Greg O'Brien (left), with Colleen, Mary Catherine, Conor, and Brendan O'Brien, has been grappling with Alzheimer's disease for the last five years. Courtesy Greg O'Brien hide caption

toggle caption Courtesy Greg O'Brien

If you need empirical information about what is happening in the brain of a dog to know that dogs think, then either you've never met a dog or your own humanity is in doubt. hide caption

toggle caption