Why Do We Crave Junk Food?

 by Anne Munier

Evolution influences human behaviour by holding on to traits that make us more likely to survive and have babies. Behaviours like avoiding vicious predators, jerking your hand away if you touch something hot, or cooperating with community members all helped our ancestors survive, and have been passed down through generations. Traits that lead to very *unhealthy* outcomes (like, say, having an irresistible urge to play with vicious predators) tend to get weeded out of the population, because kids who play with tigers generally don’t survive long enough to pass on their genes.

So why do so many of us feel compelled to overeat junk food? Junk food, for the sake of this article, means processed foods that are high in sugar, fat, and salt. This type of diet is harmful for our health, yet it is a rare person who craves steamed broccoli over milkshakes, pizza, or brownies.

Oddly enough, these cravings are very much shaped by human, and even pre-human, evolution.

A monkey with a sweet tooth munching on jackfruit

Millions of years ago, some early primates developed a taste for fruit, even though it tends to grow high up in trees, and it’s much easier to munch on plants that are close by. These particular primates did awfully well because fruit has much more energy (i.e. calories) than other foods, and is easier to digest. This leads to healthy primates in good condition to have lots of babies. These babies inherited their parents’ love of fruit, and likewise did better than their counterparts who couldn’t be bothered to climb for their food. And so it continued through the generations, until eventually the whole species were driven to eat as much fruit as possible.

(Fun Fact #1: Primate species that eat the most fruit have the biggest brains.)

Moving along our evolutionary story, early humans were developing ever-larger brains, which, along with our active hunter-forager lifestyles, meant we needed a ton of energy to keep going. We continued to love sugar from fruit or wild honey when we could get it (which wasn’t often), as well as high-fat foods, which are also high in calories. When we had the chance to eat more than we needed, our bodies stored the surplus as fat, allowing people to have more babies, and enhancing survival during times of food scarcity.

(Fun Fact #2: Humans tend to be better at storing fat than other animals. Even super-skinny humans have more body fat than the chunkiest chimpanzee).

Fast forward to the 21^st century -- most of us live in relative prosperity and have constant access to junk food. And while treats that our hunter-gatherer ancestors enjoyed came wrapped up with fiber, vitamins and minerals, today’s treats -- not so much.

We are now hard-wired to seek out sugar and fat, to the point that they stimulate pleasure centres in our brain. This is true for newborns and adults, across all cultures in the world. Healthy food elicits a bit of this pleasure stimulation, junk food elicits A LOT more. And the more junk food we eat, the more we develop a tolerance to it, so we need to eat more to get that same pleasure response. Sound familiar? Addictive substances, including cigarettes and drugs like cocaine, work on our brain in the same way.

Melt-in-your-mouth Cheetos have a very profitable mouth feel.

Then there are the manufacturers of processed junk foods. They want to maximize their profit by selling as much product as they can. And they have all sorts of tricks up their sleeves about how to get us (and keep us!) hooked on the stuff. For example, they figure out a food’s:

• Bliss point: the perfect ratio of sugar, fat, and salt to maximize deliciousness and over-consumption

• Mouth feel: how food interacts with your mouth -- the more quickly it melts, for example, the more it confuses our brain into thinking that we’ve consumed fewer calories than we really have

What is the result of these biological forces on one hand, and the commercial forces on the other?

The number of people who are obese is growing annually, as are associated conditions such as high blood pressure, heart disease, chronic inflammation, and Type 2 diabetes. Add to this the impacts on mental, psychological and dental health, and ballooning health care costs that affect everyone.

So, given enough time, could humans evolve to lose a taste for junk food, since it’s so damaging? Maybe, but let’s not hold our breath. Evolution acts genetically, by passing on genes to our children. But most disease related to excessive junk food affect people later in life, after they’ve already had (or not had) kids.

Is it inevitable then, that we’ll continue to eat excessive amounts of junk food, and our health will keep deteriorating? Not at all! Here are two things to keep in mind as we go forth in our junk food-laden society:

1. Evolution has also endowed us with big beautiful brains capable of critical thought. Even if things are stacked against us, we can make great (if sometimes tough) decisions about our eating and exercise habits.

2. We need to recognize that diet goes beyond will power. Our biology and powerful market forces are designed to make us crave junk food, which, sadly, is often cheaper than whole food. So let’s NOT blame anybody for “lifestyle diseases” caused by too much junk food. Rather let’s consider societal changes that could improve things -- like limiting marketing of junk food to children, or ensuring that healthy food is easily available to all of us. What ideas do you have?

Why Do Kids Play?

by Anne Munier

Kids doing what kids do best!

Children are playful creatures. This holds true all over the world- whether that’s playing 4-square in the schoolyard, engaging in some shadow tag if you happen to be in Ireland, or maybe partaking in a bit of luksong-baka if you’re in the Philippines (it translates to “jump over the cow”, but don’t worry, no real cows are involved!). Even back in the Middle Ages kids made toys out of wood or stones, and long before then, pre-historic toddlers finger-painted on cave walls. No matter where kids are, a day well spent is a day full of fun.

Twig figurines from the American South-West. Toys have been popular for a long time.

And it’s not just human kids -- lots of animals, especially mammals, grow up playing. Think of otters gliding down mud slides on their bellies, puppies wrestling with sticks, baby goats galloping all over each other and head butting anything in sight- they are clearly having fun! The most play-loving of all may be our closest relatives the chimpanzees and bonobos, who laugh, tickle, wrestle, play with dolls (well, with sticks that they treat like dolls, so I’d say that counts), and spend most of their childhood, well, having fun.

All this to say -- playing is genetically ingrained in humans. Kids have evolved to play.

Humans are in good company when it comes to enjoying some good playtime.

But why?? Generally we evolve attributes that help us to survive, be healthy, and have babies. But for most of our evolutionary history we were hunters and gatherers, and playing could have some serious drawbacks. For instance, play:

-Burns lots of energy, so kids need to eat more food (that can be expensive when you’re foraging and hunting every day for survival)

-Is risky -- have you ever known a kid to get hurt or lost when they’re clambering over rocks or climbing trees or exploring new areas?

-Can be loud, which would have attracted the attention of hungry predators.

Having fun? No, these kids are honing their critical thinking skills and coming up with solutions.

None of this sounds like an evolutionarily good idea! But scientists assure us that the benefits of play far outweigh the downsides, by helping kids to:

-Learn skills- children’s games often mimic adult activities, such as playing with toy tools, caring for stuffies, or building sand castles. Play allows for years of practice before taking on real life responsibilities (of renovating buildings, parenting, or designing houses for example). It also gives kids a chance to figure out what they love doing.

-Be strong! All that running around and climbing and wresting and jumping is great exercise.

-Think critically- learn how to analyze situations, come up with solutions, and then evaluate. Think of playing Capture the Flag: your team decides who does what, and how to react to certain situations (like the other team getting too close to your flag). Then you try it out, and chat about how it all went down afterwards. Critical thinking at its finest!

-Communicate, form friendships, develop confidence, and generally get along with others. Social animals (like humans, apes, or wolves) tend to spend more time playing than other species.

-Come up with solutions to life’s problems while having fun! Which, it turns out, is a far better way to learn than when you’re stressed out and running from a charging predator, say. One study observed a group of chimpanzees who all wanted some bananas that were out of reach. Which one figured out how to manoeuver them down with sticks? The one who had had the opportunity to play with sticks beforehand, learning how to manipulate them!

Science backs all this up. Bear cubs that play the most are the most likely to survive the winter. Playful yellow bellied marmots are most likely to have high status as adults. Girls in Botswana who play at pounding grain when they’re young become better grain-pounders (a very challenging job) when older. And children who play more as kids tend to become adults who are good at making friends and adapting to life’s changes.

Keep playing little bear!

The bigger problem today is that kids seem to have *less* playtime than ever before. There may be lots more organized activities in kids’ lives (sports teams, music lessons, tutoring sessions, what have you), but having time to play whatever they want - not so much. Scientists are learning that this is not good for the physical and mental health of children *or* the adults they become.

So, the next time anyone tells you that you’re wasting time playing around rather than doing something serious with your time, you can let them know that millions of years of evolution aren’t wrong. That play *is* serious business, and one of the most important things you can spend your precious time on!

The Wild Side of Everyday Food

 by Anne Munier

Thousands of years ago, in what is now Mexico, people chewed a wild grass called teosinte, enjoying the sweet juice from the stalks. The plant was short and bushy-looking, with lots of stems going every which way. People didn’t bother much with the seeds, because they were covered by a hard, protective case.

But every once in a while a mutation -- or unexpected slipup in the plant’s genetic structure -- came along, and suddenly some plants appeared without seed casings. This wasn’t great news for the plant -- animals could eat and digest these unprotected seeds, so the plant was less likely to reproduce. It was pretty good news for people though, who got to finally taste the seeds!

Teosinte seed head. Photo credit: Two Row Times

In truth, even the “naked seeds” weren’t anything to get too excited about -- there were only a few per seed head, which were dry and potatoey-tasting. But they were good enough for people to eat, and even to plant a few (perhaps inadvertently at first, when seeds accidentally fell into the soil near people’s home). 

Hard little teosinte seeds. Photo Credit: Two Row Times

These seeds produced more naked-seeded teosinte. Over time, people learned that when they planted the seeds from their favourite plants -- say those with the biggest, juiciest, or sweetest seeds; or those easiest to grind into flour; or those less vulnerable to pest attacks -- many of the next generation’s plants would have these same characteristics. 

Over hundreds, perhaps thousands of years, farmers changed the plant from a bushy wild grass with lots of tiny seed heads, into a tall, straight plant with a few large cobs, each containing hundreds of big seeds. Not only did the plant provide more food, but it was easier to harvest, easier to eat, and, well, it just plain tasted better. In short, about 9000 years ago, these Mexican farmers turned the wild grass teosinte into maize (also called corn), now one of the most important food crops in the world! 

Lots of changes on the journey from teosinte to corn! Check out how large the cob is compared to a coin. Photo credit: Nicole Roger Fuller, National Science Foundation

The process of changing wild plants (and animals!) into domestic ones by choosing the favourite ones to reproduce is called selective breeding. It’s the basis of agriculture! While corn was being domesticated in Mexico, the same process was happening with wheat in the Middle East, bananas in New Guinea, rice in China, and millet in Africa (among so many others). 

Wild relatives of modern potatoes. Photo by L. Salazar

 

A commercially-sold banana beside a wild relative. Photo by A. D'Hont

Carrots still look much like wild carrots, though larger and juicy!

It’s Thanksgiving as I write this, one of many harvest festivals celebrated around the world. As we honour food, family and friends, I think of the special debt of gratitude we owe Indigenous People in all parts of the world who -- over millennia and still today -- learned and shared so much about the local environment, and how we can sustain communities with the gifts of nature.

(Traditional knowledge has many stories for the origin of corn/maize, taro, camas, and other important foods. Some of these stories are shared in books and online resources. Indigenous people keep this traditional knowledge as part of culture, history, and how the world is understood.)

The Scoop on Poop

 by Anne Munier

The scoop on poop

We all do it, most of us don’t like to talk about it, but perhaps we should get over that, because poop is not only fascinating, it’s also powerful stuff that may be a solution to at least a couple world problems! Let’s start with the basics:

What is it? Poop is waste from our bodies. We eat, our bodies take in nutrients, and then pass out what’s not needed. So poo is basically undigested food, along with bile (more on that in a moment), bacteria, parasites, and dead cells. Other names include stool, faeces, human waste, excreta, bowel movements, and a few more that are somewhat less polite.

Why the brown colour? Poo is usually brown because that’s the colour that bile- a substance our liver produces to help digest fats- becomes as it passes through the digestive system. Fun fact: bile starts out yellow-green. When we have diarrhea (which tends to come out extra quickly), the bile doesn’t have time to change colour as it passes through the intestines, hence diarrhea is often more of a yellow or green colour.

Why are we grossed out by poo? Evolution, of course! We’ve evolved to be disgusted by poo to reduce our chances touching the stuff. This reduces the chances of being infected by disease-causing microbes or parasites that it could be harbouring. The smell, which comes from the bacteria that break down food in our digestive system, probably helps as well. 

A proud manure producer! Photo by Ian Barbour

Is poo useful? Oh, my yes! Agricultural manure is basically livestock poop (often it’s been composted first), which helps crops grow by providing nutrients and bacteria, and by making the soil more rich and fertile. It also improves soil’s ability to hold onto moisture, and can reduce erosion. Yay manure!

Anything else? You bet, now we’re getting to the really exciting part. Let’s talk alternative energy.

But first, let’s recognize that every year we produce hundreds of billions of kg of poo worldwide (yeah, take a moment to think about that. Or…. don’t). Either way, that can be a heaping sanitation problem, particularly in areas that don’t have good quality infrastructure for dealing with human waste. When people are in close contact with poo, they can get sick from the germs and parasites, which can cause diseases like cholera, dysentery, or typhoid.

So- billions of people on Earth producing billions of kg of potentially harmful waste- that’s a problem. Meanwhile we’re looking for ways to make our energy system more ecologically friendly to reduce the impacts of climate change- another problem. A response to both problems: Biogas!

Biogas is produced when organic matter (like food waste, wood, agricultural waste, and yes, human and animal poo) is digested in a sealed container without any oxygen. The gas is then captured and used for energy, like cooking gas, fuel for cars and trucks, electricity, or heat. It doesn’t even smell bad!

The solids that are left behind are a great, high quality fertilizer that can be used in landscaping or farming. Another benefit!

 

Biogas plan: Organic matter goes in, biogas bubbles out the top, and "digestate" (i.e. fertilizer) is left over

It’s a simple concept, but please don’t try it at home; it’s not *that* simple.

Let’s check out some examples: 

This Sumatran orangutan is contributing to clean energy!

• The Toronto Zoo recently started putting the 2,000 tonnes of waste that their animals produce every year to good use. They combine it with thousands of tonnes of grocery store waste, and generate enough biogas to power 500 homes! In the process they’re reducing thousands of tonnes of greenhouse gas emissions, those heat-trapping gases that are causing climate change!

• A primary school in Uganda is now able to cook student lunches thanks to human waste-derived biofuel.

• Poop power will soon be heating about 600 homes in the Vancouver area!

• England has “bio-buses” that run entirely on gas from human faeces and food.

Poo-powered buses in England!

And that’s just the start. The United Nations anticipates that human waste could power 138 million homes while improving human and environmental health. Companies investing in the technology to make it happen are popping up all over the world.

Suddenly, a waste problem becomes part of the solution to clean energy! And we certainly won’t be running out of the raw material (that is, human poop) anytime soon.

 

 

Celebrating the (Banting and) Best Anniversary Ever!

 by Anne Munier

Leonard, a Toronto teenager, arrived at the hospital weak and pale, his hair falling out. Like everyone else who had Type 1 diabetes 100 years ago, he was dying.

People with Type 1 diabetes (let’s call if T1D for short) stop producing the hormone insulin. In fact, their immune system -- which should be busy fighting off diseases -- gets confused, and starts killing the body’s own insulin-producing cells!

 

Diagram credit: MyHealthDigest

That’s a big deal, because insulin moves food energy (glucose) out of our blood, and into our body’s cells. Without it, we don’t get much energy from food. Then sugar accumulates in our blood, eventually causing a lot of damage. T1D affects children mostly, and, back in the day, they would generally die within a few weeks or months of being diagnosed.

Symptoms of T1D include:
1. Having to pee more than usual, to flush out all that sugar. (Thousands of years ago doctors noticed that ants were attracted to the urine of T1D patients, because it was sweet. The ant trick helped to diagnose new patients!)
2. Being really thirsty (to replace all that lost fluid)
3. Not having much energy (no surprise there- food energy doesn’t get where it needs to go!)

Back to Leonard. At 14 years old, he weighed only weighed 65 pounds. That was partly due to the diabetes, but mostly it was because he was barely eating. A “starvation diet” was a cruel, but popular, T1D treatment, which could extend life by several months.

Leonard before and after treatment

But this story has a happy ending.

A small research team at the University of Toronto, led by Dr.’s Banting and Best, were removing and purifying bits of the pancreas (the organ where insulin is made) from dogs and cows. They thought that injecting this into diabetic patients might provide their bodies with the insulin they so desperately needed. Leonard was about to be their first human guinea pig.

Three heroes of diabetes treatment
(Dr. Best, lab dog 408, and Dr. Banting) -
University of Toronto

Their first try was a failure -- all that happened was that poor Leonard developed an allergic reaction. Undaunted, the researchers purified the extract some more, and tried again. This time the results were quick, and they were amazing. Leonard’s blood glucose went down to near-normal levels within a day. He brightened, became more active, and felt stronger. And survived!

After Leonard came other children -- 6 year old Teddy; Elizabeth, somehow still hanging on after 3 years of the starvation diet; Elsie, in a coma, revived by insulin. Insulin has since saved the lives of millions of people.

Letter to Dr. Banting from a much-
improved Teddy (U. of Toronto)

While the treatment has become more sophisticated, T1D troopers still inject themselves with insulin every day, and carefully control their food (especially carbohydrates). There’s still no cure -- yet.

About one in every 100 Canadians has T1D. Whether we realize it or not, we’ve all been impacted by insulin, because we all know and care about people whose lives it has saved.


All this to say: Happy 100th anniversary everyone!

Looking on the bright side, with brain-altering parasites

 by Anne Munier

It’s been a tough year for many of us. Sometimes looking on the bright side and feeling grateful for all that we have helps. Other times, it can be even more helpful to look on the gruesome side, and be grateful that we are NOT infected with brain-manipulating parasites who take over our bodies and control our behaviour. In that vein, let’s take a moment to explore just how disturbing nature can be….

Zombie Ants

We’ll start in the humid tropics of Brazil, where a carpenter ant is living its best life with thousands of its buddies, foraging and defending the colony. No one would even notice the microscopic fungal spore that lands on it. But spores are like mini seeds, and this one penetrates the ant’s body and starts to grow inside. First the fungus feeds on the ant’s insides, and then it takes over the ant’s behaviour, compelling it to wander away from its colony, which is something that ants never do. The possessed ant climbs up a nearby plant, and clamps on with its jaws. At this point is it more ant or more fungus? Either way, the fungus is clearly in control. After finishing eating the insides of the slowly dying ant, it sends a stalk up through the back of the animal’s head. By making the ant climb up the plant, the fungus is now at a good height to spread its spores. They float out on the breeze, perhaps to infect the poor ant’s relatives, and the cycle starts anew.

 

A zombie ant, in the final stages of serving its fungal master - Photo Credit Bernard Dupont

A game of cat and mouse

Toxoplasmosis is a tiny parasite that infects mammals and birds around the world, but it’s mice that really need to watch out. When the parasite completes the life stage that takes place inside a mouse’s brain, it needs to make its way into cat intestines in order to reproduce. How can this microscopic parasite accomplish that? By encouraging its mouse host to be eaten by a cat! Under the parasite’s influence, mice stop being their usual fearful, cautious selves and start exploring more. They actually become attracted to the smell of cat urine (I know!!). This really increases the chances that a cat and infected mouse will find each other- good news for the cat, bad news for the mouse, and great news for the toxoplasmosis!

 

A parasite that makes mice love cats?

Baby birds taking over the nest

Not all parasites are tiny, and they don’t necessarily need to get into an animal’s brain in order to manipulate them. Some birds, like cuckoos or brown-headed cowbirds, are “brood parasites”; they’ve figured out that sneaking their eggs into the nests of other birds saves them a lot of time and energy on the parenting front. The unwitting foster parents may be suspicious, but very often they accept the egg and raise the chick as their own. The imposters tend to be the first to hatch, beg the loudest, hog most of the food, and grow the most quickly. In the case of some cuckoos things can get really nasty- the cuckoo chick hatches before the others and actually hauls the other eggs out of the nest (effectively killing its foster siblings, and ensuring that it gets all of the parents’ care). These darling babies can grow several times larger than their run-down caregivers, all while intently demanding regular feedings.

Mama warbler feeding her insatiable foster chick, the common cuckoo- Photo credit: Harald Olsen

 

Is anyone else wondering whether we humans could have parasites that, unbeknownst to us, are manipulating our behaviour? Quite possibly! Initial research suggests that people exposed to the flu virus become more social- going to more parties and visiting more friends. No strong conclusions have been reached yet, but some researchers suspect that the virus is influencing its human host’s behaviour in order to expose it to as many people (and potential new hosts!) as possible.

Love ‘em, hate ‘em or just feel grossed out by parasites, but it’s hard not to be impressed by some of the tricks that they’ve come up with. Now doesn’t life seem a bit better, knowing that we’re (most likely) not possessed by parasites controlling our thoughts, actions, and taking over our very being?