The originality of ‘new’ scientific ideas is often disputed. Whatever you come up with, someone will say that somebody somewhere has said it before. It is probably true that several people had the idea of natural selection before Darwin, but did not elaborate the concept, back it up with substantial evidence, or write about it eloquently enough to make anyone pay much attention. Equally, the Copernican revolution in our view of the solar system – from Earth-centred to Sun-centred – was re-enacting a similar shift in Chinese thinking that occurred centuries earlier. So, what of the ‘new’ ideas put forward in this book? Do I claim that there are any, and if so, am I right? In particular, do I claim that my ‘biased embryos’ approach is novel? I'll try to answer these questions shortly.

For the benefit of any readers who have jumped ahead to the final chapter from somewhere near the outset (the ‘book as a thick mud sandwich made with deliciously fresh bread’ syndrome), and for revision purposes for everyone else, here is a single-paragraph re-cap of the ‘biased embryo’ view of evolution.

Natural selection is not the ‘main’ orienting agent of evolution as Darwin claimed. Rather, it is one partner in an interacting duo that is the main determinant of the direction of evolutionary change, inasmuch as ‘main’ is a meaningful term in a multilevel process extending all the way from molecular changes in genes to mass extinctions. The other partner is developmental bias; that is, the tendency of the developmental system of any creature to produce variant trajectories in some directions more readily than others.