The enthusiastic response to my latest book, Where Song Began, has been gratifying, but I have noted that a couple of reviewers, while praising the book, hesitated over a core conclusion – that the world’s songbirds had their origins in Australia. One reviewer described this as a ‘suggestion’ as if it were just a bold theory waiting to be proved or disproved by proper evidence. That is not really the situation.
An Australian origin for the songbirds (oscines) has become the consensus position in science because the evidence is so strong, coming as it does from three sources: genetics, fossils and anatomy.
A vast number of genetic studies, using many different genetic sequences, have shown that lyrebirds are the most divergent of all songbirds, and Australian treecreepers and bowerbirds are the next most divergent. The immense genetic differences between these birds (and Australian scrubbirds, which are seldom included in the genetic studies) and other songbirds outside Australia imply that these birds last shared a common ancestor a very long time ago. It is difficult to imagine where that ancestor might have lived if not in Australia. If we were to use the language that was acceptable 15 years ago we could describe Australia as a hotspot for ‘primitive’ songbirds, and that makes it the only plausible place of origin.