FRAGMENT FROM NATURE continues from last weekend in the final section on the reversal of speciation. When I first read about this topic, it was like reading a type of heresy, a new theme quite unknown to me, and so contrary to the Darwinian viewpoint I had been brought up with. Frankly, it was shocking. The undoing of some sort of rigid linear passage of living things, compelled to forward motion, or extinction. But a reversal backwards to an earlier state?