The Natural Selection of Altruism

The Natural Selection of Altruism

– [Justin] Survival of the Fittest. For many people, this phrase is synonymous with evolution. But we see in nature that sometimes creatures can act altruistically. Meaningfully hurting their own survival and reproduction chances to help others. In this video, we’re gonna
built some simulations to get a better understanding of which kinds of
altruistic strategies work and which don’t. (soft music) Alright, let’s jump right
in with the simulation. We’ll start with the world from the video on simulating natural selection. In this world, blob
creatures start each day at the edge of the world. In the morning, the food appears and the blobs go out to eat. The amount of food the blob finds before running out of
energy and returning home determines whether it dies, survives till the next day, or reproduces, passing its genes on to another creature, except that the genes might mutate. Now, let’s get the creatures the ability to be altruistic. Here’s how it’ll work. If a blob creature
finds two pieces of food and still has energy left, it can take one of two routes. It can look out for
itself and its descendants by deciding to go home
early and reproduce, or it can be altruistic. Risking its guaranteed offspring to go and give a piece of food to another creature who hasn’t eaten yet. And yeah, they regurgitated. Nature’s gross. At the beginning of our simulation, half of the creatures will have a copy of an altruistic gene
causing them to be altruistic every time they get the chance and the other half of
creatures will have copies of a competing non-altruistic gene. When we let this simulation run, what do you think will happen? Would the selfish creatures take over or will the altruists
triumph through teamwork? Or maybe they’ll stay mostly balanced. Pause here and make a prediction. Prediction made? All right. (soft music) Okay, well that was kind of sad. It turns out that unconditionally
sacrificing your offspring isn’t a great long term strategy. So, how can we give the gene
for altruism a better shot? Well, what if we make acts of kindness a bit less punishing to
the altruistic creatures. Say, by letting the creatures
keep some reproduction chance when they give their food away. 50% instead of the previous 0%. So the cost of giving food away is half of an offspring on average. Maybe the food was already
partially digested. Again, nature’s gross but ickiness aside, this makes the interaction net positive instead of just net neutral which is actually pretty
common in the real world. Okay, so let’s restart our simulation with this lower cost altruism in place. Now what would you predict? Hmm. (light music) All right, it still doesn’t work it seems. Remember that for a gene to be
successful in the long term, it needs it’s copies to keep replicating. The problem with the gene for
purely unconditional altruism is that it helps copies of competing genes as much as it helps copies of itself and it’s competitors
don’t return the favor. So a successful gene
for altruistic behavior would need to find some way
of getting more help to itself than to it’s competitors. Even if we’re making nice creatures, the gene itself still needs to be selfish. How could a gene for altruism find a way to let it’s copies
coordinate with each other. One way is to combine two different traits into the altruism gene. First, some kind of unique
outwardly detectable trait that can let the gene be recognized and second, the trait to be
altruistic toward creatures who have that detectable trait. So let’s do that. Let’s add an outwardly detectable trait to our altruistic creatures. The classic version of this is green beard and that’s a fun thing to put on the blob, so let’s stick with that. So the next simulation we’ll try, we’ll start out with half creatures that have the green beard gene who’ll be altruistic
toward other creatures with green beards, and half creatures without green beards that will neither help nor get help. Again, pause to make a prediction. Are you convinced that the
green beards should do well or might there be another problem? Let’s see. (light music) Cool. I was honestly a little bit worried before running these simulations that it still wouldn’t work, but it does. Maybe you’re not that
surprised and that’s fine but even if you’re not, this is still a pretty cool moment. We found at least one kind of gene that can crack natural
selection by causing creatures to put others before themselves, even if it’s only sometimes. This is called inclusive fitness. The fitness includes all
the copies of the gene, not just the ones inside
a particular creature. Don’t celebrate too much though because there’s still a problem. Traits like green beard altruism aren’t actually very common in nature. There are a few known cases, for example red fire ant colonies can have more than one competing queen. And apparently, the workers
can tell which queen shares her and sets of genes with them, and then they kill the
queens that don’t match and help the queens that do match. That’s cool and everything but there just aren’t very
many examples like this. It turns out to be
pretty rare for one gene to code for two different traits that happen to work together so nicely. And even if that does happen, eventually, mutations could
produce multiple genes that each code for only one of the traits. So let’s set up a simulation
to see how it looks when the traits are on separate genes. With the traits on separate genes, they’re independent leading
to four possible combinations. The creature can have both, neither, just green beard or just
altruism towards green beards. Time to make another prediction. (light music) Okay, so as I kind of hinted
that before that simulation, the coordination between
copies of the altruism gene is broken and then the non-altruistic
creatures dominate. But hey, green beards are still cool. So, we’ve only gotten one kind
of altruism to work so far and it’s a kind that depends
on a rare coincidence and doesn’t appear much in nature. There’s got to be something better, right? Well, in fact there is. It’s known as kin altruism
or often kin selection. Instead of targeting
some outwardly detectable genetically determined trait, this kind of altruism
targets family members, whatever the traits may be. So, let’s simulate one final
version of the altruism gene that causes creatures to be altruistic toward their direct parents
and direct children. Now the whole point of
this kind of altruism is that we can’t see which
creatures have which genes. So this time, let’s hide the graph and try to predict the results together while the simulation runs. The key concern with kin selection is that even close family
members aren’t guaranteed to carry the same gene. So the altruism gene
has to do some gambling. For any kind of gambling strategy to work while in the long run, the cost of playing needs
to be lower than the payoff for a win times the chance
that you actually win. Right? The average payoff needs
to be higher than the cost. In the context of kin selection, you’ll hear this called “Hamilton’s Rule.” Looking at this simulation and thinking of the altruism
gene as the gambler, the 5% mutation chance means that there’s a 95% chance that parents and children
share the same version of the altruism gene. So that’s our chance of winning. The cost of being altruistic
as we decided before is half of an offspring on average and the benefit to a
creature who receives food is one since that food
is converted directly into offspring. These numbers aren’t exact
since both creatures involved do have other chances to get food but this should get us pretty close. And comparing, the
expected payout is almost twice the cost, so even with the inexact
cost in payoff numbers, it seems pretty clear
that the altruism gene is gonna do well here. And this is where I realized that altruism is an illusion and my heart descended into darkness only for a little bit though. Once I dug in, collected some
data on what was happening and found more precise numbers
for the cost and benefit, I figured out what was wrong. It’s that Hamilton’s Rule is a lie! Which I’m sorry to say is
gonna require it’s own video. But for now, suffice it to say that by lowering the cost
of the altruistic act, and cranking up the likelihood of winning by lowering the mutation chance, we can find a set-up where
a gene for kin selection tends to flourish. This is the kind of altruism we see all over the place in nature from parents caring for their young to sterile worker bees helping the queen, conclusive fitness can
be naturally selected. All right we spent a
lot of time in the weeds in this video, so before we go, let’s
not remind ourselves of the difference between
a creature and it’s genes. The genes involved in
altruism are still selfish. The only ones that survive are the ones that are able to coordinate their own copies. But this does not mean the
creatures themselves are selfish. They genuinely care
about and make sacrifices for each other, whether it’s because they’re family or because they just can’t
resist the look of a green beard. See you next time. Hey, thanks for watching. If you enjoy this video and
wanna support more of them, you can help by subscribing, sharing with someone else who you think might also like video, or if you’re so inclined by
supporting directly on Patreon. In any case, thanks again. (light music)

100 comments on “The Natural Selection of Altruism

  1. Rienk Kroese Post author

    Why are there no comments suggesting that the Green Beard only Altruism is like the Jewish people.
    Artificial Altruism by a beard(!).

    Footnote: I am NOT an anti-Semite. I'm just saying it looks to me that way and thought others would notice.

  2. Bogan Post author

    Let’s give this another shot.

    All first generation have the altruism gene and it has a random possibility in triggering it or choosing not to be altruist even with the gene.

    As consequence, offsprings have an increased probability in triggering their gene based on the times their relatives have been altruist.

    Also if a non-relative shows altruism towards them it will higher the probabilities of the gene to triggering again. And even a higher probability of triggering towards that “Good Samaritan”’s offspring. And so their offsprings will proceed to help each other based on their predecessors’ relationships.

    This comes with the idea that we all have the kindness in our nature, but it’s both education from our parents and decisions based on what the relatives showed us, even when they are non-blood related to trigger those genes and allow us to become altruists. Henceforth, creating a society where everyone gets to help each other peacefully and do their maximum efforts to help each other. Yes the selfish will somehow manage to prevail, but at least with the possibility to change the selfish gene and trigger the altruist gene based on other’s example will reduce the selfish gene to it’s minimum. At least I hope so.

  3. Zachary Hutchison Post author

    Objectivism says people tend to do selfless acts for selfish reasons =P I'd be curious to see what happens if the altruism gene made it so the blobs only share with individuals they've seen share with others, combined with the sense trait from your artificial selection video. This would remove the need for a second trait that effects outward appearance, which I think would enable the altruists to out compete the selfish blobs. As for the starting state, have the altruists continue searching for a 3rd piece of food to give away for as long as they can while still making it home

  4. Gueorgui Radivoyevitch Post author

    Green beards is called ethnocentrism. It works and is the best strategy in nature. It's why humanism is going to lose.

  5. Jazz and other creations Post author

    " It turns out that unconditionally sacrificing your offspring isn't a great long term strategy "

    Oh, okay, good to know.

  6. Elite BlueTides Post author

    can you do an episode of these creatures playing poker? I’ve never realized I’ve wanted this so badly

  7. persephone p Post author

    We can definitely rule out people who DONT have "green beards". Theyre the ones who call themselves "nice guys." 😂

  8. Daniel Olivença Post author

    There is another strategy the altruistic can take to will. If their actions will increase the total population, they will win. For example, if a altruistic, , after finding two foods, have a 50% of reproduction and 50% to create two or three foods. This will only work if randomness is present. For more details see "Demographic noise can reverse the direction of deterministic selection" by George W. A. Constablea, Tim Rogers, Alan J. McKanec, and Corina E. Tarnita. PNAS 2016

  9. A K Post author

    Cool video. How do you write your simulations? I would be really interesting of running some of my own, but writing some kind of system from scratch in Java or C or whatever would have way too much overhead. Is there some kind of framework you're using?

  10. Vatan Kömürcü Post author

    Altruism as a gene may work for the better of the species/population/ecosystem, but it is more likely not to as it requires specific and rare conditions.

  11. Albert Yu Post author

    If you're watching this video, you've already got way more than 2 pieces of food and being altruistic will come at 0% reproductive cost.

  12. klit Post author

    Well altruism does not exist since de person who behaves in such a manner decides to do so because the subjective reward for behaving that way is enough for them.

  13. Ultra Gman7429 Post author

    Altruism is a lie, there is only ruthlessness.

    Through ruthlessness, I gain strength.

    Through strength, I gain power.

    Through power, I gain victory.

    Through victory, my survival is guaranteed.

  14. Lorenzo Manini Post author

    I think maybe this doesn’t work because you forgot to make the gene a range from 0 and 1, make altruist blobs stay together in groups and have a chance to increase their altruism each other up to 1 every time they recieve a piece of food by another blob

  15. Merlin Lerinzerner Post author

    Well animated with a nice script to go with it on an interesting topic. Easy subscription.

  16. Yo Momma Post author

    I don't get it. The Just Green Beards are a superior version of the Neithers. They get gifts from both the Altruist camps rather than just one. Why would they not win?

  17. mark west Post author

    If green beards only gave to green beards and that's the only strategy that worked it proves that discrimination is inevitable

  18. James Murphy Post author

    The simulations are kinda cool, but you don't take in to account that as well as being altruistic, these same 'blobs' in actual nature can exclude other creatures outside of their own species or family. Or they take more than what they need for themselves and pass the surplus onto offspring. So blobs can be both inclusive and exclusive at the same time when it comes to altruism. You also didn't take into account mutually beneficial symbiotic relationships between creatures. So the simulation can't really be called representative of nature.

  19. Alex L Post author

    There's another option you could try. Make the altruist change a non-altruist to akin when giving him food.

  20. _ craig _ Post author

    Regular people: communism doesn't work

    Primer: 9 minute video "tHe nAtuRaL seLeCTioN oF ALtRuiSm"

  21. Van Ivanov Post author

    This eventually just becomes playing with numbers, making them up as you go along, to get the results you want to see. It stops being science. So, it fits evolutionary biology quite well, lots of feelings and speculations.
    Evil messes up the process of good. Everyone would be better off if all were good, but some are evil and take advantage of that, which makes many forms of altruism a weakness. That's why there has to be a hell, as evil people make heaven impossible by virtue of their nature.

  22. Glenn McConnell Post author

    Do you find such damning results for altruistic genes if your populations start off with a majority of altruistic creatures?

    What happens if you make an environment which selects for altruistic creatures?

  23. thot creations Post author

    Reminds me of people who want to forcefully be someone elses world when in fact there are billions who share the same traits and abilities… Queen bees cant feed themselves yet they bare a future, its a sustainable equality… Some humans assume thats the way to live…

  24. Nathalia Archer Post author

    Man, this explains so so much about the world on so many different levels. Amazing, thank you!

  25. WierdHairGrows Post author

    I can’t understand anything when you start taking about the math/formula behind everything

  26. 官南雄 Post author

    A minute of mourning for the blobs that perished in the middle of the board across the generational continuum.

  27. Chris Michaels Post author

    one option is to have the altruism gene influence those without by adding a high chance of changing the non altruism to altruistic, from "realizing they survived because of kindness"

  28. Martin vanhouwelingen Post author

    GreenBeard Altruism is very much alive in religion and nationalism. People from the same church are more willing (sometimes pretty much exclusively) willing to help someone from their own church, and then expands out towards their own religion. It is not that they hate people of other religions, they just feel safer with their own kind. And this is the major fundament for nationalism, because most countries are based in a single religion, and where it is not it often creates massive conflict in the population, until the other religion is accepted, which means that nationalism wins out over religion. But even then there will be slight resentment.
    Great video!

  29. RedDeadlyCreeper Post author

    I wonder how this would have played out if the offspring distance themselves from their distant relatives as time goes on, so the chance of them being altruistic gradually decays after 2-3 generations where it doesn't exist at say 5 or 6. I assume this would lead to a definitive increase in altruistic tendencies

  30. gato_feliz Post author

    1:36 i think selfish will sadly win because you didn’t code the friendly ones to remeber who was friendly or not

  31. Mr. Pokirby Post author

    Perhaps if one of the creatures was altruistic to another, the creature on the receiving end of the act would in-turn become altruistic themself, similar to how humans work.

  32. mister fister Post author

    I'm pretty sure that the green beards are just the leftover vomit from all the regurgitating

  33. Labtop215 Post author

    Shouldn't the blob that is helped only have a 50% chance of survival, while the blob that did the helping still have a 50% chance of reproducing?

  34. fylosofer Post author

    The final distribution @5:30 after ten generations is not the most statistically likely. The 'Just Green Beard' population has the most advantageous adaptation and on average will grow faster than the 'Neither' population until both 'Just Altruism' and 'Green Beard Altruism' populations die out at which point its growth rate will have parity with that of 'Neither' population. (Actually, it would still be a little better due to random mutations that prevent the other two populations from ever dying out entirely.)

  35. Crockett Post author

    I think "green beard" altruism is actually whats the case in humans, since we remember people being altruistic and helping us, and then help them in return. (one hand washes the other etc)

  36. Unauthorized Expression Post author

    If Liberals were smarter they'd be calling this racist. I know that's stupid, but I promise if you explain this video to a Liberal they will tell you this is "problematic" and probably say this is "white logic." Liberals are silly ppl.

  37. BoraCM 39 Post author

    Do a video when a predator comes and one type of blob s mote likely to be targeted, but faster.

  38. John Speigel Post author

    The evolution of altruism is one of the topics of evolutionary psychology I find most interesting, and I'd love to see you explore it further in the future. I think it would be particularly interesting to see how dividing the overall population into partially-separated subpopulations affects the dynamics here; you might be able to simulate the evolution of tribalism, to an extent, if organisms aiding other members of their own group can help their group as a whole to compete against other groups.

  39. boggers Post author

    Another take on this that you could try: When two blobs meet their numbers are averaged; the fraction of a food unit correlates to the survival / breeding chance. ie 0.8 food = 80% survival + 0% reproduce, 1.2 food = 100% survival + 20% reproduce. Both blobs would require the sharing gene for sharing to take place.

  40. Simeon Stoyanov Post author

    3:23 – "Let's add an outwardly detectable trait to our altruistic creatures. The classic version of this"..
    me: SKIN COLOR
    "Green Beard"


  41. 94982 Post author

    This is White people's biggest weakness, they are too altruistic, and they have had their sense of tribal identity brainwashed out of them, as a result, most white's of today are heading into a genetic dead end.

  42. Fancysaurus Post author

    Wouldn't Altruism thrive in a highly social group with selective mating? In essence sacrificing the good of the creature for a higher chance at reproduction?

  43. 711 MinecraftIceCream Post author

    @Primer the phrase "survival of the fittest" actually means " survival of the people that fit in", not "survival of the strongest" . I thought you should learn/know that. Aside from that, I enjoy your videos.

  44. Nate Morey Post author

    Altruism in real life seems to exist only in animals that live in groups. Which makes sense. Individuals won't benefit from it. I think altruism would help a lot more if you had competing groups.

  45. Flo One Post author

    Regarding your opening statement: survival of the fittest means of the one who fits best, not the one who strives for the most.

  46. Game World Post author

    hello! im new at the channel and first video on your channel that i've seen (that is also my favourite) was about sharing and when at the end you said about more creatures (which i was thinking of) i wanted a second part!

  47. Matthew G Post author

    I think what you need to program in to represent a real world comparison is that a newly born selfish blob should be able to have its food “stolen” from it. Only once a blob is 3-4 generations in should the blob be able to defend itself. Because the reason for altruism is mainly because a child has no way to defend itself, not because it’s a net gain in a society where everyone would be competent.

  48. Alec Raynor Post author

    Think about how altruism can be beneficial in a real-world scenario. People like people who are generous. You should have made it so the blobs have a greater chance of receiving food at a later time from those whom they have acted generously towards before.
    That would be interesting to see!
    Especially if that was passed through Generations

  49. Eleanor Polatch Post author

    What about only being altruistic with those who have previously been altruistic with you? You could have it so that altruistic creatures would have a 25% chance of unconditionally sharing their food with others, but a 50% chance of sharing food with those who had shared with them before.
    They might thrive because they would be the most likely to receive food and not die overnight – or perhaps they wouldn’t because they would still occasionally be giving food to the non-altruistic blobs.
    This does seem pretty realistic, though, and links into the idea of pack survival – how acts of kindness reward the individual because, in order to encourage the kindness trait, they will be more likely to be accepted by the pack and given kindness in return.

    Just some food for thought.

  50. Rathatamanun Charypo Post author

    Wait, the not altruistic blobs (B gene) always get survival chances at 100% even though it eats half the food from altruistic blobs (A gene). Yes, the net positive relation is common but it actually a negative competition score for A gene. B gene will get 200% chance of survival, instead, A gene will get just 75% chance of survival. That results in 27.27% chance of A gene surviving, as opposed to 72.73% of B gene.

    You didn't show if the giver and the beggar has the same 50% chance of surviving. Yes, it's net zero, but, it's like the reality.

    so, it still 75% survival for A, but, it will be 150% for B. Not increasing much but, I just want to say that if the Energy Ball is split, will my prediction become true.

    A: (50% find*50% keep) food*50% home*50% survive = 6.25% total sustainability
    B: (50% find*50% get) food*50% home *100% survive = 12.5% total sustainability
    it's 1:2 ratio of A:B in guarantee, maybe fewer for A.

    If you just make them both 50% survival if the food is shared, it can become 1:1. Though, I think that's too optimistic, probably 1.25:2 is predicted from me.


Leave a Reply

Your email address will not be published. Required fields are marked *