Honey bee swarming is an amazing phenomenon that occurs once every year, where two-thirds of the colony will depart from the hive, 'led' by the queen bee, to settle on a nearby branch for several hours, before heading off in the direction of their new nesting site. In each step of this process, there are detailed decision-making mechanisms that occur, which when interpreted correctly, can shine a light on the ways in which humans should carry out decision-making. Firstly, I will describe the process of swarming, before going on to evaluate its importance in primate decision-making.
The swarming season will begin soon after days begin to turn warmer: it must be warm enough that the colony will not lose a lot of its energy source (honey) while swarming, however, it must be early enough that the colony has time to locate a suitable nesting cavity, occupy it, build a set of beeswax combs, and store provisions to last winter. Unfortunately, starvation due to not having time to fulfil these tasks is one of the principal reasons for colony death throughout winter. Beekeepers address this through the quote 'A swarm of bees in May is worth a load of hay, a swarm of bees in June is worth a silver spoon, a swarm of bees in July isn't worth a fly'. In order to prepare for swarming, the queen bee will rear around 10 queens (redundancy), through the construction of queen cups, laying eggs, and feeding of royal jelly. It is important to note that the queen bee is genetically identical to its worker bee counterpart: the only difference is the food they are fed: worker bees are fed a mixture of pollen and nectar in comparison to the royal jelly of the queen. Throughout this period, the queen is fed less and less, her egg production declines, thus her abdomen shrinks, and workers begin to gently shove, push, and even bite her. This causes the queen to be constantly walking around, in order to try to avoid these aggressive actions. This all causes her to lose around 25% of her bodyweight, so that she has the capability to fly (she has not been able to do so since this time last year), while the worker bees increase their bodyweight by 50% through ingesting honey as a food reserve.
Once the hive decides to swarm (scouts will press their thoraxes against other bees, producing vibrations to inform workers to warm their flight muscles, and scouts bees will perform 'buzz runs'), they will settle on a nearby branch, which is when the main decision-making mechanisms occur. By creating bait hives that have different attributes, it is possible to find the most important characteristics that colonies differentiate between in swarming. Research has shown that bees prefer nest entrances that are small, high above the ground, and open in the bottom of the nest cavity. This is because small entrances can be defended easier, and will isolate the nest from the outer environment. High entrances mean that the hive will be less likely to be discovered by predators (i.e. bears), and entrances at the bottom help minimise loss of heat by convection currents. The volume of favoured nesting sites is usually at around 40 litres, which balances the need for a large space for storage of honey, and the need for a small space for efficient thermoregulation of the hive. The main units for swarming are scout bees, which are specialised and older worker bees. They will investigate prospective nesting sites, spending 13-56 minutes doing so. They use this time to make 10-30 journeys around the inside of the site, with brief periods outside between each journey, examining the exterior of the nest structure. If this site is desirable, they will revisit it at half an hour intervals, spending on average 10-20 minutes doing so. When inside the site, she will rapidly walk across inner surfaces to measure the volume in a cavity, which is proportional to the amount of walking completed to circumnavigate it (each step is a measurement). It is important to note that a honey bee will not think consciously about a site, however, her decision-making will occur through a nervous system which integrates various sensory inputs relating to characteristics of nesting sites.
Bees' debates will start slowly with an accumulation phase, where numerous alternatives are suggested by scouts (sometimes a few are suggested late into the swarming process). The way in which nesting sites are proposed to the hive is through waggle dancing. This is a form of communication between honey bees (also used in nectar/pollen foraging), where bees will move on the surface of the swarm making certain movements which encode certain information. The duration of the dance is directly proportional to the length of the outward journey (one second representing 1km on average), and the angle of the dance relative to upwards represents the angle of the outward journey relative to the direction of the dance. Other scouts on the surface of the swarm will follow the waggle dancer, copying her movements, to decode the dance and put the instructions into action. There are two levels of the intensity of the dance, firstly the number of dance circuits produced under a certain period of time, and next the physical intensity/excitedness of the dance. High desirability of the nesting site will lead to a higher period of time waggle dancing with a higher intensity while doing so. Scouts will only visit one site before either waggle dancing or not (site fidelity), so they do not have any other site to compare it to. However, in some mechanism that is not yet fully understood, they judge the absolute quality of a nesting site through an innate scale of 'site goodness', which is crucial in the way swarming functions (dispersal of scouts to different sites). A honey bee proposing a site which is favourable will lead to a higher chance of another scout following the dance, and thus visiting it, simply due to a greater amount of time dancing. This leads to a positive feedback loop occurring, where the propositions of a site are amplified mainly due to the length it is being proposed for through a waggle dance. Although there will remain some leakage of honey bees going from advertising the site to neutral as they do not think the site is of a high enough standard, the best site will still stimulate the strongest dances, thus there will be the greatest success per capita in converting neutral into supporters. These supporters have the greatest success per capita in converting neutral bees into more supporters, so the support of the nest is exponential. Although there may be variation in the strength of waggle dancing of the same site from bee to bee, on a group level between different sites there will still remain a great strength difference. Scouts will walk randomly on the surface of the swarm and follow the first dance they encounter, showing once again that the number of dance circuits that are done for a site at any one time is the main characteristic that sets apart a favourable site from a non-favourable site.
However, even though a scout may advertise a potential nesting site with high levels of excitement at first, she will eventually cease to dance for it. This may be due to an internal neurophysiological process that causes every scout to gradually lose motivation for a site. This helps dancers reach unanimity quicker, as this makes them highly flexible in support of nesting locations. However, this does not contradict the previous paragraph, as the more excited a bee is for a certain site, the more dance circuits she will complete, and hence the longer it will take for her to lose interest in the site. This highlights the first key difference between human and bee debates, where humans are often stubborn and will stick to their opinion in contrast to bees which lose interest in their side over time. This method will only succeed if all organisms apply themselves to it, as otherwise, certain individuals can take advantage.
Nearing the end of the debate, certain 'piper bees', essentially excited scout bees, will produce a piping sound by activating flight muscles in their thorax to create strong vibrations in their body. This correlates to the warming of the mantle of the swarm so that the outer bees can begin to warm their body temperatures above 35 degrees Celsius so that they have the ability to fly once again. Once all the bees in the swarm have a body temperature the same as or higher than this, the swarm will immediately takeoff in the direction of the nesting site. At the same time, buzz-running bees will run across a swarm cluster in various directions with outspread wings whirring and buzzing, either dashing over the backs of bees or bulldozing through them. Research has shown that the piping of scout bees triggers the activity of buzz-running bees, who are also piping bees, and their numbers will increase closer to the takeoff of the swarm. This buzz-running is a ritualised form of a bee’s takeoff behaviour which has become modified over evolutionary time to have a purpose (incidental). The current hypothesis for understanding how swarms know when to take off is that scouts run across the swarm quickly, measuring the temperature of bees by pressing their thorax against another, and when other bees' thoraxes are constantly above the required temperature to takeoff, then buzz-runs will occur more and more until the swarm will takeoff. In this way, a small minority of individuals collect information about the global state of the swarm, and when the swarm reaches the critical state (constantly bees have a high enough body temperature), then the signal is produced that triggers an action by the entire group.
Therefore, piping triggers the mechanism which leads to the takeoff of the swarm, and thus piping means that the honey bee scouts have resolved their debate, and chose a nesting location. Scouts will start piping when around 20-30 scouts are seen at a site (of an approximately 10,000 large colony), which means along with the scouts in favour of a site that are either waggle dancing, at the site or in the air, there are around 75 scouts in favour of the site. Bees at each site will monitor numbers (suggesting that bees vote for a site by spending time at it as well as waggle dancing) so it is known when the threshold number has been reached. Although it may seem peculiar that bees do not partake in consensus decision-making, this enables them to strike a balance between accuracy and speed in their decision-making. If a swarm was met with two very similar nesting locations, and was constantly debating between both, without a unanimous decision agreed on, honey stores would be lost while the swarm hangs on a branch, increasing the likelihood that they will starve throughout the winter. Likewise, the still high value of 75 scouts in favour of a certain site for piping to start means that there is a low likelihood that a poor location will be chosen, still allowing for high accuracy. Once all bees have a body temperature higher than the critical state, the swarm will suddenly lift off in the direction of its new nesting site.
This fascinating process of decision-making throughout the various steps of swarming can not only be marvelled at but also compared to the primate brain, where both entities have been shaped by natural selection to acquire and process information to make decisions. In both swarms and brains, sensory units will create a representation of the outside world in a system (competition between integrators of information) and the decision is made when the accumulated information in one integrator reaches a certain threshold. Once this decision is made, in swarms, piping will occur, leading to the liftoff of the swarm, and in brains, motor neurons will fire to drive a specific behavioural act. It is no surprise that evolution has built intellectual strength in colonies and in primate brains utilising similar methods of information processing which involves the optimal crossover between accuracy and speed. These behavioural decision-making schemes will have led to a higher chance of survival / offspring produced, thus being passed down to offspring. Therefore it may seem evident that these decision-making methods, which have been honed by evolution for 30 million years in the case of honey bees, will prove to be more successful than current decision-making that occurs by humans in courts, town halls, or simply between a group of friends. Therefore we can implement certain characteristics of honey bee swarming into these situations in order to optimise the decision-making that occurs here.
Firstly, it is important to note that honey bee colonies are composed of individuals who all have a mutual interest in picking the best nest: if the colony does not survive then their genes will not get passed on. Therefore, wherever possible, it is necessary that the individuals of which a group is composed will have the same shared interests in providing the best solution possible under the given timeframe. Secondly, honey bee decision-making is fully democratic between scouts (which make up 3-5% of the population), with no one individual imposing their opinion more than another. Although many think that the queen bee plays this role and is 'in charge' of the colony, other than releasing pheromones to ensure that the colony stays surrounding her, she plays no role in the decision-making process. In the same way, there should be no 'leader' in the human group, and if there must be, then they should aim to stay neutral and not release their opinion. The group should also be large enough to deal with the problem that it faces, where scouts make up 300-500 decision-making units. There should be a range of individuals with different backgrounds, opinions, experiences etc. so that all alternatives can be considered, similarly to which scouts will visit several different nesting locations in the 'information accumulation' phase. Finally, it is important to have a balance between speed and accuracy, and thus swarm decision-making will state that unanimity is not required to reach a decision. This will prove even more significant in the case of humans, as it is perhaps 'human nature' for certain individuals to be more stubborn than others and not be willing to be flexible. If a consensus is needed (as in the case of juries) then speed is highly compromised, and the time of all involved in the court case will be lost simply because of one or two individuals. In conclusion, humans should use the power of debate and foster good communication between individuals by listening critically to others.
Honey bee swarming is a highly intriguing phenomenon with several mechanisms, some of which have not been fully understood as of today. Therefore it requires further research to fully describe its mechanisms, which can provide further thought for the ways in which humans conduct decision-making.
Information that allowed me to write this article was collected mainly from the book 'Honeybee Democracy' by Thomas Seeley, which I highly recommend due to its logical nature in the ways the author went about his research on honeybee swarming. I hope you enjoyed this blog post, and keep posted for the next!
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