In on of the most influential pieces of environmental writing ever published, Aldo Leopold opened with this quote: "There are some who can live without wild things, and some who cannot. These essays are the delights and dilemmas of one who cannot."

I am also one who cannot. My name is Brit Garner, and I am obsessed with the natural world. On Nature League, we'll explore life on Earth together, and ask questions that inspire us to marvel at all things wild.

We're excited to bring you a different life on Earth theme each month, and each month we'll start with a brief lesson on the theme. So, let's get started!

[Intro]

This month, we'll start at the very beginning and ask ourselves what is life? Like, why is a rock different from a tiger? And, what's the deal with saying carbon-based lifeforms?

You might be able to come up with several answers to the first question. I mean, there are some pretty noticeable differences between rocks and tigers, right? But, in order to have a working understanding of what life is, scientists had to get pretty precise. So, let's get on their level, and check out these properties and processes that define living things.

Number one: Order. Living things are structured on almost every level, whether you're looking at the cellular level or zooming out to look at total body structure. This hierarchical, leveled, nature of living things is what allows them to exist in such amazing forms. 

Number two: Evolutionary adaptation. Living things change over time in ways that are adapted to the environment. Evolution is the mechanism that does it all! How incredible is change when you really think about it?

Number three: response to the environment. It's one thing to exist, and another thing to exist in response to your surroundings. It's a sort of deep concept, but the fact that a living think makes changes to itself in response to something else is unique to life. 

Number four: regulation. Goldilocks got it right, there really is that sweet spot that's just right. Living things have the remarkable ability of making changes to themselves in order to reach or stay in that perfect window of conditions, or homeostatis. 

Number five: energy processing. Living things take in materials and use them to create other materials. It might sound simple, but processes like photosynthesis are actually mind-blowing when you really think about it. 

Number six: reproduction. Sex, am I right? Or, not sex. Whether it entails getting it on or not, life finds a way to make more of itself, usually by means of passing on genetic material. 

Number seven: growth and development. Cells both divide and grow, meaning that living things get bigger over time. In addition to size, living things can develop into different forms throughout their lifespan. I mean, butterflies are caterpillars. What?

So what about carbon? Some of my favorite science fiction arguments are concerned with defining extraterrestrial lifeforms, and whether we would recognize and alien as alive even if it was made up of elements unlike any on our planet. This is a fun and friendly argument for a late night with friend, but life on Earth is inarguably made up of that amazing element carbon.

And, it's not just carbon on its own that's amazing, but rather carbon in combination with other elements. It's carbon's ability to bond with other elements that makes it the centerpiece of the macro molecules, or big pieces, of life on Earth. The four major macro molecules of life on Earth are, one, carbohydrates, two, lipids or fats, three, proteins, and, four, nucleic acids, like RNA and DNA. And, carbon is in the middle of all of them.

Now, the characteristics of life and carbon we've discussed here were taken from a single biology textbook. If you look around, you might find a few other characteristic, like living things are made of cells. It's totally fine if you learned a different group of life characteristics, or additional roles of carbon. The point is, what makes life life is pretty amazing, and I can't wait to explore these topics and more with all of you here on Nature League.

[Outro]