Ancient Genome Duplications Laid the Foundations of Complex Brains
16th June 2026
New findings, published today (10 June) in Nature, help to answer the riddle of how vertebrates evolved the diverse array of brain cells that distinguishes them from other animals. It appears that a dramatic expansion of the genetic toolkit more than 450 million years ago enabled the emergence of different kinds of brain cells. These cellular innovations are shared across vertebrates – from primitive fish to mammals – and form the basis of the sophisticated brains seen today.
By comparing the gene activity of single brain cells across five species, including humans, mice, lizards, lampreys (a primitive, eel-like fish) and amphioxus (one of our closest invertebrate relatives), the team reconstructed how brain cell types evolved over deep time. They found that many of the major cell type families in vertebrate brains arose after a genome duplication event in the common ancestor of vertebrates roughly 520 million years ago. A further genome duplication (around 500 million years ago) then added to this.