On August 21st, 2017 we learned about

External stimuli sets off a slate of unexpected gene expression in stickleback fish brains

In a tense situation, your body can spring into action, altering various physiological processes to help you respond to potential danger. Your heart rate may spike, you might breath faster, and the release of hormones like adrenaline can help sharpen you vision and dull pain. It’s a pretty amazing biological tool kit, and scientists have recently found that it may be more complicated than previously understood. Studies of bees, mice and now stickleback fish have found that a fleeting encounter with an intruder may trigger a flurry of activity based around the animal’s DNA, a bit of anatomy not normally associated with temporary responses to daily stimuli.

The primary function of DNA is to act as an archive or schematic of your body. Each cell has an incredibly tightly coiled series of nucleotides that are usually only unpacked when a cell is dividing and needs to help build a new cell, or when specific proteins are needed to help the body function. The complexity of the molecules involved reinforced the assumption that this was always a slow process, but researchers tracking gene expression in stickleback brains found that DNA may be more accessible than we understood. Even interactions external to the body, such as encountering an intruder in one’s territory, were enough to trigger specific genes to start producing new proteins in the fish’s brains.

Specific sequence on a schedule

There seemed to be a reliable formula to the observed gene expression. Within 30 minutes of an encounter with a potential threat, genes relating to hormone production were accessed and activated. 60 minutes after the encounter, genes that helped control metabolism were active, followed by genes related to immune function and homeostasis at 120 minutes. The fact that these genes were observed in the telencephalon and diencephalon brain centers, which are related to learning, memory and social information, may suggest that all this activity is meant to help the fish learn or at least remember their run-ins with trouble.

There’s likely more to this than simply being a reinforcement of more obvious activity between neurons. Sticklebacks are very territorial, and seem to claim any space they can control as their own. However, that means that they’re starting this chain of genetic activity many times a day, which seems energetically costly if each encounter requires unpacking sections of DNA on top of other responses. It may be that the DNA is not as immediately tied to the events themselves, but is actually priming the brain to help it learn more easily. More research is needed into how this all affects the fish’s memory, but it seems that DNA is relied upon more frequently than anyone expected.

Source: Brief Interactions Spur Lasting Waves Of Gene Activity In The Brain, Scienmag

On August 21st, 2017 we learned about

Thin, smooth bark makes Madrone tree trunks seem cool to the touch

I may need to start petting trees more often. I’ve long known of trees that had particular colors and smells in their leaves and trunks, but I only learned in the last week that some trees hold surprises for your finger tips to discover. The tree in question was a Pacific Madrone (Arbutus menziesii), and was actually hard to miss thanks to its striking red bark peeling off the trunk. The surprise was that the tree was cool to the touch, which is why it’s sometimes called the “refrigerator tree.”

For something cool to the touch, Madrone trees need lots of sunshine to thrive. If conditions are right, they can grow to be nearly 100 feet tall, but at smaller sizes Madrone trees can be mistaken for some of their red-barked relatives, like the Manzanita (Arctostaphylos). Both plants’ eye catching bark grows thin and smooth, but this trait is especially striking in mid-summer when Madrone tree bark starts to peel off the trunk. At that point, a quick touch makes it hard to ignore how much cooler these trees are than the surrounding environment.

Cold or just conductive?

Except that they’re not really cooler. The trees’ temperature is likely the same as any of the other similarly-sized plants that grow near them, just like a paper book is the same temperature as a metal keys sitting in the same room. With sufficient time, the temperatures equalize, but when we touch the metal, or the Madrone trunk, it feels colder. This is because heat is more easily transferred to certain materials than others, and when heat from our hand is conducted away we perceive it as colder. Now, a Madrone tree obviously isn’t metal, but that thin, smooth bark isn’t as good an insulator as the rough, corky bark that you find on most trees. Your hand is able to come into more contact with the smooth surface, and the sap and fluids flowing inside the trunk can then wick your body heat away.

Even if refrigerator trees aren’t actually colder, their unusual bark obviously still stands out from that of their neighbors in the forest. The thin, peeling bark that exposes the trunk may have originally evolved as a form of defense. By shedding the outer layer of bark, the tree can dump any fungi, mosses, lichens or other parasites that tried taking up residence on the red wood. The red itself is likely another form of defense, as the tannins that make up that coloration would be bitter and possibly toxic to animals that might want to munch on the tree, not unlike the colorful bark found on rainbow eucalyptus. It’s good that the peeling is helpful to these plants, because now that they know about these chilled trees, it’s going to be hard to keep my kids’ hands off them.

Source: The Refrigerator Tree by Steve, Nature Outside

On August 20th, 2017 we learned about

Ancient Romans special regard for eating jar-raised rodents

For all of the foodie-themed photos people share today, the world somehow lacks gratuitous shots of dormice being served for lunch. This seems like a missed opportunity, because edible dormice were one of the original foods to brag about, with scholars and elites writing down details about how the rodents were served in lieu of selfies and filtered photos. Like the particular interests of gourmands today, this interest wasn’t because edible dormice were a staple of the ancient Roman diet, or because they were necessarily that much tastier than any other roasted mammal. Serving up dormice was a way for hosts to dazzle their guests without making a huge investment in the process.

From pot to plate

A serving of edible dormouse (Glis glis) might include honey, poppy-seeds, pepper and bits of pork. The layered flavors alone would have been impressive to a Roman audience, as more modest meals would have been heavy on salted meat or fish, as the salt was a critical preservative for less-than-fresh foods. Dormice, on the other hand, didn’t need the space or resources a pig did, and they could be raised in a villa without much fuss. The animal was placed in a ceramic pot called a gliarium, where it was fed and watered until it was ready to be eaten. With small air holes and just enough room to move around, a dormouse didn’t have much to do besides sleep and fatten up.

Once it was time to eat, the fact that dormice weren’t actually difficult to raise didn’t seem to matter much. They were apparently valued enough that supplying them could be a profitable enterprise, but not really enough to amount to more than an appetizer. Like exotic foods of today, people made notes about eating a dormouse, particularly its size as testament to the host’s wealth, but their relative scarcity clearly helped make them more intriguing than your average squirrel or rat.

Dormice in decline

Dormice aren’t on many menus anymore, but their may still be in trouble. Hazel dormice (Muscardinus avellanarius) in England are in decline, with populations dropping 70 percent in 20 years. As their absence on Instagram proves, this decline isn’t due people making them into fancy appetizers again, but larger environmental problems. Habitat loss, climate change and local woodland management are all suspected to play a role in shrinking dormouse populations in England.

Source: Dormice, ostrich meat and fresh fish: the surprising foods eaten in ancient Rome by Emma Mason, History Extra

On August 20th, 2017 we learned about

Digital farming tools simulate a full season’s growth in a single day

Humans have been manipulating the evolution of plants for ages, but usually at a pace slow enough we barely notice. By planting seeds from specific plants that had attributes we liked more than others, say a more pleasing color, or larger amount of tasty flesh, we’ve transformed many plants into the produce we know today. However, this is a slow process, and farmers are looking for ways to speed things up while reducing the costs associated with experimenting with a whole season’s crops. The solution may be to first grow crops on a in silico, or “in silicon chips,” before ever putting a seed in the ground.

The simulations that are being developed allow for some very specific details to be tested. For instance, will you get a bigger crop yield if you plant your sugarcane in staggered rows, or all lined up? Should they be angled north-south, or east-west? A farmer could plant four different fields of sugarcane to see which did best, although in doing so they might introduce new variables to the mix. It would also be a slow process, possibly risking income for 12 months of work.

The in silico version took all the available data and came up with a prediction in 24 hours. It considered minutiae down to the amount of light that might be blocked by a neighboring plant’s leaves at different times of the day, then produced a 3D visualization to show the expected outcome of each field arrangement.  In this case, staggered plants planted on a north-south axis was predicted to increase yields by ten percent, making that a much safer test to run in the real world for confirmation.

Farming experiments made even faster

As these tools are developed, researchers hope that the speed and depth of the simulations can be improved. Not everyone can tie up a supercomputer for 24 hours to test out a new technique, and the goal is to eventually simulate a whole season’s growth in a minute, making it easier to try out different variables. The number of variables should also be increased to incorporate more data that different labs have been creating over the past decades, but that requires some serious coordination efforts. Not every research team uses the same tools or data structure to archive their experimental findings, which makes integrating existing information about crops difficult.

Still, the developers are confident that all these challenges can be met, partially because they have to. Concerns over population, soil quality and fresh-water availability suggest that farms will need to be more efficient than ever in the coming years. A tool that lets you configure and simulate new ideas in a single afternoon could save everyone a lot of time and resources.

Source: Growing Virtual Plants Could Help Farmers Boost Their Crops by Leslie Nemo, Scientific American

On August 17th, 2017 we learned about

Chilesaurus diegosuarezi’s plant-digesting gut and the origins of ornithischian dinosaurs

When we first heard about Chilesaurus diegosuarezi, the unusual dinosaur was being labeled as a rare, herbivorous theropod. The creature’s leaf-shaped teeth just didn’t look up to the task of tearing meat compared to the pointed and sometimes serrated chompers seen in most theropods. The was speculation that this strange hodgepodge creature was a weird hiccup in theropod history, but new analysis suggests that C. diegosuarezi wasn’t a plant-eating theropod, but a bipedal ornithischian. If correct, this dinosaur may represent beginnings of the family tree we now associate with Stegosaurus, Ankylosaurus, and various duck-billed dinosaurs like Edmontosaurus.

C. diegosuarezi’s interest in eating plants isn’t being questioned. If anything, it’s thought to be an important factor in why his body has some more ornithischian traits. The big deliminator between theropods and ornithischians is usually the shape of their hip bones. Theropods, both before and after C. deigosaurezi, have what’s been called a “lizard” hipbone, because the pubis bone faces forward like on modern lizards. In contrast, ornithischians have “bird” hips, where the pubis faces backward. It’s all a bit confusing, because modern birds are actually theropods, even with that ornithischian-looking hip bone. With C. deigosaurezi being classified as an ornithischian too, it means that a rear-facing pubis bone must have evolved at least twice— once when the ornithischians first branched off the theropods, then again when with the development of birds.

What pressures moved the pubis bone

This may seem like a lot of arbitrary changes in anatomy, but there are explanations for why they would help each lineage survive. The plant eating of ornithischians would require bigger, more complex guts to digest than chomped flesh would, and so they’d literally need more space their abdomens. A forward facing pubis probably didn’t leave enough room for their digestive demands, giving an advantage to herbivores with “bird” hips.

While we now have birds that eat plant-based foods like nectar and seeds, digestion probably isn’t the reason a crow or sparrow ended up with a rear-facing pubis. In that case, the evolutionary pressure may have been balance. Modern birds don’t have the thick, muscular tails older theropods had, and so as their tails were reduced to the feather-covered stumps we know today, their center of gravity shifted. To avoid tipping over too much, the pubis bone evolved to face backwards, taking a bit of weight with it.

Obviously, C. deigosaurezi’s hips weren’t putting it on the road to flight, but were making room for a bigger tummy. Combined with a mouth well-suited for eating plants, it suggests that adapting to an herbivorous diet was a driving factor in the split between theropods and ornithischians. This then raises questions about what was happening in these creatures’ environment to make plant-eating so enticing that such transitions would occur. Changes in the continents were likely leading to more moisture on land, making the world a much more attractive salad bar, providing options to creatures that were trying out eating more than meat.

Source: One of the Most Puzzling Dinosaurs Ever Discovered Just Got a Major Rebrand by George Dvorsky, Gizmodo

On August 17th, 2017 we learned about

Eclipse experiments designed to exploit the Moon’s shadow as it slides across the Earth

Monday’s solar eclipse will be exciting, strange, and possibly cause all kinds of tumult and chaos, which is pretty impressive considering it’s technically just a big shadow sweeping across the Earth. For all of the hype and hoopla, the upcoming total eclipse does offer some unusual opportunities for actual scientific research. Researchers have many experiments planned for the Moon’s shadow, many of which don’t even relate to the Moon itself. Instead, they’re looking at the Earth, Mars, Mercury and the composition of the Sun.

Earth’s atmosphere

One of the larger-scale studies planned for the eclipse will look at how a lack of sunlight changes the Earth’s ionosphere. This layer of atmosphere is normally bombarded with ions from the Sun, protecting those of us on the surface of the planet while also setting off the colorful auroras we call the Northern and Southern Lights. During the eclipse, the Moon will be intercepting those ions, and so volunteers will be measuring how this brief drop in activity affects radio wave transmissions through an unusually calm ionosphere.

Mimicking Mars

Another experiment planned for Monday involves releasing 50 high-altitude balloons into the Moon’s shadow so that we can see how a few moments in the stratosphere affects bacteria. Alongside each balloon is a metal plate swabbed with Paenibacillus xerothermodurans bacteria, which are noted for their incredible durability in harsh environments. Since it’s hard to ensure spacecraft are completely sterile before they arrive at another planet, researchers want to see how these bacteria might hold up in tough environments. The stratosphere’s thinner air, low temperatures and higher radiation levels are already a good proxy for other worlds, but during the eclipse these attributes will all be shifted to a point that closely resembles the surface of Mars. So once the balloons are recovered, researchers will get a chance to see how P. xerothermodurans might hold up on the Red Planet.

Measuring Mercury

Looking a bit deeper into space, there are plans to take advantage of the blocked sunlight to get a better look at the planet Mercury. Mercury’s proximity to the Sun makes it hard to measure, as the light and radiation levels are somewhat overwhelming for most instruments. So when the Moon makes things a bit darker, scientists plan to measure the changes in temperature around Mercury from special airplanes fitted with sensors. These planes will fly in the path of totality, or where the Moon completely blocks the Sun, in order to have more than the two minutes and 40 seconds anyone on the ground could hope for. They’ll also be flying at high altitudes to help bypass distortion that might be introduced by the Earth’s atmosphere.

Studying the Sun

Finally, at least one study will be looking at the Sun itself, which seems appropriate considering the nature of this event. Actually, scientists will be gathering data on the Sun’s corona— the wispy outer layers of plasma that will be visible during totality. As with the study of Mercury, instruments mounted on special aircraft flying at over 470 miles per hour will collect data for around six minutes to try to figure out how the Sun’s outer layers are composed, and why they’re hotter than the inner layers of the Sun. Previous measurements have found that the outer layers of the sun are hotter than most models would expect, and researchers how that this new data will help explain how that’s possible.

And of course, if anything is inclusive, we can all try again during the next total eclipse, which is only three years away if you can make the trip to Chile.



Source: Solar Eclipse-Chasing Jets Aim to Solve Mystery of Sun's Corona by Tom Metcalfe, Live Science

On August 16th, 2017 we learned about

Explaining the ink ejected from a squid or octopus’s anus

I’m not sure what this says about schools today, but my kids are learning a bit of marine biology thanks to Mario Kart. As many of you undoubtedly know, one of the more frustrating power-ups in the game is a Blooper— a squid-like character that flies in front of rival racers to squirt black ink all over them, obscuring their vision for a time. This caught my kids’ attention recently, not because of the squid flying through the air, but because of the ink. They wanted to know what was happening, and why it would happen with a squid?

Concealing and confusing

Naturally, a squid squirting ink to obscure the vision of potential threats is the most sensible aspect of a Blooper’s function in the game. Many shelless cephalopods, including octopuses, squid, and cuttlefish, do spray ink in a similar manner. They produce the ink in a special bit of anatomy called the ink sac, which includes the appropriately named ink gland. In moments of need, the squid or octopus injects this ink from the sac to the rectum where it is mixed with mucus, at which point it can be pumped out the anus with a surprising amount of control.

While squirting a cloud of dark ink into an area is pretty distracting on it’s own, some species can shape their pooped-ink to look more like decoy tentacles from their own body, or the thinner tentacles of a stinging jellyfish. Ink can be flavored to disgust some fish or attract their predators. It’s used to darken and hide eggs, or to make glowing, luminous globs to simply confuse predators, leaving them wondering what on Earth just appeared in their face.

Ink’s ingredients

The ink itself has been historically been harvested to write with, but for the most part is pretty different from what’s in your average pen. Most pens today use dyes to darken your papers, as dyes can be thinner and less prone to blockages in a pen. Cephalopod ink can contain metals, enzymes, and most importantly, melanin. Melanin is the pigment that adds color to your skin and hair, and in this case makes the ejected ink dark and opaque enough to hide the fleeing squid or octopus. The pigment is thick and usable in the oceans, but not necessarily the best fit for your favorite pen.

All this said, we still have many questions about cephalopod ink, largely because we don’t know why these creatures ever started producing it in the first place. Fossils of soft-bodied octopuses and squid are hard to come by, but ink sacs have a strange durability that makes them oddly abundant in the fossil record. Some specimens have been found from 330 million years ago, which makes this anatomy older than any dinosaur. Unfortunately, the structure of the ink sacs and the composition of the ink seems to have changed very little in all this time, leaving few clues as to how cephalopods ever got started squirting in the first place.

Source: Why do cephalopods produce ink? And what's ink made of, anyway? by Mark Carnall, The Guardian

On August 16th, 2017 we learned about

Reasons we regard Route 66 as a historic roadway

This summer, my third-grader went on a road trip with her grandmother and cousin to the Grand Canyon. During the hours of driving, the kids saw more and more signs not for the Grand Canyon, Petrified Forest or Meteor Crater, but for some mysterious entity known as Historic Route 66. It seemed to be all around them, with stretches of roadways and stores all claiming some kind of connection to whatever this 66 thing was. Hearing it was the name of a road helped a little bit, but with no yellow bricks, roadside bells or anything relating to 66, the significance of Route 66 is easy to miss, especially today.

A very particular path

The first major roadway to stretch across the continental United States was the Lincoln Highway. The road opened in 1913, enabling a relatively quick drive from Times Square in New York City to Lincoln Park in San Francisco. One road was obviously not going to be enough to satisfy the growing car and truck traffic in the United States, and legislation was introduced in 1916 to build comprehensive highway system across the country. It took ten years for those plans to come to fruition, and in 1926 Route 66 opened as one of the first new roads to allow more convenient travel from the Midwest to the west coast.

The convenience of Route 66 was a carefully nuanced balance though. On one hand, by heading southwest from Chicago across largely flat territory, cargo trucks had an easier route to California than the sometimes snowy Lincoln Highway could provide. On the other hand, the road was purposely not a straight shot to the Pacific Ocean. Planners wanted the road to meander a bit, allowing it to link hundreds of small communities that had no other major roadways to get to bigger cities. Farmers thus had an easier time transporting their goods, boosting many small economies all along the route.

From “The Mother Road” to roadside attractions

Route 66 took on some unintended significance early on as well. Laborers were employed during the Great Depression to help pave sections of road. The Dust Bowl in Oklahoma sent as many as 210,000 people to California, many of which traveled on Route 66. This significance was memorialized in John Steinbeck’s The Grapes of Wrath, marking Route 66 as “The Mother Road” in people’s minds even if they’d never driven on it themselves. Finally, as World War II loomed on the horizon, Dwight D. Eisenhower was impressed with the utility of this kind of reliable infrastructure from a military perspective, an idea he would eventually carry with him to the White House.

After World War II, Route 66 was reborn again. Instead of a necessary path for commerce, migration or commerce, tourists started flocking to the American southwest. Nat King Cole’s rendition of “Route 66” was nearly an ad jingle for tourism throughout the Chicago to Los Angeles corridor, and many businesses started directly catering to these travelers’ interests. Motels grew out of auto camps, diners and gas stations proliferated, and many odd roadside attractions were designed to catch people’s eye as much as the natural landscape could. Many of these sights are still around, now with some historical significance layered on top of their already striking appearances.

Facing the four-lane future

As my third-grader found out though, its possible to miss some of this if you don’t know what you’re looking for. This is partly due to the inevitable physical decline of the actual roadway along Route 66, spurred by it’s obsolescence as an arterial route. In 1956, then President Eisenhower signed the Federal Aid Highway Act, kicking off construction of a huge network of major highways. Unlike the meandering path of Route 66, highways like I-40 were somewhat modeled after Germany’s autobahn so that travel could be safe and efficient at higher speeds. Rather than stop in each town along the way, highways now let people zip from one destination to the next with minimal interactions along the way.

It took some time, but in 1970 four-lane roads finally allowed travelers to “skip” any portion of the original Route 66. Nobody is about to argue that Route 66 can compete on the grounds of efficiency, but there are efforts to preserve the experience, particularly the post-war tourism, as a cultural milestone in America.

Source: The History of Route 66, National Historic Route 66

On August 15th, 2017 we learned about

Gray fox specializations optimize the all that time they spend in trees

“If you ever see a gray fox, it’s not doing it’s job very well.”

Presumably, Tuscon, the gray fox wearing a leash as part of a presentation by Bay Area Wild my kids saw today, could be excused for his visibility. The 14-year-old fox had spent most of his life with an animal rescue operation, and thus had little opportunities to practice hiding from either prey or predators. He had, according to his handlers, retained at least one strong instinct from the wild, which was a taste for bird eggs. Apparently one of the reasons we don’t see gray foxes is that most of us never look for them in trees.

In contrast to their taller, larger cousins that dominate the eastern United States, gray foxes (Urocyon cinereoargenteus) have a number of adaptations that enable them to climb even fully-vertical tree trunks. Their shorter limbs and powerful hind legs let them jump onto the base of trees, at which point they can grip the bark with semi-retractable, hooked claws that barely resemble those of other canines. Gray fox wrists are also unusually flexible for a canine, and have been compared to the anatomy of an arboreal primate. All this adds up to an animal that can not only climb, but do so fast enough to chase speedy prey like squirrels right up a tree.

Arboreal advantages

Chasing squirrels probably wasn’t the driving factor in gray fox evolution though. As Tuscon’s story indicated, it’s much easier to ‘catch’ slower things in trees, like eggs and baby birds. It’s also a great place for the fox itself to stay safe, and they’ve been known to make dens in hollow trees as high as 20 feet off the ground. During their first few weeks of penthouse living, a mother and kits will be fed by the father fox, possibly putting off their first steps in actual soil for weeks. This isn’t a given, as gray foxes will also dig out or repurpose subterranean dens, but trees seem to hold a special allure that the dirt can’t compete with.

Maybe this is why some gray fox couples decorate their trees with skeletons. It’s not a requirement for tree-dwelling foxes, but some mating pairs have been known to drag fawn carcasses into trees, leaving them to decompose into rather macabre adornments. The foxes will sometimes use the bones as seating, but it’s thought that the primary attraction is the smell. Multiple trees in a mating pair’s territory may be marked with bones as a way to indicate the boundaries of their turf. The visual impact of a suspended deer skeleton probably helps distract from the small foxes sitting there as well.

Source: Tree-dwelling gray foxes decorate with skeletons by Melissa Breyer, Treehugger

On August 15th, 2017 we learned about

Even the dimmed sunlight from the solar eclipse can pose a danger to your eyes

Odds are that you’ve never directly viewed a solar eclipse, and you probably shouldn’t start any time soon for the sake of your eyeballs. While the eclipse does have interesting effects on our atmosphere, there’s nothing about the Moon blocking the Sun that magically transforms good sunlight into something dangerous. The sunlight is actually always dangerous, but most of the time it’s bright enough to remind us not to try and gawk at it. Even what seems like a small amount of light can be a health hazard to your eyes, so it’s very important to protect your peepers from the sun when things go dark on August 21st.

Our bodies are bathed in sunlight whenever we’re outside, and it’s obviously not such an immediate problem. Most skin can withstand short exposure to ultraviolet light (UV) without too much wear and tear, and our eyes handle the indirect UV light pretty well (although wearing sunglasses is certainly a good idea.) The reason this all compounds when viewing an eclipse is the that you’re looking right at the sun, and that light can be focused through the lens of your eye. Like a magnifying glass focusing sunlight to start a fire, your lenses focus light on the back of your at the retina. The intensity of directly-focused sunlight can quickly damage your cells by creating reactive molecules called free radicals, which then go on to kill the cell.

Safer ways to stare at the Sun

In most cases of this kind of damage, the damage is somewhat limited. The retina will basically be left with gaps where cells have been killed, and you will have a new set of blind spots in your eye to contend with. Sometimes people recover from this damage, but sometimes they’re left legally blind, as they can only see with the peripheral vision that wasn’t torched by the sun.

This isn’t to say that the only way to enjoy an eclipse is to avoid it. While your sunglasses are in no way up to the task of protecting your eyes when viewing an eclipse, solar-viewing glasses are designed to only allow a safe amount of light, meaning around 0.00032 percent of normal sun exposure. Alternatively, you can view the eclipse in the same way you usually take in sunlight— indirectly. A simple pinhole camera will let you safely watch a projected image of the Sun as it gets blocked out, all without staring right into the sky. If you’re looking for a closer look, don’t use your favorite telescope or binoculars unless you have specific filters for that as well, since that’s basically focusing sunlight at your retina even more effectively than your own eye’s lens can do.

My third grader asked: Isn’t the sunlight blocked enough to be less of a problem?

It takes very little sunlight to harm your eyes, especially when it’s being focused into your eyeball. However, once the Moon completely blocks the Sun during totality, it’s recommended that you take off your protective eyewear, as things will otherwise be too dark to see. With luck, you’ll get a peak at the Sun’s atmosphere around the outer rim of the Moon, and this light won’t be coming directly at you to cause harm. As soon as the Moon starts to move out of the way though, get your glasses back on since any direct sunlight can be a problem.

Source: If the Sun Is 93 Million Miles Away, Why Can't We Look Directly at It? by Rachael Rettner, Live Science