Two neuroscientists have tapped into what may represent a fundamental difference in brain development between people and other mammals.
If the findings hold up, they'll offer insight into how humans evolved an enlarged frontal cortex capable of supporting symbolic thought and language use, conclude Kresimir Letinic and Pasko Rakic of Yale University School of Medicine.
Researchers have identified many commonalties in how brains of various animal species develop. In contrast, facets of brain growth unique to any one species, including humans, have been elusive.
"There must be small differences between brain development in humans and in other animals," Rakic says. "These small differences can have a big functional impact on how the brain works."
In 1969, Rakic and his coworkers first used brain slices from human fetuses–obtained following second-trimester death–to identify remnants of a stream of neurons that traveled from the telencephalon to the