First Branch on the Tree of Life

Scientists have discovered which animal was the first to branch off from our collective common ancestor.

For years, debate had raged over whether the first to diverge was the sea sponge or the comb jelly.

Thanks to new chromosomal analysis techniques, we finally have an answer.

All animals on Earth share a common ancestor. Trace back the history of any creature from humans to slugs, and you’ll eventually be able to follow all of the branches on the animal tree of life back to its trunk.

But that trunk had to branch off at some point, or we wouldn’t have all of today’s animals. And that first split has been a bit elusive to scientists, due to it taking place around 600 million years ago.

We know a few things, though. Namely, we know that the first split resulted in the birth of two creatures—the ancestor of almost all animals, and the “sister” to that ancestor. That sister is the ancestor of just one group of modern-day animals.

For decades, scientists have debated which group of animals traces its lineage back to the “sister” of literally all other animals. They had two contenders for a long time—sea sponges and comb jellies.   READ MORE...