Friday, April 24, 2015

Mass Extinctions Revisited, Moving Octopuses

We've known about the Capitanian crisis for some time: some scientists have, anyway. What's new is the idea that it may have been a major mass extinction in its own right: a sort of prequel to the Great Dying.

Other scientists solved part of the puzzle of how octopuses coordinate their arms when moving. Their research may help folks design soft robots: useful in medicine and rescue work.
  1. A "New" Mass Extinction
  2. Octopus Arms and Intelligence
Reading up on mass extinctions while thinking about doomsday predictions, religious and secular, I wrote stuff that doesn't quite fit in this post. Instead of deleting it, or taking time to work it up to a full-fledged post, I tacked it on as an 'afterword.' I did the same thing last week. Anyway, this week there's —

Plato and Reality


Grabbing a bit of reality and running in a particular direction, I could assume that spirit and matter aren't the same (true); and that they're at war (not so much).

The notion that 'spiritual' is good and 'material' is bad goes back at least to Plato's theory of forms: the assertion that the highest reality is the realm of ideas, not the changing material world. Plato's cave is probably the best-known illustration of Platonic idealism.

Gnosticism may or may not have its roots in the Platonic Academy, Buddhism, Zoroastrianism, or 'all of the above.'

I have no trouble believing that there's more to reality than what we can see, touch, or measure. That's just as well, since that's what the Church says. Humans are creatures made of spirit and matter. (Catechism of the Catholic Church, 360-367)

I also don't have a problem with thinking that the physical world, this universe, isn't the highest reality. We've known that it's a tent, something temporary, for millennia. (April 17, 2015)
"He sits enthroned above the vault of the earth, and its inhabitants are like grasshoppers; He stretches out the heavens like a veil, spreads them out like a tent to dwell in."
(Isaiah 40:22)
However, that emphatically does not make the material world bad. I must believe that God makes this universe, that God is good: and that God doesn't make junk. (Genesis 1:31; Catechism, 295-301, 337-349, 1955)

As for the idea that 'spiritual is good, physical is bad:' Satan, a fallen angel, is pure spirit; and hardly a poster child for 'goodness.' That brings up free will, and that's another topic. (Catechism, 311, 328-336, 391-395)

Where was I? Plato, reality, Satan, getting a grip. Right.

A few more points that I've been over before, and I'm almost done.

Humans are animals: but we're not just animals. (Catechism, 1951, 1700-1706, 1730)

We don't own the world, but we've got "dominion" over it: pretty much the same way a shop foreman or steward has a degree of authority over the shop or estate. One of our jobs is managing this world's resources: for our reasoned use, and for all future generations. (Genesis 1:26-27; Catechism, 337-349, 355, 373, 2415-2418, 2456)

Knowledge is one of the gifts of the Holy Spirit. Science, the systematic pursuit of knowledge, is part of being human. It's what we're supposed to do. (Catechism, 1831, 2293-2295)

Thinking is not a sin, and that's almost another topic. (April 3, 2015; March 29, 2015)


1. A "New" Mass Extinction



(From Science Photo Library, via BBC News, used w/o permission/)
("Brachiopods like these dominated the seas prior to the Capitanian extinction"
(BBC News))
"New mass extinction event identified by geologists"
Alex Berezow, BBC News (April 21, 2015)
"Over the past 450 million years, life on Earth has been devastated by five mass extinction events that are widely recognised by geologists.

"Now, an international team of researchers proposes adding a sixth mass extinction to the list.

"The team believes it has accumulated sufficient evidence to promote the Capitanian event to the rank of mass extinction.

"The extinction occurred approximately 262 million years ago.

"Their proposal would elevate the Capitanian, which occurred during the Middle Permian period, to sit alongside the so-called 'Big Five' mass extinctions.

"The researchers, led by Dr David Bond of the University of Hull, presented their case in the Geological Society of America Bulletin.

"The status of the Capitanian crisis is disputed because little has been learned about it since its discovery 20 years ago. The majority of the existing literature is based on evidence unearthed in the tropics...."
Dr. Bond's team headed to Spitsbergen, an island between the Arctic Ocean, Norwegian Sea, and Greenland Sea. It's populated by Norwegians, Russians, scientists, and polar bears.

These scientists worked during July, so they had 24 hours of sunlight each day; and the weather is better for outdoor work. They were studying the Kapp Starostin Formation, rock layers up to 400 meters thick, with fossils from the Carboniferous and Permian periods: laid down over about 27,000,000 years.

Spitsbergen is north of Earth's arctic circle now, but Earth's surface shifts around. A quarter-billion years back, that chunk of land was in Earth's temperate zone, about halfway between the north pole and equator.

When the World was Young(er)



(From Fred Ziegler and others at the Paleogeographic Atlas Project, via Allister Rees Paleozoic/PaleoIntegration Project, used w/o permission.)
(Earth in the Wordian age, Mid-Permian, about 268,000,000 and 265,000,000 years ago.)

The Capitanian age, about two thirds through the Permian, ran from 265,000,000 to 259,000,000 years ago: give or take 400,000. As usual, things had changed.

The Carboniferous rainforests had been replaced by great deserts. Meganeura, insects with two-foot wingspans, were extinct; but Blattoptera, forerunners of modern cockroaches, mantises, and termites, survived.

So had ammonites — relatives of today's octopuses (octopi?), squid, and cuttlefish — and would endure until the end of the Cretaceous. Those critters are Coleoidea. They've been around since the Carboniferous. I'll get back to octopuses, or octopi, or whatever, in a bit.

Paleontologists knew there had been a mass extinction during the Capitanian. Two, actually: Olson's Extinction, roughly 270,000,000 years back; and another at the end of the Capitanian, or maybe during the Wuchiapingian.

Like I've said before, don't bother trying to memorize those names. There will not be a test on this.

Olson's Extinction was bad news for pelycosaurs like dimetrodon, and diadectes, reptile-like amphibians.

On the other hand, therapsids flourished in the bounce-back which followed. That's good news for us, since therapsids included critters that would eventually become mammals.

"Therapsid" seems to be distinct from "theropsid," which means pretty much the same as synapsid, and that's yet another topic. (August 8, 2014)

Dr. Bond's team thinks their analysis shows that the mid-Capitanian extinction event was global, and as significant as the 'big five."

Igneous Provinces: Lava and Mass Extinctions



(From Williamborg, USGS; via Wikimedia Commons, used w/o permission.)
("This file is an identification of large igneous provinces overlaid on a map produced by United States National Oceanic and Atmosphere Administration's National Geophysical Data Center. Intended for use in the Large igneous province page."
(Williamborg/Wikimedia Commons))
"...the team examined fossils of brachiopods and bivalve molluscs (the former resemble the latter but, existing in different phyla, are evolutionarily unrelated). The pre-extinction Capitanian age was dominated by brachiopods....

"...However, in the middle of the Capitanian strata, brachiopod diversity fell precipitously: 87% of the species vanished in a few tens of thousands of years, a mere blip on the geologic time scale. Clearly, something catastrophic had occurred.

"Dr Bond believes the extinction was triggered by the eruption of the Emeishan Traps, now located in the southwestern Chinese province of Sichuan.

"Volcanic eruptions release enormous amounts of carbon dioxide, which can cause ocean acidification. A depletion of seafloor oxygen may also have played a role.

"Then, Dr Bond's team noticed that in younger rock layers, new brachiopod and bivalve species re-emerged. The post-extinction Capitanian age shifted from being dominated by brachiopods to being dominated by bivalves...."
(Alex Berezow, BBC News)
Scientists are still figuring out how the Emeishan Traps fit into the picture.

The Emeishan Traps are many layers of igneous rock left over from a whole mess of volcanic eruptions that started about 260,000,000 years ago. They're nowhere near as big as the Siberian Traps. That series of eruptions started about nine million years later.

I'm not sure what's going on here. I've read that Olson's Extinction happened about 270,000,000 years ago, then the Emeishan Traps started forming around 260,000,000 years back — and the End-Capitanian extinction would have been roughly 259,000,000 years ago: give or take 400,000.

I'm not surprised that the numbers from various sources don't quite line up. We didn't know that Earth's billions of years old until a few centuries back, and a great deal of what we know of Earth's story has been learned in the last few generations: much of that in my lifetime. Chronological uncertainties amounting to fractions of one percent are — understandable.

Back, briefly, to that BBC News article.
"...But, just a few million years later, these new species disappeared, apparently wiped out in yet another extinction event. Following that, the End-Permian mass extinction, represented by its own unique rock layer, devastated the planet...."
(Alex Berezow, BBC News)
That End-Permian mass extinction was a bad one: the only mass extinction affecting insects. Whatever happened killed off Tabulata and rugose corals, and finished off the last of the trilobites.

But scorpions survived. They showed up about 430,000,000 years ago, surviving every mass extinction since. Cockroaches are comparative newcomers. 'Modern' cockroaches didn't start scuttling around until the early Cretaceous, maybe 100,000,000 years back.

Rats have only been around for about 54,000,000 years, but are almost as notoriously hard to exterminate as cockroaches. We're not as nearly-indestructible as cockroaches: but we're a lot smarter. I'll get back to that.

Life on Earth: Ups and Downs



(From Albert Mestre, Philcha, via Wikimedia Commons, used w/o permission.)
("Phanerozoic biodiversity as shown by the fossil record"
(Wikipedia))

The 'big five' is a somewhat-arbitrary list of major extinction events. Those whacking great numbers is how many years ago each happened:
Just to make things more complicated, the Ordovician-Silurian event happened in two pulses; The Great Dying is a more dramatic name for the Permian–Triassic event; and sometimes the End-Capitanian extinction event is called the end-Guadalupian.

Like I said, the 'big five' list is a bit arbitrary.

The Cambrian-Ordovician extinction event, some 488,000,000 years back, doesn't make the list; but it was hard on brachiopods, conodonts, and trilobites. Trilobites didn't survive the Permian mass extinction; conodonts probably got wiped out later, in the Triassic-Jurassic extinction event; and that's yet again another topic.

There may have been an End-Ediacaran extinction, about 542,000,000 years ago, that wiped out Ediacara biota, strange whatsit critters that aren't quite like anything alive today.

They're not Earth's earliest life, though: not by a long shot. Arcaea, single-cell organisms with no cell nucleus, showed up 3,000,000,000 — maybe 3,500,000,000 to 3,700,000,000 — years ago.

The Great Oxygenation Event, some 2,300,000,000 years ago, was a Precambrian ecological disaster — for anaerobic critters. (June 27, 2014)

Some scientists have said that extinction events happen in cycles, with mass extinctions every 26,000,000 to 30,000,000 — or maybe 62,000,000 — years.

My guess is that if there is a pattern to these extinctions, it's nowhere near as regular as today's seasons.

For example — it was smooth sailing between the Late Tithonian, about 145,000,000 years back, and the Cretaceous-Paleogene extinction that killed off non-avian dinosaurs: a span of 84,000,000 years. But the interval between the Triassic-Jurassic event, 201,300,000 years ago; and the Toarcian turnover 183,000,000 years back; was less than 18,000,000.


2. Octopus Arms and Intelligence



(From SPL, via BBC News, used w/o permission/)
("The study is the first to examine how octopuses co-ordinate their eight, flexible limbs as they crawl"
(BBC News))
"How octopuses co-ordinate their arms"
Victoria Gill, BBC News (April 16, 2015)

"With the aid of high-speed cameras, scientists have revealed how octopuses co-ordinate their arms to crawl.

"Researchers from the Hebrew University of Jerusalem filmed crawling octopuses to work out exactly how the animals used their almost limitlessly flexible arms when they move.

"This revealed the surprising simplicity of their motion; they just choose which arm to use to push themselves along...."
Octopuses — or octopi, for folks who like the Latin plural form — are smart critters. We're not sure how smart: yet.

That animated image is from The Octopus Group, Hebrew University of Jerusalem: whose members are humans, not cephalopods. Octopuses are smart, but they're not that smart.

Since animals use neurons to process information, we can get a very rough estimate of how smart a critter is by counting how many neurons are in its brain.

Cockroach brains, for example, have about 1,000,000 neurons. That's plenty for a cockroach's lifestyle, but nowhere near the 760,000,000 neurons in a cat's brain, or 86,000,000,000 in a human's. (August 15, 2014)

An octopus has about 300,000,000 neurons: midway between the count for a rat (200,000,000) and a cat (760,000,000). Looks like those eight-armed mollusks could be at least as smart as the lab rats used in maze experiments. It's also why some countries have protective legislation for octopuses, insisting that surgery performed on them be with anesthesia.

I think that's a good idea. Responsibilities come with being human. Using animals is okay, but making them suffer or die needlessly isn't. (Catechism, 2418)

I've read that octopus intelligence is a subject of lively debate among scientists. That's not surprising: not to me, anyway.

Mollusk Brains


We're vertebrates, mammals, so we've got a cerebral cortex (with roughly 20,000,000,000 neurons in an average human's) that handles most of what we call "thinking."

Mollusk nervous systems aren't wired like ours. Their brain is wrapped around the esophagus, spelled oesophagus in British English; the pipe running from a critter's mouth to its digestive system.

On top of that, two thirds of an octopus's neurons are in its arms. Each arm has 'limited autonomy,' is able to act on its own. Suckers on each arm 'taste' what they're touching, so the arm won't grasp one of its seven partners.

Octopus arm research has a practical side:
"...'People want to build soft robots for medical purposes and rescue operations,' said Dr Guy Levy, one of the researchers involved in the project.

"Such soft-bodied, octopus-inspired arms would not be limited by fixed joints, he explained. This could be useful to access narrow, difficult to reach spaces - perhaps getting help to people trapped at the scene of a collapsed building....

"...To find out the secrets of the octopus's remarkably efficient movement, Dr Levy and his colleague Prof Benny Hochner videoed the animals from underneath as they crawled, and analysed their motion frame by frame.

"This detailed study showed that, by shortening and lengthening, each arm pushed the body in only one direction.

" 'So the octopus only has to decide which arm to use for the pushing - it doesn't need to decide which direction this arm will push,' explained Dr Levy...."
(Victoria Gill, BBC News)
It's a simple, elegant, solution to what could be a complicated problem. All the octopus does is push with the arm that's facing away from where it wants to go. No, I don't think octopuses are people, with our sort of free will: but I'm not going to tie myself in linguistic knots, avoiding words like "wants" or "decides."

Studying the critters' neural circuits to find out how octopuses decide which arm to use is a next step in this research: and may raise more questions than it answers. As Dr. Levy said, "Every time we try to understand something new about the octopus, there are new surprises."


Another Afterword: Angst, Assumptions, and Aliens


I ran into the Fermi paradox while writing this post: something to do with mass extinctions, as I recall. The basic idea is that Earth's sun is a typical star, and it looks like this galaxy has billions of planets like Earth: but we've found no evidence of visits from other people.

We've found several ways to travel between stars: some of them very nearly ready for flight testing. Even at the ten-thousand-years-per-trip rate of the slower methods, folks like us could easily have reached Earth by now: even if they'd started on the other side of the Milky Way.

So: where is everybody?

A conventionally-pessimistic answer is that civilizations promptly destroy themselves after getting as smart and technically proficient as we are.

That may seem plausible, at least for folks who assumed that we have absolute control over nature. (February 10, 2013)

I've talked about fear, flappers, and Europe flambé, before. (August 31, 2014)

Add Cold War and environmentalist angst, and Yeats starts sounding like a starry-eyed optimist:
"...Things fall apart; the centre cannot hold;
Mere anarchy is loosed upon the world,
The blood-dimmed tide is loosed, and everywhere
The ceremony of innocence is drowned;
The best lack all conviction, while the worst
Are full of passionate intensity....
"
("The Second Coming," W. B. Yeats (1919))
Folks can make monumentally stupid, self-destructive, mistakes: and natural disasters happen.

But knowing that we live on a planet where intermittent continental glaciation, exploding mountains, and the occasional asteroid impact are facts of life doesn't fill me with dread.

Scorpions, cockroaches, and rats have endured here; we're at least as adaptable as they are; and we're a whole lot smarter.

We figured out how to use fire and string without killing ourselves — so I think we'll survive steam locomotives, PVC, and Roombas. (August 15, 2014; May 9, 2014)

As for the Fermi paradox, it hinges on a really big assumption: that folks who aren't human would think and act the way we do.

I don't think we do — or don't — have neighbors in this universe. Right now, we don't know.

But if we do meet non-human intelligence: my guess is that they won't be human. At all. And that's still another topic. Topics.

Not-entirely-unrelated posts:

2 comments:

Brigid said...

I think there may be an extra 'and' in here: "Reading up on mass extinctions while thinking about doomsday predictions, religious and secular, and I wrote stuff that doesn't quite fit in this post."

Misspelling: "its roots in the Plantoic Academy, Buddhism, Zoroastrianism, or"

Extra contraction: "known that's it's a tent, something temporary, for millennia."

The Friendly Neighborhood Proofreader

Brian Gill said...

Brigid,

Oops. Right you are. Thanks!

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I block a few of the more obvious dubious advertisers.

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Sometime regrettable advertisements get through, anyway.

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