Meet LUCA, Our Last Universal Common Ancestor

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Do you know who your ancestors are? No matter who you are, you can claim LUCA as a long-lost relative. LUCA stands for "last universal common ancestor," and was likely the single-celled being from which all life on Earth originated. It's likely LUCA lived around 4 billion years ago, and it is thought to have spawned two groups of uni-celled life: bacteria and archaea. Scientists also believed that 355 protein families descended from LUCA.

The idea that LUCA was only half alive stems from a theory that LUCA was not capable of a function that is common to almost all living cells: sending ions across a membrane to create an electrochemical gradient. The being then uses that gradient to make an energy-molecule. Studies suggest LUCA couldn't generate the gradient, but could create the energy-rich molecule by using an existing gradient. This theory suggests the idea that the first life on Earth used the natural gradient between vent water and seawater for its energy.

LUCA Is The Last Universal Common Ancestor

Meet your long, long, long, long, long lost relative.

The Biggest Organism On Earth

Blue whales are the biggest animals, but the biggest living things are actually much bigger.

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Key Facts In This Video

  1. The most extensive living organism is a fungus that covers 2,385 acres in an Oregon national forest. 00:24

  2. The clonal colony of quaking aspens known as Pando weighs more than 40 blue whales. 01:05

  3. It's likely that some of the underground connections in Pando have become severed over time. 02:07

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