In beehives, the females do all the work. The males are pretty lazy. They spend most of their time eating honey and waiting for the opportunity to mate with the queen.
Nice work if you can get it.
After which they die.
As one wag said, their lives are Honey, Nut, Cheerio.
In beehives, 99% of the inhabitants are female. And, yes, they do all the work. The males do nothing but eat and wait for an opportunity to mate with a queen from another colony. A queen mates just once in her lifetime.
When seahorses reproduce, the male gets the stretch marks.
Snerk!
I laughed. Buy that wag a drink from me.
Some of this comes down to just how we define “male” and “female”. Like, saying that “the females do all the work in a beehive”: The Queen is female, but in what sense are the workers female? One could just as well say that most of the bees in a hive are sexless.
Or, “Male seahorses get pregnant”. Well, then, how are we defining “male” and “female”? Obviously not by “the female is the sex that gets pregnant”. The underlying true statement is “the seahorse sex that gets pregnant is the one with the smaller gamete cells”, but one could just as well state that as “female seahorses have smaller gametes than males”.
They are genetically identical to a queen. They have just been rendered sterile (usually, not always completely) developmentally.
Male seahorses brood fertilized eggs deposited by a female in a brood pouch. Sometimes people refer to them as pregnant when they are brooding. But they do not produce the eggs, they fertilize them.
Sure, but genetics isn’t everything. There are plenty of species with males and females, where the males and females are genetically identical, and determined by environmental factors such as temperature, or the existing numbers of each. In some of them, individuals can even change sex.
The seahorse example seems perfectly clear. The males produce the sperm and the female produce the eggs, like in every other species. The only difference is that rather than immediately depositing the egg with a shell, or storing it internally while the egg develops into a fetus, or storing it on their own back under the skin, or in their mouth, or a million other strategies for brooding that various animals display, female seahorses deposit the fertile eggs in the male’s body. That doesn’t suddenly change their eggs into enormous sperm and make them males. I guess you could argue it does, but you’d just confuse every other biologist.
The bee example is a better one. Even if the drones possess female genes, you could argue that by the way they develop they are no longer females, but instead are members of a third non-reproducing sex. I don’t know if anyone has made that argument or if this is a useful lens to think about bees through, but it makes mucu more sense to me than arguing that eggs are big sperm and sperm are tiny eggs just because they belong to a species where the male broods the fertilized eggs.
Back to sex roles in species with unambiguously male and female sexes:
Many bird species in which nest care is shared by a breeding pair also have a lot of extra-pair mating. So a paired male is likely to be caring for nestlings that include at least some offspring of other males. (Apparently the additional mating opportunities may incentivize the extra-pair “uncles” to be more proactive in defending against predators.)
You can go further than this and make an argument that a colony of a eusocial species is a single superorganism. In multicellular organisms, somatic cells have no descendants. Your entire body foregoes any direct evolutionary future for the benefit of the descendants of your sperm and egg cells. In a genetic/evolutionary sense, the non-reproducing castes of eusocial species are analogous to our somatic cells.
I find this less convincing. I’m not sure why there is any reason to diverge from the technical biological definition that the male is the species with the small gametes. Why wouldn’t we just say that the males and females thus defined do not always follow “stererotypical” patterns of male/female roles and behaviors? Since a lot of elements of sexual dimorphism in physiology and behavior do ultimately derive from the difference in gamete size, this approach would seem to grant more insight into what’s going on. Whereas if you redefine male/female according to roles and behaviors, it makes it seem like you don’t want to let go of the stereotypes (not that I’m suggesting you really have any agenda, of course).
OK, yeah, the size of the gametes is the standard definition for “male” and “female”. But why is that the standard definition? It seems to me that most sexually-dimorphic traits ultimately derive from which sex gets pregnant (or gravid or whatever), and that they correlate with gamete size only to the extent that gamete size correlates with pregnancy.
Quibble: you mean “workers”, not drones. The drones are male, the queens are female, and the workers are usually described as sterile females. I have personally argued that the workers are members of a third, non-reproducing sex. I have no idea if biologists find it a useful way to think about the issue, but i do. The workers develop differently from the queens starting as larvae, because they aren’t fed the royal jelly that would make them develop into fertile queens. If you think sex is purely based on genes (and it’s not in lots of animals, including some fish, frogs, and alligators) then i guess it makes sense to think of the workers as female. But if you think of sex more structurally, i think it makes more sense to consider bees as having three sexes, one if which is sterile.
As the link I posted above notes even in normal hives that sterility can be incomplete, with ~1% of workers having weakly functioning ovaries. They’re just (mostly) sterile females.
In general, sexual dimorphism originates with asymmetric parental investment.
In the simple case of a species that lays eggs, fertilizes them and just wishes them good luck, the difference in parental investment derives solely and directly from anisogamy - the difference in physical resources required to produce the gametes. Small sperm are easy and cheap to produce, so males compete for access to the females who commit greater physical resources to producing larger eggs.
It’s not a coincidence that it’s usually the female that gets pregnant and makes this additional investment, since the evolutionary origins of the female strategy in anisogamy lay in committing greater resources but being picky about the male. But male pregnancy is possible, and in that case the resources committed to pregnancy dwarf the difference in resource commitment attributable to anisogamy. If that were the whole story, perhaps you could make a case to define the female as “the one that gets pregnant”.
But there’s a lot more to parental investment, since the non-pregnant mate may provide food and other resources, and both parents may contribute to post-natal care. In general, the sex that provides greater parental investment is more picky, and the other sex tends to compete. I’m not sure if there are any documented cases where the female gets pregnant but the male nevertheless invests more, but there are certainly cases where pregnancy is not involved that the male invests more and the sex roles (which sex is picky) are reversed.
In humans, there is a long period of post-natal parental investment, including unusually high male parental investment, that is at least as significant as the female’s investment in the pregnancy. So humans certainly don’t follow a simplistic “males competing for picky females” paradigm, it’s complex and the resources that a male can offer (not just the genetic quality of sperm) are highly significant.
I have seen this argument elsewhere and agree with it wholeheartedly.
On an aside, I think we should call them NBees
Usually human males contribute a lot of parental investment, and we have a lot of societal factors that encourage that. But it’s still possible for men to reproduce with almost no investment at all, and some men do still pursue that strategy. But it’s not possible for women to pursue that strategy, and so we do end up with some degree of sexual dimorphism in humans.