In “Defining ‘species’ is a fuzzy art” (SN: 11/11/17, p. 22), Susan Milius asked scientists to define “species.” Schoolbooks may define the concept as a group of organisms that create fertile ...

Thank you for publishing Malcolm G. Scully’s “Are You a Lumper or a Splitter?” (August 16, The Review). The issues are by no means limited to birds. ... A great many of my colleagues around the very ...

Colin Barras discusses chimp evolution being shaped by sex with bonobos and describes them as “close relatives” (2 June, p 4). When I studied biology many years ago, I was taught that organisms ...