Some ants can choose to live 5x as long

A discussion of gamergate(s)

It’s been a trying week for anyone who cares about the state of science in the US. Trump 2.0’s approach to US institutions seems somewhere in between “burn it all down” and “turn everything off and see who complains”. I hate this approach. I am the first one to champion the need for reform at federal institutions, including scientific institutions, but not like this. If your house’s foundations are shaky, you need to shore them up, but knocking down the house is not a good solution. There are people living there!

Anyways, I don’t want to turn this whole post into a rant, because I don’t think I can add much to the discussion besides my angst. I’m going to keep on working on my cat drugs and try to get a new dog drug off the ground. Hopefully, this stuff will figure itself out by the time we look for approval.

In the meantime, I wanted to go back to a topic I’ve addressed quite a few times in a few different ways: insulin. As you might recall, I have a lot of questions about insulin, obesity, and longevity and the commonly assumed relationship between them. Cavefish are my favorite example of how mistaken our traditional story about insulin and obesity is. When fish that live in streams get trapped in caves, they can rapidly (likely within a couple generations) become obese, insulin resistant, eyeless, sedentary, and exceptionally long lived, as I’ve written about before.

Well, I have a new cool example of how weird the connection between insulin and longevity can get, and this time, it also ties in another crucial life activity: reproduction. It comes from ants, specifically Indian jumping ants, or Harpegnathos saltator. These jumping ants are unlike most ants in that they live in small colonies consisting of males, the queen, and female, non-mating workers. When a queen dies or is removed from the colony, the females “duel” by hitting their antenna against each other, sometimes for months, until several females emerge victorious and replace the queen as the egg bearer. These pseudoqueens are called gamergates ¹.

An Indian jumping ant carrying a flower. It is unlikely that it is a gift to his love, but I choose to believe.

In all ant colonies, queens live longer than workers. Likewise, in jumping ant colonies, both queens and pseudoqueens, or gamergates, live longer than workers, about 5x longer (200 days vs. 1000 days). But, in most ant colonies, queens are physically different than workers, often being larger and winged. I can make some sense out of them living much longer than workers, given that they are physically different. But gamergates start off as workers. It’s just that the hormonal changes wrought by the duels results in their drastically increased lifespan ².

But the weirdness with gamergate life extension doesn’t stop there. Not only do gamergates have a drastically increased life expectancy when they become the pseudoqueen of a colony, but that increase in life expectancy can reverse when gamergates are themselves removed from a colony and placed in a new jumping ant colony with an active queen. Gamergates then go back to being normal female, non-mating workers with the life expectancy of an average worker ³.

This is intriguing for a couple different reasons. First of all and most obviously, this is not how we normally think of lifespan working. It’s weird enough for individuals within a species to have such dramatically different lifespans, but to be able to choose how long your lifespan is is very weird ⁴. It’s also very weird for lifespan to be so elastic, in that a single ant can go from a 200 day lifespan, to a 1000 day lifespan, back to a 200 day lifespan with no obvious repercussions, except perhaps a slightly decreased lifespan from stress upon the reversion. But it’s also intriguing because it brings in reproduction into our discussion of lifespan, which, in turn, will bring back insulin again (don’t think I’ve forgotten).

Beyond the paywall, a bit more musing about insulin and reproduction, as well as wrapping up the discussion of the paper.

Reproduction is intimately linked to lifespan. Many animals, such as female octopuses or all salmon, die after they reproduce. Castration and sterilization are linked to a longer lifespan in many species, including dogs and, possibly, humans. Many reasons have been proposed for this, such as reduced tendency for risk-taking in males, reduced risk from childbirth in females, or reduced risk of cancer in reproductive organs for both males and females.

But this gamergate paper suggests a deeper connection, leading through insulin. Insulin production in gamergates’ brains seems to be a big part of what triggers their switch to an increased lifespan and their increase and interest in reproduction⁵. Physiologically, this makes sense, as egg laying is energy and lipid-intensive, so gamergates need to use their insulin systems to start gathering more fat and energy in general.

The only issue is that gamergates would then seem to be the exception to the rule. Instead of reproduction shortening their lifespan, it lengthens it, or at least is part of the same process that lengthens it. There’s some suggestion in this paper that the life lengthening has to do with blocking the effects of insulin in the “fat bodies” (liver equivalents) of ants, although the evidence and cause and effect is still somewhat murky. Likewise, the effects of injecting insulin into gamergates is also murky: it appeared to trigger egg growth in them, but decreased their propensity to duel.

So, instead of trying to untangle what exactly insulin has to do with lifespan and reproduction in ants or humans, I’ll just leave this as another weird example of how lifespan and insulin interact.

1. Presumably at least once in the world, an entomologist and a sociologist have met who both study gamergates and have very confused ideas of what the other one does.

2. My source for most of the info in this blog is this paper.

3. That is, they then have about 200 days to live from the time of their reversion, regardless of how long they’ve lived as a pseudoqueen.

4. “Choose” might seem to be a weird word here, but that does seem to be a component of winning the duel. Any ant that doesn’t want to become a pseudoqueen and have an extended lifespan can choose to lose or leave the duel. Of course, the reverse doesn’t hold true, given that winning the duel isn’t simply a matter of choice.

5. Non-mating females naturally produce a few eggs. Gamergates produce more eggs, and they also actively participate in “nuptial flights”, where they go out and seek to be fertilized by male ants from other colonies.