SciTech Now Episode 402

In this episode of SciTech Now, a look into how scientists are using cameras to understand insect flight; the study of how plants know which way is up; the reason why yawning occurs; and a sustainable cemetery inside a nature preserve.



Coming up, understanding insect flight.

And to require us to study various aspects of insect flight.

That includes their flight dynamics, their aerodynamics, the structure and functions of the biological sensors.

How plants know which way is up.

The plant knows that this is where gravity is.

This is where we should go if I'm a root.

The science behind yawning.

The mechanism of yawning serves to increase intracranial circulation.

An eco-friendly final resting place.

What they would find that they wouldn't find in your typical cemetery is natural Florida, predominantly pine flatwoods.

It's all ahead.

Funding for this program is made possible by...


I'm Hari Sreenivasan.

Welcome to 'SciTech Now,' our weekly program bringing you the latest breakthroughs in science, technology and innovation.

Let's get started.

It's a bird.

It's a plane.

It's an insect.

Take a look as a team at Pennsylvania State University uses high-speed cameras and fluid dynamics to understand the mechanics of insect flight.

When the Wright brothers studied flight, they studied the seagull.

Elegant and efficient, they were easy to observe and easy to emulate, but there was another type of flier on that desolate North Carolina beach.

It was more dynamic than the seagull, and it broke all of the rules the Wrights worked so hard to uncover.

The fly.

Based on what we know about flight, this guy should drop like a rock.

A group of Penn State scientists, led by Bo Cheng, are trying to figure out why it doesn't.

This is a relative simple question to ask but an extremely difficult one to answer.

It seems to require us to study various aspects of insect flight.

That includes their flight dynamics, their aerodynamics, the structure and functions of the biological sensors.

To most people, flies are pests, but to an engineer, these insects can perform tasks that have no equal in the natural world.

These tiny fliers, they only have a very limited amount of neurons.

However, they are able to solve extremely challenging flight-control tasks, like the upside-down landing on the ceiling within a split of a second.

This doesn't seem like a big deal, but keep watching.

Now imagine you're in an airplane, and the only way to land is upside down at a fixed location.

No existing aircraft is capable of performing this type of maneuver, and if it did, it would take an exceptional pilot to pull it off.

Flies do it hundreds of times a day.

Cheng's team is interested in their brains and their aerodynamics.

In fact, they use [Indistinct] and the rotational flow to generate lift, and that's something perceived as pretty bad for conventional engineer to flight.

The basics of conventional flight goes something like this.

As a plane speeds up, air splits above and below the wing.

The air at the top moves faster over the curve's surface, creating low pressure.

The pressure difference between the top and bottom of the wing creates lift.

Flies create lift another way.

When the wings are moving, they generate their own aerodynamic lift, but then the LEV, the leading-edge vortex, which is on top of that, introduces an extra suction force which pulls the wing further up and helps the insects to hover or just to just fly and not fall down, basically.

Think of the leading-edge vortex as a small tornado, a rapid swirl of air riding at the top edge of the wing.

Like the airplane, the fast-moving air creates low pressure, and that creates lift.

To study this, Cheng's team has created unique devices that help them contain the flies and record them at 5,000 frames per second.

So what we do is, we attach a fly to this end of the rod, and we sort of just put it back in, and what will happen is the fly will start flapping its wings, and it'll sort of fly in a circle.

Flight mill uses electromagnets to levitate the rod.

This keeps the fly on a predictable path.

Upside-down landings are recorded using this, a Plexiglas cube surrounded by lights and high-speed cameras.

Essentially, we can track different points on the wing and then get the three-dimensional coordinates for these points on the wing or on the body, and then we can essentially reconstruct the wing motion as well as the tiny deformation of the wing, and then we will have a full understanding of the kinematics of the flight.

The team is also partnering with the University of Virginia to understand the fluid dynamics.

They want to know how wing movement can affect the stability of that leading-edge vortex we just talked about.

The team is also looking to the future.

Humans have already harnessed the power of flight, but can we take it to the next step and copy the complex movements and reaction time of bugs?

Right now, there are robotic fliers that can mimic the basic mechanics of an insect, but according to Cheng, a mechanical device capable of something like this is still decades away.

For now, all we can do is watch and learn.


Ainissa Ramirez is a scientist, author and a self-proclaimed science evangelist.

She is the creator of a podcast series called 'Science Underground.'

She joins me to discuss one of her latest podcast episodes about how plants know which way is up.

That is kind of a question I never really thought about, but, yes, why don't they grow roots going this way instead of that way?


So, it's dark.

You're a seed, and you're in the ground.

How do you know which way is up?

I mean, there's --

I got nothing.

That's right.

That's exactly it.

Well, it ends up that they have special cells that sort of look like this Mason jar.


The cells have something that's very heavy inside, and they're located at the tips of the roots, and wherever those rocks are, the roots know that that's where gravity is, and so they point in that direction.

This is inside, on a cellular level.

There are special cells.

They're called statocytes.

Statocytes, okay.

And inside are statoliths -- those are the rocks -- and so let's say the plant gets knocked over.

Your cat knocks over your plant.


Well, they're in a different position now, and so the plant knows that this is where gravity is.

This is where we should go, if I'm a root.

Now, the shoots have similar cells, too, and they go in the opposite direction.

They're like, 'Oh. If that's where gravity is, well, then, I will go in the opposite direction.'

180 degrees opposite.

That's right.

That's right.

And this is just over a couple hundred thousand million years of evolution.

Evolution, yeah.

They figured it out, and we actually have something similar in our ears.

This is how we know about... This is how we keep balance.

We have small rocks, calcium rocks, that are in our ears that tell us where to go.

And when we get dizzy, and when we get kind of out of sorts, it's that tiny...

That's right.



It's because one of these calcium cells has gotten dislodged or moved, and it's causing us to be a little dizzy.

It's a horrible feeling when you feel completely out of balance.

I mean, you could be holding on to this desk, and you still feel like you're falling or something else.

It's very unsettling, and it's so amazing that it's such a tiny, tiny object in our brains that, you know, is balancing...

Is giving us information.



Right. Yeah.

You could be completely stable, and that rock being dislodged will change your perspective.

We have also sent plants into space.

That's right.

That's right.

And so why didn't they go haywire then?

Well, this is what's interesting.

If we want to go out to Mars, we're going to have to make our own food.

We can't, you know, take-out won't go all the way out there.

I saw the Matt Damon movie.

We all know that's how it works.

That's right.

We got to science the hell out of this.

That's right.

So what we're going to have to do is, we're going to have to grow in space, and if we know that plants are, you know, they use gravity to determine which way to point their roots...


...and if we're in microgravity, what we have to do is think about how we can make sure that they feel that gravity.


The other thing that's important is that plants actually respond to light.

In fact, their shoots respond to light even more, so if you show a light, the shoot will know that this is the way I should go.

And will the other parts say, 'Well, I'm going the other way than the shoots?'

Well, it's not to the same extent, but the roots also know that if they see light, then they've gone in the wrong direction, so they'll go around.

So in zero gravity what happens?

So in zero gravity, they're still doing experiments to figure that out because this is key.

How are we going to create vegetation in space?

But they have grown things, but they're in microgravity.

Zero gravity, still to be determined.

So in the sci-fi movies, we always see this giant spinning greenhouses...

That's right.


Creating some semblance of gravity...

Yeah. That's right. try to pull the roots down.

The centrifugal force, just like if you're at the amusement park and you're in the teacup, and it's spinning you around.

That's creating a sense of gravity, so the plants will know, okay, if they're going in this direction, the rocks will actually be going in this direction because they're spinning.


That's how we're going to be able to grow food in space?

That's right.

Well, I'm glad we've sorted that out on this episode.

That's just... So is there something that we've learned from what plants do in space and even just what we've learned on the ground that helps us produce a more robust plant, one that can deal in, you know, kind of different types of soil or different light conditions and less light?

Mm-hmm, mm-hmm.

Well, scientists are working on this all the time because it ends up that when we grow corn, we want to grow it very densely so we can have a lot of it.

Now, if other corn stalks are being shaded, well, then, that one won't grow.


So we're trying to figure out how we can change the susceptibility and the sensitivity of plants so that they will continue to grow, even in a very dense situation, and people are working on that problem right now.

All right.

Ainissa Ramirez, thanks for joining us.

Thank you.

To many, yawning is simply a reflex that occurs when someone is tired or bored.

Evolutionary neuroscientist Andrew Gallup has been tirelessly studying the science behind yawning.

He joins us via Google Hangout with his insights.

First, thanks for being with us.


Thanks for having me.

So what is yawning?

Why does it happen?

Well, that's a great question, and people have been asking that question for thousands of years, and it's really only within the last decade or so that we've begun to get a handle on why we yawn.

So yawning is characterized by this deep, large gaping of the mouth with a deep inhalation of air followed by a fairly rapid closure of the jaw and an expiration, and that basic motor action pattern is ubiquitous.

We see this across vertebrates.

All mammals yawn.

All birds yawn, and even fish, reptiles and amphibians show a similar yawn-type gaping pattern.

So evolutionarily, it appears to be a very highly conserved response, which suggests that it possesses some basic function.

And some of the research that we've been doing recently is trying to uncover that function, and a lot of the work that I've done is focused on the idea that yawning serves as a brain-cooling mechanism.

A brain-cooling mechanism?



So that it is one of a variety of mechanisms which could enhance blood flow to the skull, provide a mechanism for countercurrent heat exchange, which could serve to modify intracranial temperatures.

So, wait.

When I yawn, how are we talking about temperatures in my brain?

Connect the dots for me here.

Sure, so the mechanism of yawning, that gaping of the jaw and deep inhalation of air, serves to increase intracranial circulation, so it promotes blood flow to the skull, and in addition, that ambient air exchange provides a mechanism for cooling with the ambient temperature with the internal tissues of the nasal passages and the oral orifices.

Now, the cooling of this blood draining from your face then comes into close contact with the arterial blood supply in your neck and provides a mechanism to basically increase blood flow generally, removing hyperthermic blood away form the skull while simultaneously introducing cooler blood from the lungs and extremities.

Let's say your theory is right and you've explained the mechanics behind this all.

Why is yawning contagious?

So we know that contagious yawning is elicited by social stimuli.

Seeing someone else yawn, hearing someone else yawn, and even thinking about yawning could elicit the response.

So in order to understand contagious yawning, I'd argue that we first need to understand why we yawn when we're by ourselves because the motor-action pattern of contagious yawning is indistinguishable from a spontaneous yawn.


So when we yawn because we see someone else, it still elicits that same motor-action pattern, and therefore, it likely has the same physiological consequences.

So to get at the question of why we yawn contagiously, I've hypothesized that contagious yawning may be a mechanism which evolved to promote group vigilance and coordinate arousal levels among members of a group.

So if someone in the group yawns spontaneously because of, perhaps, increased brain temperature and drops in cognitive processing...


...the spreading of that response across members of the group could enhance overall vigilance.

So one of the questions that I had from Facebook, 'I've heard that yawning is a sign of empathy, and some physicians try to elicit it in children when they screen for autism.

Is this accurate?'

Yes, so there are a number of studies that have linked contagious yawning with empathy.

However, the connection isn't as tight as once believed, so there are some studies that have been conducted looking at whether or not children with autism yawn contagiously, and some of the initial studies indicated that they failed to do so.

However, this could be a consequence of just a lack of social attention towards the yawning stimulus.

Someone asks, 'I wonder why I don't see more elderly people yawn.

Maybe I just visit nursing homes at a non-yawning time or is there something to it?

I yawn more when I'm there than anyone who lives there.'

Both spontaneous and contagious yawning rates decline with age, so that elderly populations yawn considerably less than other adult populations or younger populations.

The highest frequency of yawning, in fact, occurs within the first few weeks to months following birth, so babies are the highest-frequency yawners.

I have witnessed that.

So what's the link between yawning with tiredness as opposed to boredom?

The relationship with yawning and boredom is well documented, and again, I would argue that it's tied to just dips in arousal and alertness that may be associated with increased brain temperature and lower intracranial circulation.

In relation to tiredness... So yawning is often associated with sleepiness and fatigue, but I'd argue that the connection between those two, again, is temperature, so that our body temperature varies considerably across the day in a circadian pattern, and the highest yawning rates occur at very distinct changes in our circadian temperatures, our brain and body temperatures.

So in the evening, we're more likely to yawn spontaneously than any other time in the day, and that's when our brain and body temperatures are at their highest point.

Is there a connection between yawning and how much oxygen we need?

I mean, people keep saying, 'Oh, gosh.'

Well, one person asks, 'Why do I yawn all the time?

My mom snapped at me once, 'How much oxygen do you need?''

Yeah, and so when I poll classrooms or audiences, and I ask them, 'Why do we yawn?'

the most common response is 'Oxygen deprivation,' or that we yawn to equilibrate oxygen-CO2 levels in our blood.

This is the most widely believed reason why we yawn.

However, the research has tested that, and subsequently, that hypothesis has been falsified.

So they actually brought people into the lab and had them inhale altered contents of O2 and CO2 to see its effect on yawning...


...and they find that while you can manipulate breathing rates really effectively, that yawning rates are unaffected by the manipulation of O2 or CO2.


So the connection between breathing and yawning... They're really controlled be separate mechanisms, but it's very intuitive for us to believe that yawning is associated with respiration because it has this big inhalation component.

'Do animals catch yawning as well?

My cat seems to yawn when I do and vice versa.'

There are about a handful of animals that we have very good experimental evidence for yawn contagion and maybe another half a dozen or so in which there's observational evidence for yawn contagion.

Currently, there is no evidence that cats yawn contagiously.

However, dogs have been documented... Domesticated dogs have been documented to yawn in response to human yawns.

Andrew Gallup, a yawn researcher from, and assistant professor of psychology at SUNY Polytechnic Institute, thanks so much for joining us.

Thank you so much.

♪♪ [ Keys clacking ]

Humans continually use land for homes, businesses, farms and roads, and some of us will end up taking up a 6x3-foot plot of land when we die, but now there are efforts under way to provide a final resting place with the least amount of impact to our environment.

Here's the story.


Heartwood Preserve is a nature preserve and also a conservation cemetery.

A conservation cemetery uses green burial practices, which means no embalming, no vault, no concrete vault, just a simple biodegradable casket or a shroud or the burial of cremated remains, and we do the green burial in a nature preserve setting.

This preserve is located near New Port Richey, Florida, and has remained untouched from development.

We have a cypress-dome wetland as part of the preserve.

The other ecosystem that we're protecting is longleaf pine flatwoods.

The 41-acre preserve once was part of the sprawling Starkey Ranch.

Today, it remains adjacent to the 18,000-acre Starkey Wilderness Preserve.

This 41 acres, its value environmentally, ecologically, is larger because it borders this wilderness park.


In January of 2017, the Heartwood Preserve celebrated its grand opening.

We had over 150 or so people come out and had a really fun time.

People didn't expect to have a good time at a cemetery on a Saturday, but we had music...

♪ And I can hear a heavenly band full of angels coming to set you free ♪

We brought in a caricature artist from the Tampa area, a local artist.

He was busy the whole time he was here.

We also had a henna-tattoo artist, who painted beautiful designs on people's hands and arms and wrists, so that was really nice, and we had face painting for the little kids.

We do have walking trails and footpaths around the property, so this gave an opportunity for people to get an actual tour of the main areas of our main trails and gave people an opportunity just to get excited about what we're doing, not only as a cemetery, but as a nature preserve that is really about all of the parts of life that are happy and joyous as well as at the end of life.

By being a cemetery and nature preserve, there are some unique ways the property can be managed and maintained as natural Florida.

As a business, we're structured similarly to a conventional modern cemetery.

A percentage of your burial fee, by law, goes into a care and maintenance trust fund, and that trust fund is basically... exists to make sure that that cemetery is cared for into the future.

For us, it's more to do the land management, the ecological management of this site.

Laura wants to guarantee that the preserve remains natural, so she sought out the help of the Tampa Bay Conservancy.

The Tampa Bay Conservancy is working across this region to fill the role of a land trust.

The purpose of our land trust is to protect open space, wildlife habitat, also cultural areas that are important for the citizens of this region.

Laura has offered the preserve as a conservation easement to be controlled by the Conservancy.

Board member Ann Paul has worked with many landowners who want their property to remain wild forever.

When Laura is offering this land as a conservation easement to the Tampa Bay Conservancy, she's making a promise that this area will never be paved over for shopping development or a housing community.

It's always going to have this beautiful, open aspect with the native trees, the native plants and the native wildlife that live here today.

Wildlife biologist Dave Sumpter is working with Laura in developing a strategy to manage the land.

What they would find there that they wouldn't find in your typical cemetery is, you would find natural Florida, and the Heartwood Preserve is predominantly pine flatwoods, which is a very common native habitat in this part of Florida.

It's driven by fire.

We call those pyrogenic plant communities, meaning everything that lives in pine flatwoods is adapted to fire, and the reason it's adapted to fire is because, you know, we're in the lightning capital of the world, here, and so we get a lot of lightning strikes in the summer, and everything burns, and so things, when fire comes through, it doesn't, like, kill all the wildlife.

It actually rejuvenates the vegetation.

The important thing to recognize here is that the management of conservation areas and the protection of conservation areas in perpetuity is totally in line and compatible with an organic cemetery.

The battle over land in Florida continues where conservationists look for ways to protect wildlife corridors.

Florida has one of the most aggressive land-acquisition programs in the country, but it's still constantly kind of a land grab.

How much do we need for conservation?

How much development can we incur?


Laura Starkey grew up in this wilderness.

She feels a special connection to the land.

When I was young, it was our family and a few other families that got to know and love and touch this land and care for it.

As I've gotten older and moved out into the world and come back, I see how much it means to people to get to experience the outdoors.

They'll come out here and just go, 'Wow. It's so peaceful here, and it feels good,' and people really relate to that.

As a preserve and cemetery, the goal is to have as little impact as possible to the environment.

I like the idea of leaving this no footprint.

I really like the idea of leaving no footprint and being part, you know, the ashes-to-ashes part of the soil and part of the natural areas, and this allows you to do that.

I've already got an area back there that I would love to be placed at my time, so hopefully a long time from now, but it's a beautiful space back there that, as soon as I saw it, I thought, 'Okay.

This would be good for me.'

♪♪ ♪♪

And that wraps it up for this time.

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Until next time, I'm Hari Sreenivasan.

Thanks for watching.

Funding for this program is made possible by...