Skip to content
Series · Plants Are Not Innocent
Plants Strike Back
Episode 3 of 16
Back
Long Ago

Earth's first plants were purple

Turns out, green wasn't the OG color for all plants

By Smartasaurus· 1 min read Curious
Field test

Before the evidence lands — where do you already stand on this one?

Most people guess wrong here. Curious what you do.

The short version
  • Turns out, green wasn't the OG color for all plants
  • For perhaps a billion years, purple haloarchaea may have dominated Earth's shallow seas and shorelines, soaking up the green light and reflecting b…
  • If the story is right, the colour of every forest you have ever seen is a record of who came second.

Before Earth was green, it may have been purple — and the plants we have today are the survivors that lost the first round.

The hypothesis, proposed by microbiologist Shiladitya DasSarma in 2007, starts with a pigment called retinal. Retinal is the same molecule your eye uses to detect light, and it absorbs the green wavelengths the Sun delivers most strongly. It is also simple, ancient, and far easier to evolve than chlorophyll. The earliest light-harvesting microbes, DasSarma argues, would have used it — and a microbe full of retinal looks purple.

For perhaps a billion years, purple haloarchaea may have dominated Earth's shallow seas and shorelines, soaking up the green light and reflecting back the red and blue. When chlorophyll-based life finally appeared, it had to make do with the wavelengths the purple microbes weren't using — which is exactly the spectrum chlorophyll absorbs, and exactly why plants reflect green today.

More from Long Ago
The tiny patches of Earth that never spent a single day underwater

If the story is right, the colour of every forest you have ever seen is a record of who came second.

Certify this discovery

Two questions. Prove you actually read it.

Get both right and this discovery is certified: +50 XP toward your next rank. No account needed.

Sources (2) — tap to view
  1. 1.The Purple Earth hypothesis (International Journal of Astrobiology)
  2. 2.Retinal-based phototrophy and early Earth (Scientific American)
How did this hit you?
Free curiosity pack

100 questions that make people say “wait, what?”

Get the complete Ultimate Trivia Pack instantly. It is free right now, works on mobile, and is printable.

38-page PDF · Instant downloadGet the free pack
Forests with trees that walk and hunt
Up Next · Episode 4
Continue Series: Plants Strike Back

Forests with trees that walk and hunt

16 episodes left in this series
Play Next Episode
Comments — tap to join the discussion
Community

Discussion (0)

No account needed. Drop your name, say what surprised you.

Posting as a guest · sign in to keep a profile

Loading…