The article argues that sexual dimorphism is an extinction risk. I don't buy it: the ostrocod study doesn't generalize, and the rest of the author's links are evolutionary anecdotes.
There are plenty of species in which sexual selection has been highly adaptive, including our own: it's likely that sexual selection is what led to runaway intelligence growth. We've been incredibly successful despite being sexually dimorphic.
In fact, this article makes so little sense that I can't help but wonder whether there's a culture war aspect to it. It's become fashionable to bash masculinity.
Just look at the difference between male and female Angler fish.
>When a young, free-swimming male angler encounters a female, he latches onto her with his sharp teeth. Over time, the male physically fuses with the female, connecting to her skin and bloodstream and losing his eyes and all his internal organs except the testes.
I’m puzzled by your interpretation: One of the first things the article does is acknowledge the usefulness of sexual dimorphism, and backs it up with references to research.
I agree with you that the research on ostracods is unlikely to generalise beyond some strict conditions. And the article itself says:
> But it’s not sexual dimorphism itself that’s the problem – it’s the type of sexual dimorphism […:] males that invested more resources in reproduction did so at significant evolutionary cost
The article then jumps to evolutionary specialisation, and it’s been known for some time that this (regardless of sexual dimorphism) likely decreases adaptability.
At any rate, you seem to want to read “masculinity bashing” into the article. But this is of course not the subject of the article, and never even implied.
Specialization and adaptibality are two sides of the same coin. What is adaptibility if not the ability to specialize on occasion. And, while individual specialized species might run into a local mininum that their specialization does not get them out of, mamals and chordata in general are highly diverse...
> [mammals] and chordata in general are highly diverse
Yes but we’re speaking of adaptability on the level of species. And the more specialised a species is to an environment, the higher its investment (in terms of some vague “evolvability resource”, which we might naïvely equate with number of mutations) in one particular strategy. This pays off as long as the ecological niche exists. Changes to that niche may require (relatively) fast adaptive changes, and these are in principle easier for generalists than for specialists. This isn’t a hard and fast rule, of course, but it seems to be a robust general principle. It’s therefore not correct to say that
> Specialization and [adaptability] are two sides of the same coin
Adaptability describes the ability of a species to adapt to new conditions; specialisation describes the state after adaptation has happened. Roughly, a highly adaptable species is a generalist whereas a highly specialised species is, well, a specialist: in this sense, the terms are (at least to some extent) opposites.
Culture wars aside, the premise seems reasonable though, doesn't it? Intraspecies reproductive fitness is orthogonal to species success and there are clearly some examples (e.g. brightly colored plumage) where a trait that improves individual reproductive success is a net negative for the species.
Traits don't evolve in isolation though: the need for costly signaling may very well select for increased generalized fitness as a way to "pay" for the signaling.
Bright plumage can advertise "Look at me! I'm fast enough to look this amazing and not get eaten!" For this strategy to work, you need to actually be fast.
Is it a net negative though? I would in fact wager the opposite. The tradeoff must be beneficial else natural selection would have culled them from the population.
I believe in this specific case, it is likely more difficult for males to attract females than avoid predators.
To start off, yes, the trait needs to provide a reproductive fitness benefit. The problem is runaway sexual selection [1]. The textbook example of that being the peacock plumage, which is subject to strong sexual selection, yet is a detriment to overall fitness (see link for more details).
What makes you think sexual selection led to increased intelligence in humans? In the grand scheme of things, I'm not sure humans are even that sexually dimorphic TBH, I believe the size dimorphism is actually pretty small compared to other mammals.
Please don't break the site guideline which asks you to "avoid unrelated controversies and generic tangents". Your comment would be fine without the last sentence. Whether it is right or wrong, it's likely to lead to a repetitive flamewar.
Extravagant display was a problem for Darwin, who realized it could make individuals vulnerable to predation, until he realized that it actually supported his theory, as it is the sort of thing that could arise where selection matters, and harder to justify as the work of an omniscient creator.
Current theory often explains such displays as hard-to-fake signals of health and general fitness, but I do not know if this idea originated with Darwin.
The size of male ostrocod genitalia is a different matter, as (I assume) it is not about display, but about emphasizing reproduction at a possible cost to the survival part of the strategy.
Dead-end strategies are not a threat to Darwinian evolution, as it only optimizes for the short term, and are harder to justify as the work of an intelligent creator.
It was one for Darwin; another was Lamarckism. Once evolution began to be accepted, it was often distorted by some ill-formed concept of a bias towards progress, always epitomized by the human form. All these alternatives have trouble explaining extravagant display.
Evolution just simply lacks a teleology, or, worse, implies a teleology so divorced from any notion of progress that it's horrifying. Probably the most genetically successful dog of all time is the one that "turned into" a cancer and is now canine venereal transmissible tumor.
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[ 2.7 ms ] story [ 61.0 ms ] threadThere are plenty of species in which sexual selection has been highly adaptive, including our own: it's likely that sexual selection is what led to runaway intelligence growth. We've been incredibly successful despite being sexually dimorphic.
In fact, this article makes so little sense that I can't help but wonder whether there's a culture war aspect to it. It's become fashionable to bash masculinity.
>When a young, free-swimming male angler encounters a female, he latches onto her with his sharp teeth. Over time, the male physically fuses with the female, connecting to her skin and bloodstream and losing his eyes and all his internal organs except the testes.
https://www.nationalgeographic.com/animals/fish/group/angler...
Aren't those extinct now?
I agree with you that the research on ostracods is unlikely to generalise beyond some strict conditions. And the article itself says:
> But it’s not sexual dimorphism itself that’s the problem – it’s the type of sexual dimorphism […:] males that invested more resources in reproduction did so at significant evolutionary cost
The article then jumps to evolutionary specialisation, and it’s been known for some time that this (regardless of sexual dimorphism) likely decreases adaptability.
At any rate, you seem to want to read “masculinity bashing” into the article. But this is of course not the subject of the article, and never even implied.
Yes but we’re speaking of adaptability on the level of species. And the more specialised a species is to an environment, the higher its investment (in terms of some vague “evolvability resource”, which we might naïvely equate with number of mutations) in one particular strategy. This pays off as long as the ecological niche exists. Changes to that niche may require (relatively) fast adaptive changes, and these are in principle easier for generalists than for specialists. This isn’t a hard and fast rule, of course, but it seems to be a robust general principle. It’s therefore not correct to say that
> Specialization and [adaptability] are two sides of the same coin
Adaptability describes the ability of a species to adapt to new conditions; specialisation describes the state after adaptation has happened. Roughly, a highly adaptable species is a generalist whereas a highly specialised species is, well, a specialist: in this sense, the terms are (at least to some extent) opposites.
Bright plumage can advertise "Look at me! I'm fast enough to look this amazing and not get eaten!" For this strategy to work, you need to actually be fast.
I believe in this specific case, it is likely more difficult for males to attract females than avoid predators.
[1]: https://en.wikipedia.org/wiki/Fisherian_runaway#Peacocks_and...
The eye like patterns can scare and emulate size. The e tail does fiegn size and does not fall into the general visual bird pattern.
https://news.ycombinator.com/newsguidelines.html
Current theory often explains such displays as hard-to-fake signals of health and general fitness, but I do not know if this idea originated with Darwin.
The size of male ostrocod genitalia is a different matter, as (I assume) it is not about display, but about emphasizing reproduction at a possible cost to the survival part of the strategy.
Dead-end strategies are not a threat to Darwinian evolution, as it only optimizes for the short term, and are harder to justify as the work of an intelligent creator.
Thought: evolution is an attemp to solve the halting problem.
Shannon was right.
https://youtube.com/watch?v=kt3csIz3hEk
This is a kind of reversal of causality that is unfortunately is too common in popular discussions of evolutionary biology.
Sexual selection of males is the result of female choice.