Scientists will grow small amounts of tissue, known as brain organoids, from human stem cells that have been edited to contain "Neanderthalized" versions of several genes. "The lentil-sized organoids, which are incapable of thoughts or feelings, replicate some of the basic structures of an adult brain," reports The Guardian. "They could demonstrate for the first time if there were meaningful differences between human and Neanderthal brain biology." From the report: The latest work focuses on differences in three genes known to be crucial for brain development. Using the editing technique Crispr, changes have been introduced into human stem cells to make them closer to Neanderthal versions. The stem cells are coaxed using chemical triggers to become neurons, which spontaneously clump together and self-organize into miniature brain-like structures that grow to a few millimeters in diameter. The lack of any sensory input means the internal wiring is haphazard and varies from one blob to the next. The scientists will compare the Neanderthalized organoids and the fully human ones to assess the speed at which the stem cells divide, develop and organize into three-dimensional brain structures and whether the brain cells wire up differently. The work won't reveal which species is "smarter," but could hint at differences in the ability to plan, socialize and use language.