Could we grow resistant to our contraceptives?

gypsy_rose

Just a silly musing here, is there any chance that we could evolve to grow resistant to our own contraception (e.g. the pill) like the way bacteria grow resistant to antibiotics?

Improbable

I don't see why not. From a biochemical standpoint, if there were a series of mutations which caused a dysfunction in the mechanism which the contraceptive pill acts on, then that would mean the pill would become ineffective. Then taking it up from an evolutionary standpoint, if this was not realized as occurring over the long term, then people who had that mutation would be more likely to pass on such a mutation to the next generation.

Though take care to note that even though this could happen, this isn't the usual mechanism by which bacteria obtain antibiotic resistance. There is a lot of horizontal transfer of plasmid DNA which occurs in bacteria. It's thought that this horizontal gene transfer between even distantly related bacterial species is what mainly gives rise to antibiotic resistance more so than mutation effects.

Well this is mainly speculation, but I think there's many reasons why it wouldn't happen.

1. Time. Humans don't develop resistance to medications the way bacteria grow resistant to antibiotics. Bacteria evolve quicker than us because of their plasmid DNA, but for humans to develop a resistance to something, it would take an incredibly long time. I'm talking so long that we'd probably already be extinct by then.

2. Plasmid DNA. We don't have it. We have less mutations than bacteria and way more DNA (as far as I know), and most of our mutations are the kind that don't affect us at all, so we're far less able to adapt genetically to something than bacteria (ties into the whole time thing). The chance of having such an influential genetic change through a chance mutation is very low.

3. Hormones. Contraceptive pills act on hormones, and contain them. The system of hormones that lead to a woman becoming fertile/infertile at certain times are both complex and very old. For contraceptive pills to not work, we'd have to develop a bypass for the system of hormones a woman's body uses to become fertile. A system that's survived as long as our system of reproduction isn't likely to change so easily. It takes far more than one or two genetic mutations.

4. Survival of the fittest. It's easy for a resistant bacteria to survive because the other bacteria in it's habitat who aren't resistant die. This leaves it with free reign to replicate and use resources without having to compete with non-resistant bacteria, leaving it's habitat eventually filled with only resistant bacteria. Contraceptives don't affect our survival. While it could be argued that there's going to be higher birth rate in contraceptive-resistant groups, they'll still have to share resources with non-resistant people, so the % population resistant won't rise much.

In a case more like when you take painkillers too often and they stop working, I don't think that wouldn't happen either. The painkillers thing is that your body adjusts to the painkillers and the cells/receptors become less sensitive to them. This wouldn't happen with contraceptives because they use hormones naturally found in the body which we're used to and at levels which our bodies wouldn't need to adapt to try to cope with. Any possible resistance would be a long term, genetic thing, which (as above) is unlikely anyway.

Wow, that was long.

Improbable

The OP is more concerned about whether it COULD happen as opposed to whether it WOULD happen.

true-or-false wrote: »

Well this is mainly speculation, but I think there's many reasons why it wouldn't happen.

1. Time. Humans don't develop resistance to medications the way bacteria grow resistant to antibiotics. Bacteria evolve quicker than us because of their plasmid DNA, but for humans to develop a resistance to something, it would take an incredibly long time. I'm talking so long that we'd probably already be extinct by then.

Doesn't mean that it couldn't happen.

true-or-false wrote: »

2. Plasmid DNA. We don't have it. We have less mutations than bacteria and way more DNA (as far as I know), and most of our mutations are the kind that don't affect us at all, so we're far less able to adapt genetically to something than bacteria (ties into the whole time thing). The chance of having such an influential genetic change through a chance mutation is very low.

We are however affected by retroviruses which are another method of horizontal gene transfer.

true-or-false wrote: »

3. Hormones. Contraceptive pills act on hormones, and contain them. The system of hormones that lead to a woman becoming fertile/infertile at certain times are both complex and very old. For contraceptive pills to not work, we'd have to develop a bypass for the system of hormones a woman's body uses to become fertile. A system that's survived as long as our system of reproduction isn't likely to change so easily. It takes far more than one or two genetic mutations.

Again, doesn't mean that it couldn't happen. It wouldn't take as large a set of mutations as you might think to throw it off. We would not need an entirely new basis of reproductive cycle for the pill to become effective. A relatively simple upregulation or deregulation of some of the protein receptors or an increase in signal transduction induced by mutations in any part of the pathway could change the system.

true-or-false wrote: »

4. Survival of the fittest. It's easy for a resistant bacteria to survive because the other bacteria in it's habitat who aren't resistant die. This leaves it with free reign to replicate and use resources without having to compete with non-resistant bacteria, leaving it's habitat eventually filled with only resistant bacteria. Contraceptives don't affect our survival. While it could be argued that there's going to be higher birth rate in contraceptive-resistant groups, they'll still have to share resources with non-resistant people, so the % population resistant won't rise much.

Doesn't mean that people couldn't become resistant or immune to the contraceptive.

true-or-false wrote: »

In a case more like when you take painkillers too often and they stop working, I don't think that wouldn't happen either. The painkillers thing is that your body adjusts to the painkillers and the cells/receptors become less sensitive to them. This wouldn't happen with contraceptives because they use hormones naturally found in the body which we're used to and at levels which our bodies wouldn't need to adapt to try to cope with. Any possible resistance would be a long term, genetic thing, which (as above) is unlikely anyway.

Partly right and partly wrong. The painkillers can become less effective due to feedback mechanisms altering the amount of expression. But it has nothing to do with whether the receptor agonist or antagonist is naturally occurring or not. So it's conceivable (if you'll excuse the pun) for a contraceptive to generate a similar response.


It's extremely unlikely. And yes, it would take a very long time, but it is entirely possible. Nothing in our current understanding of biology and evolution prohibits it. Just not exactly in the way bacteria get antibiotic resistance.

gypsy_rose

Thanks for your detailed answers, I don't know enough about it to be able to think through it properly the way you obvioulsy do so it was good to read them lets hope it doesn't happen!

AtomicHorror

gypsy_rose wrote: »

Just a silly musing here, is there any chance that we could evolve to grow resistant to our own contraception (e.g. the pill) like the way bacteria grow resistant to antibiotics?

Via evolution? Only if there is a selective advantage in favour of this happening, and a mechanism by which gene products might overcome said contraceptives.

When you think about it, there certainly is an obvious selective advantage. People upon whom contraceptives do not work (or merely work less well- which is the case in the real world) will tend to produce more offspring than those who do not. So in terms of population, they will out-compete those who use contraceptives in most imaginable circumstances. Whether there are plausible mechanisms whereby our genes could make this happen is another matter. Latex degrading enzymes, changes to hormone regulation patterns, gross morphological changes to the sex organs... all things that could plausibly circumvent various kinds of contraceptive- so again, this is possible.

The problem is, even relatively simple evolutionary changes tend to take millennia to occur and spread through a population of slow breeding organisms like humans. By contrast, we can innovate with technology on the decade time scale, which is at least a couple of orders of magnitude faster than we evolve. As true-or-false mentioned, this is where the analogy to bacterial resistance really breaks down. Humans don't evolve at a rate comparable to our technological development, whereas bacteria do.

Overall, it's unlikely that we'd evolve to overcome contraceptives in general, but almost certain that we'd evolve to overcome some specific examples of such technology if they were in use on humans over a sufficiently long time-scale- though that itself is also very unlikely.

darjeeling

Taking the case of the pill, it's not impossible that resistance could evolve (as pointed out above). However there are plenty of factors against it happening at all, and becoming a problem if it ever could. Some are biological and some are to do with behaviour. Some I can think of off the top of my head are:

Contraceptive pills mimic hormones regulating the human pregnancy cycle, so anyone resistant to the pill will likely also have difficulty becoming pregnant.

By and large people choose to use contraception and do so for economic reasons; they don't have it imposed on them. I don't think people would just resign themselves to going back to huge family sizes if one form of contraception failed them.

If the pill became ineffective there would be major socio-political impetus and a huge financial incentive to develop a new one.

There must be more ...?