B(e)eing Part of Something Bigger – Social structures in the hive

Though an essay on the evolution of social structure in honeybee hives, this will simultaneously be an introduction to the most Darwinian man since Darwin himself. His name is Bill Hamilton and it was his idea (based on a paper from the Golden 20s by J. Haldene) that inspired the writing of and scientific basis for Richard Dawkins’ “The Selfish Gene”. Just on a side note, the 1970s paper by Hamilton, which Dawkins based his bestselling, award winning, revolution of a book, was titled “Selfish and Spiteful Behavior in an Evolutionary Model”. A coincidence where word – choice was involved? Dawkins fails to mention this similarity in his extraordinary lengthy introduction to his book. Without going out on a limb in terms of implications, I am sure Dawkins would like me to make sure credit is given where credit is due.

Yes, academia can be a bit of a kindergarten when it comes to the basics of refined interactive social behavior and because of the monstrosities academia throws at its employers in the form of dogmas and bureaucracy, Hamilton was almost lost to science in the first years of university. The young man struggled on during his undergrad years at the University of Cambridge and stayed true to his love and fascination for evolution, despite the nagging feeling that none of the teaching biologists lecturing there actually believed in evolution. One of the few scientists with respect for interdisciplinary research, he took part in a course in social anthropology to balance his interest in genetics and biology. He was rebuked and later ignored by his lecturer for inferring that human behavior might not be purely a product of culture, but also a product of genetics. The older a core belief system, the less likely it is to adjust its content, and being ignored by your superior is never a good thing to happen to you, no matter what field you work in. Young Hamilton nearly left academia in disappointment at the rejection. But for whatever reason (maybe a friend persuaded him to stay one late night over a beer or a time traveling, screwdriver – wielding alien brainwashed him, we will never know for sure, especially if it was an alien), Hamilton stayed and turned his attention to the problem of how altruistic behavior was able to evolve.

Bees, or at least a minority of them, live in eusocial societies, in which they have perfected the art of supreme inequality and yet harmonious living side-by-side. Except for the queen and the occasional rebel, the hive is made up exclusively of female bees that care for the brood, defend the hive, forage and take over the role of the hive janitor for several days in their lives instead of passing on their genes. Yet they do not complain, not one bee seems to questions the role they have been appointed and help their (Gelée) royal(e) mother raise thousands of sterile clone sisters.

Such eusocial behavior is truly the pinnacle of organization in an animal society, but the evolution of the behavioral trait wasn´t questioned till Hamilton appeared on the scientific stage. Back in 1859, when Darwin finally plucked up the courage to publish his biological manifesto “Origin of Species”, he failed to question the development of eusociality, and only pondered the question of how sterile workers were able to evolve specific traits when they weren´t able to lay eggs. For example, workers in a hive have brood glands, with which they feed their ever-hungry, white and wormy baby sisters. How can it be possible to develop such a physiological tool if you can´t pass on your genetic mutations that have made your brood glands just a wee bit superior to your sisters if you´re incapable of breeding? A tricky question indeed, but not the one we´re trying to wrap our heads around today. (The answer though can partly be found in the biochemistry of bees and that will be given more of an insight into in next weeks post.)

Sociobiology – the biology of social behavior – leapt unto the elegant explanation Hamilton able to offer: the “Kin Selection Theory”. This theory is based on how related siblings and offspring are to one another. The higher the relatedness ration, the more inclined relatives are to help one another raise each other. It can be summed up nicely in the equation:

c < rb

This translates to: The cost of an action should be less than the benefit to the receiving party times the level of relatedness between everyone involved. If I am a bee and losing my stinger (and internal organs and a few minutes later: my life) will be of a bigger benefit to all of my sisters back home (because this way I prevented a greedy bear from killing half of the hive and stealing all of our food), I will be more likely to do this the more related I am to everyone back home. If I´m related to them only 0,1%, that would leave the benefit in the dust compared to what it would cost me and I´d be hardpressed to give up my stinger for insects that I share nothing but a species name with.

But female bees have an unusually high relatedness ratio between one another. The biology behind this is, that bees are haplodipoid. This means, that males are born from unfertilized eggs (haploid), whereas females are born from fertilized eggs and have 2 sets of chromosomes (diploid). This can lead to some interesting riddle games you can play at home. Question: Which animal can never be a father, but – at least biologically – will be a grandfather himself to a couple of grandsons? Answer: A haploid male (bee, ant, or even a thunderbug – I love that name. It sounds like Zeus could once more not control his hormones and this time Hera turned someone into a bug instead of a cow. Io and behold the origin of the thunderbug!). Back to the relatedness ratio: haplodiploidy makes it possible for the female siblings to not be 50% like their sister, but 75% percent like them, if their mother mated with only a single male. If the workers had any offspring, they themselves would be related to their babies by only 50% – a bit of a step-down compared to helping your sisters raise more sisters. The gene wants to live on, selfish as it is, and therefore opts for compliance and eusocialty. Rebellion would be absolute nonsense, because the time a bee puts into raising her sisters is spent much more wisely than following her own dreams and reproductive ambitions in terms of reproduction.

As elegant as this explanation is, equations are always a rarity in the biological field, so naturally biologists get more excited about them than they should at times. In the past 5 years a lot of controversy has sprung up concerning the kin selection theory. Brothers, for example, shouldn´t be raised by their sisters by this line of thinking, because they´re as related to sisters as a son would be to the female workers. Multiple matings, which are common in most bee species, mess up the 75% ratio and also discredit the theory.

Yet until Darwinian natural selection, backed by empirics and mathematical evidence, can claim back its title for the most refined theory to explain the evolution of such high levels of organization, we are left to wonder how such levels of supreme inequality and harmony were able to develop in a eusocial bees world.

BeesinessThe pun in this comic was created by the brilliant mind of. E.H. (yes, Ernest Hemmingway speaks to me from the grave), a silly man with a creative head on his shoulders (which he should turn on occasionally when close to shore and strapped to a paraglider).


Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s