The most basic function of bodily fat is self-storage of food reserves. In prehistoric times, natural selection favored genotypes that could endure harsh conditions by stocking the most fat. With chronic malnutrition being the norm for most of human history, genetics evolved to favor fat storage. So when did body fat become problematic? The negative impacts of being overweight were not even noted in medical literature until as late as the 18th century.
Then, technological advances coupled with public health measures resulted in the betterment of the quantity, quality, and variety of food. Sustained abundance of good food enabled a healthier population to boom economically. Output increased, and with it, leisure time and waistlines. By the mid 19th century, being excessively overweight, or obese, was recognized as a cause of ill health, and another century later, declared deadly.
What is the distinction between being overweight and being obese? A calculation called the BMI breaks it down for us. For example, if someone weighs 65 kilgorams and is 1.5 meters tall, they have a BMI of about 29. Obesity is a condition of excess body fat that occurs when a person’s BMI is above 30, just over the overweight range of 25 to 29.9. While BMI can be a helpful estimate of healthy weight, actual body fat percentage can only really be determined by also considering information like waist circumference and muscle mass.
Athletes, for instance, have a naturally higher BMI. So how does a person become obese? At its most basic, obesity is caused by energy imbalance. If the energy input from calories is greater than the energy output from physical activity, the body stores the extra calories as fat. In most cases, this imbalance comes from a combination of circumstances and choices.
Adults should be getting at least 2.5 hours of exercise each week, and children a whole hour per day. But globally, one in four adults and eight out of ten adolescents aren’t active enough. Calorie-dense processed foods and growing portion sizes coupled with pervasive marketing lead to passive overeating. And scarce resources, and a lack of access to healthy, affordable foods creates an even greater risk in disadvantaged communities. Yet, our genetic makeup also plays a part.
Studies on families and on separated twins have shown a clear causal hereditary relationship to weight gain. Recent studies have also found a link between obesity and variations in the bacteria species that live in our digestive systems. No matter the cause, obesity is an escalating global epidemic. It substantially raises the probability of diseases, like diabetes, heart disease, stroke, high blood pressure, and cancer. It affects virtually all ages, genders, and socioeconomic groups in both developed and developing countries.
With a 60% rise in child obesity globally over just two decades, the problem is too significant to ignore. Once a person is obese, the climb to recovery becomes progressively steeper. Hormonal and metabolic changes reduce the body’s response to overeating. After losing weight, a formerly overweight person burns less calories doing the same exercises as a person who is naturally the same weight, making it much more difficult to shed the excess fat.
And as people gain weight, damage to signaling pathways makes it increasingly difficult for the brain to measure food intake and fat storage. There is, however, some evidence that well-monitored, long-term changes in behavior can lead to improvements in obesity-related health issues. And weight loss from sustained lifestyle changes, or invasive treatments like bariatric surgery, can improve insulin resistance and decrease inflammation.
What was once an advantage for survival is now working against us. As the world’s population continues to slow down and get bigger, moving and consciously eating our way towards a healthier weight is essential to our overall well-being. And with the epidemic affecting every country in the world for different socioeconomic reasons, obesity cannot be seen as an isolated issue.
More global measures for prevention are essential to manage the weight of the world.
Charles Osborne began to hiccup in 1922 after a hog fell on top of him. He wasn’t cured until 68 years later and is now listed by Guinness as the world record holder for hiccup longevity. Meanwhile, Florida teen Jennifer Mee may hold the record for the most frequent hiccups, 50 times per minute for more than four weeks in 2007.
So what causes hiccups? Doctors point out that a round of hiccups often follows from stimuli that stretch the stomach, like swallowing air or too rapid eating or drinking.
Others associate hiccups with intense emotions or a response to them: laughing, sobbing, anxiety, and excitement. Let’s look at what happens when we hiccup. It begins with an involuntary spasm or sudden contraction of the diaphragm, the large dome-shaped muscle below our lungs that we use to inhale air.
This is followed almost immediately by the sudden closure of the vocal chords and the opening between them, which is called the glottis. The movement of the diaphragm initiates a sudden intake of air, but the closure of the vocal chords stops it from entering the wind pipe and reaching the lungs.
It also creates the characteristic sound: “hic.” To date, there is no known function for hiccups. They don’t seem to provide any medical or physiological advantage. Why begin to inhale air only to suddenly stop it from actually entering the lungs? Anatomical structures, or physiological mechanisms, with no apparent purpose present challenges to evolutionary biologists.
Do such structures serve some hidden function that hasn’t yet been discovered? Or are they relics of our evolutionary past, having once served some important purpose only to persist into the present as vestigial remnants? One idea is that hiccups began many millions of years before the appearance of humans.
The lung is thought to have evolved as a structure to allow early fish, many of which lived in warm, stagnant water with little oxygen, to take advantage of the abundant oxygen in the air overhead. When descendants of these animals later moved onto land, they moved from gill-based ventilation to air-breathing with lungs.
That’s similar to the much more rapid changes faced by frogs today as they transition from tadpoles with gills to adults with lungs. This hypothesis suggests that the hiccup is a relic of the ancient transition from water to land. An inhalation that could move water over gills followed by a rapid closure of the glottis preventing water from entering the lungs.
That’s supported by evidence which suggests that the neural patterning involved in generating a hiccup is almost identical to that responsible for respiration in amphibians. Another group of scientists believe that the reflex is retained in us today because it actually provides an important advantage. They point out that true hiccups are found only in mammals and that they’re not retained in birds, lizards, turtles, or any other exclusively air-breathing animals.
Further, hiccups appear in human babies long before birth and are far more common in infants that adults. Their explanation for this involves the uniquely mammalian activity of nursing. The ancient hiccup reflex may have been adapted by mammals to help remove air from the stomach as a sort of glorified burp. The sudden expansion of the diaphragm would raise air from the stomach, while a closure of the glottis would prevent milk from entering the lungs.
Sometimes, a bout of hiccups will go on and on, and we try home remedies: sipping continuously from a glass of cold water, holding one’s breath, a mouthful of honey or peanut butter, breathing into a paper bag, or being suddenly frightened. Unfortunately, scientists have yet to verify that any one cure works better or more consistently than others. However, we do know one thing that definitely doesn’t work.
Sunscreen comes in many forms, each with its own impacts on your body and the environment. With so many options, how do you choose which sunscreen is best for you? To answer that question, we first have to understand how sunscreens work. Sunlight is composed of electromagnetic waves and is our primary source of ultraviolet radiation, which has a shorter wavelength than visible light and carries more energy. UVA, UVB, and UVC are classified according to their wavelengths.
Short wavelength UVC never reaches the Earth’s surface, but UVB and UVA do. Medium wavelength UVB rays can enter the skin’s superficial layers and long length UVA rays can penetrate into the deeper layers. UVB in small amounts actually helps us make vitamin D, which enables our bodies to build and maintain strong bones.
However, prolonged exposure to UVA and UVB can damage DNA, age your skin, and promote the development of potentially deadly skin cancer. Sunscreen protects your skin either physically by deflecting UV rays with an inorganic blocker like zinc oxide or titanium dioxide, or chemically by using carbon-based compounds to absorb UV photons that are then harmlessly dissipated as heat.
So, what differentiates one sunscreen from another? When we choose a sunscreen, we can compare application method, the SPF, and the active ingredients. Sprays can be convenient to put on, especially when you’re wet, but a recent study found that most people don’t apply a thick enough layer to get full protection.
And the possible health risks of inhaling sunscreen compounds from a spray cloud might make you consider reaching for that bottle of lotion instead. Opt for a sunscreen with an SPF of at least 15, although 30 is better. SPF is a nonlinear scale of how much UVB radiation is needed to give protected skin a sunburn. SPF 15 does a pretty good job by blocking 93% of UVB rays. You get a slight increase as SPF goes up, with SPF 30 blocking 97%, and 50 blocking 98%. SPF is based on the quantity of solar exposure.
So how much time you have before you start to burn really depends on a long list of factors, including your genetics, and when, where, and how you spend your time in the sun. Even though US marketed sunscreens have been deemed safe by the FDA, scientists are still researching the effects of many active ingredients on the human body.
So if you’re worried about potential irritants, look for mineral-based formulas with zinc oxide or titanium dioxide. Even though they may go on a bit thick at first, they’re less irritating than carbon-based chemical sunscreens. These mineral-based sunscreens are preferential for the environment, too.
If you plan on catching rays while splashing in a river or the ocean, keep in mind that carbon-based chemical sunscreens can harm marine life. Take coral reefs, for example. Although they cover less than 1% of the Earth’s underwater surface, they’re home to nearly 25% of all fish species, making them the most diverse and productive marine ecosystems.
Research shows that carbon-based chemical sunscreen ingredients, like oxybenzone, butylparaben, octinoxate, and 4MBC contribute to a stress condition called coral bleaching in corals, which are living creatures. Exposure to these organic compounds results in the death of the coral’s symbiotic algae. In addition to providing a reliable food source, these algae give coral their brilliant rainbow of colors. Without them, corals turn a bleached white and are susceptible to disease and possibly death.
And once the coral dies, the entire reef ecosystem is not far behind. So you’re now ready to make an informed choice when picking out your next sunscreen. SPF is clearly labeled on the front. On the back under “active ingredients,” you can find whether zinc oxide, titanium dioxide, and those coral-harming components are present.
Taking a bit more time to check can be well worth it for both you and the environment.
You’d have a hard time finding KÃ¶nigsberg on any modern maps, but one particular quirk in its geography has made it one of the most famous cities in mathematics. The medieval German city lay on both sides of the Pregel River. At the center were two large islands. The two islands were connected to each other and to the river banks by seven bridges. Carl Gottlieb Ehler, a mathematician who later became the mayor of a nearby town, grew obsessed with these islands and bridges.
He kept coming back to a single question: Which route would allow someone to cross all seven bridges without crossing any of them more than once? Think about it for a moment. You should. It’s not possible. But attempting to explain why led famous mathematician Leonhard Euler to invent a new field of mathematics.
Carl wrote to Euler for help with the problem. Euler first dismissed the question as having nothing to do with math. But the more he wrestled with it, the more it seemed there might be something there after all. The answer he came up with had to do with a type of geometry that did not quite exist yet, what he called the Geometry of Position, now known as Graph Theory. Euler’s first insight was that the route taken between entering an island or a riverbank and leaving it didn’t actually matter.
Thus, the map could be simplified with each of the four landmasses represented as a single point, what we now call a node, with lines, or edges, between them to represent the bridges. And this simplified graph allows us to easily count the degrees of each node. That’s the number of bridges each land mass touches.
Why do the degrees matter? Well, according to the rules of the challenge, once travelers arrive onto a landmass by one bridge, they would have to leave it via a different bridge. In other words, the bridges leading to and from each node on any route must occur in distinct pairs, meaning that the number of bridges touching each landmass visited must be even.
The only possible exceptions would be the locations of the beginning and end of the walk. Looking at the graph, it becomes apparent that all four nodes have an odd degree. So no matter which path is chosen, at some point, a bridge will have to be crossed twice. Euler used this proof to formulate a general theory that applies to all graphs with two or more nodes. A Eulerian path that visits each edge only once is only possible in one of two scenarios.
The first is when there are exactly two nodes of odd degree, meaning all the rest are even. There, the starting point is one of the odd nodes, and the end point is the other. The second is when all the nodes are of even degree. Then, the Eulerian path will start and stop in the same location, which also makes it something called a Eulerian circuit. So how might you create a Eulerian path in KÃ¶nigsberg? It’s simple. Just remove any one bridge. And it turns out, history created a Eulerian path of its own.
During World War II, the Soviet Air Force destroyed two of the city’s bridges, making a Eulerian path easily possible. Though, to be fair, that probably wasn’t their intention. These bombings pretty much wiped KÃ¶nigsberg off the map, and it was later rebuilt as the Russian city of Kaliningrad.
So while KÃ¶nigsberg and her seven bridges may not be around anymore, they will be remembered throughout history by the seemingly trivial riddle which led to the emergence of a whole new field of mathematics.
There are four billion hours of travel delays in America each year, contributing to pollution, fossil fuel waste and costing us all money; an estimated $87.2 billion dollars! Not to mention traffic is just plain annoying! But is there a solution to your traffic woes? Traffic is often due to construction, an accident, or bottlenecks created by on-ramps and tunnels. But do you ever feel like congestion seems to appear for no reason? You aren’t imagining it! In a 2008 experiment, drivers were instructed to drive along a circular road, following the car in front of them while trying to maintain a constant speed. As the participants drove, they started to have fluctuations in speed.
These fluctuations increased, eventually causing cars to stop completely which broke the free flow and led to traffic jams without any added factors. Researchers compare traffic jams to the particles in a liquid and a solid; moving cars are like the free flowing particles in a liquid, but can undergo a â€˜phase transitionâ€™ to that of a compacted solid. Once the particles/cars reach a critical density, gridlock happens. One of the key reasons gridlock happens is our inability to maintain a constant speed. When a traffic break happens, most accelerate to catch up to the vehicle ahead, resulting in eventual braking, that forces the drivers behind to slow down, cause the jam to grow.
When you’re in a traffic jam, you’re part of the problem. Studies show that 80-90% of drivers think the you’re better than the average driver, which is…impossible. Additionally, as humans our attention is selective, and we tend to forget that other drivers are people too – kind of like commenting online, we can dehumanize other drivers in ways we wouldn’t face-to-face. This leads to jerks on the road – following too closely or constantly changing lanes – which contributes directly to the congestion that creates traffic jams. Thankfully, as a good driver, you can make a difference! Pay attention to the car ahead and behind you to keep a buffer of space around you.
This way, if the driver in front of you brakes, you have room to slow down and wont pass the braking tension along the chain of traffic. Drive slower. Set your car to cruise control or try driving at a consistent speed. In Belgium and the Netherlands, there aren’t a technique implemented at times of high volume known as it block-driving where a chain of cars drive at a consistent speed to help others keep pace. Police have also used this strategy for 15 years, driving at an appropriate pace in groups to keep the flow of traffic moving. Of course, the advent of autonomous self-driving cars will see automobiles that are able to connect and communicate with one another, vehicle-to-vehicle, and is expected to reduce traffic jams significantly.
Additionally, researchers are using biologically inspired algorithms to reduce travel times. In one study, researchers applies a model based on ant travel behaviour as a way to route traffic. Changes in infrastructure work too; recently LA became the first city to synchronize every street light, causing lights to make automatic adjustments based on flow, which has reduced travel time by 14%. Traffic aside, another solution is taking public transit when possible. An MIT study of Boston traffic found that if 1% of current drivers took transit, everyone’s commute would be reduced by 18%.
Of course, companies like Toyota – who supported this episode – are finding new ways to address mobility challenges, developing future technologies to interconnect drivers and vehicles with road infrastructure. Toyota is launching their new Corolla iM Hatchback with the Toyota Safety Sense technologies like pre-collision systems, automatic high beams, and lane departure alert – all of which will be standard and launching across Canada this September. They also have a goal to produce vehicles with zero emissions by 2050 which is something we really support! So, special thanks to Toyota for supporting our channel, and being a leader in the science and technology space