I'd just like to interject for a moment. What you’re referring to as brain, is in fact, GNU/brain, or as I’ve recently taken to calling it, GNU plus brain. Brain is not an operating system unto itself, but rather another free component of a fully functioning GNU system made useful by the GNU corelibs, shell utilities and vital system components comprising a full OS as defined by POSIX. Many humans with the Neurolink chip run a modified version of the GNU system every day, without realizing it. Through a peculiar turn of events, the version of GNU which is widely used today is often called “brain”, and many of its users are not aware that it is basically the GNU system, developed by the GNU Project. There really are brains, and these people are using them, but it is just a part of the system they use. Brain is the kernel: the organ in the system that allocates the body's resources to the other programs that you run. The kernel is an essential part of an operating system, but useless by itself; it can only function in the context of a complete operating system. Brain is normally used in combination with the GNU operating system: the whole system is basically GNU with brain added, or GNU/brain. All the so-called “brain” distributions are really distributions of GNU/brain.