Slashdot Mirror
New Theory Links Biodiversity to the Stars
eldavojohn writes "Space.com's Mystery Monday has an article proposing a hypothesis that our solar system's undulations directly affects biodiversity on earth through cosmic-ray exposure. There's data that, through the fossil record, shows us earth's biodiversity peaking again and again until a great cataclysmic period where it is greatly reduced. The theory essentially suggests that this 62 million year cycle can be attributed to how our solar system moves within the milky way galaxy which turns out to be a 64 million year cycle. It's a plausible explanation though very tough to prove, hopefully we don't have to wait around 64 million years to draw a conclusion on this hypothesis."
This general idea has been around for a very long time, I've come across it several times in various magazines like Scientific American, etc.
Astrologists are freaking out across the world at the first sign of honest scientific news that shows a link between stars and life on earth, telling everyone that they knew all along the stars are what makes everything the way it is.
There is no replacement for displacement.
One interesting hypothesis is is that a red or brown dwarf in a highly elliptical orbit with our sun periodically (every ~26M years) passes through the Oort Cloud and pulls comets into the inner solar system, causing a wave of extinctions.
BTW, one of the physcists researching this idea, Richard A. Muller teaches a great physics course, titled "Physics for Future Presidents" which is available online for free on google video.
Please consider making an automatic monthly recurring donation to the EFF
This is not meant to be a funny post.
Here's an article on extinctions in Wikipedia.
Here's a snipet from that article about mass extinctions:
There have been at least five mass extinctions in the history of life, and four in the last 3.5 billion years in which many species have disappeared in a relatively short period of geological time. The most recent of these, the K-T extinction 65 million years ago at the end of the Cretaceous period, is best known for having wiped out the non-avian dinosaurs, among many other species.
In other words, don't laugh about the 62-64 million year cycle. We are due for a mass extinction, according to the fossil record. Maybe this phenomenon has something to do with it. Note that when biodiversity goes down in a species, that's not good, biologically speaking. Less diversity means less chance of a species being able to survive a catastrophic event.
Take it for what you want, but all those people laughing about having to wait 64 million years, my point is, I don't necessarily think you have to wait all that long.
"All great wisdom is contained in .signature files"
It's hard to read off the chart, and I didn't see mention in the article, but this submission immediately brought a few things to mind:
About 55 million years ago the earth apparently underwent a significant warming event called the Paleocene-Eocene Thermal Maximum that resulted in the extinction of 30-40% of deep sea life, and may have been equally instrumental in the emergence of mammals as the asteroid 10 million years before that killed off the dinosaurs.
The trigger is unknown, but it is believed that warming oceans due to a natural cycle caused the sublimation of large quantities of methanes from clathrate deposits on the sea-floor. Methane, of course, is a potent greenhouse gas. The result was average ocean surface temperatures as much as 10 deg C warmer than before. The cause of the natural cycle is unknown. However, I just did some digging around, and it appears the major long term thermal cycles (based mostly on O-18/O-16 ratios in sediments, is my understanding) run 140 million years on average, but higher frequency signals definitely exist.
Now, there has been some recent research finding that cosmic ray activity may be an influencing factor on global warming (Note: No need to revive the global warming debate...I'm just sharing my thoughts, and am not claiming anything). Basically cosmic rays appear to affect the formation of clouds in the upper atmosphere, which in turn effects solar insolation.
It would be very interesting if this 62 million year cycle happened to coincide with the PETM extinction 55 million years ago. My thought being perhaps a cosmic ray cycle caused a typical warming cycle that happened to induce the "big burp" of methane-clathrates, which significantly magnified the warming effect.
Actually, with some further poking around, I see this basic theory has been proposed for explaining the 140 MY cycle, minus the methane-clathrate bonus.