Life on Earth wiped out every 27 million years (but we've got about 16 million years until the next

im more worried about the next 6 months , i cant afford a bomb shelter ,never-mind a nuke suit.....

the world is going to be a horrible place to live in when the west attacks iran and the middle east join forces to the fight the west....



the fight will be christian v muslim for world domination...

I am having trouble finding information on the Bottleneck theory of Human Evolution. Supposedly, millions of humans became only a few thousand in a few hundred years. We are all decendants of those few that survived. The evidence is in our DNA.

reply to post by Portugoal


Actualy the suns supposed to go into red giant phase some time during the 3600 time period. That gives us some time to find another world to live on, before earth is vaporized when the sun expands outward.

Originally posted by Portugoal
but we've got about 16 million years until the next one

Oh thank goodness - for a moment there I was terrified you'd say we only have 50 000 years.

Originally posted by theability
reply to post by Portugoal

 

Let me get this straight:

Every 27 million years life gets wiped out, we have 16 million to the next one.

27 - 16= 11 million years ago there was a mass extinction?

I don't remember one at that time, but I do remember one that happened 63-65 million years ago.

And for the record there has been 5 extinction events in the last 540 million years. Or one every 108 years.

These are known as the BIG FIVE.

I wonder how they come to these new conclusions?

I agree the big five are the ones to look at, there have been other extinctions, but they were smaller.

So let's look at the big five:

en.wikipedia.org...

The classical "Big Five" mass extinctions

Million years ago --- million years since previous major extinction
450 Mya--- ?
370 Mya--- 80 MY
251 Mya---129 MY
205 Mya--- 46 MY
65 Mya--- 140 MY

So let's see if they happen like clockwork, 80 million years, 129 million years 46 million years, 140 million years are the time intervals separating the classical "Big Five" mass extinctions. It doesn't look like clockwork to me.

I'm sure most of you know there's a mass extinction going on right now:

Holocene extinction

The Holocene extinction is the widespread, ongoing extinction of species during the present Holocene epoch.

scientists estimate that during the 20th century, between 20,000 and two million species actually became extinct, but the precise total cannot be determined more accurately within the limits of present knowledge. Up to 140,000 species per year (based on Species-area theory)[2] may be the present rate of extinction based upon upper bound estimating.

In broad usage, Holocene extinction includes the notable disappearance of large mammals, known as megafauna, starting 10,000 years ago as humans developed and spread. Such disappearances have normally been considered as either a response to climate change, a result of the proliferation of modern humans, or both

Overall, the Holocene extinction is most significantly characterised by the presence of human-made driving factors and climate change.

reply to post by Eye of Horus


You're off by 5 billion years or so.

reply to post by Arbitrageur

The premise is not based on actual extinction events but on a loss of biodiversity in the fossil record. It seems to require a bit of data "stretching" to arrive at the periodicity and it is not generally accepted that it really represents specific events rather than an ongoing process (called evolution).

As you point out, we are currently seeing a loss of biodiversity. Does that mean that it is a global "extinction event"? The holocene extinction is attributed in great part to us...people. It shows how biodiversity can be dependent on something relatively simple, a single species. Due to ecological considerations, the success (or failure) of a single species can affect a wide variety of other species. If one species disappears (or appears) others may disappear (or appear), leading to a domino effect. Does that single domino, the first one, have to be the result of a cosmic event?

[edit on 7/17/2010 by Phage]

Current extinction rates show that we are in fact undergoing a mass extinction at the moment.

Originally posted by Phage
The premise is not based on actual extinction events but on a loss of biodiversity in the fossil record.

If that's what they meant maybe that's what they should have said? From the OP article:

"Life on Earth is wiped out every 27 million years – and we have about 16 million years left until the next extinction, according to scientists.

Research into so-called ‘extinction events’ for our planet over the past 500 million years - twice as long as any previous studies - has proved that they crop up with metronomic regularity."

Somehow I got the idea they were talking about extinctions because of the use of the word "extinctions". Or maybe I don't understand how you are differentiating the difference between an "extinction" and a "loss of biodiversity"?

Regarding the "data stretching" you refer to, that looks like an understatement, I'm looking at the graph in the OP article and I think it's a complete invention, like the so-called "bible code" or something. There are dotted lines that have no points circled on them, and some circled points that don't fall on a dotted line. I don't have data to calculate a correlation with but I'd say the correlation shown in that graph is extremely low.

Does that single domino, the first one, have to be the result of a cosmic event?

No, did somebody say that it had to be cosmic?

There was a lot of debate about the KT extinction and whether that was caused by a cosmic event, and I think the debate has mostly been settled by concluding that life wasn't doing all that well before the cosmic event due to non-cosmic sources, specifically volcanism related to the Deccan Traps. But I think most now agree that even so it was a cosmic event that was the straw that broke the camel's back so to speak.

Regarding prior major extinctions, while we suspect cosmic events may be a possible source for some of them, I don't think any of them have been proven to have a cosmic source to the certainty of the KT extinction.

And as you point out, one species like humans may result in an extinction, though it remains to be seen if humans will cause the extinction of 75% of the species on Earth. I wouldn't rule out the possibility yet. It would be interesting to look at that graph in the OP updated 100 million years from now, and see how big the current extinction peak, resulting largely from human activity, finally turns out to be. It may not take another 16 million years to reach that peak as the article would suggest.

[edit on 17-7-2010 by Arbitrageur]

reply to post by Arbitrageur

Re: the cosmic aspect.
Yes, there have been many attempts to connect "periodic" extinctions with cosmic origins. This study disputes the Nemesis hypothesis but leaves the door open for other causes. Other than external to Earth, it's hard to come up with any process which would lead to a 27 million year "cycle".