Why do Three-Toed Sloths Come Down From Their Trees to Defecate?

Our bodies are most robust and most fragile at the same time. Recently completed the excellent book Evolution gone wrong the curious case why our body fails us? by Alex Bezzerides

Well written and extremely fun to read. Filled with many funny but insightful why questions. Here’s a small sample from the book on pooing sloths?

Why do three-toed sloths come down from their trees to defecate?

On the surface, this behavior is baffling. Why risk the chance of encountering a predator? Why not just let it fly from the branches? In class, my students work together to develop hypotheses and design hypothetical experiments to test their hypotheses. Are sloths fertilizing their trees in a targeted manner? Is it some way of marking their territory? Is it an atypical type of mate attraction?

Acutely observant scientists solved the mystery only recently with a great deal of patience.

They first observed that sloths have algae growing in their fur, which gives the sloths a green tint. The algae help the sloths blend in with the forest canopy, but the story goes beyond organic camouflage.

The sloth scientists noted sloths feeding on their homegrown algae and in doing so, supplementing their otherwise nutrient-poor diet. Eating their own fur algae is admittedly weird, but it gets even stranger than that.

A population of moths lives in the fur of each three-toed sloth. The moth population increases the nitrogen content of the fur and thus promotes the growth of the algae the sloths snack on.

When the sloths make their weekly treks to the bottoms of trees, the female moths lay their eggs in the fresh sloth dung. The tidy sloths cover up their mess with some leaf litter, and after the eggs hatch, the moth caterpillars dine on the sloth poop, grow up, become adults, and fly to the canopy layer to colonize sloths just as their parents did.

Sloths risk their lives to make a dung nursery for the moths on whom they depend for fertilizer to grow the algae they not only use as camo but also eat from their own fur for an extra shot of nutrition. Bam! Mystery solved. We can finally let the sloths poop in peace. Next question.

I hope this sloth-and-moth story has made the point that ultimate questions are fascinating to consider. They push researchers in completely different directions compared with proximate questions. The answers to ultimate questions are also often wildly unexpected.

This is what the book delivers answers to the ultimate questions on human anatomy? Do give it a read if you get a chance?

Do you have other interesting books to recommend, please let me know in the comments below?

Related Post you might like.

Why Many Doctors Recommend a High-Fiber Diet?

This might be simplistic, but a good explanation of why you should eat more fiber?

Whatever our small intestine does, it always obeys one basic rule: onward, ever onward!

This is achieved by the peristaltic reflex. The man who first discovered this mechanism did so by isolating a piece of gut and blowing air into it through a small tube and the friendly gut blew right back.

This is why many doctors recommend a high-fiber diet to encourage digestion: indigestible fiber presses against the gut wall, which becomes intrigued and presses back.

These gut gymnastics speed up the passage of food through the system and make sure the gut remains supple.

From the excellent book Gut by Giulia Enders

Related Posts

The Man Who Boiled Urine to Get Gold.

Ever since we moved our dinner out of our TV room, dinner time has been a constant source of enjoyment. Sometimes kids tell their stories and sometimes I tell them stories that I have read from the recent books I have been reading.

Last month told an interesting story to kids from the Book Elemental by Tim James. I was hoping to post it here on this blog but my Son beat me to it. He likes these stories and wastes no time in sharing them if they are interesting on his blog. Do read this. You will love the story.

The man who boiled urine for gold.
Click on the image to read.

Its a story of a late seventh-century German experimenter named Henning Brandt who proved everyday substances had elements locked inside them and most of the stuff we thought pure was not so.

Do give it a read. The Man Who Boiled Urine.

Related posts:

Thermodynamics, Life and Universe

Thermodynamics was my favourite subject when I was in college. The subject felt close to something I can relate to. I did not know why I like it better than others, I liked fluid dynamics too but thermodynamics was always my top one. Reading the book Einsteins Fridge did rekindled that love of that subject.

Here’s a quote from the book.

At its heart are three concepts energy, entropy, and temperature. Without an understanding of these and the laws they obey, all science physics, chemistry, and biology would be incoherent. The laws of thermodynamics govern everything from the behavior of atoms to that of living cells, from the engines that power our world to the black hole at the center of our galaxy.

Thermodynamics explains why we must eat and breathe, how the lights come on, and how the universe will end.

From the book

Some Related Posts:

It’s Not What You Want…

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Johannes Gensfleisch was a German inventor, printer, publisher, and goldsmith who introduced printing to Europe with his mechanical movable-type printing press. His work started the Printing Revolution in Europe and is regarded as a milestone of the second millennium.

Here’s a story from the book From Gutenberg to Google: The History of Our Future Hardcover by Tom Wheeler on what he might have felt after inventing the movable type and how it would be Guternber day.

It is worthwhile pausing at this point to savor Gutenberg’s success.

Imagine the exultation and celebration that must have gripped Johannes Gutenberg as his first printed book was bound!

More than a decade in development, Gutenberg’s understanding that a page of information was the sum of its parts had required a “secret art” to both discover a revolutionary new process and find the means of adjusting a seemingly endless number of variables into harmonious production.

Now it was done. Success had been achieved in twenty-eight pages of Latin grammar instruction.

The Western world had never before seen the rapid production of hundreds of perfect-quality pages, each one identical to the others. It was a moment to be savored, a decade-long quest with a transformative result.

Unfortunately, the exultation would be short-lived.

Other mass-market documents flowed from Gutenberg’s printing shop. The earliest dated work was a papal indulgence of 1454. Having spent more than a decade perfecting his technique, however, Gutenberg, it would appear, was not satisfied with such run-of-the-mill products. He wanted a monument. Today we call that monument the Gutenberg Bible.

It would be his downfall.

The Gutenberg Bible, Tim Hartford says in his book called Adapt: Why Success Always Starts With Failure., was a failure. It’s a pretty strange example of failure since it was the first book printed with movable type which started 500 years of mass communication. What we do now is pretty much the result of Gutenberg bible.

Believe it or not, the Gutenberg Bible was a total flop for Johannes Gutenberg, the father of the printing press. He went bankrupt trying to make money printing this book. Just like with any new technology, it was very expensive to print books. It was actually so expensive that you might as well hand write them rather then print them. The business model which eventually worked out a bit after Gutenberg’s time was printing leaflets for the church. These early leaflets for the church kept the early printing industry afloat.

Pair this with these posts.

The Easiest Path to Happiness is …

The easiest path to happiness is to do something.

As the Dalai Lama said

“Happiness is not something ready-made. It comes from your own actions.”

Tackle the challenge that’s been nagging your family, tweak the routine that’s not working any longer, have a difficult conversation, pull out the game from the back of the closet.

from the book Secrets of Happy Family

More Posts:

Books Read in 2021 Part 2

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This is part 2 of the book read post. If you haven’t read the previous part, read here.

A friend of mine once suggested, a line or two of context on the books rather than just giving the names of the book, hence posted last year’s list this way.


So here’s the rest of the book list.

The Dhandho investors by Monish Parai.
In my local area, most of the shops from chemist to hardware sales are mainly run by Rajasthan’s and Gujratis. Dhandho means business in Gujrati. This book marries the attitude of these business men and how their thinking style can be used for equity investing.

The invention of Air by Stephen T johnson.
I like books by Stephen T Johnson, so wanted to read this one for a long time. Finally got it on my kindle and was not disappointed. This is a book on life of Joseph Pristley and the discovery of Oxygen. Not the best book from Stephen but worth a read.

The Clever Guts Diet by Michael Mosely
Not as good as the book written by Guilia Enders’s book Gut, but this book talks more about the food and recipes. I specially liked the initial bits than the specific recipes

The Unusual Billionaire by Saurabh Mukherjee.
My first book by the author and loved the thesis and research he presented in the stories of the business and their founders. Liked the way it was presented. Lot of graphs and data points which will satisfy the inner analyst in any reader.

Noise by Sunstein Cass R.
I had high expectations from this book but after the initial chapters the book was a chore to read. Mostly peppered with US centric examples, the book soon lost its plot for me. A good read for the big concepts it presented.

An Arranged murder by Chetan Bhagat
A simple murder mystery. I like the simple writing style of the author. Not his best but definitely something that can be read once.

How to Avoid a Climate Disaster by Bill Gates
I did not want to read this as I thought I knew what is coming but I was surprised. The book is one the best book I have read this year. Not because of the topic but because of the way of thinking that the book encouraged. Definitely picked up few tips and applying them to my own investing journey.

Exercised: The science of Physical activity, Rest and Health by Daniel Lieberman
Loved this book. Takes the reader to a journey. Is sitting good? How much exercise is enough? etc. All questions answered and explored as Daniel Lieberman takes the reader on this discovery.

The Last Human by Lee Bacon.
Read this after the glowing review from kids. A good and well written story. Check my post about it here.

Einstein’s Fridge by Paul Sen
Thermodynamics was my favorite subject while studying engineering. Never thought I will encounter it in this book. Pleasantly surprised and absolutely loved this book. Another one I can’t recommend enough.

Positioning by Al Rise and Jack Trout.
A classic recommended by many. Loved this. Before reading I thought I would have heard the ideas but I was wrong. A good book on positioning and loved each page of it.

Coffee Can Investing by Saurabh Mukherjee and Pranab Uniyal.
I encountered this term in his book on the unusual billionaires so thought of reading this book. Yes a good book but I like his other books better. The book for me came out as a prescriptive, which was off-putting.

Numbers Don’t Lie by Vaclav Smith.
If you have to read one book by the author let it be this. He has written a lot of books which are still in my to-read list. This particular books in on the range of topics and presents a picture of the world through numbers and how they are not usually what we think they are.

The President’s Daughter by Bill Clinton and James Patterson
Have read the previous book by Bill Clinton, liked it. So picked this up. Was not disappointed. Not bad for one time read.

Skin in the game by Nassim Nicholas Taleb.
A yearly ritual in book reading is that I re-read one of Taleb’s book. So picked this up during the fag end of the year. Again the re-read was as usual much more insightful than the previous reads.

The Biography of a Failed Venture by Prashant Desai.
My last read of the year. This was about an Indian entrepreneur’s failed attempt to start a business. Liked the way the book was written and got a lot of insights on how business work particularly in India.

So one quick question, which book are you interested in reading from this list?

Other book related posts are mentioned below.

Books Read in 2021 – Part 1

Like most people, due to pandemic, due to working from home, I have worked from various different places last year.

My most reading used to happen during office commute, so reading time was already down. And this movement from one place to another reduced this further. This reflects in the number of books I have read.

Here’s the rundown of the books I liked and read through in 2021.

Gut by Giulia Enders.
My 3rd book on the subject and by far the most interesting and something that I have enjoyed and learnt a lot. Have wrote a few posts regarding this book last year. A tale of the most underrated organ of the body.

Why we Eat (too much) by Andrew Jenkinson.
Written by a doctor, this has surprisingly good insights. Have added a few of this book’s insights to my life. Good to see how eating habits, the structure of cells and environments all come together.

The Snowball: Warren Buffet and the Business of Life by Alice Christie.
This book was long pending. Did not want to start as I thought I already know a lot about Warren Buffet. But boy I was wrong. A good portrait of the oracle of Omaha. Must read for anyone interested in investing and in life lessons. Have posted a few insights from the book here in this blog post.

The Thirteen Problems by Agatha Christie.
One of the things I miss about the UK is the TV shows portraying Agatha Cristie’s detectives. Picked this book to reminisce about the old days. This book has 13 simple mysteries. I loved most of them. Does anyone know of a contemporary author who writes in this genre?

The Oxygen Advantage by Patrick Mackeown
Started reading this after a blog post. Simple idea but the author took a long time harping on this. A simple idea beat to death by repetition. Also, there’s a slant of marketing in the book which was offputting.

How long is a piece of String by Rob Eastaway
It’s a book on maths. Marrying common sense with mathematics and tying all this through very common examples from daily life. I will reread this again.

Upstream by Dan Heath.
This was my first and only audiobook this year. We tend to downplay the preventive measures and this book shows why we shouldn’t. Lots of good stories and a lot of insights. Nudged by this book, I solved a few long-standing minor annoyances of daily life.

Sapiens by Yuval Noah Harari.
Re-read this book. I recommended this book in one of the office daily standups and went ahead re-reading it. A highly recommended book.

From Gutenberg to Google by Tom Wheeler
A book on the spread of communication systems. I loved this book. The history buff in me was satisfied in reading how people were reacting to new tech. Found many parallels to how the current techs like crypto/AI/ML and how we are reacting to it. Tie it with this post Machine Learning – Thou aimest high

How to Decide by Annie Duke.
Disappointed. Annie Duke’s last book thinking in bet was way way better. This one was like a sermon.

7 Mistakes every investor makes by Joachim Klement.
A good read. Learnt a few new things and reinforced a few old concepts. This is the time I decided I will read one investment-related book a month.

Never split the difference by Chris Voss.
I had this book with me for 2 years now but never felt any desire to pick this up until this year. But boy I was surprised. A good book on negotiations and human behaviour in general. Kept me thinking. I will re-read it again.

A world without email by Cal Newport
A good read. Much before reading this had implemented a system for kids to study using the nudge from the book upstream. This is a book I will revisit again.

A Triump of Genius by Ronald K Fierstein
A long book on the life of Edwin land and Polaroid. An inside view on how the legal system for industrial disputes between Kodak and Polaroid played out. A good read to see how companies react when disruptions happen. Very relevant for the current times.

I think this is enough for now. More in the next post.

Few past book related posts listed below.

Holiday Books Recommendations by Bill Gates

I like books recommendations posts. Most of the books that I read come from these sources. One of the consistent recommendations comes from Bill Gates.

His recommendations are almost always paired with a video. For the current recommendations, he had such a good video that I couldn’t help posting it here.

Haven’t read any of the books mentioned in the video but three of them are on my reading list for the coming year.

What’s your pick on or off the list?

If you liked this, you might like these…..

The Freak Became the Norm

Recently reread the book The Gene By Siddhartha Mukherjee. It’s an extremely well-researched book. Dotted with the right amount of details and stories about so many characters who are part of humanity’s discovery of genes.

Here’s a beginning extract for the flavor of the book

Darwin could almost see the process unfolding on the salty bays of Punta Alta or on the islands of the Galápagos, as if an eons-long film were running on fast-forward, a millennium compressed to a minute. Flocks of finches fed on fruit until their population exploded. A bleak season came upon the island—a rotting monsoon or a parched summer —and fruit supplies dwindled drastically. Somewhere in the vast flock, a variant was born with a grotesque beak capable of cracking seeds. As famine raged through the finch world, this gross-beaked variant survived by feeding on hard seeds. It reproduced, and a new species of finch began to appear. The freak became the norm. As new Malthusian limits were imposed—diseases, famines, parasites—new breeds gained a stronghold, and the population shifted again. Freaks became norms, and norms became extinct. Monster by monster, evolution advanced.

Read somewhere that books are paper-ships that take you on a journey. This book definitely does that. Highly recommend.

The Pursuit of An Easier Life

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Sapiens: A Brief History of Humankind by Yuval Noah Harari is one of those book that doesn’t have sometime new. But the stories it weaves, the way it’s written brushes off the dust and lets us see the old as new. They tell the best stories. This is one of my top recommended books and recent re-read just strengthens the recommendation.

Why did people make such a fateful miscalculation? For the same reason that people throughout history have miscalculated. People were unable to fathom the full consequences of their decisions. Whenever they decided to do a bit of extra work say, “to sow the fields instead of scattering seeds on the surface ” people thought, “Yes, we will have to work harder. But the harvest will be so bountiful! We won’t have to worry any more about lean years. Our children will never go to sleep hungry.”

It made sense. If you worked harder, you would have a better life. That was the plan. The first part of the plan went smoothly. People indeed worked harder. But people did not foresee that the number of children would increase, meaning that the extra wheat would have to be shared between more children. Neither did the early farmers understand that feeding children with more porridge and less breast milk would weaken their immune system, and that permanent settlements would be hotbeds for infectious diseases. They did not foresee that by increasing their dependence on a single source of food, they were actually exposing themselves even more to the depredations of drought. Nor did the farmers foresee that in good years their bulging granaries would tempt thieves and enemies, compelling them to start building walls and do in-guard duty.

The pursuit of an easier life resulted in much hardship, and not for the last time. It happens to us today. How many young college graduates have taken demanding jobs in high-powered firms, vowing that they will work hard to earn money that will enable them to retire and pursue their real interests when they are thirty-five? But by the time they reach that age, they have large mortgages, children to school, houses in the suburbs that necessitate at least two cars per family, and a sense that life is not worth living without really good wine and expensive holidays abroad. What are they supposed to do, go back to digging up roots? No, they double their efforts and keep slaving away.

What is one of your top recommended books?

“You Should Read This”

“Dad, you SHOULD read this”. This is the second time that I have heard this same words in two weeks.

This time it came from my daughter. A week back, my son said the same thing.

2 weeks back seeing Barun, getting restless and spending more time on tab. I got them the book ‘The last human’ by Lee Bacon. They had enjoyed his last book during the lockdown.

He is like me in reading. If he likes a book, he never leaves it until it’s finished. This book he finished in two days. Pointing at the book, he excitedly remarked “Dad you should read this, I like Lee Bacon”

With strong recommendations from my kids, I took to reading the book.

Here’s a starting chapter from the book.

Hello world!

I blinked into existence inside a large windowless cube. The walls were made of smooth metal. The air was circulated by a fan near the ceiling that breathed a steady mmmmmmmmmm.
Something inside me knew where I was.
I was home.

A door whooshed open. Two robots entered the cube. Their movements were smooth and graceful. Their features were identical.

As they gazed at me, their perfectly round eyes glowed brighter.

“We have been assigned to oversee your development,” said the nearest one. “We are your FamilyUnit.”

The other spoke next. “You may refer to us as Parent_1 and Parent_2.”

I am pleased to join your FamilyUnit. This is what I tried to say, but my speech settings were still adjusting. The words came out all wrong.

“Hwroooooooot!” I said.

Parent_1 moved closer. It reached out, wrapping a metal arm around me. As it did, a vocabulary word pinged deep inside my programming.

Hug. Verb. 1. To squeeze someone or something tightly in one’s arms. Noun. 1. An ancient gesture used by humans to show affection.

Is that what Parent_1 was doing? Hugging me? My mind was still fresh from the assembly line. I did not know the answers to these questions. And so I did what any newborn robot would do.

I hugged Parent_1 back.

My joints whispered as I raised my arms. My motion controls had not yet been calibrated. The gesture was awkward.
Clank! Metal bumped against metal.

Parent_1 froze.

Its head turned to look at me. Confusion ticked beneath its smooth features.

A moment came and went.

Then it continued what it had been doing. Its arm reached behind me and grabbed hold of a power cable. With a sharp tug, it removed the cable from the charging dock.

That is when I understood my misunderstanding.

Parent_1 was not hugging me.

It was unplugging me.”

From the book The Last Human by Lee Bacon

Beautifully written and a good story. I can only say, “You should read this!”

The History of “Hello”

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A book I want to reread is “A Million Years in a Day by Greg Jenner”. It has an interesting take on history relating it to a modern day.

Here’s a small sample on how ‘Hello’ came to be.

Apparently, when Edison first witnessed a demonstration of Bell’s contraption, America’s leading inventor exclaimed ‘hullo!’ in total amazement that it actually worked. ‘Hullo’ was the nineteenth-century version of ‘fancy seeing you here!’ the kind of disbelieving greeting we’d blurt out if we met our dentist at the top of some remote volcano but, with our sceptic’s hat on, this story sounds a little too charming to be true.

However, it was definitely Edison who pushed a slightly amended version, ‘hello,’ into the public consciousness as the official telephone greeting. He thought that ‘hello’ had strong, clear syllables, and this was important because he envisaged telephones would primarily be used between businesses, and that the lines would remain permanently open rather than there being a ringing sound for each call. In short, ‘hello’ was chosen specifically because it wasn’t a familiar word used in ordinary office chat, so hearing it would immediately notify someone that there was a call for them.

While Edison’s greeting is now one of the most recognizable words on the planet, I must admit I’m slightly disappointed that Bell’s alternative suggestion, borrowed from nautical terminology, wasn’t picked up instead: just imagine the musical majesty of Lionel Richie singing: ‘Ahoy, is it me you’re looking for?

From the book A Million Years in a Day by Greg Jenner

What Snacking has to do with cleaning?

Found this highlighted text from the excellent book Gut by Giulia-Enders

Everyone has heard their little housekeeper at work. It is the rumbling belly, which, contrary to popular belief, does not come mainly from the stomach, but from the small intestine.

Our bellies don’t rumble when we’re hungry, but when there is a long enough break between meals to finally get some cleaning done!

When the stomach and the small intestine are both empty, the coast is clear for the housekeeper to do its work. If the stomach is involved in the lengthy process of grinding down a steak, the housekeeper just has to be patient.

Only after six hours of churning in the stomach and around five hours of digesting in the small intestine is the steak safely gone and the housekeeper can start clearing up.

We don’t necessarily always hear the housekeeper at work. It depends on how much air has found its way into the stomach and the small intestine.

If we eat something before the cleanup is finished, the housekeeper immediately stops working and returns to waiting mode. Food needs to be digested in peace and not swept ahead too soon in a cleaning frenzy.

Constant snacking means there is no time for cleaning. This is part of the reason some nutritional scientists recommend we leave five hours between meals. There is no scientific evidence proving that the interval must be precisely five hours.

Those who chew their food thoroughly create less work for their housekeeper and can listen to their belly when it tells them it’s time to eat again.

Two things I have started doing after reading this are.

  1. Eat slowly. I was usually a moderate speed eater but now I have slowed it down to match my daughters eating speed who is naturally a slow eater in the family.
  2. Increased gap between meals which essentially means reduced snacking, be it tea or other small treat breaks.

Am I Getting Enough Sleep?

Last year read the book, Why We Sleep: The New Science of Sleep by Matthew Walker. It’s a good book, explains a lot about sleep and what part it plays in our life. Worth a read to anyone interested in sleep.


Here’s a passage that answers the question that almost everyone has about their own sleeping habit. Am I getting enough sleep?

Setting aside the extreme case of sleep deprivation, how do you know whether you’re routinely getting enough sleep?

While a clinical sleep assessment is needed to thoroughly address this issue, an easy rule of thumb is to answer two simple questions. First, after waking up in the morning, could you fall back asleep at ten or eleven a.m.?

If the answer is yes, you are likely not getting sufficient sleep quantity and/or quality. Second, can you function optimally without caffeine before noon? If the answer is no, then you are most likely self-medicating your state of chronic sleep deprivation. Both of these signs you should take seriously and seek to address your sleep deficiency.


In general, these un-refreshed feelings that compel a person to fall back asleep mid-morning, or require the boosting of alertness with caffeine, are usually due to individuals not giving themselves adequate sleep opportunity time at least eight or nine hours in bed.

When you don’t get enough sleep, one consequence among many is that adenosine concentrations remain too high. Like an outstanding debt on a loan, come the morning, some quantity of yesterday’s adenosine remains. You then carry that outstanding sleepiness.

A book worth reading whatever your sleeping habits.

Paper Ships

“If you love to read, or learn to love reading, you will have an amazing life. Period. Life will always have hardships, pressure, and incredibly annoying people, but books will make it all worthwhile. In books, you will find your North Star, and you will find you, which is why you are here.

Books are paper ships, to all the worlds, to ancient Egypt, outer space, eternity, into the childhood of your favorite musician, and — the most precious stunning journey of all — into your own heart, your own family, your own history and future and body.

Out of these flat almost two-dimensional boxes of paper will spring mountains, lions, concerts, galaxies, heroes. You will meet people who have been all but destroyed, who have risen up and will bring you with them. Books and stories are medicine, plaster casts for broken lives and hearts, slings for weakened spirits. And in reading, you will laugh harder than you ever imagined laughing, and this will be magic, heaven, and salvation. I promise.”

Source: A Velocity of Being: Letters to A Young Reader by Anne Lamott

The Hardest Financial Skill

The hardest financial skill is getting the goalpost to stop moving.

If expectations rise with results there is no logic in striving for more because you’ll feel the same after putting in extra effort. It gets dangerous when the taste of having more—more money, more power, more prestige—increases ambition faster than satisfaction

Modern capitalism is a pro at two things: generating wealth and generating envy. Perhaps they go hand in hand; wanting to surpass your peers can be the fuel of hard work. But life isn’t any fun without a sense of enough.

Happiness, as it’s said, is just results minus expectations.

From the book Psychology of Money by Morgan Housel