Time Has Only Strengthened These Ancient Roman Walls

J. P. Oleson
J. P. Oleson

Any seaside structure will erode and eventually crumble into the water below. That’s how things work. Or at least that’s how they usually work. Scientists say the ancient Romans figured out a way to build seawalls that actually got tougher over time. They published their findings in the journal American Mineralogist.

The walls’ astonishing durability is not, itself, news. In the 1st century CE, Pliny the Elder described the phenomenon in his Naturalis Historia, writing that the swell-battered concrete walls became "a single stone mass, impregnable to the waves and every day stronger."

We know that Roman concrete involved a mixture of volcanic ash, lime, seawater, and chunks of volcanic rock—and that combining these ingredients produces a pozzolanic chemical reaction that makes the concrete stronger. But modern cement involves a similar reaction, and our seawalls fall apart like anything else beneath the ocean's corrosive battering ram.

Something else was clearly going on.

To find out what it was, geologists examined samples from walls built between 55 BCE and 115 CE. They used high-powered microscopes and X-ray scanners to peer into the concrete's basic structure, and a technique called raman spectroscopy to identify its ingredients.

Microscope image of crystals in ancient Roman concrete.
Courtesy of Marie Jackson

Their results showed that the pozzolanic reaction during the walls' creation was just one stage of the concrete toughening process. The real magic happened once the walls were built, as they sat soaking in the sea. The saltwater did indeed corrode elements of the concrete—but in doing so, it made room for new crystals to grow, creating even stronger bonds.

"We're looking at a system that's contrary to everything one would not want in cement-based concrete," lead author Marie Jackson, of the University of Utah, said in a statement. It's one "that thrives in open chemical exchange with seawater."

The goal now, Jackson says, is to reproduce the precise recipe and toughen our own building materials. But that might be harder than it sounds.

"Romans were fortunate in the type of rock they had to work with," she says. "They observed that volcanic ash grew cements to produce the tuff. We don't have those rocks in a lot of the world, so there would have to be substitutions made."

We still have a lot to learn from the ancient walls and their long-gone architects. Jackson and her colleagues will continue to pore through Roman texts and the concrete itself, looking for clues to its extraordinary strength.

"The Romans were concerned with this," Jackson says. "If we're going to build in the sea, we should be concerned with it too."

Human Body Temperatures Are Dropping, and Science Might Know Why

dcdp/iStock via Getty Images
dcdp/iStock via Getty Images

In 1868, German physician Carl Reinhold August Wunderlich started to popularize what’s become the most recognizable number in all of medicine: 98.6°F or 37°C, which is thought to be the normal average human body temperature. Though his methods later came under scrutiny—Wunderlich stuck an enormous thermometer under the armpits of patients for 20 minutes, a less-than-accurate technique—this baseline has helped physicians identify fevers as well as abnormally low body temperatures, along with corresponding illnesses or diseases.

More than 150 years later, 98.6° may no longer be the standard. Humans seem to be getting cooler. Researchers at Stanford University School of Medicine, in a paper published in the journal eLife, compared three large datasets from different time periods: American Civil War records, a national health survey from the 1970s, and a Stanford database from 2007-2017. By comparing recorded body temperatures, the researchers founds that men are now averaging a temperature .58°C less than what's long been considered normal, while women are .32°C lower. On average, each has decreased roughly .03°C every decade since the 1860s.

What drove us to chill out? Scientists have a few theories. A number of advances in human comfort have been ushered in since the 1800s, including better hygiene and readily available food, which may have slowed our metabolic rate (temperature is an indication of that rate). Chronic inflammation, which also raises body temperature, has decreased with the advent of vaccines, antibiotics, and better healthcare. The researchers propose that, on average, our bodies are healthier and slightly less warm.

After all, the average life expectancy in Wunderlich’s era was just 38 years.

[h/t The Independent]

Last Wild Grove of Wollemi Pines, the Endangered ‘Dinosaur Trees,’ Saved From Australia's Wildfires

Marina Denisenko, iStock via Getty Images
Marina Denisenko, iStock via Getty Images

Almost three decades after they were rediscovered, the ancient "dinosaur trees" of Australia's Wollemi National Park were nearly wiped out for good. Wildlife officials in New South Wales feared that the last natural stand of Wollemi pines would be counted among the billions of plants and animals destroyed by Australia's recent wave of wildfires. But thanks to quick action from firefighters, the ancient grove has been saved, The Guardian reports.

The first Wollemi pines date as far back as 200 million years, and the trees reached peak numbers 65 million to 34 million years ago. Since then, populations have shrunk so drastically that the species was thought to be extinct until it was rediscovered 26 years ago. Fewer than 200 wild specimens exist today, and they're all concentrated in a protected sandstone grove in Wollemi National Park, about 125 miles northwest of Sydney, Australia.

The Wollemi pines' fragile status means that one bad forest fire could spell its end. With this in mind, the New South Wales National Parks and Wildlife Service and NSW Rural Fire Service prioritized their protection this bushfire season. Before the Gospers Mountain fire spread to the canyons where the trees grow, a team of firefighters was sent there by helicopter to install an irrigation system. This kept the trees hydrated and made them less vulnerable to flames. Helicopters also dumped fire retardant around the grove to weaken the fire when it arrived.

The efforts weren't able be able to save every Wollemi pine from damage and destruction—a few trees survived with charring and two more died—but they were enough ensure the continuation of the species. With a population this small, protecting it is a never-ending battle. In addition to fire, visitors stepping on seedlings and introducing diseases also pose a threat. For that reason, the Australian government has chosen to hide the exact location of the grove from the public.

[h/t The Guardian]

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