Category Archives: Biology

How much energy is in a thought?

Sometime during the last months of grad school I was in the office late, polishing off one too many coffees, and dipping into my emergency ramen noodle stores. I was searching for that elusive (and perhaps illusory) moment of clarity that, one hopes, arrives to propel a manuscript forward. But, the long hours and coffee caused my mind to wander into distant realms of science. I had just finished teaching about neurons and action potentials and brain activity in my physiology class (100 billion neurons, forming 100 trillion neural connections—more connections than stars in our galaxy—sparking up right now allowing you to think this!) and I had a cool thought:

I am converting these cheap noodles directly into science and new insight. I am a biochemical machine that converts packs of 10 cent fake noodles into knowledge.

And then, the natural follow-up: at what rate? What is the cost of a thought? How many noodles does my brain burn to construct a statement? A paper? A dissertation?

Now that I do not have a dissertation submission deadline looming, I have some time to explore these thoughts—thankfully while burning some higher-grade fuel than emergency ramen! Warning: the calculations that follow are extremely ‘back of the envelope,’ and should be taken with a heaping helping of salt and skepticism. This is just a fun exploration.

How much energy is burned in a thought?

First, let’s gather some parameters. How much energy does the brain use? The short answer is: an incredible amount. Despite only accounting for 2% of the body’s weight, the brain uses 20% of the body’s energy (that figure is for an adult, in newborns it is 44%!!) The brain uses 2–3 times the amount of energy that the heart uses.

[Aside: the brain is extremely efficient at what it does—processing information using orders of magnitude less energy than the best supercomputers.]

So, let’s say that the brain uses 20% of the body’s basal metabolic rate, and the basal metabolic rate is 1500 kcal/day. That means the brain uses about 300 kcal/day, or 0.0035 kcal/second.

The next question is: what is a thought? How much time does one take, and what proportion of the brain’s energy is devoted to “thinking”? I don’t know! But, does anyone know? I don’t know that either. Since it is my blog, I am at liberty to define a thought. Let’s say, for the sake of argument (and feel free to argue in the comments) 100% of the brain’s energy is required for “a thought,” and all thoughts are created equal. And let’s also say that a thought is a statement, and that it takes as much time as one would take to think or read a sentence. For instance, here is a thought:

“Wow, I am thinking this thought about thinking; this is one of the things that hydrogen atoms do given 13.82 billion years of cosmic evolution, and it’s super cool.”

How long did it take to think that specific (extended) thought?  More than a couple of seconds, less than 10? Let’s say a substantial thought takes 5 seconds. At 0.0035 kcal/second, that’s about 0.02 kcal/thought!

So, how many ramen noodles are burned for a thought? At 400 kcal per block, and 150 noodles per block, we have 2.67 kcal per noodle. Assuming the average noodle is 33 cm long, we find that there are 0.08 kcal/cm of noodle—and every thought burns about 0.25 cm of ramen noodle! Your brain is incredibly efficient—no wonder that future AI are always super jealous and vindictive in sci-fi movies.

Now we can readily convert thinking-time into calories, and content creators can register their influence in energy. For instance, if 100 people read this blog post, consuming 5 minutes of calories thinking through the content, then about 100 calories would be burned on my words. 400 people and an entire block of ramen has been consumed by my words.

I wonder how much ramen has been burned by Shakespeare?

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My spot, your spot.

I grew up on an island with seven million other people. Let’s just say it was difficult to find a spot to call your own. One day, as a youngin’ exploring the world on my bike, I broke off a path that ran along Sunrise highway and continued on down a hiking trail that snaked along a waterway in the local state park. I eventually came to a small clearing, sat down, and heard the weirdest thing. Nobody. No cars, no lawnmowers, no people. Just the birds and the chipmunks and the occasional splash of a fish.

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I felt as if I had stumbled on secret treasure. I spent a lot of time at this spot over my formative years, reading and thinking and being alone with my little patch of Long Island wilderness.

Before I left town for college I carved a “V” into the tree next to the water and said goodbye. While at college, I decided to major in biology, a decision shaped by my time out in the woods watching nature. I even wrote an essay about this spot for my freshmen writing class.

That biology major took on a life of its own, turning into an adventure through states, labs, and disciplines, and eventually resulting in a PhD from a zoology department and a dissertation on cancer and aging.
Last weekend Begum and I were visiting my parents and we decided to go for a quick hike before the ferry back to CT. A rush of memories came back, and I ran along this trail explaining my spot to her. She eventually found the V for me.

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Both of these images are from June 2017

It was the first time in over a decade that I set foot in this clearing. Needless to say, it was a powerful experience, and it sparked a bout of retrospection that, thankfully, I have been happy to ride.
I said a thank you, and another goodbye, and we ran to catch our ferry.

This summer, I hope you go out and explore, and find your own spot.

Spider Sunday is back! Kind of.

Spider Sund… err… Monday is back!

Back when we lived in Florida, stumbling on cool spiders was easy. Just open your door, take a few steps, and BOOM, golden orb-weaver (not to be confused with a yellow garden spider) taking care of your wasp problem. Or role out of bed to discover your new roommate, a Carolina Wolf, is on the prowl for mice (I presume). Maybe she’ll even bring along her closest 100 kin.

But New England, with its “seasons,” is a different story*. So, imagine my surprise and delight when Begum and I were hiking around Farm River State Park and saw this little fella scurry across the path:

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At Farm River State Park, CT. Picture taken with Galaxy s7. 

After some quick searches, I outsourced my initial guess to the amazing sciencesphere of twitter:

@HereBeSpiders11 with the save! Looks like this is a type of ground spider (we did find it on the ground), specifically it looks like a male Sergiolus capulatusThanks!

Some suspect that the awesome pattern may be an adaptation to mimic the velvet ant (which is actually a wingless wasp), known for their extremely painful stings!

Looking forward to what we find on our next hike.

*Actually, maybe it is not such a different story. Looks like we will just have to be more attentive on our next hike!

Want to find life on Mars? There’s a catch…

There has been a lot of talk recently about “getting our ass to Mars” (to phrase it as Dr. Buzz Aldrin has on social media). Whether it’s Elon Musk talking about the new SpaceX plan to colonize Mars (first passengers might be taking off by 2024, start saving!), the record low global sea ice levels here on Earth, or just the results of recent elections (Fig. 1) — people have been thinking about extraterrestrial adventures.

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Figure 1: Google Trends for “I dont want to live on this planet anymore” searches. November 8th 2016 was election day in the USA.

This gives me a good excuse to share one of the most interesting challenges we face when finding a landing spot on the Red Planet.

Surely, when sending a Rover to Mars in search of life, like we will in the year 2020, we would want to send it to the place that is the most likely to harbor life (or has the ingredients necessary for life according to our understanding of what life requires here on Earth). Right? This is probably true for when we want to send humans there as well— the more similar to Earth, the higher our chances of survival. But, there is a catch.

The site we think would be the most likely to harbor life would also be the most likely to be infected with life from Earth­— life that could outcompete the local Martians and lead to a planet-wide extinction. We (or, our microbes) could be the classic Hollywood alien invaders who annihilate local life in the search for resources.

Now, someone who has never read this blog or sat through a microbiology class might think “Hey, easy solution, just sanitize things before takeoff! Plus, the harsh conditions of space travel will get rid of any pesky stowaways.” Not so easy.

Firstly, let’s pretend for a moment that our bodies are not harboring a complete ecosystem of microbial life, and that somehow we can guarantee that humans and their waste never contact the surface of Mars. Still, microscopic life is everywhere on Earth. And I mean everywherelike 800 meters below the ice in an Antarctic subterranean lake everywhere. I think it is safe to say that some of this life will contaminate anything we send to Mars. In fact, 65 species of bacteria were found stowed away on the 2012 Mars Curiosity Rover.

Secondly, some microbial Earthlings are extreme. And I mean extreme— like proliferating at 403,627 × Earth’s gravity extreme. Like living in a liquid asphalt desert extreme. And yes, like living outside in space for 1 and a half years extreme.

So, the possibility of microbial stowaways surviving to mars is real.

And, of course, NASA knows this. In fact, they have a whole Office of Planetary Protection devoted to, among other things, “Avoiding the biological contamination of explored environments that may obscure our ability to find life elsewhere – if it exists; …”. The United Nations knows this as well. The Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, including the Moon and Other Celestial Bodies includes:

States Parties to the Treaty shall pursue studies of outer space, including the moon and other celestial bodies, and conduct exploration of them so as to avoid their harmful contamination and also adverse changes in the environment of the Earth resulting from the introduction of extraterrestrial matter and, where necessary, shall adopt appropriate measures for this purpose.

The possibility of contaminating planets that may harbor life presents a real ethical dilemma for robotic and human colonists. Should we search out life on a planet surface and also risk infecting the planet with Earthling microbes? Should we colonize another planet if it means we may destroy the local inhabitants? I’m not going to try and answer those questions here, but feel free to leave thoughts here or tweet them to me.

Spider Sunday is back! This week: Wolves in Your Backyard.

I have a confession. When I was young I wasn’t very kind to spiders. My behavior can likely be attributed to fear; growing up we are surrounded by imagery of spiders being dangerous and alien. We fear what we don’t understand. The internet says Marie Curie once said “Nothing in life is to be feared, it is only to be understood. Now is the time to understand more, so that we may fear less.” And it’s true, the more I learned about spiders the less I squashed them. Now that I’m older, and a biologist, and living in Florida (read: constantly surrounded by giant spiders), I see spiders as fascinating, useful, and largely innocuous. And I’m on a mission to spread this view in order to gain back all the biology-karma I lost squashing spiders in my childhood. So, here are some neat facts I just learned after to a recent encounter.

Storytime. The other night I was outside enjoying the (relatively) cooler Floridian night and getting some work done. Suddenly I glimpsed a familiar shape darting towards the leg of my chair. A few inches long, but too meaty and agile to be an orbweaver or banana spider, I knew it had to be a wolf spider. So, I jumped up and reached for my phone and rushed to snap a picture before she retreated. When the flash went off I was greeted with a surprise…

Proud Wolf Spider Momma

Proud Wolf Spider Momma

Reflections. Reflections from eyes. But wait, why are there reflections coming from the spider’s abdomen?

Woah. Cool! Ok, so now I know that wolf spider’s eyes are reflective, just like I’ve seen (and posted about) before in Golden Orb-weavers…

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Golden Orb-weaver, La Chua Trail, Gainesville FL.

This is very similar to the reflections we’ve all seen before when shining a light towards certain mammals at night, such as cats or raccoons.

Raccoon hanging out behind UF's Science Library, Gainesville FL.

Raccoon hiding out behind UF’s Science Library, Gainesville FL.

So, what’s going on here? By reflecting light back through the retina there is more light available to the photoreceptors- enhancing night-vision. In vertebrates this is accomplished by the tapetum lucidum, or “bright tapestery” in Latin, a thin tissue membrane in the back of the eye. It looks like the tapetum has evolved independently in invertebrates and vertebrates, and actually exists in several invertebrate taxa including scallops, crustaceans, scorpions, and dragonflies. The tapetum in invertebrates consists of parallel strips of reflective guanine crystals- the same type of crystals that give fish their shiny metallic skin and allow chameleons to shift their skin color.

Want to see it for yourself? Go outside at night and shine a bright light into the grass. Those hundreds of reflective dots shining back? Wolf spiders looking at you. But fear not, for now you understand more. Just wear shoes.

(and share your cool spider pictures with me!)

Dragonflies are awesome.

Alright, so my wife and I both think dragonflies are really cool. We never really thought about exactly why we think this, it’s just this inherent neatness about them. Maybe it’s how they hover like brightly colored silent helicopters and then quickly dart about like… I don’t know, some sort of alien spacecraft. And, unlike some of our other backyard insect friends (I’m talking about mosquitoes and red imported fire ants, both of which seem to have an affinity for my skin in particular), dragonflies don’t bother us.

This last weekend I was fortunate enough to have a dragonfly interaction that got me falling down the wikipedia rabbit hole learning about our flying friends, so I figured I’d share some of what I found here. First, for the fateful interaction:

I was grilling up a batch of beer in preparation for the summer…

You read that right. Cannataro’s Brewery Summer Saison will go on tap June 2015.

… and I was joined by a male blue dasher!

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He hung out for a while, flew to different perches, and even let me get a few close-ups.

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Smiling for the camera. Which, by the way, was just my cell phone (galaxy s4).

Eventually my wort was ready to start cooling and he was done patrolling the garden so we exchanged our goodbyes and went our separate ways.  Little did I know the carnage that was awaiting me the next morning. Warning, dear reader, the next image is graphic.

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My dragonfly friend had been decapitated! By one of his own! Well, kind of. That new, green, living dragonfly is (I believe) a female eastern pondhawk. After I took that picture she flew off, taking the body with her, leaving just his head as evidence. Woah. Talk about cool backyard biology! Down the wikipedia rabbit hole I went. Time for some rapid fire fun dragonfly facts.

Dragonflies have been on Earth in pretty much their present form for over 300 million years. In fact, the largest insect to ever exist was an ancient dragonfly (with an estimated wingspan of 28 inches!). They can spend years in their underwater nymph form, which has extending and retractile lower jaws (remind you of any alien characters?) and can feed on vertebrates (small fish, tadpoles) and mosquito larvae (thank you).

The adults enjoy mosquitoes as well (told you they were awesome).

The nymph crawls out of the water and transforms directly into the adult in a process called ecdysis. They have a unique mating system where the male grabs the female behind her head with the claspers at the end of his abdomen and they form a heart-shaped mating pair. Their wings are self-cleaning and water repellant due to the lotus effect. I can go on and on, but if you want to learn more you should check out this video:

So next time you look at a dragonfly think about how you’re looking at the 300 million year old body plan of a ruthless killing machine with a 95% hunting success rate. Dragonflies are awesome!

 

January 2015 fun facts

Woah, I’m way backlogged on blog posts! Don’t worry, I have some cool stuff in the works and I’ll share soon. In the meantime check out some of the science I’ve been starting my classes off with this month.

Aging research: blood to blood – scientists can splice animals together by creating a wound in each animal and sewing them together- their natural wound healing mechanisms join their bodies and their blood (it’s called parabiosis)! If you splice an old animal to a young one the tissue in the old animal gets “rejuvenated” by the young animal’s blood.  Sounds like the premise for a horror movie.

Scientists have discovered a new antibiotic that kills pathogens without detectable resistance.

Scientists have discovered that tumor cells can actually acquire previously lost DNA (in this case mitochondrial) from “normal” cells, and that the newly acquired DNA restores missing function. Think about that. Somatic cells (or cells that were once deemed somatic but now have become tumor cells) can horizontally transfer DNA. Biology textbooks get rewritten every day.

And, of course, I can’t introduce metabolic scaling and not discuss the invariance of heartbeats.

Enjoy!