Re: poly: The Handicap Principle

From: Hal Finney <>
Date: Mon Jun 08 1998 - 14:33:18 PDT

Robin Hanson, <>, writes:
> "The Handicap Principle, A Missing Piece of Darwin's Puzzle",
> by Amotz Zahavi And Avishag Zahavi, Oxford Univ. Press, 1997.
> The most powerful conceptual tool in the information economist's
> tool kit is "costly signaling". It was been used to understand
> dozens (at least) of types of economic phenomena since its
> celebrated theoretical elaboration in the mid 70s.

I found this book at the library. To give a better idea of what it is
about, here is how the introduction begins:

"We start with a scene of a gazelle resting or grazing in the desert.
It is nearly invisible; the color of its coat blends well with the desert
landscape. A wolf appears. One would expect the gazelle to freeze or
crouch and do its utmost to avoid being seen. But no: it rises, barks,
and thumps the ground with its forefeet, all while watching the wolf.
The thumps of the gazelle's hooves carry through the desert ground over
long distances; its curved horns and the dark-and-light pattern on its
face clearly reveal that the gazelle is in fact looking at its enemy.

"If the wolf comes nearer, one would expect the gazelle to flee as
fast as it can. But no again: often the gazelle jumps high on all
four legs several times and only then begins to run, wagging its short
black tail against its conspicuous white rump, which has a black border.
These high jumps are very clearly linked to the approach of the wolf.
Yet a gazelle escaping immediate, urgent danger - such as hunters in a
jeep - flees in an entirely different manner: it runs away silently at
great speed, making good use of the topography to conceal its escape.

"Why does the gazelle reveal itself to a predator that might not
otherwise spot it? Why does it waste time and energy jumping up and down
(_stotting_) instead of running away as fast as it can? The gazelle is
signalling to the predator that it has seen it; by 'wasting' time and by
jumping high in the air rather than bounding away, it demonstrates in a
reliable way that it is able to outrun the wolf. The wolf, upon learning
that it has lost its chance to surprise its prey, and that this gazelle
is in tip-top physical shape, may decide to move on to another area;
or it may decide to look for more promising prey."

I've only read the first 20 or so pages, but the book is well written
and has many provocative examples. The authors don't shrink from applying
their principles to human interactions, which adds interest but also makes
it easier to question their explanations.

It seems to me that they are overreaching in some cases, applying their
principle in ways which don't seem completely convincing. In the gazelle
case, bluffing is not possible because a sick or weak gazelle can't
jump high like a healthy one. But in other cases the authors describe,
bluffing could work, with the only consequence being that if the bluff
is called, the bluffer will then be at a disadvantage. If bluffing
is possible, it is necessary to call the bluff occasionally or else it
will become common. Perhaps the authors will discuss this further in
the rest of the book.

Received on Mon Jun 8 21:54:15 1998

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