritus we leave on earth we have already left crap in space, on the moon and on mars. Not to mention the ever expanding radio bubble caused by TV and radio broadcasts

[wright]

Life on Earth has a long history; we know the very general outlines but are always finding details that surprise us. There's definitely enough time preceding us for other intelligent species to have developed.

One thing to keep in mind is that humans existed for the better part of a million years before settling down and developing agriculture, division of labor and the like. Aside from a few worked bits of stone and some burial sites, nothing remains of pre-agricultural peoples. So I find it plausible for say, a hunter-gatherer society of some dinosaur species to have existed.

But stone tools last a long time and if they were found mixed with dinosaur bones, it would be a major discovery. Even bones worked with stone knives have pretty distinctive marks, and trained paleontologists know the difference between those and the marks teeth and claws leave. There would also be middens, the remains of mass kills; a fossilized mound of tool-worked bone would be pretty distinctive. So if such a species existed, we haven't found their traces yet.

The existence of post-agricultural societies that predate the ones known is less plausible. With excess labor, big projects get done: temples, canals and aquaducts, roads, fortresses. I really think we'd have found such, barring them getting a direct hit by a meteor or other major disaster. And the empires known to history influenced surrounding cultures over great distances; just because Atlantis sinks doesn't destroy all the (hypothetical) trade goods in Europe and the Americas.

[ParkingPlaces]

I don't want to send anyone into a funk, but the earth will stop being inhabitable by humans in about half a billion years. The sun will start growing and the heat/radiation level will do us in. Smaller critters and bacteria may thrive, but not you and me.

Extinction events can happen, as our geologic and biologic history shows. At one times our human ancestors were down to something like 2,000 people. It could have been worse. And of course critters and plants are fading from view all the time even when things aren't terrible. So when things are bad, major species can disappear.

I suspect we humans will do ourselves in without needing much help from our friendly local asteroids or supervolcanos. Any disease that may wipe us out will probably be made worse by its immunity to overused antibiotics. Of course, we may just glow ourselves to death with a few more major radiation accidents. And of course war on an unimaginable scale is, sadly, still imaginable.

Its hard to know exactly what has happened, and just as hard to predict how stupid we will be in the future. Or how big the next surprise asteroid will be when it hits our atmosphere. But on the bright side, we can merrily live along, fearful of everything that moves and half the things that don't, and be happy we are alive.

[Wasserbuffel]

I don't want to send anyone into a funk, but the earth will stop being inhabitable by humans in about half a billion years.

Now I'm just depressed. 

[Nam]

I don't want to send anyone into a funk, but the earth will stop being inhabitable by humans in about half a billion years.

Now I'm just depressed. 

Sad you won't be there?

-Nam

[Fiji]

How about a stone age society of ... cephalopods?
Sure, we've been diving all over the place, for almost two centuries now but how much of the ocean floor have we explored? 0.1%? that seems way to large a number. 0.01% maybe? If that.
So, intelligent cephalopods who used whale bones, shark teeth and walrus skins could have existed for millions of years and we'd be non the wiser.
Now, I have looked in to the possibility to use thermal vents for smelting purposes. The hottest thermal vents are hot enough to melt lead, zinc and tin.
How the cephalopods are supposed to get close enough to actually work these metals without becoming pickled calamari ... I have no idea. Nor do I know if any of these metals are even available to them. But just imagine ... metal working cephalopods! And the chances of us finding out about them would be next to zero.

[Nam]

fiji,

I had the thought of, "What if Atlantis does exist, and it's at the bottom of the ocean?" Though, I still find it to be a fictitious place, there is so much of the world, today, that has yet to be explored--some places may never be but it does make me wonder.

-Nam

[Fiji]

How about ... 'Atlantis' was a cephalopod outpost that traded with the Ancient Greeks. Traded what ... I have no idea. The Ancient Greeks liked dolphins ... maybe the cephalopods herded them? "You want dolphins to swim to the right of your ship as its leaving the harbour so that people will see it as a good sign? Ok, that'll be 20 bronze knives."

After a while, the cephalopods figured these human-thingies were bad news and should not be trusted. One day a ship sails to Atlantis and ... nothing. They dive all over the place ... no cephalopods anywhere. Some creative writing and boom, legend born.

[wright]

How about a stone age society of ... cephalopods?
Sure, we've been diving all over the place, for almost two centuries now but how much of the ocean floor have we explored? 0.1%? that seems way to large a number. 0.01% maybe? If that.
So, intelligent cephalopods who used whale bones, shark teeth and walrus skins could have existed for millions of years and we'd be non the wiser.
Now, I have looked in to the possibility to use thermal vents for smelting purposes. The hottest thermal vents are hot enough to melt lead, zinc and tin.
How the cephalopods are supposed to get close enough to actually work these metals without becoming pickled calamari ... I have no idea. Nor do I know if any of these metals are even available to them. But just imagine ... metal working cephalopods! And the chances of us finding out about them would be next to zero.

Interesting and plausible idea, Fiji. Arthur C. Clarke used it in a short story and a novel. I also came across these examples of aquatic aliens that made use of deep-sea vents: the Hov's'sa (http://www.orionsarm.com/eg-article/4a64799a16573) and the Paulans (http://www.orionsarm.com/eg-topic/4802872e8ba1a).

You're right: there could be tool-using species in the deep sea. We arguably know more about the surface of the Moon than the topology of our own oceans.

[Nam]

If only we could build something that wouldn't implode under the pressure of such a depth. Think about the marine life down there yet to be discovered.

-Nam