Log in

No account? Create an account

t3knomanser's Fustian Deposits

Welcome to Earth: Scale

How Random Babbling Becomes Corporate Policy

run the fuck away

Mad science gone horribly, horribly wrong(or right).

Welcome to Earth: Scale

Previous Entry Share Next Entry
I haven't really delved into human biology much in my "Welcome to Earth" columns. This is a mistake that deserves to be rectified. You can't understand an organism's behavior until you understand the biology that drives that behavior.
It's really impossible to discuss the human biology without first touching upon the scale of human beings. They are massive creatures. Epic by many standards. Size, of course, is relative. Compared to a planet, they're minuscule. But compared to most common life forms- well, let's put them in context.

Earth does things large, when it comes to life. Perhaps it's a side effect of the weak gravity of this tiny terrestrial rock, but things grow to enormous proportions on Earth. Titanic mammals that can only exist suspended in the world's water oceans. Forests that share common root structures and are like one gigantic tree. Compared to these, humans are modestly sized, but these organisms are outliers. Compared to the most common forms of life- well, humans and whales are on the same order of magnitude.

All life on Earth starts with proteins. Complex carbon molecules that can form long chains (hey, I told you they like everything large) bind up into interesting chemistry. The simplest forms of life are parasitic bundles of protein called viruses. They can get fairly large for protein crystals, but for terrestrial life, are about as small as it gets. This economy of size is offset by some major failings- they need other organisms to make their lifecycle work.

The bulk of all life on Earth is organized into cells. While there's a lot of variation in size, the same basic model is used across all cells. At the center, the complex proteins that carry inherited information. A water based jelly provides suspension for all the various organelles in the cell; once again, mostly proteins. The whole thing is wrapped up in a lipid bubble that provides a membrane to keep the cell's parts in and the world out. This membrane-barrier life strategy is unique to Earth, and itself provides curious insights into why life behaves the way it does. But that's for a later article.

This lipid-wrapped bundle of protein and water is about 10µm across, and they're everywhere. Earth teems with these cellular organisms. The air, the water are filled with them. Every surface is coated with them. And most of these organisms are just one cell.

Humans are made up of these cells, but they are made up of about 1014- 100 trillion cells. For another comparison, a single cell is 10µm across. Humans, on their longest axis, are about 2 meters across- 106 times larger. In contrast, the Earth is about 6 megameters- about 106 times larger than a human.

Think about that. Single celled organisms are to humans as humans are to their planet.

Imagine such a creature, perhaps living in a puddle of water. A human walks by and carelessly steps in that puddle. The resulting disruption is geological in scale. While the single celled organism has little awareness of what has transpired, its environment has been devastatingly altered. The water displacement causes turbulence that reorganizes all of the life in the pool. Sediments are stirred up, clouding the water (a hindrance to the many photosynthetic lifeforms that could be there). Cells from the human become part of that sediment (they constantly shed dead cells). Living cells, carried their on the human's skin may join the pool. Maybe they are prey, perhaps they are predator. Either way, an incredibly alien event has transpired.

The analogy of size, Cell:Human::Human:Planet is an excellent analogy. Humans don't interact with the single-celled world merely by crashing through puddles. They are so large that they constitute an entire ecosystem. Their body is more than just a collection of human cells; it's a breeding ground for other organisms, ranging in size from single celled organisms to much larger and vaster insects (themselves large enough to carry hosts of smaller organisms).

Like any other ecosystem, humans and their occupants live in careful balance. Some are mere parasites, ranging from a host of bacteria that excrete chemicals harmful to humans, to blood sucking insects or worms that feed on human digestive efforts.

Most, however, are welcome occupants that provide valuable services to their host planet. Nearly every orifice plays host to colonies of bacteria. In females, for example, their genitals depend on a healthy colony of bacteria to function successfully. A variety of maladies can be caused by an imbalance on those colonies. In both sexes, one of the more critical colonies is in the large intestine. These play a vital role in human digestion; they help extract vital nutrients from the food humans eat and make them accessible to the human body.

There are others that are generally welcome or ignored, until they attack their environment in some way. The skin, for example, is coated in bacteria that do little to contribute to their environment, but also do little to harm it. Occasionally though, these colonies grow too aggressively, and interfere with the human skin's own maintenance processes- the result is ugly and painful blemishes that are attacked by the human's immune system.

This bears repeating: humans are so large that they are coated inside and out with all manner of bacteria and other single celled creatures. Arachnids and insects are the giants in this universe; they live off of the dead skin and dust that collects on the humans. The human body is not a single organism, nor even a single ecosystem, but a collection of very different environments that are the stage for thousands of species to live out their lives. Some live in harmony with their environment, some in ignorance of it, and a few actively try and profit from it.

There's one more denizen of the human body that I want to mention. You see, most human behavior appears to arise within the human brain- a collection of highly specialized cells that work as a massively networked computer system (these cells are among the larger cells out there- they grow long arms to build this network). It's very tempting to think that much of their behavior and personality arises there. This is foolish because of the many, many systems in their body that are more powerful motivators, but that's for another essay. You see, there are some unicellular creatures that actually know how to "hack" the brain's network. They can actually control, to a limited extent, the personality and behaviors of a human being. Some drive them mad. Some are more benign, and merely try and make the humans good prey for their preferred host. In either case, there is not a single system in the human body that is not somehow dependent on, host to, or manipulated by some smaller, more humble organism.
  • Boooring
  • I like.

    Quibbles: Nucleotides are not really proteins, although they do have nitrogenous bases. They do not have amino acids, and do have sugars and phosphate groups worked in. The RNA type of nucleotides is central to the process of synthesizing proteins.

    The lipid bubble is not made up of just lipids, but also phospholipids, which are polar. Polarity enables the cell to not only keep the world out, but also to selectively let parts of the world in.
    • All true, but this wasn't really intended as a primer to organic chemistry. Considering our target audience doesn't have much personal experience with molecules, let alone these needlessly complex organic molecules, I didn't want to get too bogged down in details.
      • Polarity? Needlessly complex? SPLODEY.

        But c'mon. Nucleotides are not proteins, no matter how simple you go.
    • Again, our target audience has no exposure to things like proteins. They've only recently become aware that it's possible to form life out of any kind of molecules.

      Molecular chemistry giving rise to life? Until a short time ago, it was considered impossible.
      • Polar molecules are not all that rare. They are not unique to organic life. Many molecules that have an oxygen, fluorine, or nitrogen atom somewhere in there end up being polar. Carbon polymers not necessary. Observing the behavior of polar molecules in liquid water... now that may be something quite exotic. Or maybe not. In 2007, they found a new planet whose spectra and distance from its primary suggested the presence of liquid water.

        As for proteins and nucleotides, they're shaped different, made of different things, and do different things!

        • Of course polar molecules are rare! Molecules themselves are vanishingly uncommon. I repeat: our target audience was, until recently, unaware that molecules did anything terribly interesting. The idea that it's possible for self-reproducing life to be made out of molecules is very cutting edge.
      • Being that they're lacking in chemistry exposure, you'd most likely take the molecular physics tack. Polarity is ALL about the physics - negative and positive charges and so forth. This is just strong nuclear force, weak nuclear force, and electromagnetism.

        "Blob o' stuff. Negative charge is clumped over on that side of the blob. Makes it do funny things to the stuff around it!"
        • I did mention that cell membranes would be discussed in more detail later. The concept of selective permeability is crucial to terrestrial life.
      • what do you mean molecules are vanishingly uncommon?

        I don't remember much of my chem classes (and I had to take it three times to pass the lab portion in college) but I could have sworn that the really basic stuff went:

        Atom's are little solar systems and are the smallest things on our scale of reference (anything smaller starts to be universal and therefore can't be differentiated into something recognizable). Also, an atom is 1 of an element (where element is something that appears on the chart labeled periodic table of elements in the chem room). Only elements have atoms.

        If it's not an element, the smallest recognizable bit you can break it into is a molecule. And most of the elements also like to hang out in pairs, which are also molecules.

        Therefore, everything is made of molecules and molecules must therefore be like the most common thing in existence. Their kinda like the pixels on a computer screen - everything is made of them.

        So how can molecules be uncommon?

        Also, please verify that I'm correct in thinking that molecules are smaller than, and join up to make, proteins and nucleotides.
        • Molecules tend to cluster in clumps. While there are some loose clouds, they're not very dense and don't really have too many molecules to speak of. A big chunk of matter is of the WIMP variety (dark matter), and of course, most of the universe is empty space.

          Most living organisms that we know of are either WIMPs or structured EM interference patterns. A few are plasmas, which is the closest thing to molecule based life forms. They're at least "regular" matter.

          Humans are made out of matter which forms molecules which only exist in quantity in small outposts of gravitationally bound matter. In most of the universe there are no molecules, or what molecules there are are so spread out they don't do anything terribly interesting.

          One must admit that, even if we narrow our focus to just the terrestrial stellar system, most of the mass is not bound in molecules. It's highly energized plasma contained in the sun. Most of the space is empty.
        • Proteins, lipids, and nucleotides ARE molecules. They're rather large and complex ones.

          Molecules are made of atoms. Technically speaking, an atom is a VERY simple molecule, composed of only one atom. (The hydrogen molecule and the hydrogen atom are two names for the same thing.)

          In most parts of the universe, there is nothing, at least in terms of matter. Here and there a hydrogen atom, that's about it.

          In most parts of the hydrogen atom, there is nothing. There's a proton and a neutron at the center, and somewhere around the periphery, an electron. The relative distances dwarf the relative distances you find in a solar system. So even in dense matter, like lead, it's STILL mostly empty space.

          If our theoretical audience is not made of matter; if for instance, they inhabit the vast areas of vacuum between galaxies, they might ignore the rare hydrogen atoms as unimportant anomalies, and they've probably NEVER run into anything as complex as even water or methane unless they're really inquisitive and prone to exploring.

          And, whatever they're made of, if they inhabited the spaces between subatomic particles, they might not be aware of (or be only theoretically aware of) atoms, molecules, and the things they make up. It would be like us finding out that our galaxy is a single cell in a single person, and we're so vanishingly small and basic that we amount to something like a quark or a gluon...
          • Erg wait. Does hydrogen even have a neutron? Nope.

            Me = fail! :p
            • Depends on the isotope. Deuterium is Hydrogen with one neutron. Tritium is two neutrons. I don't think there are any larger stable isotopes.
              • Oh yeah, can't believe I forgot about that. That's what I get for not having taken a science course in a DECADE.

    • I agree that polarity is very simple and even people like me (who is possibly too proud of having figured out that nucleotides are the stuff that DNA and RNA are made of before googling and checking wikipedia) can understand polarity. After all, we've all got magnets on the fridge. We may not really understand why they work, but we know *how* they work.

      So, these nucleotide things, do plants have them too? I'm thinking it could go either way, since t3knomanser called them proteins, and you don't get protein in significant amounts from most plants (but you do from some, like legumes, so maybe plants do have them).

      Oh, and t3knomanser, given the rest of this thread here, you should s/lipid/fat/ - I was pretty sure lipid was a fancy word for fat, but from what I'm able to pull from wikipedia, "lipid" is more like "fat" than "nucleotide" is like "protein".

      • Plants have plenty of proteins! For instance, they have enzymes and hormones just like us, both of which are proteins. Nutritionally speaking, plants aren't an ideal source of protein because
        1. you have to eat a lot of plant matter to satisfy human dietary requirements from protein
        2. you have to combine different kinds of plants to get all the kinds of protein you need (often legumes and grains, for instance, beans and rice or beans and corn.)

        Similarly, plants also have nucleotides. Nucleotides are the "building blocks" of DNA and RNA. All life on earth reproduces itself using DNA and RNA. (Some viruses only have RNA; everything else has both.)
        If plants and animals didn't share the same genetic language, genetic engineering tricks, like making a tobacco plant glow like a firefly's butt wouldn't be possible. http://en.wikipedia.org/wiki/Image:Glowing_tobacco_plant.jpg

        In fact, plants and animals sometimes have identical genes that code for identical proteins (such as hormones and enzymes.) The biochemical parallels between plants and animals are what make plants useful as a source of drugs.
  • *Engage Silly Mode*

    Your audience wants to abduct you and give you an anal probe so they talk to your symbiotes, the REAL intelligent life on this planet. ; )
  • http://www.nytimes.com/2008/05/23/science/23gene.html?em&ex=1211688000&en=f50b7a016640c414&ei=5087%0A

    somewhat related articel
    • Hah, that's cool. There's always some new critter we didn't know about before making it self at home on our body.
Powered by LiveJournal.com