Feeds

Life on Earth gets wiped out every 27 million years, say boffins

'Nemesis' dark star theory poohpooh'd, though

Business security measures using SSL

Much of life on Earth gets regularly wiped out every 27 million years, according to boffins. It had been thought that this was caused by a dark star named "Nemesis", but apparently that was wrong. The next globo-extinction event is due in about 16 million years' time.

A plot of extinction intensity in the past. Credit: Richard K Bambach, Adrian Melott

Call that a mass extinction? Rubbish. In the old days we had proper mass extinctions.

The revelations are made in a new paper from paleontologist Richard K Bambach of the Smithsonian Institution and astronomer Adrian Melott, flagged up by the Physics arXiv blog and viewable online here.

According to Bambach, there's no doubt at all that every 27 million years-odd, huge numbers of species suddenly become extinct. He says this is confirmed by "two modern, greatly improved paleontological datasets of fossil biodiversity" and that "an excess of extinction events are associated with this periodicity at 99% confidence". This regular mass slaughter has apparently taken place around 18 times, back into the remote past of half a billion years ago.

This had previously been noted by other scientists - though not confirmed so far back into the past - which had led to theorising on what could have caused such long-separated, regular disasters.

One theory which seemed to fit the facts was the "Nemesis", the idea that a huge, dark companion body orbits the Sun so far out that it comes near only on a 27-million-year cycle. At that point it ploughs into the Oort Cloud - the zone beyond the planets where comets spend most of their time - and causes a shower of comets to rain into the inner solar system, smashing up life on Earth.

Unfortunately, according to Melott, the very regularity of the extinctions means this can't be true. At various points in the last 500 million years the Sun has passed close enough to other stars that any Nemesis object would have had its orbit significantly affected, so that the sequence of disasters on Earth should have changed interval.

The two boffins write:

We confirm the originally noted feature in the time series for extinction. However, we find that it displays extremely regular timing for about 0.5 Giga-years. The regularity of the timing compared with earlier calculations of orbital perturbation would seem to exclude the Nemesis hypothesis ...

According to the handy chart furnished by Bambach and Melott above, one can see that the apocalypses don't exactly run like a Swiss watch. The mass die-offs (circled peaks) are usually pretty close to the vertical dotted lines showing the 27-million-year time tick, but they can easily be a few million years off either way.

They aren't universally fatal, either: the last one saw less than ten per cent of all species then alive wiped out.

If nobody manages to work it out, and provided that humanity doesn't meanwhile become disembodied minds, depart in an interstellar exodus or get wiped out early in some kind of unscheduled disaster, we'll eventually find out by observation what the underlying cause is. The next dotted line is due in 16 million years, but the associated extinction could be as much as 10 million years early. ®

Providing a secure and efficient Helpdesk

More from The Register

next story
SCREW YOU, Russia! NASA lobs $6.8bn at Boeing AND SpaceX to run space station taxis
Musk charging nearly half as much as Boeing for crew trips
PORTAL TO ELSEWHERE scried in small galaxy far, far away
Supermassive black hole dominates titchy star formation
Boffins say they've got Lithium batteries the wrong way around
Surprises at the nano-scale mean our ideas about how they charge could be all wrong
Edge Research Lab to tackle chilly LOHAN's final test flight
Our US allies to probe potential Vulture 2 servo freeze
Europe prepares to INVADE comet: Rosetta landing site chosen
No word yet on whether backup site is labelled 'K'
Cracked it - Vulture 2 power podule fires servos for 4 HOURS
Pixhawk avionics juice issue sorted, onwards to Spaceport America
City hidden beneath England's Stonehenge had HUMAN ABATTOIR. And a pub
Boozed-up ancients drank beer before tearing corpses apart
prev story

Whitepapers

Providing a secure and efficient Helpdesk
A single remote control platform for user support is be key to providing an efficient helpdesk. Retain full control over the way in which screen and keystroke data is transmitted.
WIN a very cool portable ZX Spectrum
Win a one-off portable Spectrum built by legendary hardware hacker Ben Heck
Saudi Petroleum chooses Tegile storage solution
A storage solution that addresses company growth and performance for business-critical applications of caseware archive and search along with other key operational systems.
Protecting users from Firesheep and other Sidejacking attacks with SSL
Discussing the vulnerabilities inherent in Wi-Fi networks, and how using TLS/SSL for your entire site will assure security.
Security for virtualized datacentres
Legacy security solutions are inefficient due to the architectural differences between physical and virtual environments.