For example, ants or bees can collectively gather resources… but that is only possible because most of them are infertile children of the queen, so they cannot spread their genes better by defecting against the queen.
It’s worth noting that the infertility of worker bees is itself (seemingly) a form of genetic sacrifice, so it doesn’t really explain why cooperation evolved among bees. The explanation that I’m familiar with is that male bees (this is also true of ants, but not molerats) only have one set of genes, instead of the usual pair, which means that their daughters always inherit the same genetic material from the father. This means that in the case that two bees share both the same father and mother (which isn’t actually always the case in evolutionarily modern beehives, more thoughts on this later) then those bees will have 75% consanguity (improperly speaking, share 75% of their genes), whereas a mother bee only has 50% consanguinity with her own daughters (the same as between human siblings or between human parents and offspring). This means infertility can actually be a very effective strategy, and not at all altruistic, since a bee more effectively propogates her own genes by helping raise her younger (full) sisters than by raising children of her own.
But it’s worth noting that many haplodiploid species are not eusocial (for example wasps), and modern beehives often contain bees that have different fathers. Bees have the same consanguinity with half-siblings as humans have with their half-siblings (25%), and in principle, a bee should be able to better propagate her genes by having children of her own than by helping her half-siblings, yet we see bees helping raise their half-siblings all the time. While I wasn’t around to watch the evolution of bees myself, here’s one plausible story of how this situation could have come about:
In the original beehives, a mother bee would have several children with one father. Since bees are more closely related to their full siblings than to their own offspring, most of the female bees would spend more time helping raise their siblings than on having children themselves. At this point in the process, if a bee tried to raise a family with many different fathers, the household wouldn’t cohere very well, and would be outperformed by households (hiveholds?) with only a single father. We should expect that if we examined bee families in this early stage, we would see a noticeable bias towards families with one father (who likely played no role other than providing genetic information), and under this regime, something recognizeable as the eusocial beehives we know today would have been the result, just with one father instead of many, making every bee in the hive a full sibling of the other hivemates.
However, while having a singular father is conducive to eusociality, this actually poses a problem for the hive. To illustrate, you may be aware that the bananas we eat today aren’t the same bananas that used to be eaten 80 years ago; since we plant bananas in such a way that one banana is genetically identical to (has 100% consanguinity with) every other banana of the same cultivar, this makes them particularly vulnerable to infections and parasitism; the Gros Michel cultivar that used to be popular got entirely wiped out by a fungus, F. oxysporum cubense, referred to as Panama disease; the lack of genetic variety ensured that the moment a strain of F. oxysporum could infect one Gros Michel, it could run wild through every single Gros Michel in existence. Similarly, in a beehive containing tens of thousands of nearly identical bees, if a parasite or germ can infect one bee, it will spread like wildfire and destroy the hive.
This creates a conundrum for the hives: if it only takes genetic material from one father, it can easily be wiped out by disease; If it took genetic material from multiple fathers, any disease will likely only affect a fraction of the population, but there will be less incentive for the bees to take care of the hive. One semi-stable setup for a hive under these conditions may be for a hive to contain 3-6 different “clans” of bees with the same father (so a few different fathers for the whole hive). We would expect to see strong cooperation within each clan, but weak cooperation between clans (similar to how half-siblings usually interact). This would still provide much of the benefit of a homogenous beehive, but also ensure that the hive can survive after a given disease.
However, diseases would still cause problems as hive size increases, and from the perspective of the hive (as well as the individual in some circumstances), the decreased level of cooperation isn’t ideal. We should expect that if the bees are able to detect when a bee is defecting against the hive (either by trying to reproduce, or by trying to collect and reserve food for their own clan instead of the entire hive, or by any other possible way), it would be in a bee’s best interest to punish their half-siblings for defection, to help ensure that they contribute to the entire hive’s effort (we observe this happening in modern hives). Hives that have more robust traditions of detecting and punishing cheating would be able to outperform hives that don’t, by being able to maintain higher levels of cooperation even as the number of “clans” in the hive increases, thereby increasing resistance to disease, and thereby increasing the maximum size of the hive, while still being able to operate as a single organism.
Note that the entire evolutionary story above is made up, and I don’t claim to have any scientific or historic evidence backing it up, though it is roughly in line with my knowledge of evolutionary principles.
… Maybe I should just make this into a post. I didn’t realize I had so much to say on this topic.
It’s worth noting that the infertility of worker bees is itself (seemingly) a form of genetic sacrifice, so it doesn’t really explain why cooperation evolved among bees. The explanation that I’m familiar with is that male bees (this is also true of ants, but not molerats) only have one set of genes, instead of the usual pair, which means that their daughters always inherit the same genetic material from the father. This means that in the case that two bees share both the same father and mother (which isn’t actually always the case in evolutionarily modern beehives, more thoughts on this later) then those bees will have 75% consanguity (improperly speaking, share 75% of their genes), whereas a mother bee only has 50% consanguinity with her own daughters (the same as between human siblings or between human parents and offspring). This means infertility can actually be a very effective strategy, and not at all altruistic, since a bee more effectively propogates her own genes by helping raise her younger (full) sisters than by raising children of her own.
But it’s worth noting that many haplodiploid species are not eusocial (for example wasps), and modern beehives often contain bees that have different fathers. Bees have the same consanguinity with half-siblings as humans have with their half-siblings (25%), and in principle, a bee should be able to better propagate her genes by having children of her own than by helping her half-siblings, yet we see bees helping raise their half-siblings all the time. While I wasn’t around to watch the evolution of bees myself, here’s one plausible story of how this situation could have come about:
In the original beehives, a mother bee would have several children with one father. Since bees are more closely related to their full siblings than to their own offspring, most of the female bees would spend more time helping raise their siblings than on having children themselves. At this point in the process, if a bee tried to raise a family with many different fathers, the household wouldn’t cohere very well, and would be outperformed by households (hiveholds?) with only a single father. We should expect that if we examined bee families in this early stage, we would see a noticeable bias towards families with one father (who likely played no role other than providing genetic information), and under this regime, something recognizeable as the eusocial beehives we know today would have been the result, just with one father instead of many, making every bee in the hive a full sibling of the other hivemates.
However, while having a singular father is conducive to eusociality, this actually poses a problem for the hive. To illustrate, you may be aware that the bananas we eat today aren’t the same bananas that used to be eaten 80 years ago; since we plant bananas in such a way that one banana is genetically identical to (has 100% consanguinity with) every other banana of the same cultivar, this makes them particularly vulnerable to infections and parasitism; the Gros Michel cultivar that used to be popular got entirely wiped out by a fungus, F. oxysporum cubense, referred to as Panama disease; the lack of genetic variety ensured that the moment a strain of F. oxysporum could infect one Gros Michel, it could run wild through every single Gros Michel in existence. Similarly, in a beehive containing tens of thousands of nearly identical bees, if a parasite or germ can infect one bee, it will spread like wildfire and destroy the hive.
This creates a conundrum for the hives: if it only takes genetic material from one father, it can easily be wiped out by disease; If it took genetic material from multiple fathers, any disease will likely only affect a fraction of the population, but there will be less incentive for the bees to take care of the hive. One semi-stable setup for a hive under these conditions may be for a hive to contain 3-6 different “clans” of bees with the same father (so a few different fathers for the whole hive). We would expect to see strong cooperation within each clan, but weak cooperation between clans (similar to how half-siblings usually interact). This would still provide much of the benefit of a homogenous beehive, but also ensure that the hive can survive after a given disease.
However, diseases would still cause problems as hive size increases, and from the perspective of the hive (as well as the individual in some circumstances), the decreased level of cooperation isn’t ideal. We should expect that if the bees are able to detect when a bee is defecting against the hive (either by trying to reproduce, or by trying to collect and reserve food for their own clan instead of the entire hive, or by any other possible way), it would be in a bee’s best interest to punish their half-siblings for defection, to help ensure that they contribute to the entire hive’s effort (we observe this happening in modern hives). Hives that have more robust traditions of detecting and punishing cheating would be able to outperform hives that don’t, by being able to maintain higher levels of cooperation even as the number of “clans” in the hive increases, thereby increasing resistance to disease, and thereby increasing the maximum size of the hive, while still being able to operate as a single organism.
Note that the entire evolutionary story above is made up, and I don’t claim to have any scientific or historic evidence backing it up, though it is roughly in line with my knowledge of evolutionary principles.
… Maybe I should just make this into a post. I didn’t realize I had so much to say on this topic.