Life

Top left clockwise: lichen on rock, hawk on street light, autumnal trees, grasses, plants, cheeky squirrel 

Top left clockwise: chipmunk (also cheeky), moose, duck, the same hawk, milkweed

Most people would consider all those things to be living things, but what do they have in common that makes them "living" and how do they differ from these things

Top left counterclockwise: minerals at the School of Mines in Golden, Colorado, cabbage rolls, fire (too close to my fingers), water worn arcose sandstone pebble, water from our tap

 things that people consider non-living like rocks and fire and tornadoes and steaks and (and this is a really tough one), viruses.

Animals are animated....they move around under their own volition. It's no coincidence that the two word, "animal" and "animated" are similar. In classical Greek thought, the soul (animus) is what animated animals. An animist is a person who believes that everything possesses soul (or spirit, those two words tend to be rather nebulous in meaning, sometimes interchangeable, sometimes not) but they don't usually require motion, just some kind of self recognition. The closely related panpsychic is a person that believes that everything has consciousness.

Animation might be regarded as a characteristic of living things. Even plants move in relation to light. But a lot of things move. Air and water move, generally in response to gravity, but plants and animals also move in response to other things. Fire spreads. Maybe movement isn't a good choice for something that's fundamental to life.

These problematic things that I listed above: rocks, fire, tornadoes, steaks and viruses......maybe they have to display a set of characteristics to qualify as "living", what Wittgenstein called a "family resemblance.

Not long ago, most people who even thought of such things were vitalists. They believed that living things were living because they possessed a mysterious energy that animated them, but the more people studied living things, they first found that the chemicals that percolated through living bodies, organic chemicals, could be produced from inorganic chemicals through regular chemical changes, and that life seemed to emerge from chemical reactions.

Over time, scientists came up with a list of characteristics that qualified things as "living". Here they are:

1. Living things grow. They take materials out of their environment and make it part of themselves.

2. Living things reproduce. They create similar things to themselves with important modifications  

3.  Living things respond to their environment.

4. Living things use and emit energy using chemical reactions called "metabolism.

5.  Living things maintain their internal state within tolerable limits. That's called "homeostasis".

6. Living things evolve. When they make copies of themselves, they do so to adapt their kind to their environment. They tend to create offspring that work better than themselves 

The mineral crystals grew into the form they display in the School of Mines museum, but any internal change of state is driven by outside influences. 

The cabbage roles used to be alive but they can't create other cabbage roles by themselves. They'll never produce seeds like the cabbages they once were . If they're hot, it's because the air around them heated them. They can't maintain a constant body temperature.

The fire uses fuel to transform chemicals into heat and it grows and can even split into more fires, consuming as they go. But they can't maintain an internal state that allows them to just keep going.

The rock and the water are at the mercy of their environment. They can't protect themselves.

These are the things I'll be looking at in the future. 

Go outside and look around. Do you see all the living things? Are you missing anything? Did you notice the fungi in the soil beneath you? What about yourself? You carry a world of living things around with you.....tiny mites that clean your skin and hair of microorganisms, bacteria in your gut that help you digest your food.....Did you look under the rocks? Look closer.