| Did Radar Tracking of Bee Flight Paths Resolve the Bee Language Controversy? |
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10 June 2005 Ruth Rosin recognized that
element of the problem when she posted (6 June 2005) the following
comment (in part) on the honey bee e-mail network (BEE-L):
Two days earlier she had also
written to me (in part):
During the past 35 years, the dance language controversy has centered on the question, "Can someone prove a hypothesis true and expect that hypothesis to become a fact, a fact no longer open to question?" Bee language advocates would have us believe so. Those who study scientific process feel otherwise. We published the results of our double controlled and strong inference experiments in the late 1960s and 1970s, results that did not mesh with predictions of the dance language hypothesis (see below). Ever since then, research on honey bee recruitment to food crops has remained in a crisis state, with millions having been spent on efforts, in various series of experiments, to "prove," once more, that bee language is real. In each attempt, bee researchers have admitted that previous attempts had not sufficed - but did so only after they felt certain that their own efforts had succeeded. The recent radar tracking studies
of bee flight paths that left the hive is just one more in such
a series of attempted "proofs." On 14 October 2003
James Fischer posted the following statement on BEE-L, one made
by those involved in that radar research:
In the first few words of their 2005 Nature report, the radar tracking researchers also used the phrase, "the dance language" of bees instead of more objective phrases, such as: "the waggle dance," or "the dance maneuver." It became clear soon thereafter in their letter that they had started their experiments with the assumption that bee language is real and then had tried to prove it true (circular reasoning?). The renowned science philosopher Karl Popper would have been appalled at such a brazen and naïve approach. For instance, in 1957 he stated: "It is easy to obtain confirmations, or verifications, for nearly every theory - if we look for confirmations." In scientific experimentation, the easiest one to convince is oneself. That is why we need blind, double controlled, and other rigorous designs in experimentation - elements lacking in the present study. Background Information Karl von Frisch abandoned an earlier odor-search hypothesis and proposed his dance language hypothesis in 1946, a conclusion that rapidly became accepted nearly universally (including by me for my doctoral studies in the 1950s). That hypothesis provided a rational (though not exclusive) explanation about how newly recruited bees might manage to find a food source exploited by regular foragers. His interpretation morphed into the status of fact ("proved" or "discovered"), rather than remaining in people's minds the hypothesis that it was. What few appreciate today is
that von Frisch's language conclusion was at odds with his earlier
published results and conclusion; that is, recruited bees use
odor, and only odor, after leaving their parent colony in search
of the crops exploited by experienced foragers. In 1937, for
instance, he wrote:
For more information on that point, please access: http://www.beesource.com/pov/wenner/bw1993.htm The exotic notion of bee "language,"
though unproven and lacking rigorous experimental tests, eclipsed
von Frisch's earlier odor-search hypothesis. One prominent bee
researcher, H. Kalmus, held out. He wrote in 1960 (Simple
Experiments with Insects. Doubleday & Company, Inc.
Garden City, NY. p. 96):
That comment by Kalmus thus matched the firm conclusion von Frisch had published in 1937. Although I conducted my doctoral research in the 1950s with the belief in bee language, later experiments by my co-workers and myself yielded results clearly at odds with that hypothesis. A series of unfortunate and unexpected events (for example, see http://www.beesource.com/pov/wenner/aoac.htm) led us to execute rigorous experimental tests of the language hypothesis during the 1960s, the first such real tests ever conducted. (For clarification, experiments designed to gain support for a hypothesis do not count as tests.) The first set of experiments involved a double control design. Bees from one hive foraged at only one station in a set of four; bees of another color foraged at all four stations. In contrast to predictions of the dance language hypothesis, recruits from both hives ended up in equal proportions at the four stations, despite the wide disparity of information presumably provided by dancing bees in the two hives. For details, see: http://www.beesource.com/pov/wenner/scifeb1967.htm The second set of experiments involved only one hive. In that case, a constant set of marked foragers imbibed scented sugar solution at two stations for 3 hours each day during a 24-day period. All unmarked bees were caught and tallied during that period. On some of the days, we switched to unscented food at the target stations but provided the scented food at a third station. On those subsequent days, recruited bees ignored the dance maneuver information in their parent colonies and arrived, instead, at the third station where we had used scented food that had been provided on the previous day. For details see: http://www.beesource.com/pov/wenner/sci1969.htm Those sets of experiments are straightforward (with mutually exclusive designs) and the results should have been heeded. That did not happen. Instead, bee language proponents (by then, their numbers were legion) erred most seriously in two ways, errors repeated up to the present time: 1) Language advocates ignored
Karl Popper's caution: "Some genuinely testable theories,
when found to be false, are still upheld by their admirers -
for example, by introducing ad hoc some auxiliary assumption,
or by re-interpreting the theory ad hoc in such a way
that it escapes refutation." Back in 1865 Claude Bernard admonished against falling into such error: "[The experimenter] must never answer for [Nature] nor listen partially to her answers by taking, from the results of an experiment, only those which support or confirm his hypothesis." In short, during the past few decades, bee language advocates have repeatedly committed the error of only focusing on supportive evidence, while ignoring or discounting other evidence that does not fit within their "belief system." That is, only positive evidence counts. Flaws in "Proof" Experiments During the past few decades we have seen the same mistakes occur repeatedly; language advocates have sought and embraced supportive evidence and dismissed negative evidence in an almost pathological manner. Any new supportive evidence always received wide acclaim, with great fanfare in the media (the exotic sells). Manuscripts submitted in support of the language hypothesis became published readily. Grant proposals that might yield positive evidence received funding. In fact, during the past several decades, millions have been spent on efforts to "prove" the language hypothesis true, once and for all. Time in Flight and Success Rate for Searching Recruits First came the results of some experiments by three undergraduates (Gould, Henerey, and MacLeod) that actually yielded results that did not mesh with predictions of the language hypothesis. For example, they had marked with individual numbers a couple of thousand bees in the hive. They recorded 277 that left the hive after contacting a dancer. Of those, only 37 found either one of the two stations located in opposite directions from their hive. However, a third of those ended up at a station in the exact opposite direction from which the dance maneuver had presumably indicated the food location. Nevertheless, they concluded that attendant bees had used direction information obtained from the dancing bee. Despite that serious discrepancy, the journal (Science) would not permit us to publish a rebuttal (see: http://www.beesource.com/pov/wenner/EXC.htm). "Misdirection" Experiments Next came James Gould's "misdirection" experiments. By shining a bright light at an angle to dancers in the hive, he reportedly changed the direction of the dance maneuver. For his first publication in that series (Nature 1974), in support of bee language, he included the results of only three of the 33 half-hour runs he had run. While first hailed as "elegant," it later became apparent that the small sample sizes in his experiment and repeated publication of the results of his experiments in different display formats grossly exaggerated the importance of his contribution. Neither has anyone successfully repeated his experiments. Mechanical Bee Experiments After people finally became disenchanted with Gould's results, researchers in Germany and Denmark published (with much fanfare) the results they had obtained by use of a mechanical bee ("robot" bee). They also claimed that they had obtained the final resolution of the controversy. Once again, though, it became apparent that they had not resolved the matter after all. They had to use odor in their experiments in order to obtain recruitment. (Without odor, there is no recruitment, just as von Frisch observed.) In one experiment, two real foragers plying between hive and station resulted in 50 recruits showing up at the test station. By contrast, only two recruits finally arrived at the feeding station after numerous bees had attended a robot bee. Support for their conclusions gradually faded. It is no wonder that the honey bee dance language controversy has now persisted for nearly half a century. Others conducted less exotic studies during the past few decades and claimed that they had successfully resolved the issue of bee "language." As usual, though, they tailored their experimental designs toward gaining supportive evidence for the hypothesis - rather than conducting true tests of that hypothesis. Radar Tracking of Recruited Honey Bees The latest "high tech confirmation" experiments involved radar tracking of recruited honey bees. Once again we see the usual pattern: a small sample size, biased researchers, much media splash, and dogmatic conclusions. Never mind that the evidence doesn't fit the original hypothesis; they now considered that they had obtained "proof" of bee "language." In an interview with a science reporter for the San Francisco Chronicle, for example, the lead scientist of the radar tracking project was quoted as insisting: "'no really sensible person can come to any other conclusion' than that von Frisch was right." In their experiments the radar tracking researchers made some serious errors in approach. Consider some background. The researchers had some bees trained to fly out to a feeding station and saw them later dance. They followed a bee that attended such a dance, caught it as it left the hive, attached a transponder onto its body, released it, and then followed the path of that bee with radar. To conduct their study they embraced a number of assumptions: 1) That a bee attending a dancer
has the neurological/physiological equipment to obtain abstract
physical information from another bee. From the account published in Nature, it appears that some critical controls were missing, including: 1) Flight paths of bees that
had been similarly treated but had not attended a waggle dance.
That is, the reasoning seems to be: if the escaping bees fly off in the "right" direction (the only direction arranged for), then they have used their language. All of the above reminds me of a 1971 statement by Nobel Laureate Albert Szent-Gyorgyi (biochemistry): "If you know in advance what you are going to do, or even to find there, then it is not research at all: then it is only a kind of honorable occupation..." What do beekeepers think? What percentage of them accept the assumption that one can grab a bee, attach something to its body, release it, and then expect it to go on its way as if nothing had happened? In my experience, such a bee would fly an escape path and would not likely continue a presumably "programmed" behavior. Those interested in what recruited bees normally might do after leaving the hive, including search for an odor source can access: http://www.beesource.com/pov/wenner/az1991.htm That publication of ours contains several quotations by von Frisch that stand in sharp contrast to the observations and claims made in this latest Nature publication. Some other questions might have occurred by now to beekeepers and bee researchers: 1) What about the very small
sample size - can the behavior of 19 disturbed bees undermine
the results obtained from hundreds of unrestrained bees searching
for odor sources in our double controlled and strong inference
experiments? (And, note, only two bees showed up near the target
station in the radar tracking experiment after some unspecified
time delay.) Tracking recruited bees with radar to study their flight paths after leaving the hive is a noble goal, provided the bees have not been disturbed. Neither do results obtained without the use of odor have relevance to the language hypothesis (as pointed out by Rosin, above). Also, the experimenters should not bother to conduct research unless they can set aside any vested interest in the outcome; that is, that they should instead execute a true test of the language hypothesis and not attempt only to seek confirmation of their prior entrenched beliefs. As is usual in such a case, some reporters contacted me for my impressions of the Nature report. David Perlman of the San Francisco Chronicle recognized that I had not had time to study the publication and came out with a fairly accurate assessment in his article. Other reporters would not accept my explanation that I would need a few days to study the original publication, with a rather common comment: "I have a deadline to meet." No, I don't think that the behavior of 19 bees will resolve this controversy, one that has run now for well more than three decades. Nor will beekeepers benefit from the claims made in this latest effort. They can go back to worrying about varroa mites, small hive beetles, and other real problems with, hopefully, some real solutions appearing in the near future. Consider the money and time spent on this supposedly final solution to the bee language controversy! Wouldn't that time and effort have been better spent on breeding a varroa resistant bee, for example? Despite assertions by the radar tracking crew, the exotic bee language controversy will remain with us for quite some time to come. As stated at the outset, the controversy does not revolve about evidence with respect to validity of the hypothesis. The dance language hypothesis fails to account for all the available evidence with respect to the fundamental question: "How does a naïve bee find a target food source? Bee language advocates should
now address the really important question (how do they find food)
instead of attempting to prove a hypothesis. The favored hypothesis
continues to be elusive. Until they address the full role of
odor as first elucidated by von Frisch, we will continue at a
stalemate in the controversy (see: http://www.beesource.com/pov/wenner/jib2002.htm).
Adrian M. Wenner |