Why Is All Life Carbon-Based?

Feb 17, 2013 By Sarah Charley

You’ve probably heard the phrase “carbon based life” or “organic molecules” tossed around at some point in your life.  But what does “carbon based life” truly mean?  Are we really made out of that black charred stuff left over after a campfire, or the carbon (aka graphite) inside pencils?

The short answer is…yes!  Carbon atoms form the “backbone” of almost all the important biological molecules floating around in our bodies (except water, of course.)  Therefore, when we say life is “carbon based,” we mean that our skin, hair and cells are all made out of molecules that contain large amounts of carbon.

But what is carbon?

Courtesy NPR

Carbon is an element, one of the 118 elements listed in the Periodic Table of Elements.  Everything we are familiar with -- you, me, the air, the ground, plants, animals, minerals -- are made up of atoms. 

There are 118 different types of atoms, but only a handful of these different types are actually important in our everyday lives.  In fact, about 97% of the human body is made out of only six elements — carbon, hydrogen, nitrogen, oxygen, phosphorous and sulfur, also nicknamed the “CHNOPS” elements.  The rest of the human body is an eclectic mixture of minerals and metals: calcium (in our bone and teeth), iron (in our blood), potassium, sodium, zinc etc.

But why carbon?

Let’s get to the true question here—why is life carbon based, and not based off of one of the other 118 elements?

Out of all the elements on the periodic table, carbon is arguably the best at bonding. Carbon loves bonding, and it is not picky about who it bonds with.  Carbon will bond with any of the “CHNOPS” elements, and it will bond with other weirder atoms, like zinc and iron. 

Oxygen and some of the other CHNOPS elements can form bonds as well. But what makes carbon unique is that it can bond with other carbon atoms to create long carbon chains and rings. No other element is capable of forming molecules as large and complex as carbon based molecules (think about it—without carbon chains and rings, there could be no DNA!)

Also, most carbon-based molecules are very stable and will not spontaneously fall apart. But they can also react to make new molecules. Our bodies need to be able to digest the compounds we consume (aka food) into small and simple tidbits, so that biological processes can then “click” and “snap” these tidbit back together into useful molecules. Carbon based molecules are strong enough that these small and simple tidbits will stay intact, allowing our body can arrange and rearrange them into useful molecules.

It is no wonder then that carbon-based molecules are the best suited to sustain life.  Life is complex; therefore, life molecules need to have the capability to be complex as well!

For more information, see my blog post on Inside NOVA: “Finding Life Beyond…Carbon?”

normanzhaopvz   35 weeks ago


Iron Boy (not verified)   2 years ago

Very Nice And Easy To Understand

Rayan1   2 years ago

very intresting!!

DJrockid   3 years ago


sylviaf2   3 years ago


chingling   3 years ago


carsonl3 (not verified)   3 years ago


greta   3 years ago

Very interesting! i like it :)

lori101 (not verified)   3 years ago

that was a very intresting awsomeeee

happy (not verified)   3 years ago

this was awesome!

7-em   3 years ago

Hehe that's cute:) with the picture and the heart up there :) yes this stuff is intresing to learn about :)

Jessa   3 years ago

Haha I loved the video

Great article!

really girl1202 (not verified)   3 years ago

i liked the video

mylovely26196725 (not verified)   3 years ago

nice video

kristinas (not verified)   3 years ago


889988 (not verified)   3 years ago


tileyc2 (not verified)   3 years ago

i think that is verry interesting cause that carbon is in your body and i found this at para 4 and it said "thats it in your bones and teeth and that iron and your blood" thats what i thought was interesting.

austind   3 years ago

I learned that your body is made up nof six elements.They are carbon, hydrogen, nitrogen, oxygen, phosphorus,and sufur. They are also kown as chnops.

tristanm (not verified)   3 years ago

Carbon Dioxide with Oxygen can be very important to people and animals.

loganm10 (not verified)   3 years ago

Very interesting

FuzzUzzle (not verified)   3 years ago

Very interesting! I'm learning about molecules and atoms now. It's really cool. I haven't learned anything about the elements, though.

Tressa   3 years ago

Are you homeschooled?

FuzzUzzle (not verified)   3 years ago

Yeah. Are you?

Tressa   3 years ago


Tryn28   3 years ago


To add comments...


Carbon “backbone”

People will sometimes say that a molecule has a carbon “backbone.”  But what is a carbon backbone?  To understand this, we need to know a little about molecules, and specifically, organic molecules.  Molecules form when atoms bond together to make larger structures.  

An organic molecule is a molecule that is created—or theoretically could be created—by a living organism. Sugar, DNA and fat are all organic molecules.  Quartz, graphite and plastic are not organic molecules.  Most organic molecules have a carbon backbone, meaning that their structure is made up of carbon atoms bonded to other carbon atoms. There are still other atoms in the molecule, but without the structural support provided by carbon, the entire molecule would all fall apart.