Saturday, April 19, 2014

Contributing to the common good: through taxes or labor

meerkets live in and defend multi-generational colonies
(here tracking the flight of a bird of prey)
They come in flocks and herds, packs, prides, and pods, as well as troops, swarms, gaggles, murders and colonies.

Many species of animals are social - they live in groups, recognize each other (by sight or smell), and work together to find food, avoid getting eaten, defend a territory, or care for young ones.

This week was Tax Week in the United States, so this post is in honor of hard-working people in the US who have just spent their hard-earned time figuring out whether, based on their hard-earned income and expenses, the government thinks they've contributed too little or too much during the past year for the broader society to function effectively.


note the gender distinctions in some social insects...
image: Mike Barfield
Here is a quick look at some other famously hard-working animals that give their all for the good of their societies.

While animals of all shapes and sizes live in social groups, insects are superb examples.

Ants, bees, wasps, and termites are well-known social insects: most species live in the tight quarters of their colonies of tens to thousands, living, working, and sacrificing together.

Have a look at this wonderful BBC video, which gives a sense of the rise, inner workings, and fall of a bee colony, our representative social animal for today. (Sorry, BBC won't let me embed it, but David Attenborough stars – can't go wrong!)

honeybees hard at work in tight quarters
photo: Alanna Spence
The colony begins with a single queen, who finds a suitable site, lays a few initial eggs, helps her first daughters -- the worker bees -- build the first few cells, and goes about her life laying thousands of additional eggs. From these hatch many new worker bees to build up the colony of up several thousand bees.

For me, the video gives new meaning to the phrase busy as a bee.

After they hatch, worker bees do just that -- they work to keep the hive functioning -- cleaning up, finding food, feeding and caring for larvae and young bees, etc.

The workers not only contribute their labor day after day, they also give up their own breeding potential for the good of colony stability.

honey bee returning with pollen attached to her legs
photo: Muhammad Mahdi Karim,Wikimedia
We love bees because their pollinate our crops, but when the workers actually bring protein- and energy-rich pollen back to the hive, they don't even eat it. Instead, they give it to the larvae, who are not their kids, so these future co-workers can eat it and grow strong and healthy.

Why don't these workers, who are all females, also breed and lay their own eggs?

They'd like to, as it would, of course, increase their biological fitness, but the queen produces a chemical (a pheromone) that prevents it by keeping the workers sterile. She also destroys the unfertilized eggs they do lay.

queens can be real tyrants
photo: Timeout-London
She's quite a tyrant, but the colony is doomed without her, since sterile workers cannot produce more workers (which develop only from fertilized eggs) – and they do all the work the keep the hive alive.

If she is aging naturally, the queen starts producing fewer pheromones and laying eggs in special, larger cells in the hive. Both processes signal the workers to start preparing for a new queen.

If the queen dies suddenly (or is killed by a worker mutiny, as in the video), the workers prepare existing eggs to be queens.

Newly-hatched larvae that are fed royal jelly, instead of pollen or nectar, develop into fertile females that can mate and lay the eggs that go on to produce a new corps of workers to keep the colony going.

larvae developing in queen cells with royal jelly
photo: Waugsberg, Wikimedia Commons

At this point, some workers might start laying (unfertilized) eggs that produce drones, but drones don't work, so the colony will die with the current generation of workers.

So does this mean that the queen is the only one that benefits in terms of fitness, by passing on her genes to the next generation? Nope. Evolution of social behavior is more subtle than that. Stay tuned for a discussion of inclusive fitness.


More on bees and social behavior


Some honeybee basics
How social behavior evolves, from Nature.com
The series of short videos on social behavior, from the BBC


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