UNNATURAL CONSTRUCTIONS - Making Sense of Nature - page 122

how metaphor is used,
it works by invoking one meaning system to explain or clarify another. The first
meaning system is apparently concrete, well understood, unproblematic and
evokes the familiar; in linguistic theory it is known as the 'source domain'. The
second 'target domain' is elusive, opaque, seemingly unfathomable, without
meaning donated from the source domain.
(Smith and Katz, 1993: 61)
Gene maps, as one commentator puts it, 'represent the relative and abso-
lute positions of genetic sequences on the 23 pairs of chromosomes that sit
within the nucleus' (Hall, 2003: 152). However, they are precisely not the
same as conventional maps in that they don't comprise graphical represen-
tations of a microscopic territory, country or city with a scale, key or grid
coordinate system. Mapping, therefore, is very much a metaphor for represent-
ing genes, not a literal description of the representational process or eventual
product. And yet , as Smith and Katz note, all metaphors are nonetheless
intended to point to some real (or imagined) similarity between the source
and target domains - they enable substantive comparisons to be made . 10
In light of this, we can ask what it is about the source domain that
has made the map metaphor so widely used in presentations of molecu-
lar biology leading up to and since the completion of the HGP. As several
commentators have suggested, it's surely that we normally take maps to be,
indeed, positively expect them to be, accurate depictions of landscapes that we
could only perceive directly if we were flying high and looking down. In the
words of one geographer,
people rely on the map as an accurate representation of the world under
scrutiny. The power that maps exert in society is bound up with the impres-
sion of exactitude and precision that they convey.
(Livingstone, 2003: 154)
The metaphor of a 'genetic map' thus signifies the search for, and achieve-
ment of, truthful representation. It trades on the idea of mimesis and
correspondence, and it implies facticity. 11 In contrast to conventional maps,
the need for genetic maps arises not from the fact that the 'landscape' is too
large to perceive without a representational aid, but on the contrary that it
is much too small .
Is mapping a fitting metaphor for discussions of human genes, gene
sequence and the genome? It depends on whether one chooses to take the
conventional understanding of the source domain at face value. In daily life,
most of us would do, wouldn't we? After all, if my A-Z city map or my car's
sat-nav system get me to my destination, then I have no reason to ques-
tion the assumption that maps belong to the meta-genre of 'realist' forms
of representation. However, over the past 25 years, several historians and
geographers have shown convincingly that, in Denis Wood's memorable