Intelligence on Earth Evolved Independently at Least TwiceNEWS | 14 May 2025The findings emerge in a world enraptured by artificial forms of intelligence, and they could teach us something about how complex circuits in our own brains evolved. Perhaps most importantly, they could help us step “away from the idea that we are the best creatures in the world,” said Niklas Kempynck, a graduate student at KU Leuven who led one of the studies. “We are not this optimal solution to intelligence.”
Birds got there too, on their own.
Pecking Disorder
For the first half of the 20th century, neuroanatomists assumed that birds were simply not that smart. The creatures lack anything resembling a neocortex—the highly ordered outermost structure in the brains of humans and other mammals where language, communication, and reasoning reside. The neocortex is organized into six layers of neurons, which receive sensory information from other parts of the brain, process it, and send it out to regions that determine our behavior and reactions.
In the 1960s, the neuroanatomist Harvey Karten’s research into avian neural circuits changed how the field viewed bird intelligence.
“For the longest time, it was thought that this is the center of cognition, and you need this kind of anatomy to develop advanced cognitive abilities,” said Bastienne Zaremba, a postdoctoral researcher studying the evolution of the brain at Heidelberg University.
Rather than neat layers, birds have “unspecified balls of neurons without landmarks or distinctions,” said Fernando García-Moreno, a neurobiologist at the Achucarro Basque Center for Neuroscience in Spain. These structures compelled neuroanatomists a century ago to suggest that much of bird behavior is reflexive, and not driven by learning and decision-making. This “implies that what a mammal can learn easily, a bird will never learn,” Güntürkün said.
The conventional thinking started to change in the 1960s when Harvey Karten, a young neuroanatomist at the Massachusetts Institute of Technology, mapped and compared brain circuits in mammals and pigeons, and later in owls, chickens, and other birds. What he found was a surprise: The brain regions thought to be involved only in reflexive movements were built from neural circuits—networks of interconnected neurons—that resembled those found in the mammalian neocortex. This region in the bird brain, the dorsal ventricular ridge (DVR), seemed to be comparable to a neocortex; it just didn’t look like it.
In 1969, Karten wrote a “very influential paper that completely changed the discussion in the field,” said Maria Tosches, who studies vertebrate brain development at Columbia University. “His work was really revolutionary.” He concluded that because avian and mammalian circuits are similar, they were inherited from a common ancestor. That thinking dominated the field for decades, said Güntürkün, a former postdoc in Karten’s lab. It “sparked quite a lot of interest in the bird brain.”
“We are not this optimal solution to intelligence.” Niklas Kempynck, KU Leuven
A few decades later, Luis Puelles, an anatomist at the University of Murcia in Spain, drew the opposite conclusion. By comparing embryos at various stages of development, he found that the mammalian neocortex and the avian DVR developed from distinct areas of the embryo’s pallium—a brain region shared by all vertebrates. He concluded that the structures must have evolved independently.
Karten and Puelles were “giving completely different answers to this big question,” Tosches said. The debate continued for decades. During this time, biologists also began to appreciate bird intelligence, starting with their studies of Alex, an African gray parrot who could count and identify objects. They realized just how smart birds could be.Author: Reece Rogers. Yasemin Saplakoglu. Eric Morgan. Molly Taft. Caroline Haskins. Fernanda González. Will Knight. Sandro Iannaccone. Stephen Ornes. Anna Lagos. Source
