As Richard Feynman points out, every ‘why’ question in science needs to be treated with caution. This is because there are always several different levels at which a why problem can be answered, depending on what kind of response you’re looking for.

Taking Feynman’s illustrative example, if pizza arrives at your door and your partner asks why pizza has come, you could fully answer the question in any of the following ways:

1. Because I was hungry so I ordered pizza.
2. Because someone drove the pizza here from the pizza shop.
3. Because in a capitalistic society, you can exchange money for pizza.
4. Because I have UberEats on my phone, so I can order food whenever I’m hungry.

And so on and so forth. The same goes for why questions in biology – we can go pretty deep if we try hard enough.

So like any good 5 year old, in this article I’ll do just that and keep asking why until we get somewhere interesting.

Table of Contents

1. Bee stingers are fishhooks
2. A biological poison pump
3. Super-organisms, the immune system and colonial life
4. Group selection
5. Kin selection and biological altruism
6. Indirect fitness and the haplodiploidy hypothesis
7. The haplodiploidy hypothesis isn’t perfect
8. Conclusion

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Bee stingers are fishhooks

First, we need to be clear about what is actually happening when a honey bee stings you. Rather than a clean hypodermic needle, a honey bee’s stinger is actually covered in barbs.

Looks like a very fancy fishhook right? Except it’s more gruesome than a fishhook, because after a bee has stung you, it tries to fly away. The barbs keep its stinger in place and the result is the picture at the top of this article. Ouch.

So at a first glance, the answer to the main question is easy. A honey bee dies when it stings you because its stinger is covered in barbs, causing its abdomen to get ripped out when it tries to fly away. And surviving with your guts spilling out everywhere is pretty bloody hard.

But why on Earth would evolution have favoured such a suicidal mechanism? Isn’t natural selection supposed to favour survival of the fittest not survival of the suicidal?

A biological poison pump

If we take a look at the entire mechanism of the honey bee stinger we can begin to understand why this suicidal strategy is so effective.

Although the ripping out of the stinger does cause the bee to eventually die, in this process, a venom sack along with a muscular pump are also left behind.

Rather than just sitting in your skin like a static fishhook, the stinger continues to pump venom into your skin long after the bee has flown away. This is made possible by the autonomous muscles and nerves in this pump, which work independently from the rest of the bee’s nervous system. Up close in real life, this is pretty creepy and zombie-like.

If you don’t pull the stinger out, the pump will keep on delivering every last drop of venom right into your skin. This mechanism is much more effective in terms of ‘sting to volume of venom delivered’ ratio compared to the short prick of a wasp.

Though this is actually an interesting comparison, because to us, a wasp’s sting is just as painful as, if not even more painful than, a bee’s. Wasps can also sting you several times without dying, multiplying the pain, so what gives?

Why does a bee have to die via this complicated, suicidal venom-pump mechanism whilst the wasps seem to do just fine with their non-barbed stingers?

Super-organisms, the immune system and colonial life

A simple answer to that would be: “bees die to defend the colony.” Although compelling on the surface, this explanation would give a huge incentive for any individual bee to just hope that someone else sacrifices themselves other than them.

If you lived in a group of willingly sacrificial bees, it would be a very good strategy for you to be selfish and not sacrifice yourself. You can safely bet that someone else will take care of the cumbersome suicide, while you can kick back and enjoy the good life.

So why haven’t selfish non-barbed-stinger bees become the norm?

To dig deeper, we need to look not just at the anatomy of the stinger itself but at the broader reproductive biology of the honey bee.

As I’ve mentioned previously on the blog, honey bee colonies have a distinctive social structure with the queen doing all the reproductive work, the female workers carrying out the honey production and the male drones providing the matching 16 chromosomes to fertilise bee eggs.

Drones don’t do much for the colony besides that, and they don’t have stingers like the workers or the queen.

The key point here is that the worker bees are reproductive dead ends for the wider colony (though there are some exceptions). So from an evolutionary perspective, it doesn’t matter too much if they die, since they were never going to have kids anyway.

This does not mean that they are useless.

To see this, we can look at our own immune systems. For instance, immune cells inside your body known as neutrophils are just as suicidal as the worker bees. When bacteria invade your body, neutrophils migrate to the site of infection, unleash a whole cocktail of toxins onto the bacteria, and then proceed to die within 1-2 days.

In both cases, the suicidal nature of neutrophils and that of worker bees benefit the bigger entity that surrounds them. For worker bees, their death may save the colony from Winnie the Pooh, and the death of Neutrophils may save you from dying from a bacterial infection.

In both cases, the reproductive parts (the queen or the genitals) of each broader entity are preserved, whilst a disposable part (workers or neutrophils) which was never going to reproduce anyway, is destroyed.  And for natural selection to do its thing, all we need are the reproductive parts to stay intact.

This line of thinking really does lead us to think of honey bee colonies as single super-organisms. Workers are just the cells of the organism that aren’t going to have kids, so when they die, nothing too bad happens. Just like when you’re skin cells or neutrophils die, which happens everyday by the way.

More importantly, with this distinction made, the “defence of the colony” explanation can be made to work if we reframe it slightly in terms of “defence of the queen” or “defence of the genitals.”

This actually isn’t the full story because as I’m sure you’re aware, wasps also live in nests and so we could apply the same super-organism logic to them. Worker wasps ought to be just as dispensable as worker bees.

The reasons for why wasps are less suicidal than bees actually leads us down a different evolutionary path which we won’t touch. But in short