What makes a galaxy dead or alive is simple: internal stores of gas.

The low-mass, dusty, irregular galaxy NGC 3077 is actively forming new stars, has a very blue center, and has a hydrogen gas bridge connecting it to the nearby, more massive M81. As one of 34 galaxies in the M81 Group, it’s an example of the most common type of galaxy in the Universe: much smaller and lower in mass, but far more numerous, than galaxies like our Milky Way. The young stars within it have formed from gas reservoirs still present within this galaxy, indicating an “alive” galaxy.

Inside living galaxies, gas is required to enable the formation of new stars.

The enormous bar at the core of galaxy NGC 1300 spans many tens of thousands of light-years, nearly the full width of the galaxy. While many spiral galaxies contain large, prominent bars such as this one, our Milky Way’s central bar is far more modest, extending only about a third of the way out to the Sun’s position. The pink regions found along the spiral arms are evidence of new star formation, triggered by the interaction of internal gas and the density waves of the internal structure.

When massive gas clouds gravitationally collapse, new stars inevitably arise.

Star-forming regions, like this one in the Carina Nebula, can form a huge variety of stellar masses if they can collapse quickly enough. Inside the ‘caterpillar’ is a proto-star, but it is in the final stages of formation, as external radiation evaporates the gas away more quickly than the newly-forming star can accrue it. Within the first ~2 million years of this star’s birth, protoplanets should already begin arising within the accompanying protoplanetary disk.

As matter fragments, the various clumps grow rapidly, forming new stars and massive star clusters.

The central concentration of this young star cluster found in the heart of the Tarantula Nebula is known as R136, and contains many of the most massive stars known. Among them is R136a1, which comes in at about ~260 solar masses and shines brighter than more than 8 million suns, making it the heaviest known star. Although great numbers of cooler, redder stars are also present, the brightest, bluest ones dominate this image, although they have the shortest lifetime, living for between 1-10 million years only. Within a cloud of gas, the process of core fragmentation leads to enormous populations of large numbers of stars.

Many events trigger galactic star-formation, including:

The Southern Pinwheel Galaxy, Messier 83, displays many features common to our Milky Way, including a multi-armed spiral structure and a central bar, as well as spurs and minor arms, plus a central bulge of stars. The pink regions showcase transitions in hydrogen atoms driven by ultraviolet light: produced by new stars. The Southern Pinwheel galaxy is one of the closest and brightest barred spiral galaxies at a distance of just 15 million light-years, and has a similar diameter (118,000 light-years) to our own Milky Way.

• internal dynamics,

The spiral galaxy UGC 12158, with its arms, bar, and spurs, as well as its low, quiet rate of star formation and hint of a central bulge, may be the single most analogous galaxy for our Milky Way yet discovered. It is neither gravitationally interacting nor merging with any nearby neighbor galaxies, and so the star-formation occurring inside is driven primarily by the density waves occurring within the spiral arms in the galactic disk

• external gravitational tugs,

The Whirlpool Galaxy (M51) appears pink along its spiral arms due to a large amount of star formation that’s occurring. In this particular case, a nearby galaxy gravitationally interacting with the Whirlpool galaxy is triggering this star formation, but all spirals rich in gas exhibit some level of new star birth.

• or even galactic mergers.

Zw II 96 in the constellation of Delphinus, the Dolphin, is an example of a galaxy merger located some 500 million light-years away. Star formation is triggered by these classes of events, and can use up large amounts of gas within each of the progenitor galaxies, rather than a steady stream of low-level star formation found in isolated galaxies. Note the streams of stars between the interacting galaxies, which can either become part of a population of stars in the post-merger galaxy’s stellar halo, or could get expelled from the post-merger galaxy entirely, roaming the intergalactic medium.

Isolated galaxies are more likely to form stars quiescently: at slow, steady rates over long timescales.

The isolated galaxy MCG+01-02-015, all by its lonesome for over 100,000,000 light years in all directions, is presently thought to be the loneliest galaxy in the Universe. The features seen in this galaxy are consistent with it being a massive spiral that formed from a long series of minor mergers, but that has never experienced a major merger, and where star-forming activity has been relatively quiet for the past several billion years. A galaxy such as this may continue forming new stars in an ongoing fashion for much longer than the present age of the Universe.

However, once a galaxy becomes gas-depleted or even gas-free, star-formation ceases within it.

This nearby galaxy, NGC 1277, although it may appear similar to other typical galaxies found in the Universe, is remarkable for being composed primarily of older stars. Both its intrinsic stellar population and its globular clusters are all very red in color, indicating that it hasn’t formed new stars in ~10 billion years. Some of the earliest living planets and worlds may have arisen in “red and dead” galaxies such as these.

Without gaseous material, there’s no “fuel” for future generations of stars.

This snippet from a structure-formation simulation, with the expansion of the Universe scaled out, represents billions of years of gravitational growth in a dark matter-rich Universe. Even after galaxy clusters form, surrounding galaxies and galaxy groups, including initially Milky Way-like galaxies, get drawn in. Over time, they will lose their gas and eventually cease forming new stars.

This is often the fate of even initially Milky Way-like galaxies as they fall into galaxy clusters.

Galaxy clusters, like Abell S740, are the largest bound structures in the Universe. When spirals merge, for example, a large number of new stars form, but either post-merger or by speeding through the intra-cluster medium, gas can be stripped away, leading to the end of star formation in that galaxy and, eventually, a red-and-dead final structure.

Inside rich clusters, galactic mergers are common, with major mergers often leading to galaxy-wide starbursts.

The galaxy NGC 7727 shows extended spiral arms: likely the aftermath of a recent major merger between two comparably massive galaxies. The presence of two supermassive black holes inside this galaxy, as well as the extended streams of gas and stars, show one possible outcome of a major merger of two similar-mass, initially gas-rich galaxies.

These violent episodes of star-formation generate incredible winds, expelling large reservoirs of gas.

This close-up view of Messier 82, the Cigar Galaxy, shows not only stars and gas, but also the superheated galactic winds and the distended shape induced by its interactions with its larger, more massive neighbor: M81. (M81 is located off-screen, to the upper right.) When star-formation actively occurs across an entire galaxy, it becomes what’s known as a starburst galaxy, characterized by violent, gas-expelling winds.

Furthermore, galaxy clusters contain a gas-rich intracluster medium.

Located within the Norma cluster of galaxies, ESO 137-001 speeds through the intracluster medium, where interactions between the matter in the space between galaxies and the rapidly-moving galaxy itself cause ram pressure-stripping, leading to a new population of tidal streams and intergalactic stars. Sustained interactions such as this can eventually remove all of the gas from within a galaxy, eliminating its ability to form new stars. Phenomena such as this allow us to conclude that the galaxy, the cluster, and the gas within it are all made of matter, not antimatter.

Rapidly speeding through it strips a galaxy’s gas away.

When galaxies like the spiral galaxy at right, D100, speed through a rich environment (like the Coma Cluster, which D100 is a member of), the friction with the environment can cause gas stripping, leading to the formation of stars and increasing the dark matter-to-normal matter ratio of the host galaxy. The central feature is evidence of ram pressure stripping as the galaxy speeds through the intracluster medium, quickly losing its capacity to form new stars. The galaxy next to it is simply an older version, having already become ‘red-and-dead’ many billions of years ago by a likely similar process.

The end state of a gas-free galaxy is a giant elliptical where only old stars survive.

A map of neutral hydrogen (in red) overlaid on the galaxy D100 in the Coma Cluster shows how much gas is being quickly stripped from this galaxy as it travels through the cluster. Galaxies found in environments like this one become ‘red-and-dead’ far more quickly than galaxies in less dense regions of space.

With many mergers and constant gas stripping, galaxy clusters are graveyards for Milky Way-like galaxies.

The Coma Cluster of galaxies, as seen with a composite of modern space and ground-based telescopes. The infrared data comes from the Spitzer Space telescope, while ground-based data comes from the Sloan Digital Sky Survey. The Coma Cluster is dominated by two giant elliptical galaxies, with over 1000 other spirals and ellipticals inside. Gas-free, red-and-dead elliptical galaxies are very common, especially toward the cluster center, in large galaxy clusters such as this one.

Mostly Mute Monday tells an astronomical story in images, visuals, and no more than 200 words.

This article Galaxy clusters are graveyards for Milky Way-like galaxies is featured on Big Think.

A new electrically conductive “eSoil” could make hydroponic farming even more productive — and help ensure a sustainable new source for the human food supply.

“[W]e can get seedlings to grow faster with less resources,” said Eleni Stavrinidou, leader of the Linköping University team that developed the new substrate.

The challenge: Much of the world is perpetually in a food crisis. An estimated 735 million people experienced chronic undernourishment in 2022, a number that has increased by 122 million since 2019, a major setback after decades of progress. The struggle to expand food supply is likely to face new stresses in the future. 

“The world population is increasing, and we also have climate change,” said Stavrinidou. “So it’s clear that we won’t be able to cover the food demands of the planet with only the already existing agricultural methods.”

The idea: Hydroponic farming — a technique where plants are grown in water rather than soil — could help the world meet some of its future food needs. 

Not only does it enable farming in places that lack arable land, hydroponic systems can also be paired with lights to grow plants indoors. Trays of crops can then be layered vertically, allowing more food to be grown in an area than would be possible with traditional farming.

​​“We can’t say that hydroponics will solve the problem of food security, but it can definitely help, particularly in areas with little arable land and with harsh environmental conditions,” said Stavrinidou.

The biggest challenge with indoor hydroponic farming is the cost — it’s far cheaper to let the sun provide light than it is to power LEDs — so finding ways to make the process more efficient is key to helping it meet its potential.

What’s new? Stavrinidou’s team has now developed a new substrate for hydroponic farming. This is the material the plants’ roots attach to in a hydroponic system, instead of soil, and the standard option is mineral wool, which is made through an energy-intensive process.

The new substrate, called “eSoil,” is made out of cellulose, a material found in plant walls, and PEDOT, an electrically conductive polymer.

This conductivity made it possible to apply a small voltage to the roots of barley plants growing in the substrate. That electrical stimulation made the plants grow 50% larger (by dry weight) than control seedlings grown in eSoil with no stimulation during a 15-day study.

The cold water: This isn’t the first study to show that electrical stimulation can help plants grow. However, the Linköping team says previous studies have used higher voltages, while their eSoil requires a low voltage and has a very low energy consumption, which could make it more practical.

Because the controls were also grown in eSoil without electrical stimulation, though, it’s not clear how this approach compares to barley grown in a traditional substrate. The study also ended while the plants were still seedlings, so more research is needed to test the longer term impact of the eSoil and stimulation.

Looking ahead: The next step for the Swedish scientists will be figuring out how their approach works so that they can further optimize it for use during hydroponic farming.

“We don’t yet know how it actually works [or] which biological mechanisms that are involved,” said Starvrinidou. “What we have found is that seedlings process nitrogen more effectively, but it’s not clear yet how the electrical stimulation impacts this process.”

This article Zapping plants in “eSoil” makes them grow 50% larger is featured on Big Think.

Stand on the rocky shoreline near the foot of the Pointe Aux Barques lighthouse, at the tip of the thumb of Lower Michigan, and look north across the blue expanse of Lake Huron. You will not see any caribou. But they were there, as were the humans that scientists believe hunted them nearly 10,000 years ago.

Now, thanks to innovative technology, determination, and luck, archaeologists are bringing this lost human history to the surface, and piecing together the mystery of a hunter-gatherer society unlike any other in the region.

The North American Great Lakes, sometimes called inland seas, are the world’s largest freshwater system. They seem as immense and ancient as any ocean, but Superior, Michigan, Huron, Erie, and Ontario, as we know them today, are younger than Stonehenge. For generations, people watched them form and adapted as the landscape changed again and again.

Between the end of the last ice age more than 10,000 years ago and about 3,000 years ago, the entire Great Lakes region experienced dramatic shifts in environment, climate, and elevation. Glaciers that covered it retreated in fits and starts, and paleolakes formed and disappeared again, leaving behind boggy tundra. The bedrock itself rose and fell like a very large trampoline. Through it all, humans moved across the landscape, hunting, foraging, and even trading along networks spanning thousands of miles.

A satellite view of the North American Great Lakes; a submerged feature called the Alpena-Amberley Ridge is just to the right of image center, off the thumb of Lower Michigan. (JEFF SCHMALTZ, NASA/PUBLIC DOMAIN)

Understanding these radically evolving landscapes and the people who lived on them has long been a challenge for archaeologists—especially if you’re looking on land. Large portions of the land around today’s Great Lakes have acidic soil, which quickly breaks down everything from bones to wooden structures. Centuries of farming and other intensive land use have also destroyed or damaged many possible archaeological sites.

Beneath the waves, however, it’s a different story. There, archaeologists have found hunting structures and hearths, weapons and tools, all swallowed by rising waters and untouched for millennia.

“The stuff in the Great Lakes is like Pompeii, where the water is like the ash, sealing these deposits completely intact,” says Ashley Lemke, an archaeologist at the University of Wisconsin-Milwaukee who studies hunter-gatherers of the Great Lakes and other regions.

Lemke is part of the team that has spent years exploring an underwater site more than 60 miles north of Pointe Aux Barques, and currently about 120 feet below Lake Huron’s surface. The site, known as Drop 45 Drive Lane, hints at the ingenuity of some of the earliest humans in the Great Lakes region—but also presents a mystery about who these people were.

The roughly 20-acre submerged site is named both for how it was found (during an acoustic survey) and for what the team believes it is: a human-built structure that drove animals into a narrow space, or lane, where hunters waited.

Since its discovery more than a decade ago, Drop 45 has yielded artifacts big and small, from stone hunting blinds to flakes of chert, a type of rock often used for making tools, including arrowheads and spear tips. Flakes of obsidian were also found at the site. The specific chemical signature of these pieces of volcanic glass indicates they came from formations in Oregon, more than 2,500 miles away, hinting at a cross-continental trade network nearly 10,000 years ago. But the story of Drop 45 began long before then.

Rock of Ages

If you drained today’s Great Lakes—or just looked closely at a modern bathymetry chart—you might notice that Lower Michigan sits in the middle of several rough concentric ridges. These erosion-resistant walls of rock mark ancient shorelines of a sea that shrank over hundreds of millions of years. The most prominent ring of this geological bull’s-eye, the Niagara Escarpment, arcs westward from the famous falls of the same name to a humbler formation in southeastern Wisconsin known as Brady’s Rocks. A portion of another ring, parallel to the Niagara Escarpment, is called the Alpena-Amberley Ridge (AAR) and cuts across what’s now Lake Huron. These ridges are truly ancient, even geologically speaking: They formed on the paleocontinent of Laurentia nearly half a billion years ago, and saw the dinosaurs come and go. During the last ice age, the AAR was largely buried under the ice, but it would have been largely high and dry during portions of the transitional postglacial period.

John O’Shea, who heads the University of Michigan’s underwater archaeology program, was attracted to the AAR as a potential study area more than 20 years ago. The ancient ridge, only a few miles wide in places, would have been a relatively stable feature on the landscape and, he thought, might have offered attractive camping and hunting sites to humans in the area.

During the last ice age, which peaked about 20,000 years ago, ice sheets scraped back and forth across what’s now the Upper Midwest. Paleolakes such as Algonquin, Stanley, and Chippewa—think of them as early drafts of the Great Lakes—formed during periods when glaciers were melting, and were reshaped as the ice retreated or advanced. All of this makes recreating the shifting landscape in any detail extremely challenging. “The glacier part is tricky,” says Lemke. “Glaciers erase all the evidence of former glaciers.”

Another process had even greater influence on the landscape once the ice retreated for good: Areas of bedrock, freed from the tremendous weight of mile-thick glaciers, bounced back, a process called isostatic rebound or adjustment. It continues today in many previously glaciated areas, including the Great Lakes region, and adds another variable to a complex, constantly changing set of systems. “That rebound isn’t even, it sort of hinges, so you’ve got this weird thing happening south to north,” says O’Shea. “As that plane is tipping back and forth, you’ve got different openings and closings and different lake outlets. This is why you have periods when you have a lot of water trapped there.”

As ice sheets steamrolled back and forth, lakes grew and shrank and filled again, rivers appeared and vanished, flora and fauna also changed—shifts can be documented by evidence such as ancient pollen. O’Shea calls it a landscape of “migrating ecotones,” or transitions between different kinds of environments. “There’s an ecological zone close to the ice front. It’s wet and tundra-like,” he says, adding that it would have been an attractive environment for cold-adapted animals, such as caribou, musk ox, and Arctic fox.

A satellite view of the North American Great Lakes; a submerged feature called the Alpena-Amberley Ridge is just to the right of image center, off the thumb of Lower Michigan. (JEFF SCHMALTZ, NASA/PUBLIC DOMAIN)

“As the ice moves north, the ecotone moves north … but this doesn’t happen overnight,” O’Shea says. “You get a succession of vegetation, from scrubs to spruce to pine. There’s a readvance of the ice so the pine goes away and the spruce comes back. Then you get mixed hardwoods.”

These shifts were not sudden, but the people living on the landscape would have been aware of them, similar to the way Arctic communities are experiencing permafrost melt and other consequences of climate change today. “You would have seen it on a generational basis, like ‘Oh, Grandpa used to hunt over there but now it’s a marsh,’” says Lemke.

At points early in the postglacial period, the AAR was a ridge flanked by tundra and wetlands. A little later, during a period roughly 9,000 years ago, the ridge would have formed a narrow land bridge between the two halves of Lake Stanley, the predecessor to Lake Huron. Migrating animals—likely including caribou—would have used this narrow corridor of dry land. And that made it attractive to humans. “The movement of animals would have been very predictable,” O’Shea says. “This would have been a tremendous thing for hunters.”

Unique Tools of the Trade

O’Shea, Lemke, and colleagues used an array of underwater survey techniques along the now-submerged AAR to identify the most promising areas. The remote survey tools, including advanced sonar, are now refined enough that they can reveal stone tools scattered across the lakefloor beneath layers of sediment, and human-built structures under smothering blankets of invasive mussels, which have overrun much of the Great Lakes. Once the surveys identified potential signs of human presence, submersibles and divers investigated the areas further. During their work, the team found several sites with hunting blinds or other human-made features, including the evocatively named Dragon Drive Lane. But Drop 45 appears to be the most complex site discovered so far.

The more the team learned about Drop 45, the more it surprised them. The site features multiple hunting blinds and a cleared, stone-lined lane that hunters used to funnel game toward them. Along with the other AAR hunting sites the team has identified, these structures are unique in the Great Lakes region—though similar hunting sites exist in the Arctic.

“Nobody had any idea that people were using that hunting architecture in the Great Lakes,” says Lemke. “It’s only because it’s underwater that those hunting structures are preserved. If they were on land, they wouldn’t look like much and people would just move them around.”

Several rock structures near Alaska’s Kuzitrin River are believed to have been used as ancient caribou hunting blinds. The remains of similar structures have been found in Lake Huron. (BERING LAND BRIDGE NATIONAL PRESERVE, CC BY 2.0/WIKIMEDIA)

The specific layout of the hunting blinds at Drop 45 suggests they were oriented to different directions caribou would have traveled during fall and spring migrations. The team recreated the landscape in a virtual reality setting and showed the site to traditional caribou hunters in Alaska. They confirmed how the drive lane and blinds would have been used, Lemke adds.

In addition to unique hunting structures, the stone artifacts retrieved from Drop 45 are unlike any others found in the Great Lakes region, raising questions about who the people hunting on the AAR were. We know they were not the first humans in the region: There are older archaeological sites around the Great Lakes, including the 12,000-year-old Gainey site, discovered near Detroit more than 40 years ago, and the Belson site in southwestern Michigan, described in 2021 and likely about as old.

The artifacts at both of those sites have been categorized as northern offshoots of the Clovis tradition, one of the earliest styles of toolmaking in the Americas. The distinctively fluted Clovis projectile points and other artifacts have been found across much of North America, but are fairly rare in the Great Lakes region. The artifacts found at Drop 45 and other sites along the AAR seem to have no connection to the Clovis tradition, however, and appear to belong to a previously unknown style, according to the team.

By about 8,000 years ago, as water levels rose, the AAR had become an archipelago, and eventually was fully inundated as Lake Huron filled. Caribou had moved out of the region, and evidence of the people adapted to hunting them vanishes from the archaeological record.

The team continues to explore the submerged landscape for more sites, including in areas adjacent to the AAR that would have been tundra before Lake Stanley formed. It will take multiple artifacts from multiple sites to understand who was in the area—and to convince some peers who believe the team’s findings are too speculative.

As O’Shea and his colleagues venture deeper into Lake Huron and the past, he’s hopeful but realistic about what they may find. “You can only approach this with humility. We’re talking thousands of years here,” says O’Shea. “We try to get together the pieces we can.”

This article How the Great Lakes formed—and the mystery of who watched it happen is featured on Big Think.

In their ongoing hunt for extraterrestrial life, astronomers are searching for three key ingredients: liquid water, a source of energy, and complex organic molecules, which make up the basic building blocks of life as we know it.

If a planet has all three, it’s considered a more promising location for life to emerge — but it’s not as easy to discover as it sounds. 

Evidence for life? Tantalizingly, all three of these ingredients may exist on some of the moons of Jupiter and Saturn, which host vast oceans of liquid water below crusts of ice kilometers thick. 

As they orbit their host planets, both Europa (Jupiter’s fourth largest moon) and Enceladus (Saturn’s sixth largest) are stretched and squeezed by tidal forces, a source of energy that helps heat their subsurface oceans to far more comfortable temperatures than their frigid exteriors would suggest.

That leaves just the third key ingredient. That one is ultimately far more difficult to detect from Earth, yet across several missions to Jupiter and Saturn over the past few decades, astronomers have now gathered enticing evidence that complex organics may be abundant on both Europa and Enceladus. 

In 2015, NASA’s Cassini probe passed directly through an icy plume that had erupted from a crack on Enceladus’ south pole. With its in-built Cosmic Dust Analyzer, the probe identified the signature of complex organic molecules in the ice grains. However, the measurements were not enough to pin down the origin or identity of the molecules.

The challenge: As ice grains in the plume were ejected into space at speeds of over 400 meters per second, they would have impacted Cassini’s detector at colossal speeds. 

According to some astronomers, these impacts may have been violent enough to break apart any organic molecules riding along inside the grains, degrading any samples picked up by the probe. Yet due to the limited resolution of Cassini’s measurements, we can’t be sure whether or not this really happened. 

Ultimately, without a clear understanding of what happens to complex organics during these detector impacts — be it with Cassini or any future missions to Europa or Enceladus — astronomers can’t make any particularly reliable predictions about the life-harboring potential of these icy moons. 

The experiment: In a new study published in PNAS, Robert Continetti and a team of astronomers at UC San Diego have shed new light on the problem. They wanted to imitate the impacts taking place as Cassini passed through Enceladus’ icy plume, combined with measurements from a state-of-the-art mass spectrometer.

The researchers started by preparing a water-based solution of various amino acids — those are the molecular building blocks of proteins, which are essential to all life on Earth. Through a technique named “electrospray ionization,” they then pushed the solution through a thin capillary tube while subjecting it to a high voltage.

In the process, the liquid became charged, creating a fine spray of charged droplets just a few hundred nanometres across as it emerged from the end of the tube. Continetti’s team then injected the droplets into a vacuum, where they immediately froze into tiny, solid ice grains, much like those picked up by Cassini. 

From here, the grains were accelerated by strong electric fields and then passed into a custom-built instrument named the Hypervelocity Ice Grain Impact Mass Spectrometer. Crucially, this device could select grains with specific ratios between their mass and charge — a value determined by their amino acid contents — to impact an ion detector at the back of the instrument. 

Withstanding impacts: Remarkably, the team found that each type of amino acid they studied survived the impact, even when the grains were accelerated to speeds of over four kilometers per second, which is much faster than the speeds of the ice grains picked up by Cassini.

Their results were consistent with Cassini’s data and also showed that the amino acids became less detectable when prepared in salty solutions. Since Enceladus’ ocean is likely very salty, this result goes further to explaining the probe’s observations.

Altogether, the results provide the first unambiguous evidence that, using similar instruments, future missions could safely fly through the icy plumes of Europa and Enceladus and study them without damaging any complex organic molecules in the process. 

Continetti’s team now hopes their results could offer important guidance for future missions to the icy moons of Jupiter and Saturn — including NASA’s Europa Clipper Mission, due for launch in October this year. In turn, they may even bring us a step closer to knowing whether life may yet exist on other worlds in our solar system.

This article Ice plumes could reveal signs of life on Europa and Enceladus is featured on Big Think.

Did you get a little bit bigger over the holiday season? Well, so did America. You may not have noticed in the pre-Christmas rush, but on December 19, 2023, the U.S. added an area of about 1 million km2 (roughly 386,000 square miles). That’s about the size of one Egypt or slightly more than two Californias.

How did you not notice? Well, perhaps because no shots were fired, no flags were raised, and no actual land was gained. The newest bits of America are all maritime, way out on the high seas. (The more appropriate unit of measurement should therefore be 292,000 square nautical miles.)

Biggest enlargement since the Alaska Purchase

America’s most significant enlargement since the 1867 Alaska Purchase was reported by the U.S. State Department in a terse communiqué, saying it had defined “the outer limits of the U.S. continental shelf in areas beyond 200 nautical miles from the coast, known as the extended continental shelf (ECS),” which the department noted is an “extension of a country’s land territory under the sea.”

“Like other countries, the United States has exclusive rights to conserve and manage the living and non-living resources of its ECS,” the State Department said. “The United States also has jurisdiction over marine scientific research relating to the ECS, as well as other authorities provided for under customary international law, as reflected in the 1982 UN Convention on the Law of the Sea.”

The 1982 UN Convention on the Law of the Sea (UNCLOS for short) gives coastal states the right to claim an Exclusive Economic Zone (or EEZ) that extends 200 nautical miles from their shoreline. It also allows them to include the ECS: The areas where the continental shelf — the gently sloping underwater extension of a land mass before it drops off to the ocean’s depths — extends beyond those 200 nautical miles.

To date, more than 90 other countries have already claimed their ECS.

• An EEZ should not be confused with territorial waters, which typically end 12 nautical miles out from the shoreline. This is where coastal states have full sovereignty.
• In contrast, countries only have economic jurisdiction over their EEZs. That’s not to be sneezed at: They have the sole right to exploit that zone’s natural resources (fish, oil, minerals, etc.) and to deploy other economic activities (such as wind and tidal power generation) within it.
• An ECS is different still. Rights pertain only to the seabed and the subsoil, not to the water column (including the fish), as is the case in an EEZ.

Although not a signatory to the convention itself, the U.S. recognizes UNCLOS as the basis for international maritime law and in 1983 declared its own 200-mile EEZ. America’s EEZ was the largest in the world. At 3.4 million square nautical miles (11.6 million km²), it is bigger than the land area of all 50 states combined.

Know thy shelf

The ECS adds another 30% to the waters that are under some degree of U.S. jurisdiction. The addition was made possible by a 20-year data-collecting project conducted by the National Oceanic and Atmospheric Administration (NOAA) and the U.S. Geological Survey (USGS). The project to determine the size of the ECS involved 40 mapping expeditions costing tens of millions of dollars, making it America’s largest offshore mapping effort ever.

So, where exactly did the U.S. get bigger? The ECS is not one contiguous zone but consists of seven distinct maritime areas.

• Of these, the Arctic ECS, a wedge-shaped slice of the Arctic Ocean north of Alaska, is by far the largest: it comprises 520,400 km² (151,725 sq nmi), or 52.7% of the total. That’s half an Egypt or one California.
• The Atlantic ECS (239,100 km², or 69,710 sq nmi) is 24.2% of the total. This slim-waisted band of ocean stretching from the Bahamas to Canada is slightly larger than Romania and slightly smaller than Michigan.
• Plugging a hole in the U.S.-Russia maritime border, the Bering ECS (176,300 km², or 51,400 sq nmi) is the third-largest addition (17.8% of the total), about the same size as Uruguay or Missouri.
• The Pacific ECS, a bulge off the coast of northern California, is the biggest of the smaller additions (3.3% of the total). Covering 32,500 km² (9,475 sq nmi), it’s slightly larger than Belgium and about the same size as Maryland.
• Two neighboring patches in the Gulf of Mexico add up to 1.9% of America’s ECS: a larger zone in the east (11,800 km², 3,440 sq nmi) and a smaller one in the west (6,300 km², 1,840 sq nmi), together roughly equal in size to Kuwait or Connecticut.
• That leaves the Mariana ECS, a small triangle of no more than 1,300 km² (380 sq nmi), or 0.1% of the total. That’s about the size of Hong Kong, or one-third of Rhode Island.

Of those seven, the most important chunk is the Arctic one — not just size-wise but also in terms of its resource potential. It’s also a strategic position for the U.S., considering this area will likely grow more important for global shipping as global temperatures rise.

Claims, counterclaims, conflict?

However, unilaterally extending claims on real estate, even of the aquatic kind, may invite counterclaims. While previous agreements with Russia, Mexico, and Cuba exclude the risk of overlap, America’s ECS does intrude on analogous claims by Canada, Japan, and the Bahamas.

Fortunately, the risk of conflict with any of those countries is small. Even though it is a non-party to UNCLOS, the U.S. has stated its claim within the internationally agreed framework of that Convention. That means any disputes are likely to be settled according to the Law of the Sea as agreed by most United Nations member states.

It’s not every day a country manages to enlarge itself with an area the size of two Californias (or one Egypt). Thanks to the strategic location of the Arctic ECS, it may prove as consequential as the Louisiana Purchase. So even though it might have passed you by over Christmas, America’s ECS extension will make it into the history books.

Strange Maps #1229

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This article In case you missed it: America just effectively got much bigger is featured on Big Think.

Humans used to hunt and gather. Now, we have 9-to-5 jobs. Anthropologist James Suzman joins us to talk about  the historical roots of our desk jobs and how they all connect back to the agricultural revolution. 

The definition of work is ever-evolving, with each new era posing unique challenges. In this interview, Suzman explains how each era has actively contributed to humanity and how we can use this knowledge to help us prepare for (and even reconsider) our future.

This video How did we end up here? Anthropologist explains how work has shaped society is featured on Big Think.

It’s late in the night, and Mollie and Seb have been having the same argument for an hour now. Everyone else has gone quiet. They occasionally throw in a line or two, but they mostly just want to go to bed. The argument has long since gone around in circles. It’s going nowhere. It’s not a shouting match by any means. Mollie and Seb are both reasonable, respectful, and calm. It’s just that they’ve reached “That Point.”

That Point is the part of a debate where rational argument can go no further. They’ve each unpacked one another’s premises and called out non-sequiturs, ad hominem arguments, and false dichotomies aplenty. But That Point cannot be crossed. It’s a locked door and an unbudgeable rock. That Point is the moment you say, “Well, that’s just what I believe.”

Consider the following argument, examined in Alasdair MacIntrye’s After Virtue:

“Justice demands that every citizen should enjoy, so far as is possible, an equal opportunity to develop his or her talents and his or her other potentialities. But prerequisites for the provision of such equal opportunity include the provision of equal access to health care and to education.”

It’s a rational, convincing, and plausible ethical position. Yet nothing can budge. The debate depends almost entirely on the weight you ascribe to “justice.” That Point is known as aporia in philosophy. There are moments when there is a problem or a conflict with no possible (or, at least, no apparent) resolution. An unsolvable puzzle. A riddle with no answer.

We look at how common aporia is and how we can deal with it in the workplace.

Let’s agree to disagree

In our opening example, let’s imagine Seb is trying to persuade Mollie that battery farms are immoral. They debate and argue, and Seb says, “Don’t you care about animal suffering?” and Mollie honestly replies, “Well, no, not really.” Where does Seb go from here? What more can Seb say?

In our everyday social interactions, there will come a point when you meet someone who holds drastically and fundamentally different views from you about a topic. Their starting position and their initial premises are different. This is aporia. When this occurs, what usually happens is one of two things. Either you resort to name-calling,: “You monster!” Or, you agree to disagree and hope to go about your lives as smoothly as possible.

The defining characteristic of aporia is that there is no workable compromise position. Let’s say, at work, that someone prefers meetings in the morning and someone else prefers them in the late afternoon. A compromise position might be to arrange meetings around 11 a.m. or even to mix it up. No one’s entirely happy, but the meeting gets done, and the conflict has been resolved. Aporia, though, allows no middle ground. Two rams will butt heads until one is either broken or has fled.

Resolving the unresolvable

What happens, then, if aporia pops up in your workplace? How do you deal with unresolvable dilemmas and uncompromisable positions in your interactions with colleagues? Here we look at three examples and possible solutions.

Get rid of the personality. There are few things so popular in the corporate world as a good, increasingly old-fashioned psychometric test. Even if your company hasn’t officially conducted one, you can bet many people think in terms of them. “Oh, she’s such a Type A person,” someone might say. Even if you’re suspicious of psychometric tests, the fact is that you will find some people at work hard to work with. You’ll find conversations hard, and the workflow is more work-trickle. How, then, are you to reconcile the fundamental difference in personality? One study from the University of Minnesota, Minneapolis, offers up two practical pieces of advice. First, “start the discussion by describing the gap between the expected and observed behavior.” Be honest about how you see yourself and how you see other people. Second, “[begin] with the facts from your perspective… and share all appropriate and relevant information.” Keep it as neutral, objective, and professional as you can. In other words, if there’s a clash of personalities, try to get rid of the personality.

Use cutting-edge translation tools. There is nothing so unresolvable as literally not understanding someone. It’s rare for a company to have people of entirely different languages, but it’s increasingly common for a colleague’s language to be a second language. Struggling to communicate with someone can be both demoralizing and inefficient. Time is lost explaining terms and ideas. The instructions or requirements might be confusing. There are two ways to resolve this. The old-school way is to invest in translation services or use more visual aids. Reduce the use of overly complex language, where possible. The second way is more modern. This year will be the year of AI translation. There are already a great many options for “live translations,” and it’s a safe bet these will be common and freely included in existing services by the end of the year.

Build in a response buffer. It’s likely that you will, eventually, have some kind of conflict with someone at work. Often, that will be about some moveable and time-sensitive issue. At other times, it’s aporia. It’s irreconcilable. In these instances, it can be quite easy to simply label that someone as “that conflict person.” You will go into meetings with them tense. You’ll be looking for slights and annoying habits. You want them to fail, and you’re ready to pounce on the smallest mistake. On Big Think+, Dan Shapiro, Director of the Harvard International Negotiation Program and author of Negotiating the Nonnegotiable, calls this “repetition compulsion.” It’s a Freudian idea that you will behave with someone out of habit, not rationally. In the video, Shapiro gives a great many ways to combat the issue, for example, by just taking ten minutes to think before you respond to someone you find hard.

This article Workplace “aporia”: How to handle unresolvable arguments is featured on Big Think.

Here on Earth, one of the greatest geological wonders of all is the Grand Canyon. Carved by the Colorado River over millions of years, which connected multiple older segments of the canyon together, the full extent of this giant, steep-sided valley is now remarkable and impressive. Spanning 446 kilometers (277 miles) in length, the canyon is up to 29 kilometers (18 miles) wide and up to 1.857 kilometers (1.153 miles) deep. The advance, retreat, and melting of glaciers, combined with the release of enormous amounts of water, have exposed a wide variety of rocks formed throughout Earth’s geological history, including formations as many as 2 billion years old.

And yet, the full extent of Earth’s Grand Canyon pales in comparison to the grandest canyon in all the Solar System: Valles Marineris on Mars. Mars, a much smaller planet than Earth with a very different geological past, might not seem like the ideal candidate for such a gigantic feature, and yet not only is it present, it was likely created in a very different fashion than the Grand Canyon was on Earth. But how, precisely, did it form? That’s what Rosa Been wants to know, asking:

“You know how Mars has a huge scar in it? Like 6 miles deep. I was curious what caused it. I’ve heard it could be an asteroid or solar flare kinda thing etc.”

It could have been a lot of things, and in reality, it was probably formed by many processes combined. But the greatest lesson of all for its formation may not come from Earth’s Grand Canyon at all, but a very different feature. Here’s the most likely story we’ve been able to piece together.

This colorized topographic map of Mars, made with Mars Orbital Laser Altimetry (MOLA) data, showcases a difference of more than 20 kilometers between the deepest depths, such as in the deep outflow channels of Valles Marineris that lead into the northern hemisphere’s deep (oceanic) basin, and the highest heights of the mountaintops of the high mountains in the Tharsis region of Mars.

What you see, above, is a topographic map of Mars. Although there are many notable features, there are a few prominent ones that are relevant when it comes to discussing the grandest canyon of them all, Valles Marineris, which appears just south of the Martian equator and just slightly to the east of what’s known as the Tharsis bulge on Mars: the high-elevation region (in red) that’s home to many of the largest volcanic mountains in all the Solar System, including Olympus Mons, which is the lone white-capped mountain at the western edge of the Tharsis bulge. On either side of the Tharsis region are “dark blue” regions, which correspond to low-elevation regions that likely once were home to ancient Martian oceans.

While today, Mars is a cold, dry, desert world, where liquid water cannot persist on its surface due to the overwhelmingly low atmospheric pressure – just 1/140th of Earth’s at the Martian surface – in the past, Mars was very different. Although we still have enormous uncertainty about many aspects of our Solar System’s past, we now know enough to reconstruct a very interesting, detail-rich history of Mars from many lines of evidence. While a lot of what follows is a speculative story, this is presently the best consensus picture of how Mars came to be the way it is today, and in particular, how the “grandest canyon” in all the Solar System came to be on Mars.

Although we now believe we understand how the Sun and our Solar System formed, this early view of our past, protoplanetary stage is an illustration only. While many protoplanets existed in the early stages of our system’s formation long ago, today, only eight planets survive. Most of them possess moons, and there are also small rocky, metallic, and icy bodies distributed across various belts and clouds in the Solar System as well.

In the beginning, the Solar System took shape from a pre-solar nebula and a protoplanetary disk surrounding it. At the center of this nebula was a proto-star that would grow into our Sun, while the disk developed instabilities within it. Over time, nuclear fusion ignited in the proto-star’s core, transforming it into a full-fledged star: our Sun. The instabilities within the protoplanetary disk, likely over the span of just a few short million years, began to form what would become the cores of many protoplanets and, eventually, full-fledged planets. We are relatively certain that there were more than eight such worlds, initially, and that the extras were either ejected, hurled into the Sun, or collided with other bodies in events that created larger-mass planets and that gave rise to moons.

While the most well-known of these early planetary collisions was between the young Earth and a now-deceased world that we’ve named Theia – resulting in the kick-up of debris that would coalesce into our Moon – there were other collisions that occurred as well. Out in the distant reaches of the Kuiper belt, a world collided with Pluto, giving rise to Charon and the other four, smaller moons that orbit Pluto. It’s possible that collisions occurred on Venus and Uranus, perhaps giving them their unusual axial tilts. And on Mars, a giant collision also took place, leading to the formation of not merely its two surviving moons, Phobos and Deimos, but a third, larger, innermost moon as well: one that was transient, and destroyed not long after it formed.

Rather than only the two Martian moons we see today, Phobos and Deimos, a collision followed by a circumplanetary disk may have given rise to three moons of Mars, where only two survive today. The idea is that Mars’s once-innermost moon was destroyed and fell back onto Mars long ago. This hypothetical transient moon of Mars, proposed in a 2016 paper, is now the leading idea in the formation of Mars’s moons, and helps explain the enormous differences in topography between Mars’s northern and southern hemispheres.

That Moon, most likely, was first destroyed by the gravitational tidal forces exerted by the parent planet, Mars, where it was stretched out into a ring of debris. Unlike the modern Martian atmosphere, early Mars possessed a thicker planetary atmosphere more similar to that of a young Earth, likely augmented by the volatile gases emitted by the same continuous volcanic activity that persists even today on Mars. That ring-like debris from its larger moon then began interacting with the Martian atmosphere, where the drag forces eventually brought the entire ring – a full large moon’s worth – back down onto Mars, where it struck the surface and altered the landscape of the planet. The northern hemisphere of Mars, perhaps as a result of these processes, is at a significantly lower elevation than the southern hemisphere.

Just as early Earth had copious amounts of water on its surface, it was very likely that so did early Mars. While the combination of Earth’s size and mass, its active core, its volcanic activity, and the lubricating effects of surface water all contribute to Earth’s plate tectonics, tectonics on Mars operated very differently, even in these early stages. As a much smaller planet, Mars cooled far more quickly than the Earth did, while volcanic activity created the Tharsis bulge. This combination of impacts, external heating, internal volcanic activity, and planetary cooling likely created conditions that led to an important event: the formation of a strike-slip fault zone on Mars.

The Dead Sea Rift, also known as the Dead Sea Transform, is a rift that occurs between the African plate to the west and the Arabian plate to the east. The yellow arrows indicate current motion of the Arabian plate relative to the African plate at a rate expressed in millimeters-per-year.

Here on Earth, we have familiarity with a very analogous tectonic feature: the Dead Sea Rift, which is actually a fault system that runs for around 1000 kilometers between two adjacent plates: the African Plate to the west and the Arabian plate to the east. Over time, the two plates have displaced relative to one another by more than 100 kilometers, and have experienced this relative motion only in geologically recent times: over no more than the past 50 million years or so. Rift zones occur all over an active planet with plate tectonics routinely, and represent a “pulling apart” of two portions of the lithosphere. Lake Baikal, the deepest, largest, oldest lake on Earth, formed because of this type of rifting phenomenon.

For a very long time – all of the 20th century and more than the first decade of the 21st – the explanations for the formation of Valles Marineris were inadequate, relying on ideas like:

• erosion from water,
• permafrost melting in glacier-rich regions,
• the sudden withdrawal of subsurface magma,
• or tensional fracturing which caused solid rock to split.

But in 2012, a scientific study came along that changed everything: using surveyed data of Mars from space, UCLA scientist An Yin (who died in 2023 at the relatively young age of 64) determined that features on one side of this valley, including features left by ancient crater impacts that still survive, were displaced from matching features on the valley’s opposite side of between 150-160 kilometers.

An ancient impact basin on Mars, outlined with a black circle, has been shifted/offset due to the relative motion of the top and bottom sides of Valles Marineris. This 150-160 km offset, first identified in 2012 by An Yin, is some of the strongest evidence about the origin of Valles Marineris and the early geologic history of Mars.

That rifting behavior along a fault line was the first step in the creation of Valles Marineris, but that’s only the beginning of the story. As Mars still possessed liquid water well into its history – for perhaps the first 1.5 billion years of our neighboring planet’s existence – erosion and the collapsing of rift walls are generally accepted to have then enlarged and expanded the long, narrow valley that initially rifted apart. (There is a possible analogy to the East African Rift here on Earth.)

Beyond the forces of erosion, there were also landslides that no doubt occurred, perhaps being connected to the watery past conditions on Mars but also subsequently, including long after the planet lost the last of its liquid surface water. This provides a possible explanation as to why, when we examine the walls on either side of Valles Marineris, we see that they appear to show evidence of enormous numbers of deposits on the floor of this canyon.

Landslides could also have contributed to further expanding the width of the canyon (at the expense of its depth, suggesting that it may once have been even deeper than it is today), which could have been further exacerbated by both marsquakes and by subsequent, late-time impact events. The formation of the relatively recent crater Oudemans, for example, may have triggered one of the landslides that occurred within Valles Marineris long after its initial formation.

The impact crater Oudemans, shown here with its location overlapping with the highest-elevation basin of Valles Marineris in the inset image, may have been one of a few impact craters primarily responsible for late-time landslides that helped widen and fill in the deepest depths of the Solar System’s largest canyon.

However, there’s a tremendous difference between tectonics on Mars and tectonics on Earth, which is extremely important for understanding why Valles Marineris has persisted for so long and grown so large, whereas practically all of the rift valleys on Earth, as well as even our largest canyons, are under 100 million years old. Here on Earth, our planet’s lithosphere – the crust and the upper mantle – is fragmented into many large plates, which “float” atop the asthenosphere (the lower mantle). As those plates collide, spread apart, slide across one another, and otherwise generally move, features like mountains, volcanoes, and rifts form on our world.

On Mars, however, there’s evidence that even though it possesses tectonics, the notion of many separate, mobile, large plates is incongruent with the overall geological history of the planet. The three biggest geological features on Mars are as follows.

1. Its northern lowlands, including indicators that the crust of Mars’s northern hemisphere is very thin and was resurfaced (by lava) relatively recently compared to the older southern hemisphere.
2. Its southern highlands, whose surface is older than the northern lowlands and contains the oldest, most ancient impact craters found on Mars.
3. And the Tharsis bulge: the equatorial highlands that contain Olympus Mons and several other large mountains: among the largest in the Solar System.

When we put all of these pieces of information together, we can tell a story – perhaps a likely, but unproven, past history of Mars – that explains the formation of Valles Marineris.

A large impact from an asteroid billions of years ago may have created the moons of Mars, including an inner, larger one that no longer exists today. Although this is not a likely explanation, on its own, for the formation of the Tharsis region and Valles Marineris, it may be primarily responsible for the northern/southern hemisphere dichotomy that plays a major evolutionary role in the red planet’s geological history.

First, the giant impact that created Mars’s moons occurred, and then the largest, innermost moon fell back onto Mars. It’s plausible, but not necessarily certain, that this created the dichotomy between the northern and southern hemisphere. Then, a combination of volcanic activity and the “floating” of the thickened crust atop the mantle – known as isostatic uplift – occurred over what would become the Tharsis region of Mars.

However, because Mars’s lithosphere was not mobile, meaning that the volcanic “hot spots” weren’t moving relative to the surface features on the planet, depressions began to form and the crust began to spread out in that region, widening the Tharsis bulge and the plateau-like region it inhabited. This may have caused the Tharsis bulge to begin shifting relative to the volcanic hot spots beneath it, and may have gone as far as to shift the entire Martian crust and/or lithosphere relative to those volcanic hot spots.

Because the stability of the crust atop the mantle is dependent on being in what’s known as isostatic equilibrium, like a boat floating atop the ocean, shifting the position of the crust relative to the mantle beneath it results in instability. And, with so much mass to carry, the weak regions will begin to fracture.

This color-coded map of Mars highlights the enormous scar, or canyon, known as Valles Marineris. With a maximum depth of approximately 7 kilometers (23,000 feet), there is no single feature in the Solar System that has a combined length, width, and depth more extreme than Valles Marineris. Initially, a fracture in the crust, likely induced from stresses arising from the uplifted Tharsis region, gave rise to the first, most important steps in forming this rift valley.

One of these fractures – perhaps the largest fracture of any location in the Solar System, even including the cooling-induced fractures that formed on Mercury – extended for some 4000 kilometers (2500 miles) across the surface of Mars, creating the initial rift that would lead to the modern-day Valles Marineris. The new locations of the volcanic hotspots would lead to the major Martian volcanoes that came to exist today, including Olympus Mons, Alba Mons, and the three Tharsis Montes, all of which are still actively growing even at present.

Additional volcanic and tectonic activity led to the further rifting of Valles Marineris, including the 150-160 kilometer “shift” identified between the northern and southern portions by An Yin. For as long as water flowed on Mars, Valles Marineris probably provided the main channel by which ices, snows, and other forms of water would flow eastward into a one-time ocean, creating a network of outflow channels that are still visible in modern-day altimetry data.

Finally, even after Mars became a dry, barren planet – after its core dynamo died, after its atmosphere was stripped away, and after liquid water became impossible on its surface – further landslides, possibly driven by quakes, tectonic activity, and/or subsequent impacts, created the landslides that further widened the grandest canyon of them all, at the expense of filling in its deepest depths, rendering them shallower than they were previously.

A breathtaking view of Mars from space, showcasing the majestic landscapes reminiscent of the Mars Grand Canyon.

You have to realize just how impressively large Valles Marineris is to fully appreciate it. From end-to-end, it’s about 4000 kilometers (2500 miles) across, giving it a similar extent to the continental United States or the continent of Australia. At its widest, it’s approximately 200 kilometers (120 miles) from the uppermost high-walled rim to the lowermost rim on the opposite side of the valley: more than six times the maximum width of the Grand Canyon on Earth. And, despite the fact that landslides have filled in the deepest depths of this valley over billions of years, it’s still some 7 kilometers (23,000 feet) deep: deeper than all but the absolute deepest ocean trenches on Earth.

It’s even more impressive when you consider that Mars itself is a much smaller planet than Earth; with a Martian circumference of “only” 21,000 kilometers (about half that of Earth), Valles Marineris spans about 20% of the planet’s full physical extent. With a lower mass than Earth, Mars has a much smaller force of gravity at its surface than our planet does, allowing mountains to reach higher and valleys to form deeper than they can stably form on Earth. It isn’t a surprise that Mars would have larger mountains and deeper valleys than Earth, but the full extent of the grandest canyon of them all, Valles Marineris, never fails to impress!

Send in your Ask Ethan questions to startswithabang at gmail dot com!

This article Ask Ethan: Why is there a grand canyon on Mars? is featured on Big Think.

It is increasingly well understood that the countless microbes in our guts help us to digest our food, to absorb and produce essential nutrients, and to prevent harmful organisms from settling in. Less intuitive — perhaps even outlandish — is the idea that those microbes may also affect our mood, our mental health and how we perform on cognitive tests. But there is mounting evidence that they do.

For nearly two decades, neuroscientist John Cryan of University College Cork in Ireland has been uncovering ways in which intestinal microbes affect the brain and behavior of humans and other animals. To his surprise, many of the effects he’s seen in rodents appear to be mirrored in our own species. Most remarkably, research by Cryan and others has shown that transplanting microbes from the guts of people with psychiatric disorders like depression to the guts of rodents can cause comparable symptoms in the animals.

These effects may occur in several ways — through the vagus nerve connecting the gut to the brain, through the influence of gut bacteria on our immune systems, or by microbes synthesizing molecules that our nerve cells use to communicate. Cryan and coauthors summarize the science in a set of articles including “Man and the Microbiome: A New Theory of Everything?,” published in the Annual Review of Clinical Psychology. Cryan told Knowable Magazine that even though it will take much more research to pin down the mechanisms and figure out how to apply the insights, there are some things we can do already.

This conversation has been edited for length and clarity.

“Man and the Microbiome: A New Theory of Everything?” — with all due respect, isn’t that a wee bit ambitious?

That title is admittedly a bit overstated. But the point we are trying to make is that it isn’t really so odd that the microbiome is involved in everything, because the microbes were there first, and so our species has evolved in their presence. We have been able to show that growing up in a germ-free environment really affects the development of the mouse brain, for example, in a variety of ways.

Our immune system is also completely shaped by microbial signals. Via that route, inflammation in our gut can affect our mood and cause symptoms of sickness behavior that are quite similar to important aspects of depression and anxiety. Many psychiatric disorders are also known to be associated with various gastrointestinal issues, though cause and effect often aren’t clear yet. So if you study the body, including the brain, you ignore microbes at your own peril.

Most people are on board with the idea that gut microbes affect our health, but it may be more difficult to accept that they also influence how we feel and think. How did you convince yourself this was true?

I’m a stress neurobiologist, so I was trained in stress-related disorders like depression and anxiety, and my interest was really in using animal models of stress to look for novel therapeutic strategies.

When I moved to University College Cork in 2005, I met a clinical researcher, Ted Dinan, and we started working together to study irritable bowel syndrome, a very common disorder that is characterized by alterations in bowel habits and abdominal pain.

That was interesting to me, as it had become very clear that this is also a stress-related disorder. So we started working on an animal model called the maternal separation model, where rat pups are separated from their moms early in life and develop a stress-like syndrome when they grow up.

Siobhain O’Mahony, a graduate student at the time, also wanted to look at the microbiome, and I remember telling her, “No! Focus, focus!” But she went ahead anyway and found a signature of this early-life stress in the microbiome of adult rats. That was kind of a eureka moment for me.

The next part of the puzzle came when we showed that mice born in a germ-free environment have an exaggerated stress response when they grow up. So we’d already shown that stress was affecting the microbiome, and now we’d shown that the microbiome is regulating how a mouse responds to stress. It turned out that a very nice study from Japan had already shown this.

The third part of the puzzle for me was to ask whether we could alter the microbiome to alleviate some of the effects of stress. In 2011, we were able to show that a specific strain of the bacterium Lactobacillus, when given to normal, healthy mice in a stressful situation, was able to dampen down the stress response, and that the vagus nerve connecting the gut to the brain was required for that.

These three things together, from 2006 to 2011, really crystallized my interest in the link between the gut microbiome, brain and behavior. Since then, we’ve been on this magical journey to try and understand these discoveries, uncover the mechanisms and find how they translate to humans.

Can you explain what a depressed or anxious mouse looks like, and how you quantify that?

One way to look at fear is to quantify how often mice venture into wide open areas, which they normally avoid. If we give a mouse Valium or another anxiety-reducing drug, it will go out and explore and be carefree, not to say a bit reckless. Depression is often studied by looking at mice in a cylinder of water. They are good swimmers, but they don’t like swimming, so after a while, they’ll stop and adopt an immobile posture. Yet if you give them antidepressant drugs, they keep going.

These types of paradigms have shown their validity in studies of pharmacological agents used in human psychiatry, and so they’re ideal to explore whether microbiome manipulations have similar effects. This can be done by transplanting the microbes from a mouse model for a psychiatric disease to a healthy mouse to see whether that creates similar issues, or vice versa, to see if it can resolve them.

Following a similar logic, we have shown that the microbiome can be important in brain aging and cognitive decline. We took the microbiome from eight-week-old mice and gave it to 22-month-old animals — these are very old mice. And we were able to show wide-scale changes across the body — in the microbiome and the immune system, but also in the hippocampus, a brain structure involved in memory.

In the old animals that received the microbiome from young ones, the hippocampus looked completely rejuvenated in its chemical composition. They also performed significantly better in mazes designed to test their memory. This finding has now been replicated in two other labs, giving it further credence.

Such experiments are difficult if not impossible to do in people. How to make that jump?

One thing we can do is to transplant microbes from the guts of people with psychiatric disorders to rodents, to see if they cause comparable behaviors. This has now been done for depression, anxiety, schizophrenia, social anxiety disorder and even Alzheimer’s disease. In one of our own studies, we transferred fecal microbiota from depressed patients to a rat model. This resulted in behavior reminiscent of that in rat models for depression, such as increased anxiety and an uninterest in rewards, in addition to inflammation.

In addition, we can see if bacterial strains we’ve identified as troublemakers in rodents also occur in people with psychiatric issues, and if strains that are beneficial in rodents can help humans as well.

What I’d really like to do is follow a large group of healthy people for a couple of years and track their mental and brain health as well as the changes in their microbiome, and regularly transplant their gut microbes into mice. This would give us a much better view on how this relationship evolves.

Do you think some of the probiotics available in stores today might be helpful, or not quite?

In my opinion, many so-called probiotics aren’t probiotics at all. Probiotics, per definition, are live microorganisms that, when taken in adequate amounts, can confer a health benefit. Most of what’s for sale in shops would never meet that criterion. To demonstrate that something confers a health benefit, you need clinical trials to show it is more effective than a placebo. That’s the first thing. Second, you have to show that the microbes are alive, and that they can survive the stomach acid.

There have been properly randomized controlled trials for some products. But for most products available over the counter today, such studies haven’t been done, because the regulatory authorities do not require them for probiotics as they would for medicines.

There’s a lot of snake oil out there. For most people, it’s probably harmless, but if you are immunosuppressed, it could be dangerous: Even beneficial bacteria can cause great harm if your immune system does not function properly.

Don’t get me wrong, I think there are many promising findings, but this field is very much in its infancy. I’m much more enthusiastic right now about whole-food approaches that adjust people’s diets to include more fermented foods — a source of beneficial bacteria — and the fibers that many beneficial members of our microbiome need to survive. And this, everyone can already do.

Have you done any experiments that show such a diet can improve mental health?

We’ve just done a small study with what we call a psychobiotic diet. Kirsten Berding, a German dietician who did a post-doc in my group, took a group of people with bad diets who were stress-sensitive — namely, our student population — and put them on a one-month diet to really ramp up fermented foods and fibers to the benefit of the microbiome. What we showed was that the better individuals followed the diet, the greater the reduction in stress.

The study wasn’t perfectly blinded, because people knew what they were eating, but they didn’t know what they were eating it for. And this was just the beginning: We’re now doing a much longer study trying to really untangle this.

We’ve also done a small randomly controlled study with a polydextrose fiber that was shown to improve the performance of healthy volunteers on a range of cognitive tests.

Obviously, more work of this kind is necessary. But in this case, I don’t think we should wait for that. Think about the experiment where we’ve transplanted microbes from young to old mice, for example: I’m not advertising poop transplants for aging adults. What we’ve found is that the more diverse your diet, the more diverse your microbiome, and the better your health when you get old. If you look at the beige, bland food served in many nursing homes and hospitals today, that is not the kind of diet that helps people to maintain a healthy microbiome and therefore a healthy brain.

We’ve done a study in mice where we adjusted their diet to contain much more inulin, a fiber that we know supports the growth of beneficial bacterial strains, and found we could dampen down the neuroinflammation that is often associated with cognitive decline in aging. This fiber is present in our everyday diet — there is a lot of it in vegetables like leeks, artichokes and chicory. So perhaps if you’re thinking of having a midlife crisis, forget about the motorbike and start growing vegetables.

This is all in healthy patients. Do you think the diet might also help people with mental health issues?

I do, but we need to test it, of course. An earlier study of ours showed that students born by C-section, who missed out on some of the microbes that newborns acquire during vaginal birth, had an elevated immune and psychological response to both chronic and acute stress, in line with our findings in mice. It would be very interesting to test if a psychobiotic diet might benefit them.

As I said, many psychiatric disorders are also associated with inflammation and other problems in the gut. Of course, this relationship works both ways, and it’s not always clear to what extent the irregularities in the gut are the cause or the result of the mental issues — or whether it’s a bit of both. But if we can show a healthier microbiome can improve mental health, that would be great news.

This is what’s appealing about the microbiome: It’s probably more modifiable than the rest of our body. If we understand how it works, that might give people more options to improve their health, even if they didn’t have the best start, microbially speaking. That’s what we hope to achieve.

This article The growing link between microbes, mood, and mental health is featured on Big Think.

What is science for? What does it do? One answer to this question is that science describes reality: Its foremost job is to provide an account of the world we see around us, and it accomplishes this task via theories that provide a coherent and objective story about the world.  

But what, exactly, is that story? The orthodox view is science provides a narrative of the Universe without us. It’s a story of what I often call the “God’s eye view,” or, as the philosopher Thomas Nagel calls it, “The View from Nowhere.” According to this account, science gives us the story of an external, independent, and objective reality (an EIOR). It’s a beautiful and enticing idea. Unfortunately, there’s a big problem with this story about science that lies in science’s own most powerful tool: quantum mechanics. 

Quantum mechanics is what we physicists use to describe the microworld of molecules, atoms, and their constituents. Besides its century of spectacular success, what really makes quantum mechanics remarkable is that no one knows what it means. The story it tells about reality is so strange that it requires an interpretation to connect its mathematical formalism to the everyday world we experience. There is, however, a long list of these interpretations to choose from: “many-worlds” interpretations, “objective collapse” theories, “pilot-wave” theories, etc.  

QBism

For me, however, there is only one well-developed interpretative framework that has really listened to what quantum physics has been trying to tell us for the last century. It’s called “QBism.” The name is a shorthand for “quantum Bayesianism” (which itself comes from the Bayesian interpretation of probabilities). Over the past few months, I’ve been writing a series of posts introducing and unpacking QBism’s interpretation of quantum theory. Today I want to dive back into it by addressing its view on the question we began with: What is science for? Or to put it another way, what is science about?

Up until the birth of quantum physics in the early 20th century, the dominant philosophy associated with science was that it was all about that world without us. The principal players in this story (now called classical physics) were objects like particles and the laws that governed them (i.e. Newton’s laws of motion). The laws themselves held a special kind of position and were seen as timeless, eternal expressions of an underlying fabric of reality (again, a world without us). The laws were objective structures where “objective” means existing independently of anything associated with human beings and their messy subjective experiences. There were, of course, “observers” in the theory who took data by making measurements. But the presence or the actions of those observers never played any fundamental role in physics.  

Quantum mechanics killed that story forever by forcing measurements into the narrative in a way that classical physics never required. My friend and 13.8 co-conspirator Marcelo Gleiser has written a wonderful history of quantum physics where you can see how measurement appeared in quantum formalism. The single point we want to focus on here is how QBism understands the role of measurement.

While other interpretations of quantum mechanics work very hard to find a way to recover the easy dismissal of the observer enjoyed by classical physics, they must always pay a price. Sometimes that price is allowing for an infinity of unobserved parallel universes (as in the many-worlds interpretation). Other times, the price is different but equally strange. QBism, however, looks the problem straight in the eye and admits that quantum mechanics puts measurement front and center because it’s not a theory about some imagined objective world without us. Instead, QBism says that quantum theory is a potent description of agents taking actions on the world, which then responds.  

Agents and actions

QBism wants us to see that from the very beginning, quantum mechanics was a science that relied on machines to carry out measurements in a world we did not directly experience. In this way, the machines (our instruments) acted as extensions of our experience. Quantum physics acknowledges that an action must be taken — i.e. a measurement — to set its mechanics in motion. But in reality, that action is always taken by somebody (i.e. an agent). You can tell stories about electrons making measurements by hitting a proton but that’s not actually what happens in quantum measurements. It’s always some agent setting up an apparatus and using quantum mechanics to predict what that apparatus will record.  

It’s in this way that measurement’s explicit appearance in quantum mechanics implies that it’s always been a theory about those who make the measurements (i.e. us). We are the agents who use quantum mechanics to learn about the world. From QBism’s perspective, quantum theory is like a rulebook. It’s something we are given by the world (in our investigations of that world) that tells us how to make the best bets about the outcome of our actions. The idea of a “rulebook for betting” appears a lot in the QBist literature because QBism places such a strong emphasis on the fundamental role of probabilities in quantum formalism.

There is no doubt that this emphasis on agents and their actions is a radical idea. As I have written before, every quantum interpretation comes with a price. Gone is that comforting view of the world without us — of science providing a quasi-platonic view into the eternal order of mathematical perfection. What we get instead with QBism is an emphasis on agents and their actions. This new emphasis is, however, not some wooly-headed muddle. Instead, QBism offers a precise account, grounded in the tools of quantum information science, of the world and us together rather than just the one-sided world without us. Given that the price of such world-without-us views is hypotheses about infinite and unobservable parallel universes, QBism’s change in emphasis is not such a loss in my opinion. It responds honestly to quantum mechanics’ emphasis on measurement rather than trying to imagine it away. Just as important, switching to a story of the world and us opens up entirely new vistas for thinking about our place in the Universe.  

Peering into those new horizons is what we will take up in the next installment of our tour of QBism.

This article What reality does quantum theory describe? QBism has a radical answer is featured on Big Think.