Editor’s note: The following is an excerpt from the newly released book, Animal Algorithms: Evolution and the Mysterious Origin of Ingenious Instincts, from Discovery Institute Press.
The minute dimensions of some animals’ brains are as astounding as the homing capacity of some of their owners.1Bernd Heinrich
Till now we have mainly focused on the navigational feats of various birds, but nature’s master navigators can also be found under water and among various insects. Let’s start small and work our way up to loggerhead sea turtles and then tie it all together by comparing the most impressive instances of animal navigation with the most advanced navigational systems on modern aircraft.
Approximately 3.5 trillion insects migrate annually just within the United Kingdom.2 The magnitude and scope of insect migration is impressive. So too is their steadiness of purpose in these long treks. It used to be thought that insect migration basically consisted of moving with the wind, in whatever direction it happened to be blowing, but research has shown otherwise. Studies of insect migration in the UK found that the direction of migration is consistently north in the spring and south in the fall, and the insects frequently fly in a direction different from the prevailing winds.3 Clearly these insect navigators have a purpose they are pursuing, wind direction be hanged.
Purpose and tenacity are common hallmarks of insect navigators. Take honey bees. They face many navigational difficulties related to foraging and establishing new colonies. In covering as much as 150 square miles around a nest,4 they use several methods of navigating, including visual landmarks, sun compass, and polarized light compass. Each is employed depending upon the circumstances. Under good visual conditions with sufficient references the bees navigate primarily by visual landmarks, while also maintaining the sun-compass information. On cloudy days when the sun is not directly visible they can use the polarized sunlight compass.
When a scout bee locates a good feeding source, it navigates back to the hive and communicates the location of the feeding source through what is known as a waggle dance. The Goulds call this curious dance “the second most information-rich exchange in the animal world,”5 second only to human language. That is quite a statement considering the communication is by insects with only 950,000 neurons, compared to humans with about eighty-five billion. Honey bee brains are less than one cubic millimeter in size.6 That is, a thousand of their brains together wouldn’t amount to even a single cubic centimeter. A curiosity is that honey bees have brains only about half the volume of bumble bee brains, yet exhibit a larger repertoire and more complex behaviors than bumble bees.7
While the details of the waggle dance are still not completely understood, a significant amount of research, starting with Karl von Frisch, has revealed the basic methodology. The behavior develops in adult honey bees who have emerged from the pupa stage and chewed through the protective cell to join the colony. Honey bees are able to interpret the dance after about one week. The development includes electrophysiological changes in brain neurons, evident when comparing mature foragers with newly emerged bees.8 Therefore, the behavior appears to be a combination of innate capabilities and pre-programmed learning.
To Do the Waggle Dance
The waggle dance consists of several elements that convey navigation information. The waggle itself is where the bee shakes its body at a rate of about 15 times per second. This occurs during the middle of a sequence where the bee movement is in the form of a figure eight. The orientation of the bee during the waggle portion of the dance conveys the direction of the food source. The way this is done is not straightforward. The orientation of the movement is relative to the vertical direction on the honeycomb wall in the hive. The angle between the direction of the dance and vertical represents the angle of the vector of the food source relative to the sun. If the direction of the food source is toward the sun, the dance orientation is vertical (regardless of what direction the sun actually is). If the direction is 40 degrees clockwise from the sun, the dance orientation is 40 degrees clockwise (or right) of vertical.
The dance and associated vector information are relative to gravity and not to Earth’s geomagnetic field, as some had speculated.9 However, the vector angle communicated in the dance is relative to the sun. This means that honey bees have a mechanism for detecting the gravitational field, although the exact mechanism is yet to be determined.10
The duration of the dance conveys the distance of the source, where one waggle run (in the figure eight) signifies a standard distance, which varies between five and fifty yards, depending upon the species. How the bee calculates distance is still to be determined. Some suggest it is based on optic flow, the progression of objects across the animal’s visual scene.11
In any case, the waggle dance communicates the full vector information (direction and distance) necessary for other bees to locate the food source. Another impressive aspect of the waggle-dance communication: it compensates for the movement of the sun over time. Thus, when the bees perform the dance and convey the vector angle leading to the food source, they adjust the angle based on the time of day.
A Most Complex Behavior
Everything about this behavior is complex. It starts with bee foragers being able to determine the distance and compass heading relative to the food source. The bees must then translate this information into a message they convey to other bees via the dance. Other bees in the nest then must be able to interpret this information and use it to navigate to the food source. How can their tiny bee brains manage all this? Australian biologists Andrew Barron and Jenny Plath note that despite bee researchers investigating the subject at great length, “We still know very little about the neurobiological mechanisms supporting how dances are produced and interpreted.”12
The temperate-zone honey bee waggle dance, it’s been postulated, may have evolved from the dwarf honey bee (Apis andreniformis and Apis florea), which resides in the tropics. Dwarf bees build their hives in the open with a nearly flat top. Their waggle dance is oriented directly toward the food source.13 Several decades ago Martin Lindauer proposed a similar process, where the complexity of the waggle-dance communication evolved incrementally.14
While these theories may appear reasonable at first blush, given the complexity of the behavior it is unclear how a Darwinian process can be a plausible explanation. There is a suite of individual capabilities and behaviors involved (including navigation, data processing, mathematics, and communication), requiring an engineering process as well as the development of computational algorithms, which are encoded in the brains of honey bees. Such information-rich programs are not known to spring up through a series of small, purposeless evolutionary steps, with or without the benefit of something like natural selection. And there is nothing approaching a detailed proposal, credible or otherwise, for how these complexities might have developed in the case of honey bee communication and navigation.