The idea that the Cretaceous had ended with the impact of an asteroid was formally introduced in 1980 in a paper from a team of researchers led by physicist Luis Alvarez. It was immediately treated with a huge amount of suspicion, scorn, and vocal opposition by geologists around the world.
This isn’t because geologists hate new theories. And only a little of it was because Alvarez was regarded as a laboratory guy who didn’t know a rock from a hole in his head. Or … maybe more than a little of it came from that second point. But in any case, geologists had a very good reason to resist the import of Alvarez’ theory. That reason isn’t in the history of the rocks. It’s in the history of the science.
Modern geology got its start in the 18th century. It is especially indebted to Scottish farmer and rock hound James Hutton (about whom I’ve done a whole video and podcast — coming soon). What Hutton gave to geology, and to biology and every other science was simple: Time. A gift of time.
Hutton began studying geology when European naturalists still assumed the world was no more than about 6000 years old. Because of that assumption, there simply wasn’t room for the structures of the world—and the animals and plants who lived on it—to have been produced by slow, gradual processes. You couldn’t have evolution that worked over hundreds of generations if there had not been hundreds of generations. You couldn’t have layers of rock formed over processes taking millions of years if there simply had not been millions of years.
When men like Thomas Jefferson, a man who systematically produced a version of the bible from which miracles had been excised, still seemed to be appealing to some mystical “spirit” or “providence” behind nature, it’s because there was no other choice. Without time, without deep time, there is no option but to hand off to some version of God and punt. The world had to be the product of forces that were no longer active in day to day life.
Even after geologists had begun to suspect that the age of the Earth was numbered in first millions, then billions of years, the early science carried with it an acceptance that many of the features we saw around us were the product of near-instantaneous processes. That’s in part because many of these men were still deeply wedded to the idea of biblical events like Noah’s flood, but because that was a deeply established way of thinking. This school of thought—catastrophism, or the idea that the Earth had been formed through a series of catastrophes—soon came to war with an opposing idea whose roots went back to Hutton. Gradualism. The idea that Earth had been formed, not through extraordinary events, but through events that went on day by day, year after year, century after century. Wearing down, building up, wearing down again.
An intrinsic part of the attraction for gradualism was that it made geology a science in the same sense as chemistry or physics. If Earth’s structure were the result of processes acting slowly in ordinary settings, those processes could be observed today. Tested today. Geologists could learn about sandstones by walking beaches and rivers and observing the way sand was deposited. They could sort out shale by looking at ocean muds and look for the origins of coal in peat bogs.
I’m simplifying the centuries-long struggle between catastrophism and gradualism to the extent that I’m leaving out some fundamental points and making adherents of both sides seem a bit ignorant. But I’m running long on this so … just trust me. Even today, when we understand that the Earth began in a series of catastrophes and endured millennia of heavy bombardment, even when we know more about everything from ice ages to geologists hew toward gradualism. Not least of all because geologists love to go into the field and find something that helps explain what they’re seeing in the rocks.
That’s the reason I’m bringing this up today. Because an international team set out to do just that—test something in the geologic record by looking for an equivalent in the world today. And what they found was both fascinating … and it has a connection to Jurassic Park. Come inside and see.
Paleontology and geology
How well do insects in amber reflect what was around at the time?
You’ve seen it in Jurassic Park, and likely you’ve seen it in museums and rock shops—insects trapped in amber. Amber, which is nothing but hardened tree resin, captured specimens so perfectly that it really does seem like a miracle. From tiny frogs to delicate feathers, to even ancient mammals, all kinds of fossil remains have been found in amber. Fantastic as the preservation may seem, it doesn’t actually keep DNA intact. However, it does preserve soft tissue structures lost in most forms of fossilization and provides almost all the information we have about some otherwise poorly preserved creatures like land-based insects.
But when we look at what is preserved in amber, just how complete a picture are we getting of insects that were around at the time? Are we seeing a fair representation of the whole assemblage of tiny creatures tromping around forests millions of years ago, or are we only getting those who are particularly poor at keeping their limbs out of the tree sap? An international team determined to find out in a gloriously simple way: They looked at what is being trapped by resin that spills out of trees today and compared that to the surrounding community.
How good a photograph of the local ecology does amber preserve? Not very good. The results of the study show that ” amber does not record the true past biodiversity of the entire forest.” Though some amazing things are preserved in amber, the results from looking at modern resins suggest we’re only seeing a fraction of what was actually around. The amber does seem to provide of a provide a pretty good picture of those insects and other arthropods (spiders, isopods, etc) that actually spend their lives on these sticky trees, but not a very good job of capturing what lives around them, even if what’s around them does spend time visiting those trees.
So, returning to my opening page theme, is this gradualism? Not really. Or only with a pretty hefty stretch. But it’s in the spirit of gradualism. While a hypothetical catastrophist might have argued that amber was produced under only extraordinary circumstances—such as trees bowled over by the wave of that incoming Great Flood—gradualists just go out an look at what trees are doing now, today, in real forests. It gets back to the idea of why many geologists didn’t immediately latch onto the idea that the K-T boundary event was literally a bolt from the blue. Because that’s hard to test—especially on the kind of budget that is generally left over for geology departments.
If the actual paper seems a bit daunting (though really, this is a pretty interesting an enjoyable article), there’s also an attached article from PNAS writer Derek Briggs which does a much better job of summing up the work than I’ve provided in this short space.
A fly and a mite were discovered trapped in a spider web in Early Cretaceous amber from Spain, and a scale insect in mid-Cretaceous Burmese amber is associated with eggs and freshly hatched nymphs, showing that brood care in insects dates back at least 100 My. Some amber insects even retain the cellular structure of internal soft tissues, such as muscle. However, amber does not trap all of the animals in the forest, and even the insects are subject to sampling bias. This is an important consideration when we use the evidence of fossils entombed in amber to interpret terrestrial environments and ecosystems of the past.
A low-oxygen Earth at the time of early dinosaurs.
The extinction event at the start of the Triassic gets a lot of attention—and it should, considering that the “Great Dying” was the largest known loss of species since the evolution of complex life on Earth. But the Triassic period, which saw the end of several ancient reptilian lineages which had previously dominated the planet and also introduced the first dinosaurs, didn’t just start with a disaster, it ended with another. The Triassic-Jurassic boundary might not represent quite the nearly-clean-slate as that marked by the Permian-Triassic boundary, but it was still a pretty awful period for life on Earth. Now a multiple university team, led by researchers from Florida State University, has managed a new measure on one of the things that made the beginnings of the Jurassic period so awful.
We reconstructed global oceanic (de)oxygenation using thallium isotopes from two ocean basins that suggest a stepwise decline of oxygen that initiated before and extended well after the classically defined [previously known low oxygen period]. This initial deoxygenation occurs with the start of massive volcanism and marine extinctions, while a later shift corresponds to the traditional [low oxygen period].
This isn’t the only period during dinosaur’s early days where oxygen levels were significantly lower than they are today, and much lower than they had been in previous ages of life on Earth. Several researchers have suggested that the edge that really vaulted dinosaurs to center stage wasn’t a propensity for large size, but extremely effective lungs and an elaborate system for gathering oxygen that extended oxygen-exchange surfaces even inside bones, a system preserved in birds today.
Math and Politics
Legislative districts, inequality and … dammit.
Though in a sense it is possible to divorce any science article from politics, especially in these times, there are few so directly connected as this article in the Proceedings of the National Academy of Sciences where Stephen Ornes discusses the math behind partisan gerrymanders overturned by federal district courts.
It would be one of many gerrymandering cases. In February, the US Supreme Court rejected a request by Republican lawmakers to stay a lower court's decision—which drew on mathematical evidence—that Pennsylvania’s congressional maps were partisan-gerrymandered and required redrawing. The Pennsylvania Supreme Court released its new map later the same month. This summer, the US Supreme Court is also expected to decide whether Wisconsin legislators must return to the districting drawing board to create new state legislative districts; the transcript of oral arguments made in the case include tens of pages of math exposition. In March, US Supreme Court justices heard oral arguments about districts in Maryland. Increasingly, social scientists, mathematicians, and statisticians have been drawn into debates over whether existing districts accurately represent the will of the voters.
However, in an unfortunate bit of timing, the Supreme Court actually ruled on the Wisconsin case this week. In their ruling, the Court showed that it can still easily add one and one and find that it’s perfectly acceptable to put both of those Democrats in one extremely squiggly district created for the purpose of making more Republican districts.
medicine
How to mend a broken heart.
Carolyn Beans has a fascinating article at PNAS on multiple teams working to provide heart patients with an option to either having a transplant or living with a damaged heart.
In the lab of biomedical engineer Nenad Bursac of Duke University, patches of human heart tissue beat rhythmically on their own accord. Each translucent patch—on some days up to about 15 patches, 4 centimeters by 4 centimeters each—sits suspended in its own dish on a gently rocking platform. A red broth washes over the cells as the tissues strengthen. If these patches can get strong enough, and functional enough, they may just revolutionize heart repair.
That work is just one of several efforts to find ways of addressing hearts that have lost tissue due to injury, disease, or blood restriction during heart attacks. Beans’ article provides insight into why it’s so difficult to repair an organ that’s in constant motion (you can’t exactly put a splint on the heart and wait for it to heal) and the efforts of teams to produce lab-grown heart tissue as well as to use other muscles—including tissue taken from the thigh—to repair and strengthen hearts in trouble.
This is not a peer-reviewed paper, but an overview of several works in progress, and it’s definitely worth a read.
Astronomy
‘Oumuamua, strange visitor from another solar system, is stranger still.
When ‘Oumuaua came streaking through the solar system, whipped round the sun, and headed out again into the truly great unknown, it was the first time astronomers had detected an object that we were sure came from beyond the limits of our own solar system. The sheer speed of ‘Oumuamua was enough to ensure that, even though it may have given our sun a brush pass, gravity was simply not going to keep it local.
Early in the observations of the incoming object, it was thought to be a comet. But it never developed a tail, and attempts to image the fast-moving intruder suggested that it was very elongated ("like a cigar" according to perhaps 10,000 articles) and that it was also making a low-speed tumble as it plunged inward. With the odd shape, apparently solid structure, and no visible tale, 'Oumuamua was reclassified as something closer to an asteroid.
But now a team of ESA and JPL researchers have crunched the numbers and determined that the course the interstellar visitor took can't be explained by gravity alone.
Here we report the detection, at 30σ significance, of non-gravitational acceleration in the motion of ‘Oumuamua. … After ruling out solar-radiation pressure, drag- and friction-like forces, interaction with solar wind for a highly magnetized object, and geometric effects originating from ‘Oumuamua potentially being composed of several spatially separated bodies or having a pronounced offset between its photocentre and centre of mass, we find comet-like outgassing to be a physically viable explanation, provided that ‘Oumuamua has thermal properties similar to comets.
So, ‘Oumuamua didn’t just come plunging through the system like a rock. It was a rock … that came complete with thrusters.
Look, I’m not saying it was aliens. Just that ... it would be a shame if Rama came calling, and we missed our rendezvous.
Image
As usual, this morning’s image comes from Andy Brunning at Compound Interest. For a larger version that’s easier to read, visit his site.