When It Comes to Avoiding Flies, Stripes Are In, Solids Are Out (McGill OSS)

2 minute read

Fairy tales about the origin of zebra stripes are abundant. Some blame sunlight filtered through tree leaves for tanning the zebras hide, others claim the dark lines are scorch marks, acquired after stumbling into fire during a fight with a baboon. Scientists’ ideas of the stripes’ origins are less fanciful, but no less varied. From thermoregulation to signalling to other zebras, a lot of theories have been floated. Fewer theories have been tested, and only recently did support arise for one hypothesis: avoiding fly bites.

Despite their name, horseflies do not limit themselves to horses. There are well over 2000 species of horsefly that target a wide variety of animals, including humans. However, horseflies earned their moniker due both to horses, donkeys and zebras’ extreme prevalence, and the risks these bugs pose equids. Amongst other diseases, horseflies are infection vectors for equine infectious anemia, a retrovirus from the same genus as human immunodeficiency virus (HIV).

Within the Equus family, all 7 extant members have long tails to help flick away pesky insects. But the 3 living species of zebras have an additional tool in their anti-fly arsenal in their fur patterns.

Japanese Black cows painted with white to mimic the zebra coat received 50% fewer deerfly bites compared to those painted with black stripes, or no stripes at all.

Black cow painted with white stripes

Photo sourcehttps://journals.plos.org/plosone/article?id=10.1371/journal.pone.0223447

Don’t go painting yourself or your animals to avoid deerfly bites just yet though. There is one important specific you need to know first: the critical width. Black and white stripes present a sort of optical illusion to deerflies. Scientists believe that stripes narrower than a critical width (approximately 5 cm) trigger what we call the Wagon-wheel effect. This illusion makes a wheel, propeller or other regularly rotating object appear as if it is spinning backwards. You can see an example of it here.

When faced with black and white stripes, horseflies approached their target faster and failed to decelerate in the final stages of their flights, before contacting zebra surfaces. It’s not just painted mammals that seem to work though. Researchers demonstrated that horseflies will avoid landing on horses wearing a striped blanket, or other surfaces with thin stripes or small (<10 cm in diameter) polka dots.

This article was written for the McGill Office of Science and Society. View the original here: https://www.mcgill.ca/oss/article/environment-did-you-know/when-it-comes-avoiding-flies-stripes-are-solids-are-out

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Peckers Get Smaller Where It Gets Colder (McGill OSS)

1 minute read

Charles Darwin postulated that Toucan’s massive beaks might be for sexual selection purposes. Other scientists have theorized that it could be for shows of intimidation, for actual defence or for peeling fruit. Given the beak’s serrated edge, it was once thought that toucans used it to catch and eat fish. We now know that toucans are almost entirely fructivorous, although they do opportunistically eat insects, lizards, and even small birds.

Another thing we now know is that the main function of a toucan’s beak is actually thermoregulation! Just like elephants do with their ears and dogs with their tongues, Toucans rely on their big beaks as heat sinks to maintain their homeostasis and save them from overheating.

Bird beaks across the globe follow a trend called Allen’s Rule, which proposes that the appendages of endotherms (warm-blooded animals) are smaller, relative to body size, in colder climates in order to reduce heat loss. A study of 214 bird species from every continent found strongly significant differences in their beak sizes according to latitude and local environmental temperatures. From penguins to parrots, the species that live in colder places have smaller peckers.

This article was written for the McGill Office for Science and Society. View the original here: https://www.mcgill.ca/oss/article/did-you-know/peckers-get-smaller-where-it-gets-colder

Squirrels can survive a fall from any height, at least hypothetically (McGill OSS)

1 minute read

Squirrels, in theory, can survive a fall from an object of any height due to two factors: their size and their mass. A force (such as the force of gravity) is calculated by multiplying mass and acceleration. The acceleration due to gravity on Earth is always roughly 9.81 m/s2, regardless of what object it is acting on. Squirrels are not very heavy—a grey squirrel only weighs about 0.5 kg—meaning that the force acting on a falling squirrel just isn’t that big.

Force = mass*acceleration = 0.5 kg * 9.81 m/s2 = 4.9 N

We measure forces in a unit called “Newtons”, named for Isaac Newton who gave us Newton’s three laws of motion.

Compare this to, for example, a falling 60 kg human, which would be pulled downward with a force of about 489 N. A factor of 100 higher!

On top of being small, squirrels are fluffy and intuitively spread their bodies out when falling. This allows them to experience as much wind resistance as possible, slowing down their rate of descent. Some squirrels even use this fact to glide through the air. While gliding is not the same as flight, we nonetheless call them flying squirrels.

For these two reasons, the terminal velocity (fastest speed while falling) of squirrels is slow enough that they will, at least in principle, never fall so hard that they hurt themselves.

This article was originally posted here: https://www.mcgill.ca/oss/article/did-you-know/squirrels-can-survive-fall-any-height-least-hypothetically

Birds Seem To Be Scared of Googly Eyes, and That’s a Good Thing (McGill OSS)

3 minute read

Every year upwards of 25 million birds are killed in Canada due to collisions with buildings, communication towers, wind turbines, and as a result of being tangled into marine gillnets. From window decals to flashing lights, humans have tried numerous preventative measures to stop these deaths. Their degree of success depends on the method, the location, and the types of birds in that ecosystem—amongst many other factors—and results are highly variable.

What may seem like benign interventions that—at worst—just won’t work, actually have the capacity to do harm. As an example, In Peru, bycatch (i.e., accidental catch) of Guanay Cormorants was reduced more than 80% after researchers attached green lights to gillnets. At the same time, bycatch of Peruvian Boobies increased. Possibly due to the boobie’s attraction to the lights.

Similarly, when researchers set out to the Baltic sea to compare the effects of attaching light panels, constant green lights, or flashing white lights to gillnets on sea birds (in particular the Long-tailed duck, a vulnerable species) they found that the nets with flashing white lights caught more ducks than the normal, non-illuminated ones.

One approach that is so far quite promising involves using giant looming googly eyes.

To continue reading for free, click here- https://www.mcgill.ca/oss/article/did-you-know-general-science/birds-seem-be-scared-googly-eyes-and-thats-good-thing

Why is poop brown? (McGill OSS)

1 minute read

A certain amount of the muddy colour can be attributed to the different colours of food we eat. Like mixing all the paint colours together, the result is a dull brown. But, much bigger factors for humans’ brown poop are bilirubin and bile. Bilirubin is a yellow substance found in the liver, the product of the breakdown of old red blood cells. Bile is dark brown or green and is produced by the liver to help digest fats. Both of these substances are secreted into the small intestine during digestion, and slowly make their way into poop, bringing with them a dark brown hue.

Bird poop, on the other hand, is not brown but white. That is because—unlike mammals—birds don’t pee!

To read the entire article, click here: https://www.mcgill.ca/oss/article/health-and-nutrition-did-you-know/why-poop-brown

Luciferin and GFP: The Fluorescent Chemicals Used by Insects, Sea Creatures and Humans! (McGill OSS)

Image source

5 minute read

How do fireflies create their telltale glow? It differs slightly depending on species—there are more than 2000 species of fireflies found across the world, including many that do not glow—but the one we know the most about is the North American Firefly (Photinus pyralis). It uses a molecule named luciferin and its enzyme buddy luciferase. Luciferase reacts with luciferin, causing it to break down into two compounds and release CO2 One of those two compounds has a bit of excess energy that it releases as light!

The production of this light has three requirements, other than luciferin and luciferase: magnesium, oxygen and ATP. That ATP requirement is a big part of why the luciferin assay has become an important tool for biochemical research. Adenosine-5′-triphosphate (ATP) is the universal “energy molecule” of all forms of life. So, luciferase and luciferin can be used to test if something like a cell is alive and still producing ATP.

……

One group of fireflies, however, use their glowing abdomens to hunt. Females of the genus Photuris engage in aggressive mimicry by imitating the flashing patterns of other species’ females to lure and eat the males who seek mates.

Unfortunately, due to habitat loss and climate change, firefly numbers are declining across much of the world. The lack of appropriate green spaces for fireflies to live and mate is compounded by the sedentary nature of many firefly species. The larvae of the common European glow-worm are reported to move only about 5 meters (16.4 feet) per hour. Light pollution as well may be impacting fireflies’ ability to thrive. In one study, light pollution reduced the flashing of Photuris versicolor by almost 70%.

To read the entire article, click here.

How dogs are improving the mental health of humans (Canadian Dogs Annual)

When we think of dogs-with-jobs our minds tend to go straight to police, search and rescue, drug-sniffing and guide dogs. But therapy dogs are the unsung heroes of the working dog world! These four-legged therapists undergo detailed training to help comfort, support and encourage people suffering from a variety of mental health issues. They work in all kinds of conditions — from hospitals to group homes — to bring their special brand of assistance to those who need it most. Let’s take a closer look at how these four-legged heroes are helping humans.

Read the entire article here: https://canadiandogs.com/dogs-helping-mental-health-humans/

Why Don’t Humans Have Whiskers? (McGill OSS)

2 minute read

Humans might not have hair as thick as chimpanzees covering their body, but our arm, leg and eyebrow hair all serves as reminders of our primate ancestry. So why don’t Homo sapiens have whiskers like other simians? To answer that, let me explain first what whiskers do, besides look adorable.

Whiskers are vibrissae, keratin filaments that grow out of different follicles than hair. Whisker follicles are much deeper than hair follicles and are surrounded by pockets of blood that amplify vibrations to better communicate information to the nerve cells beside the follicles. You may have noticed when looking at your cat that there are 2 kinds of whiskers, long and short. Long whiskers are macrovibrissae and can be moved voluntarily. Animals use these to sweep areas (called whisking) to navigate spaces and generally feel the world. Short whiskers are microvibrissae, and they cannot be moved voluntarily. These are used specifically for object recognition, whether it’s your rat’s favourite toy or your hand. 

In general, animals use whiskers to help them ‘see’ the world, navigate it and identify features. Humans used to have whiskers too (about 800 000 years ago we lost the DNA for whiskers), but have now largely integrated the function performed by whiskers into their brains, specifically into their somatosensory cortex. The human brain devotes relatively huge portions of itself to sensing and processing touch. 

Certain areas of the body, like fingertips, lips and genitals have much greater sensitivity to touch than other areas like the back or legs. A visual representation of this sensitivity to touch can be seen in the Cortical homunculus, or by performing a simple test: Have a friend use 2 pencils to touch your arm, while you close your eyes. Have them move the pencils closer and closer together. At a certain point, you will not be able to distinguish whether you are being touched by 1 or 2 pencils. Have the friend repeat this activity on your fingers, then your back. You’ll quickly notice that you have a much more sensitive sense of touch on your hands, feet and face. This test is called the 2 point discrimination test, and it’s often used to test patients for paralysis. 

So we as humans may not have cute whiskers anymore (though our simian cousins still have microvibrissae), but rest assured we’re no worse off for this loss, just slightly more dependent on our brains. 

Original article posted here: https://www.mcgill.ca/oss/article/did-you-know-history/whiskers-humans

Poinsettias Are Not Going to Poison Your Pet or Kid (McGill OSS)

1 minute read

If you have avoided having poinsettias in your home because of small children or animals, you’re not alone. But despite the commonly held belief that poinsettias are toxic, they aren’t. This myth seems to have originated in 1919 with a misattributed poisoning of a child and perhaps persisted because several members of the same family as the flower are quite toxic.

Despite fears of poinsettia poisonings in over 22 thousand calls made to American Poison Control about children eating the red leaves, there wasn’t a single fatality. A 50 lb (22.68 kg) child would need to eat 500-600 leaves to exceed the doses that have been proven experimentally safe.

These leaves, however, aren’t meant for your salad, so eating even a couple can give you an upset stomach or cause vomiting. This is the reaction commonly seen in dogs and cats, but since these symptoms are mild, oftentimes no veterinarian care is required, although you should contact your vet if your pet is sick for more than a few hours.   

The biggest risk comes from touching, rather than eating, the plant, as it produces latex from its stem (like thousands of other plants) that can cause skin or eye irritation in humans and non-humans alike

Original article posted here: https://www.mcgill.ca/oss/article/did-you-know-health-and-nutrition/what-you-need-know-about-poinsettias-and-poison

Human-Guided Evolution Closer Than You Think (Skeptical Inquirer)

9 minute read

Evolution is often thought of as a solely long-term process. But the conception that its effects are only seen after millions of years ignores a crucial part of the evolutionary process: adaptation. Because we tend to fixate on the drastic changes caused by evolution over huge timescales, it’s easy to ignore the small variations between generations that add together over time to form the big evolutionary changes we focus on. This unintentional side-lining of small adaptations can blind us to the ways in which humans are directly affecting the evolutionary processes of nature. From tuskless elephants to fish that can’t smell, animals are developing specialized adaptations to allow them to live in ecosystems that have been disrupted and altered by mankind. These adaptations are one step in the evolutionary process that already bears the unmistakable marks of humanity’s influence.

Just as humans are changing the planet, they’re changing the fauna that inhabit it. Here are some examples of how.

You can read the entire article here: https://skepticalinquirer.org/exclusive/human-guided-evolution-closer-than-you-think/