Nemesis not to blame for mass extinctions

We have all heard that the fossil records show a curious cycle of every 27 million years, Earth has been bombarded so heavily as to cause a mass extinction. Some scientists blamed a star dubbed Nemesis. In a recent IO9 article, Adrian Melott of the University of Kansas and Richard Bambach of Smithsonian Institution Museum of Natural History, say that the theory that every 27 million years, Nemesis would swing through the outer system bringing with it vast quantities of material from the Ort cloud. Melott and Bambach researched the fossil records and indeed found an extremely accurate record of mass extinctions every 27 million years, further back than anyone else had researched. And that accuracy it appears, is the failing point of the Nemesis as the cause. Because the occurrences are SO regular it can not be a Nemesis object, because it is SO regular!

Melott and Bambach postulate that if Sol had a binary companion, their shared orbit around a common central point would distort the regularity of each body around the system. This means that each time Nemesis swung in, its orbit would change and the occurrence would not and could not be the same as the one before and the one after. The change might be subtle but it would be enough for the regularity of the events to be wildly different instead of every 27 million.

You can read the whole article on IO9 here

Would an Earth without Humans recover?

Has anyone been watching the series on the Discovery Channel called, life after people? This fascinating program shows the short term repercussions on structures after all Humans have left. Here is an article about a possible cause and the long term effects.

Shaun Saunders sends us in a a new "word for the day" that just screams science fiction to me.

From the pages of New Scientist we read an article about chemist Paul Crutzen who has coined the word Anthropocene. Crutzen coined the word about 10 years ago when he formulated a startlingly new concept. The idea being that human activity is now affecting the Earth so profoundly that we are entering a new geological epoch.

Needless to say, this is far from a universally accepted theory, has yet to be accepted as a geological time period. At it's base is the assumption that in just a few centuries, the pressure humanity is placing on the ecology leads to ecological collapse and a mass extinction. Possible scenarios include a collapse of society, leaving just a few hundred thousand eking out a meager stone age existence.

Most of the argument is based on earlier carbon spikes in past geological periods. And of course mass extinctions are far from unique, however in most of the previous examples, the Earth was substantially different in areas like temperatures.

Read complete article in New Scientist

America - distroyed by a comet?!

Now here is an interesting article. It seems, that North America has been destroyed by a comet strike taking all life with it. Not in the past though...well not in the distant past, but a short 13000 years ago.

This article from IO9 describes newly uncovered evidence that supports earlier research that suggested that the Clovis people, who went extinct nearly 13,000 years ago — and the disappearance of the pygmy mammoth may in fact have been victims of a large impact event. That research in 2007 suggested that the impact set off huge continental fires that brought about the disappearance of the Clovis people, but also the extermination of 35 mammal genera, including mammoths, mastodons, ground sloths and camels.

Read complete article at IO9 here

Asteroid Couldn't Have Killed The Dinosaurs?!

IO9 in it's never ending quest to shake up everything we thought we knew, has posted an extremely compelling article about Princeton geo-scientist Gerta Keller. Keller's research has new evidence to support her alternative theory that volcanoes, not meteorites, wiped out the dinosaurs.

Now I know, this isn't strictly speaking new stuff here, but what makes this article very interesting is that it is backed up with some serious research. Keller's research shows that far from wiping out the dinosaurs 65 million years ago, not a single species went extinct after the Yucatan event. In fact there may have been as much as 300,000 years between the impact and the extintion event.

From the article:

• Keller suggests that the massive volcanic eruptions at the Deccan Traps in India may be responsible for the extinction, releasing massive amounts of dust and gases that could have blocked sunlight, altered climate and caused acid rain.

read complete article here

Volcanoes May Have Killed the Dinosaurs?!

For the last 30 years, the prevailing theory has been that an asteroid, around six miles across, hit the Yucatan peninsula 65 million years ago, throwing debris into the atmosphere, blocking the sun and chilling the planet to the point that nearly half of all species went extinct. Ah but here's the rub, recent discoveries can not tie a single extinction event to the Yucatan / Chicxulub event.

Evidence is accumulating that it wasn't an asteroid that did the beasts in, but volcanoes. Volcanic events lasting almost 10,000 years, laying down miles deep deposits and throwing more that 10 times the amount of more climate-changing emissions into the atmosphere than the asteroid impact. Also supporting the volcanic theory is fossil evidence from Texas and Mexico that most of the species extinctions coincided with the final pulse of eruptions, not with the asteroid impact, which may have occurred approximately 300,000 years earlier.

There is even evidence that dinosaurs lived in India (where the massive eruptions occurred) right up to the last phase of the volcanic event - but not afterward.

The argument against of course is that there is volcanism, there was volcanism and there always will be.... so volcanism alone is not in and of itself unique. However the asteroid impact was and therefor can not be dismissed out of hand.

<- read more in Wired ->

"assisted colonization"

Here is something that could be right out of Brin's uplift. A new buzz word that has science fiction written all over it. Assisted Colonization. From Wired magazine I read that conservationists are now so concerned about species extinction, which has been set by some organizations to be 100 times faster than just 1 century ago, that they are now considering something that was once unthinkable. Relocating whole species that are at risk of extinction. Take for example the Arctic polar bear. At the present rate of decline of its' habitat, the bear could become extinct within a handful of decades. Plans have been formulated that would take the bear and other species of the Arctic and relocate them in the Antarctic.

Once dismissed as wrongheaded and dangerous, assisted colonization -- rescuing vanishing species by moving them someplace new -- is now being discussed by serious conservationists.

Even the often concervative Ecological Society of America's annual meeting in August will be preceded by a three-day discussion of assisted colonization, by ecologists.

- wired -

Exploding Asteroid May Have Killed Off Mammoth & Humans!

13 thousand years ago may have been a very bad time for North American Mammoth and early human inhabitants of the north American continent. Geological evidence found in Ohio and Indiana recently is strengthening the case suggesting that a phase of extinction for animals and humans at the end of the last Ice Age was a cataclysmic comet or asteroid explosion over top of Canada. The theory puts forth that an object exploded just above the earth’s surface over Canada, producing a massive shock wave and a super-heated wave that set large parts of the northern hemisphere ablaze. Some of the most telling evidence is samples of diamonds, gold and silver found in sites in Ohio and Indiana are from deposits in Canada. The only plausible scenario for explaining their presence this far south- researches say - is this type of cataclysmic explosive event.

<more in ScienceDaily>

Humans almost went extinct!

CNN is reporting findings that were published in the American Journal of Human Genetics, reporting that early human populations may have had a brush with extinction 70,000 years ago. It is estimated that the number of early humans may have shrunk as low as 2,000, reduced to small isolated groups in Africa, apparently because of drought. Eastern Africa experienced a series of severe droughts between 135,000 and 90,000 years ago, and researchers said this climatological shift may have contributed to the population changes, dividing into small, isolated groups that developed independently. Recovering from this population bottleneck seems to have brought about migrations to other parts of the world which appears to have begun about 60,000 years ago.

Large Asteroid Breakup May Have Caused Mass Extinction On Earth 65 Million Years Ago

from sciencedaily.com:

The impactor believed to have wiped out the dinosaurs and other life forms on Earth some 65 million years ago has been traced back to a breakup event in the main asteroid belt. A joint team of researchers suggests that the parent object of asteroid (298) Baptistina (was) disrupted when it was hit by another large asteroid, creating numerous large fragments that would later create the Chicxulub crater on the Yucatan Peninsula as well as the prominent Tycho crater found on the Moon. At approximately 170 kilometers in diameter and having characteristics similar to carbonaceous chondrite meteorites, the Baptistina parent body resided in the innermost region of the asteroid belt when it was hit by another asteroid estimated to be 60 kilometers in diameter. This catastrophic impact produced what is now known as the Baptistina asteroid family, a cluster of asteroid fragments with similar orbits. The team investigated the origins of the 180 kilometer diameter Chicxulub crater, which has been strongly linked to the extinction of the dinosaurs 65 million years ago. Studies of sediment samples and a meteorite from this time period indicate that the Chicxulub impactor had a carbonaceous chondrite composition much like the well-known primitive meteorite Murchison. This composition is enough to rule out many potential impactors but not those from the Baptistina family.

Click the article title or here for the complete story (art by Don Davis)

NASA lacks funds to find killer asteroids

NASA officials say the space agency is capable of finding nearly all the asteroids that might pose a devastating hit to Earth, but there isn't enough money to pay for the task so it won't get done.

The cost to find at least 90 percent of the 20,000 potentially hazardous asteroids and comets by 2020 would be about $1 billion, according to a report NASA will release later this week. The report was previewed Monday at a Planetary Defense Conference in Washington.

Congress in 2005 asked NASA to come up with a plan to track most killer asteroids and propose how to deflect the potentially catastrophic ones.

These are asteroids that are bigger than 460 feet in diameter -- slightly smaller than the Superdome in New Orleans.

The agency is already tracking bigger objects, at least 3,300 feet in diameter, that could wipe out most life on Earth, much like what is theorized to have happened to dinosaurs 65 million years ago.

But even that search, which has spotted 769 asteroids and comets -- none of which is on course to hit Earth -- is behind schedule. It's supposed to be complete by the end of next year.

Mass Extinction Changed Ecology of Earth's Oceans

The earth experienced its biggest mass extinction about 250 million years ago, an event that wiped out an estimated 95% of marine species and 70% of land species. New research shows that this mass extinction did more than eliminate species: it fundamentally changed the basic ecology of the world's oceans. Ecologically simple marine communities were largely displaced by complex communities - higher-metabolism, mobile organisms (such as snails, clams and crabs) that actually go out and find their own food and the decreased diversity of older groups of low-metabolism, stationary organisms (such as lamp shells and sea lilies) that filter nutrients from the water.