Impacts, extinctions and life

Asteroids, gotta love the yummy things.  For example: asteroid 5748 Davebrin made its closest approach to Earth April 4. (1.7 AU). Hey! I can see my house from here! Come on guys, it's mine so let's go melt it down and get rich.

And yes, this means it is time for one of our "look up!" postings, here on Contrary Brin!  For example...

Many of you recall the thrilling sight of Jupiter getting whacked multiple times by the comet Shoemaker-Levy 9 in 1994. Now Phil Plait reveals some video taken this month by an amateur astronomer, which appears to reveal another one smacking the King World. And hints there may have been another collision some years ago.

Yipe!  This’ll affect the statistics, for sure. No fluke, after all.  As Goldfinger said: "Three times, Mr. Bond, is enemy action."

What do we know about the asteroids out there? The website Asterank offers a scientific and economic database of over 600,000 asteroids, as well as wonderful 3D animation. This extensive database gives a perspective to the places to go within our solar system, including each asteroid’s mass and composition.. .and likely profitability for mining. You can even hitch a ride on one of the objects mapped and see where it takes you! And yet, this list is made obsolete with each day’s new discoveries. Also I wonder if the estimated profits take into account the fact that gold, silver and other metals prices will plummet when asteroid mining truly delivers its promised riches. The pursuit of a few forward looking visionaries such as Planetary Resources and Deep Space Industries. 

== Impacts and Extinctions ==

Speaking of planet smackers, we’ve known since the 1980s that asteroids and comets have had a major “impact” on the history of life on Earth, and not only the dinosaur killing and Cretaceous-ending rock that impacted the Yucatan, 66 million years ago.  Researchers such as Raup & Sepkoski have plumbed the paleontological record for exceptionally sudden die-offs of numerous species and found that it appears to happen at roughly 26 to 30 million year intervals, a possible cycle which has been studied more closely by Michael Rampino of New York University. (Keep an eye for Michael’s new book on the subject, this coming year.)

What could provoke mass extinctions at such a very long-but-regular interval? Well, decades ago Daniel Whitmire and John Matese proposed – in parallel with Luis Alvarez and his team -- the notion that this scale could represent the orbit of a distant planet X, whose rhythmic passages through the cometary Oort Cloud surrounding our sun might perturb clusters of iceballs, sending them plummeting toward hapless Earth,  This theory for mass extinctions appeared in the journal Nature in 1985.  

The notion of a Planet X was given added impetus lately when researchers Konstantin Batygan and Mike Brown from Caltech inferred its existence based on orbital anomalies seen in objects in the Kuiper Belt, a disc-shaped region of comets and other, larger bodies beyond Neptune. Though at more than 1,000 a.u., it might be very weakly bound in orbit around the sun.  

Problem.  Not all of those rhythmic mass extinctions in the past show any clear signs of being cause by impacts.  Several others evidently happened due to massive releases of volcanism from the Earth’s interior, whose traces are still seen in basaltic flow formations called the Siberian and Deccan “traps.”  

There is an astronomical phenomenon that has timing on the scale of tens of millions of years -- our solar system's orbit around the Milky Way galaxy.  While a full orbit takes more than 200 million years (at our distance from galactic center), there is a way to match intervals. In fact, back in the 1980s I had a paper suggesting we'd get this timing from some ferocious object that laps us every 30 million years or so, orbiting closer to galactic center.  See my earlier article:  "The Deadly Thing at 2.4 Kiloparsecs."

Far fetched? Okay here's another interval match. Our sun's path dips in and out of the galactic plane  - like a pleated skirt - more often. In fact, pretty much at that 30 million year interval. 

This led some to ponder whether our passage through the plane might, each time, result in collisions with gas or dust clouds that trigger comet infall from a disturbed Oort cloud. Interesting! But that theory had several problems.  
 (1) Sometimes there would be a cloud and sometimes (more often) not.  
 (2) the needed Planet X would orbit so far out that its ties to the Sun might be tenuous. And
 (3) again, some extinctions seemed more related to volcanism than rock or comet impact.

So Michael Rampino has suggested another concept -- that dark matter in the galactic rim may be a factor causing extinctions and massive volcanism. If dark matter clusters in the skirt of the galaxy, then each time we pass through, it might both disturb the Ooort Cloud a bit and fill the Earth's core with enough DM to heat it just enough to spur added volcanos.  Huh!  What an idea.

See also Lisa Randall's recent book exploring this topic - Dark Matter and the Dinosaurs: The Astounding Interconnectedness of the Universe.

Oh. In a possibly related item, analyses of Iron 60, a decaying isotope, in sub-ocean crustal core measurements, has revealed likely supernovae relatively nearby (within a few hundred light years) occurring 1.5 million, 2.3 million and 8 million years ago. The last of these might bear some relation to the start of the Ice Ages.  

Fascinating. And it just goes to show.  The universe is a rough neighborhood.  We may have been lucky.

== The lesson from all this? ==

We need to grasp the tiller of our destiny.  That means learning not to make the sort of big mistakes that Jared Diamond talks about in his book Collapse: How Societies Choose to Fail or Succeed, grievous blunders that brought ruin to other societies. Like eco-mismanagement. Only we may be doing it on a planet-wide scale.

And learning how to prevent all sorts of natural disasters from ending our hopes, as well.  It has been suggested that: "There are no more dinosaurs, because they lacked a space program."

Well said. 

Though of course there are still dinosaurs.  Descendants of the ones that at least learned to fly.  If you cannot prevent disaster, at least be able to ride it out.  We need both anticipation and resilience.

 Always on the lookout for such tasty aphorisms of wisdom, I perked up when a member of this community – Mike DeSimone -- offered another quotation that I intend to use:  

“Humanity has two possible destinations: stars or strata.” 

A look back at our origins

We are the first human civilization to remove our envisioned "golden age" from an imagined-nostalgic past and instead plant that better-than-the-present era (tentatively) in a potential future.

The irony? We can only achieve that great accomplishment if we learn as much as possible, about where we came from.  How we (species, society, individual) came about. What parts of our heritage must be overcome, and what hidden, potential gifts have yet to be realized, or even discovered.

Exploring all of this is exciting stuff. And so, in honor of a newly minted Physical Anthropologist we happen to know, let's start as deep in time as possible.....

...like how about a newly discovered missing link between prokaryotes and eukaryotes? Amazing. Of the three major super-domains of cellular life on Earth – bacteria, archaea and eukaryotes (which include metazoan, multi-celled organisms, like us), it now appears that we are more closely related to the archaea, which were discovered as a separate clade not so long ago and were at-first thought to be a relic corner of life’s diversity. This sure puts Greg Bear’s weird novel VITALS in a new light. 

== Galaxies and deadly rhythms! ==

Did Dark Matter Doom the Dinosaurs? “We know there’s a lot of dark matter in the Milky Way, and it’s possible dark matter isn’t evenly distributed but occurs in dense clumps. Maybe our solar system passes through clumps of it periodically." If those clumps are dense enough to wreak havoc, they could knock comets loose and cause collisions...

... or else maybe heat Earth’s interior and cause massive volcanic eruptions?  Or somehow set loose all sorts of other species-obliterating disasters. That’s the premise behind a recent paper by New York University geologist Michael R. Rampino.

Back in 1984 I had an article in ANALOG that calculated a different hypothesis to explain a 26 to 30 million year extinction cycle . What if such a recurring pattern were caused not by the Earth passing through the galactic disk, but by something  'lapping" us, as it orbits, farther in toward Galactic center?  The article was "The Deadly Thing at 2.4 Kiloparsecs," Analog's most popular science bit, that year. Almost any extinction cycle  might correlate with some Lapping Object, which might sear a swathe of devastation on its way around the galaxy, wreaking some degree of havoc, each time it sweeps past our solar system.

I mention this to suggest that there are many potential ways to get galactic time scales in cycles of extinctions.

Speaking of mass extinction events… O-o-okay... folks at CERN now say they might make micro-black holes after all.  And there's nothing to worry about!  In fact, my logical side is not worried.  

But still... I described one potential outcome... in EARTH.

== Becoming Human ==

Do tools make man? Pushing our origins back even further...the world's oldest stone tools have been found in Kenya: stone flakes and anvils found off the shores of Lake Turkana date back more than 3.3 million years ago -- half a million years before the appearance of our genus Homo.

Another re-assessment of our ancient family tree comes from a partial jawbone discovered in Ethiopia, radiometrically dating to nearly 2.8 million years ago -- which makes it the oldest known fossil of our genus Homo. 

How has biology shaped humanity? How did humans rise to dominance on planet earth? In Sapiens: A Brief History of Humankind, historian Yuval Noah Harari tracks the evolution of homo sapiens from the Paleolithic to modern-day, charting three major upheavals...

the cognitive revolution, the agricultural revolution and most recently, the scientific revolution, that shaped the trajectory of humanity and human civilization -- covering some of the same ideas as Jared Diamond's 1999 classic book, Guns, Germs and Steel. See an extensive review of Sapiens in the Wall Street Journal.

== Bottlenecks of Evolution ==

Indeed, genetics has shed light on what may have been “bottlenecks” in human evolution.  One of them, purported to have been 70,000 years ago, might have reduced the population of human ancestors under 10,000 and threatened extinction. 

Now, another bottleneck is proposed that might have occurred as recently at 8,000 years ago, while early agriculturalists were preparing to leap into urban life. By studying Y-chromosome DNA and mitochondrial DNA, scientists are able to deduce the numbers of female and male ancestors a population has. It's always more female, which is consistent also with mammals, in general. Not all males get to breed.  But the normal human ratio is about 1.3 female breeders-to-one male. Apparently is was much bigger disparity, during a period around 8000 years ago. Explanations range from a sudden advantage to certain kinds of males to some sort of weird virus that only affected males across the whole globe, just before large villages formed towns.

Or did agriculture itself, often requiring brutally hard physical labor, play a role? Might the "taming" of human males, making them suitable for denser living, have had some weird side effects? Will we ever know? See: A recent bottleneck of Y chromosome diversity coincides with a global change in culture.

Another look at a leap for human evolution: Did humans -- and their dogs -- help drive Neanderthals to extinction? See this explored in The Invaders: How Humans and their Dogs Drove Neanderthals to Extinction, by Pat Shipman. 

More evidence for 'recent' human interbreeding with Neanderthals: Genetic analysis 40,000-year old jaw from Romania revealed that 5 to 11% of this ancient European man's DNA was Neanderthal -- indicating that he must have had a Neanderthal ancestor in the previous four to six generations. 

Insight into the darker side of the human past: Paleolithic remains show cannibalistic habits of our ancestors -- at sites in England dating back about 15,000 years ago.

== even weirder ==

Marshall Brain’s new book “The Second Intelligent Species: How Humans Will Become as Irrelevant as Cockroaches” wins a prize for telegraphing its point in the title, alone!  

It explores how the future will unfold as the second intelligent species – Artificial Intelligence (AI) -- emerges.  Well, well.  

We are getting plenty of folks taking up extreme apocalyptic or utopian views of all this.  But I just don’t think that way.

Where are we headed? Looking ahead: The Atlantic Council has reprinted my brief future projection: The Avalon Missions: Race for the Stars.

== Mickey points the way? ==

Disney is “betting a billion dollars on a magical wrist band.” A new ticketing method that will let each member of your family get personalized treatment from the instant you enter the park, always welcomed into the correct line, walking out of stores with merchandise paid for without visiting a cashier, ordering food before arriving at a restaurant and sitting at any table, knowing the food will arrive….

…And if someone doesn’t add this to my predictions registry wiki, then I don’t have fans anymore! 

Read this chapter from EXISTENCE --- The Shelter of Tradition -- set at the Shanghai World of Disney and the Monkey King, in the year 2045.  And tell me Disney shouldn’t at least give me a nice family pass. Only the date was wrong.  

Stuff catches up with science fiction faster and faster.