Julian O'Dea said:

> If you refer to the recent Esch et al. paper in "Nature",
> you will see that the authors themselves, despite being
> dance language believers, see the problem.

They said no such thing.
They implied no such thing.
They did not even hint at it.

Here is a link to the paper, in Adobe pdf format, so all can read it.
http://www.klab.caltech.edu/cns186/papers/bee-dance.pdf

They did not even suggest any sort of "problem" that might
call "dance" into question as the mechanism used by bees
to communicate about forage sites.

In fact, by fooling the bees with "optical illusions", they verified
that the current interpretation of  "dance" is accurate, and that
recruited bees tend to go where the dances direct them, even
when the dancer has been "fooled".

By using odorless sugar solutions, they also added yet another set
of detailed and repeatable experimental results to the very tall pile
of results showing that "odor" is not required for bees to find a
nectar source, report that source to the colony, and recruit others
to travel to the same location.

They were even able to manipulate the environment with a tunnel to fool
the bees, proving that they clearly understood the mechanisms at work
in great detail, understood how to interpret the dances, and how to
use the dances to predict where the recruited bees would go.

> ...despite being dance language believers...

The phrase "dance language believers" is an unacceptable accusation
of bias.  The letter presents certain experimental results, nothing more.
The statements made are all well-supported by the data presented, and
the conclusions are conservative in light of the data presented.

> ...see the problem.

The word "problem" does not even appear in the letter.
What they actually said was:

    "Why did the recruited bees search at twice the
     distance we expected from the distance calibration
     curve of Fig. 1?..."

     "...in this series of experiments, the recruits also
     read the dances of tunnel bees like a human observer
     and responded accurately."

    "The fact that calibration curves are different for flights in
     the southern and northwestern directions implies that the
     distance calibration of a bee's 'odometer' is not absolute;
     rather, it depends on flight altitude and the nature of the
     landscape through which the bee flies. This is to be
     expected from a visually driven odometer. The flight path
     to control stations in the southern direction led up a slowly
     ascending hill. The 120-m control site was 10m higher than
     the hive, and the 450-m control site was 30m higher still..."

So, they saw no "problem", what they saw was that bees measure
distance based upon visual input, (optic flow), and will dance a
distance vector based upon that optic flow.

> As their data show, the "information" on distance contained
> in the dance varies hugely depending on the direction to the
> resources.

Again, they said NO SUCH THING!
Please re-read the letter!
What they said was:

     "...the distance calibration of a bee's `odometer' is not
     absolute; rather, it depends on flight altitude and the nature
     of the landscape through which the bee flies."

The "direction" was nothing more than the position of their
tunnel in various tests.


> So, the authors write, "... there must be a high
> selection pressure to ensure that a dance signals the
> direction of the food source as precisely as possible."

Yes, they did say the above, but there is no implication in the
letter that this is a problem for "dance".  It should be obvious
that natural selection will tend to kill off strains of Apis that
cannot forage efficiently due to imprecise communication
about food sources.  It follows that, in a natural setting, bees
will, if left alone to survive or die on their own, get "better"
at precisely communicating dance vectors.

> However there is evidence that direction information is
> also not accurate (Vadas, 1994):

The paper by Vadas you cite can be read here:
http://www.beesource.com/pov/wenner/oikos94.htm
It is a mere editorial masquerading as a literature review.
It presents no new experimental results, it simply tells
once side of a long-winded story.  It uses terms and
phrases not appropriate in scientific dialogue, thus
revealing the author's lack of objectivity, such as:

  "...at best ignored, at worst chastized and censored..."
  "...battle of the personalities..."
  "...paranoid villain..."
  "...antagonism..."
  "...philosophical implications..."
  "...did not give up the fight..."
  "...philosophical perspective..."
  "...Kuhn..."  (mere mention of that person's name will
                     prove just how quickly one can be sent
                     to the trauma center with multiple contusions
                     by a group of mild-mannered, hard-working,
                     and physically unimposing scientists.)

Of course, one can talk about BOWIE Kuhn, Commissioner of
Baseball from 1969-1984, with many scientists and have an
interesting and friendly discussion.  :)

        jim