1.2.2 Beware of seeking unknowable answers
What we would like to know about the past, and what we are
able to know about the past are two separate things. Some of
the answers we would like to find are quite simply
unknowable. It is useful to explore the concept of
‘knowability’ so that we can understand where these
boundaries lie. It would be futile to expend time, energy and
money on questions that cannot be resolved. Clearly, the
boundaries of knowability are not static: technological
innovation continues to ‘push the envelope’. For example,
before the advent of methods for sequencing ancient DNA,
the genetic divergence between Neanderthals and modern
humans was unknowable. Now we have a measure of this
divergence, for one locus at least (Section 8.7). Nevertheless,
despite recent advances that have brought this issue into the
realm of the knowable, many others, such as whether
any two extinct ape species were interfertile, remain
unknowable.