This year, io9 brought you in-depth explainer stories on topics ranging from physics and history, to cognitive science and the politics of teaching evolution in schools. Here are 23 of the most exciting ones which you may have missed.

These are our best features of the year. You can also check out our stories about 2013's biggest scientific news and breakthroughs.

How 19-Year-Old Zack Koppelin Is Making Life Hell for Louisiana's Creationists

8 Incredible Facts You May Not Know About Human Evolution

Americans — Why Do You Keep Refrigerating Your Eggs?

This Tiny Wearable Patch Makes You Invisible to Mosquitoes

Wine Tasting Is Bullshit — Here's Why

The 12 Cognitive Biases That Prevent You From Being Rational

What the Death of the Sun Will Look Like

The Worst Lies You've Been Told About the Singularity

Gay Marriage in the Year 100 AD

Why Does Coffee Make You Poop?

9 Ruined Cities That Remain a Mystery to this Day

The Mysterious Law That Predicts the Sizes of the World's Biggest Cities

The Science Behind What Makes an Introvert and an Extrovert

This Is Why You Aren't Sleeping Right

Why Do We Have Sex at Night?

What Is the Purpose of the Universe? Here is One Possible Answer.

Has Humanity's Explosion Become a Population Bomb?

Why You Should Starve Yourself a Little Bit Each Day

Where Memes Really Come From

Why We Should Switch to a Base-12 Counting System

The Evolutionary Biology of Star Trek