Welcome to Quantum Magazine's podcast.

Each episode we bring you stories about developments in science and mathematics.

I'm Susan Vallett.

The neocortex stands out as a stunning achievement of biological evolution. All mammals have this swath of tissue covering their brain,

and the six layers of densely packed neurons within it

handle the sophisticated computations and associations that produce cognitive prowess.

Since no animals other than mammals have a neocortex, scientists have wondered

how such a complex brain region evolved. But now, they might have a clue. That's next.

Quantum Magazine is an editorially independent online publication supported by the

Simon's Foundation to enhance public understanding of science.

The brains of reptiles seemed to offer a clue to how the neocortex of mammals evolved.

Reptiles are the closest living relatives of mammals.

Their brains have a three-layered structure called a dorsal ventricular ridge, or DVR,

with functional similarities to the neocortex.

Or in the words of evolutionary and developmental

biologist Maria Antonia Tosquez.

It's really interesting because reptiles are the only other vertebrates, other than mammals,

that have a part of their brain that is defined by classical neuroanatomists as a cerebral cortex.

For more than 50 years, some evolutionary neuroscientists

have argued that the neocortex and the DVR were both derived from a more primitive feature

in an ancestor shared by mammals and reptiles. But now, by analyzing molecular details

invisible to the human eye, scientists have refuted

...