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The Big and The Little


spiderI caught a small spider in my room this morning.

It was a deft operation, because I didn’t want to kill it.  I like spiders – they eat a lot of things I really don’t like, like baby cockroaches, mosquitoes, and flies.  I used a small, transparent case to cover it, slid an index card underneath it, flipped the works over and put the lid on.

And then I got to thinking – what’s the spider thinking?  I suspect the spider wasn’t particularly aware of me – it was aware of the transparent case and the card and the flipping over – but it was hard to imagine it was aware of me.  And then I imagined some large beast capturing me in the same way, but I couldn’t quite do it.

Are humans large or are they small?  I think we tend to think of ourselves as small.  We know we’re not the biggest creatures on the planet, and we can think of any number of things larger than us that we wouldn’t want to be put in a cage with – gorillas, tigers, hippos, rhinos.  We know about the dinosaurs who once roamed the earth.

And yet none of those things, or elephants or whales or walruses either – could do what I did to the spider, which seems still more evidence of our smallness.  We associate agility and dexterity with smaller creatures – we’re agile and dextrous – so we must be small.  When I try to imagine a creature as large to me as I am to the spider, I have a hard time imagining such an enormous thing could also have the precision in movement to capture me quickly and painlessly and in that way.

How big would such a thing be?  An average adult male human is 2 meters tall, allowing for rounding to whole numbers.  That spider I would judge to be about a centimeter long, or call it 2 cm to make the math straightforward.  I am, in other words, just about exactly 100 times as tall as that spider is long, and so the creature capturing me in my imagination would have to be 200 meters tall in proportion.  For the metrically-impaired, that translates to 656 feet tall – just about 2 Statues of Liberty stacked on top of one another.

But that comparison doesn’t quite do it justice.  I’m far more threatening to the spider than 100 times.  My dominance over the spider comes not from the differences in our heights but rather our weights.  I didn’t have the presence of mind to weigh my little prisoner, but I would guess between 100 mg and 1 g.  This would make me about 100,000 times as large as my spider friend.  The equivalent beast to loom over and capture me would have to weigh over 16 million pounds, or 8,000 tons.  That’s the weight of 36 Statues of Liberty.  So now I must imagine the Statue of Liberty coming to life, doubling in height, becoming morbidly obese, and having the dexterity to painlessly capture me in 5 seconds.  That’s us, to the spider.

When you put it that way, we’re big – big and remarkably skilled.  Our motor coordination is good enough to capture the spider without hurting it, but we’re also powerful enough to hold our own in a fight with probably 99.9% of the biome.  The number of creatures we fear in a battle of size are few – but more importantly, even when you imagine the largest organisms on earth – say the blue whale – they’re not that much bigger than us.  Okay, they’re a lot bigger than us, but not relative to how much bigger we are than the world’s smallest creatures.  The blue whale weighs about 200 tons and is about 30 meters long.  So by both the length standard and the weight standard, there’s no comparison.  I am far larger than the spider relative to how much larger the whale is compared to me.


Better, there’s no going larger than the blue whale.  It’s the largest creature that exists on earth and the largest creature to have ever existed on earth.  There’s many biologists that believe that the blue whale may represent close to the maximum size of a living creature.  Even if it isn’t, the blue whale would have to get much bigger to compare with me and the spider.

The kicker, of course, is that while we can’t go any larger than the blue whale, we can go much smaller than the spider.  To be sure, we can’t go much smaller and still expect me to be able to handle it so dextrously – the man/spider comparison is just about perfect for illustrating how different two things can be in size and still interact on some sensory-motor basis.  But just in terms of size comparisons, the spider is hardly the smallest insect, and insects are hardly the smallest creaturesdog-flea_1592349i.

Consider the flea (the giant scary monster to the right is an electron microscopic image of a dog flea).  These aren’t easy to catch, but we can sometimes see them and we sure as heck can feel them.  A flea is just over a mm long, making it 10 times tinier than my spider friend.  As for their weight, I struck out trying to find a reliable figure.  I was able to find an estimate of the weight of Flea from the band Red Hot Chili Peppers, but apparently there aren’t too many people weighing the fleas of dogs and cats.  (Ironically it is very easy to find the statistic that fleas can consume 15 times their body weight in blood each day – so somebody must know the weight of a flea – but I suspect that scary statistic doesn’t represent a whole awful lot of blood.)

Once we leave the realm of the flea, we leave the realm of living creatures we can reasonably react to with our unaided senses.  But we know that there are one-celled organisms, so we might ask: how many cells do our bodies have?  Here’s a secret – no one’s counted – but estimates range from about 15 trillion cells to about 70 trillion cells, depending on whether one estimates by volume or by weight.  Thus, we weigh about 70,000,000,000,000 times as much as a typical one-celled organism.  The creature compared to me which is like me compared to a one-celled organism would have the weight of 29 billion blue whales.

I would argue from all this that humans are not only large, they’re enormous.  We are right to be impressed and humbled when reminded that we live on a small planet surrounding an average star in a galaxy of 100 billion stars in a universe of 100 billion galaxies.  That makes our sun one of 1022 stars in the universe. But when you consider there’s about 1014 atoms in a single human cell, and more than 1013 cells in the human body, we’re in some ways about as big as we are small.  We are almost centrally positioned between the big and the little.

(To those of you who know that the name of this blog is inspired by an Isaac Asimov quote, bonus points for those of you who recognize that the title of this post, The Big and The Little, is taken from the title of one of the Good Doctor’s Foundation stories.)



  1. Steven, blue whales can weigh up to 190 tonnes (210 old-style “tons”), as opposed to the 20 tons you cite. They are the heaviest creatures ever to live on our planet by a wide margin. But to continue your line of thought, I’d like to mention the Quaking Aspen (Populus tremuloides). Being a clone organism with a shared root system, the quaking aspen known as Pando near Fishlake, Utah weighs 6,000 tonnes. It is the largest known living thing. And at an estimated age of 80,000 years, it is also the oldest known living thing.

    We humans can be humbled by what other sorts of life exists. Compared to a Populus tremuloides, we are very small and we live very short lives.

    • NeuroProf says:

      William, thank you for the information on “Pando”! I hadn’t considered non-animal life at all in my essay, so that definitely adds to the discussion. And now you have me thinking about an essay on life expectancy too – we may be in a similar place on the life expectancy scale as on the weight scale.

      I’m also very grateful to you for pointing out the error on the blue whale’s weight. I’ve gone ahead and corrected that in the text above (using the figure 200 tons to keep the math straightforward). That gave me a chance to clean up some typos as well.

      Thanks for stopping by and commenting.

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