Photo: NASA

Evolution is everywhere — including in the news! That's why each month we publish a new Evo in the News feature on our Understanding Evolution website. This month, we focus on oxygen as an evolutionary constraint. When life began 3.5 billion years ago, all organisms were tiny. Today, earth has some pretty big inhabitants, like the blue whale and the giant sequoia. Learn how the amount of oxygen in the atmosphere opened the door for the evolution of these big organisms. Read the latest Evo in the News story, oxygen as an evolutionary constraint!

Click here to read more Evo in the News stories.