Welcome back to the Abstract! We’re back to our regularly-scheduled programming this week, so here are the studies that flooded the zone, joined the chorus, reminisced about the past, and gave live birth.

First, scientists reconstruct a devastating series of floods that swept across Europe in the 1340s, offering lessons for our present-day climate crisis. Then: the affairs of amorous amphibians, the mystery of memory, and the case of the Triassic mommy.

the BeX Files.

A lot of water under the bridge

In the summer of 1342, central Europe was devastated by the Magdalena Flood, one of the worst natural disasters of the medieval period. This brutal deluge killed thousands of people, wiped out whole villages, and spread economic turmoil and disease. Its frightening depths are recorded by high watermarks on some buildings in Germany, which are often over 20 feet above ground, a sobering reminder of the horrible event.

Now, scientists have discovered that this catastrophe was part of a series of 16 major floods that swept over Europe from 1342 to 1343, many of which have been overlooked or forgotten. By poring over contemporary sources from the time such as chronicles, annals, administrative records, and correspondence, the team reconstructed the timing and intensity of this period.

“It is…surprising that, out of the 16 events described here, only the Magdalena Flood survived in public memory,” said researchers led by Andrea Kiss of the Vienna University of Technology.

“This may be because it was the first time in the German areas when numerous flood marks and memorial plaques were mounted by local authorities and as a community effort and warning on the walls of iconic buildings whereas, for example, no flood marks were set for the Candlemas Flood in Prague,” they continued. “The establishment of such material markers has been shown to play a crucial role in shaping long-term risk awareness and collective memory.”

Extreme weather events, including floods, are becoming more frequent and intense due to climate change. Hopefully, these historic watermarks will not be surpassed by future floods, but the team warned that “sequences of very large floods, more extreme than those in recent decades, are possible and may occur again” and that current flood management is “not necessarily prepared for such sequences.”

As I’ve noted before, any study based on historical documents is likely to have a banger supplementary materials section, and this one is no exception. The authors pulled together dozens of accounts from people who endured these challenging times with entries that bear witness to submerged castles and towns, and expose the search for meaning in the aftermath. Some blame the stars, or unbalanced elements, or “the sins/ungratefulness of people” (always a classic).

“People barely escaped in the uppest parts of houses; but many people and animals died, as they could not – had no time – run to the hills,” reads one eerie fragment, translated from Latin and written in Magdeburg in 1342.

At least the survivors had time to recover and rebuild, because we all know nothing else bad happened in Europe in the 1340s. Oh wait.  

In other news…

The Polyfroggic Spree

Thanks to the surge of interest in Homer’s Odyssey, we all know what a problem it can be when too many suitors occupy too small a space. It turns out that this is also a real-world issue for female frogs, who can experience “choice overload” when confronted with a cacophony of different male mating calls at once, according to a new study. 

“During a breeding season, males gather in dense choruses, sometimes numbering in the hundreds and often including multiple species, where males call to attract females and deter rivals,” said researchers led by Claire Hemingway of the University of Tennessee, Knoxville. “These advertising calls can be remarkably loud, reaching a peak sound pressure level (SPL) of up to 108 dB at 50 centimeters.”

That’s quite an earful. How’s a frogette supposed to find her prince in the noise? To answer that question, the researchers placed a series of female Cope's gray treefrogs (Hyla chrysoscelis) in a small enclosure and serenaded them with recorded male calls from speakers in different locations. Females prefer longer calls, and hoped toward those sounds when fewer calls were played at once. But they became unable to identify the extended songs as more voices were added to the choir. 

“We found that as the number of calling males increased, receivers became less likely to choose the preferred target signal, took longer to decide, and became more likely to defer their decision,” the team said. “Together, these findings provide support that choice overload exerted a strong influence on female decision-making.”

Time to tap into the frog dating market. An app called Ribbit? I’m spitballing here.

Total recall (mouse version)

The ephemeral nature of memories is a touchstone of human experience—and a major mystery in neuroscience. How can we recall memories from long ago, even though the brain is constantly replacing its circuits?

To shed light on this question, researchers studied the brains of mice placed in artificial hibernation. This state was of interest because memories are related to neural connectivity in the hippocampus, a brain region that effectively flatlines during hibernation, with activity dropping by 70 percent.

Mice lose half their synapses in this deep sleep, making it a natural test of memory retention after a significant disruption of brain connectivity. Yet when the mice in this test awoke from their slumber, they were able to remember the location of treats in a maze that they had explored before the experiment.

The results revealed that despite this “profound reduction in neuronal activity… mice retained previously acquired memories and preserved neuronal representations of experience,” said researchers co-led by Y. J. Lin of the Okinawa Institute of Science and Technology.

“Rather than relying solely on the strength of individual synapses, the brain may store memories through higher-order structural architecture embedded within the neuronal network,” the team concluded.

The team has a lot more smart scientific stuff to say, but my basic takeaway is: Memories are brain ghosts.

You cynodont say

Almost all mammals give birth to live young—a reproductive strategy called viviparity—with the exception of platypuses and echidnas, which insist on laying eggs. Now, scientists have discovered that the origins of mammalian viviparity are far older than previously known, thanks to newly identified features in a fossilized “cynodont,” a mammal ancestor that lived 236 million years ago in the late Triassic period.

The team examined adult fossils of the cynodont species Chiniquodon theotonicus and identified a preserved “neonatal line,” which is a growth ring associated with viviparity. The discovery pushes the timeline of birth in mammal ancestors back by a whopping 90 million years.

“Our results provide evidence of viviparity in Chiniquodon theotonicus, which ties in with recent findings showing that other remarkable features of present-day mammals” originated with these early Triassic ancestors, said researchers led by Leandro Carlos Gaetano of the National Scientific and Technical Research Council in Argentina. 

“If Chiniquodon theotonicus was viviparous, as our results suggest, this invites a revisiting of the evolutionary history of this reproductive mode,” they concluded. 

With that, it’s time to viviparty.

Thanks for reading! See you next week.