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There's a diagram about halfway through that illustrates how this works. I miunderstood the article at first and was wondering why you wouldn't just say that th

There's a diagram about halfway through that illustrates how this works. I miunderstood the article at first and was wondering why you wouldn't just say that there are two species, but the diagram sorted me out. The tan stripe birds almost always mate with the white stripes, and the offspring have a 50/50 chance of having the mutation. I wonder if the birds instinctively "know" that they have 4 sexes

taneq 10y ago
Ah, thanks. This was confusing me too. Weird (and interesting)!
throwaway4891a 10y ago
"They almost always pair with the opposite color morph for breeding. The two color morphs occur in approximately equal numbers. Both male and female white-striped birds are more aggressive than tan-striped birds during the breeding season." https://en.wikipedia.org/wiki/White-throated_sparrow https://en.wikipedia.org/wiki/White-throated_sparrow
vorg 10y ago
> The tan stripe birds almost always mate with the white stripes The "almost" hints at the origins of homosexuality.
- astrodust 10y ago
  Same sex birds adopting eggs from other breeding pairs are quite common in the avian world, especially among populations that nest in close proximity such as penguins. There's no "origin" to homosexuality. If anything having differentiated sexes is an aberration, the majority of plant species have both as well as many of the precursor species to modern mammals like snails and flatworms. In situations where the separation of the sexes provided some kind of evolutionary advantage it took hold. In others it never happened. Also our preconceptions about gender goes out the window when there's four possible expressions as in the case with these birds.
  - vorg 10y ago
    > There's no "origin" to homosexuality Did I use the word "origin" incorrectly? Because evolution of a second sexual system in these birds results in white-striped birds and tan-striped ones mating only with the other almost all the time instead of always all the time, homosexuality is being built into the differentiation of a species into 2 sexes, I presume because DNA processing can never be error-free. I didn't imply it starts happening after the differentiation.
    - astrodust 10y ago
      The term doesn't even apply here since the physical expression of gender is more complicated than the typical binary variant seen in mammals. white/male + white/female is not "homosexual" by any conventional definition. If anything it's "homomorphic". Birds, like any creature, don't do anything all the time. I think you're reading way too much into these observations.
      - vorg 10y ago
        > white/male + white/female is not "homosexual" by any conventional definition. If anything it's "homomorphic" Did I use the term "homosexual" incorrectly? Perhaps "origins of homosexuality" would be more accurate. That's what I said in the first place. The article says "the researchers had come up with the concept that the birds were evolving a second set of sex chromosomes" and "the inversion on chromosome 2 doesn't include genes that determine sexual development — but it does contain some that affect the birds' reproductive behaviour". The tan-striped "swingers" are monogamous and fiercely protect their hatchlings from predators, whereas the white-striped "singers" are aggressive, promiscuous, and more cavalier about their offspring. The tan stripe birds almost always mate with the white stripes, but there are exceptions. We're seeing here firsthand (on a genetic time scale) the origins of homosexual behavior. I appreciate your comment because when I first got the 5+ downvotes without any comments, I thought it was homophobic attitudes from HN readers. But now I know they could also be anyone with an overly pedantic reaction to the use of certain words.
        10y ago

taneq 10y ago

Ah, thanks. This was confusing me too. Weird (and interesting)!

throwaway4891a 10y ago

"They almost always pair with the opposite color morph for breeding. The two color morphs occur in approximately equal numbers. Both male and female white-striped birds are more aggressive than tan-striped birds during the breeding season." https://en.wikipedia.org/wiki/White-throated_sparrow https://en.wikipedia.org/wiki/White-throated_sparrow

vorg 10y ago

> The tan stripe birds almost always mate with the white stripes The "almost" hints at the origins of homosexuality.

astrodust 10y ago
Same sex birds adopting eggs from other breeding pairs are quite common in the avian world, especially among populations that nest in close proximity such as penguins. There's no "origin" to homosexuality. If anything having differentiated sexes is an aberration, the majority of plant species have both as well as many of the precursor species to modern mammals like snails and flatworms. In situations where the separation of the sexes provided some kind of evolutionary advantage it took hold. In others it never happened. Also our preconceptions about gender goes out the window when there's four possible expressions as in the case with these birds.
- vorg 10y ago
  > There's no "origin" to homosexuality Did I use the word "origin" incorrectly? Because evolution of a second sexual system in these birds results in white-striped birds and tan-striped ones mating only with the other almost all the time instead of always all the time, homosexuality is being built into the differentiation of a species into 2 sexes, I presume because DNA processing can never be error-free. I didn't imply it starts happening after the differentiation.
  - astrodust 10y ago
    The term doesn't even apply here since the physical expression of gender is more complicated than the typical binary variant seen in mammals. white/male + white/female is not "homosexual" by any conventional definition. If anything it's "homomorphic". Birds, like any creature, don't do anything all the time. I think you're reading way too much into these observations.
    - vorg 10y ago
      > white/male + white/female is not "homosexual" by any conventional definition. If anything it's "homomorphic" Did I use the term "homosexual" incorrectly? Perhaps "origins of homosexuality" would be more accurate. That's what I said in the first place. The article says "the researchers had come up with the concept that the birds were evolving a second set of sex chromosomes" and "the inversion on chromosome 2 doesn't include genes that determine sexual development — but it does contain some that affect the birds' reproductive behaviour". The tan-striped "swingers" are monogamous and fiercely protect their hatchlings from predators, whereas the white-striped "singers" are aggressive, promiscuous, and more cavalier about their offspring. The tan stripe birds almost always mate with the white stripes, but there are exceptions. We're seeing here firsthand (on a genetic time scale) the origins of homosexual behavior. I appreciate your comment because when I first got the 5+ downvotes without any comments, I thought it was homophobic attitudes from HN readers. But now I know they could also be anyone with an overly pedantic reaction to the use of certain words.
      - 10y ago