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What an Extinct Bird Re-Evolving Says About “Species” (nautil.us)
75 points by dnetesn 26 days ago | hide | past | web | favorite | 29 comments

Convergent evolution is fascinating.

Environments produce animals in some way and a similar environment will cause similar animals to evolve again given time.

New Zealand's kiwi is a bird version of a mouse because mice weren't around to fill that niche.

There are many examples that are bafflingly similar yet share very distant common ancestors:


Makes you wonder if the sci fi with human looking aliens is not so far off.

The difficulty of defining a ‘species’ reminds me of one of my favorite essays about how we categorize things.


See also: https://en.wikipedia.org/wiki/Celestial_Emporium_of_Benevole...

(Which I also discovered via Scott, as it happens.)

Just wait until the start re-evolving back into dinosaur form, then you are really going to be in trouble :-). I believe there is probably a good fictional short story involving a scheme to remove CO2 from the air to fight climate change, having it go amok and instead result in a second "oxygenation event"[1] making very large animals practical again from an energy conversion standpoint.

[1] https://simple.wikipedia.org/wiki/Great_Oxygenation_Event

If anyone finds a story like that I would be very interested.

> This raises an interesting question: Can birds on different branches of the evolutionary tree really be part of the same species? The answer depends on what you mean by “species.” This is the species problem, one of philosophy of biology’s persistent demons. As it turns out, it is difficult (and some would argue, impossible) to conceptualize species in a way that fully, and without exception, captures what it is that makes a group of organisms one species and not another.

I’ve always found clicking through species pages on Wikipedia to see the variations of different animals and the often surprising ways they are interconnected.

It seems like an incredibly hard thing to get right as the categorization constantly changes as more and more DNA analysis disrupts the old lines.

I’d be interested in reading the history of this labelling system and how it evolved. There might be some connection to software and language itself.


Now... if you read the article. This animal lived only on this island, then, the island was submerged with water and "The birds (and all other land species living on the island) went extinct."

This sounds plausible to me. But you think that it is easier that somehow some birds survived the submersion of the island?

Playing the devil's advocate here -- GP is resorting to attacks and straw arguments, but let's try to come up with something plausible. GP raises several examples of species once thought extinct, whose habitat never disappeared. However, the flightless rails appear to have lost their habitat. Did they?

It's well known that flightless animals, such as moose, can and do migrate significant distances and colonize islands. They do it by swimming. Could flightless birds do the same? Quite possibly.

It seems reasonable, to me, that a population of these flightless birds would colonize nearby land. What sounds more incredible is that they would then up, leave, and find their way home, thousands of years later -- all without leaving a trace. Perhaps this leads to an interesting follow-up study: are there geological records, or populations, of flightless rails on neighboring islands or nearby land masses?

You make a good point. Birds, especially, tend to float in water, given that they evolved specifically to have a low density in order to fly (i.e. float in air). A bird left floating for a long time will probably die of starvation or dehydration; but it's much less likely than a mammal to drown when it tires. So there's a better chance that it will still be alive when it washes up on some other beach, if that happens within a couple days.

Why does all critical thinking go out the window when it comes to evolution? (As well as being downvoted.)

The atol in question was surveyed in the early 1900s. The rails were there. There has never been a time -- that we know of -- when the rails weren't there.

There are also dozens of other types of birds, giant non-marine tortoises, flying squirrels, bats, and a huge assortment of reptiles.

The only 'fact' that underpins this story is the assumption that "all life on the island went extinct" at some point AFTER some particular fossil of the rail was found.

There is no basis for this 'fact'. It's absurd. There is also no explanation regarding where the other non-marine animals on the island came from after this speculated 'extinction' event.

To be clear, there is no story here UNLESS one assumes the entire atol was submerged at some time AFTER the fossilization event.

Rails exist there today. The fossil record has rails. There has never been a time when there weren't rails that we know of. And there is no solid evidence that all life went extinct on the atol, and a large amount of evidence that there was no extinction event.

Calling people "idiots" doesn't help your case. And that's almost certainly what was getting you downvoted.

> To be clear, there is no story here UNLESS one assumes the entire atol was submerged at some time AFTER the fossilization event.

Figure 3 of the original article suggests exactly that. Rather than call people idiots and heaping scorn for a "lack of critical thinking", find a counter-argument. Like, perhaps the atoll was taller, and a few meters' erosion could make the difference. But I'm not a geologist, so that's just an armchair guess.

Out of curiosity, are you religious?

Disclosure - I am not, consequently I have no vested interest in either explanation (the article's considered, moderate, science-based proposal, or your knee jerk dismissal).

I am confident the authors of the article considered the possibility that the animal(s) never actually went extinct, though the basis for their conclusions seem sound. The journals would be full of wild claims if things not seen for a few decades were deemed to be miraculously rediscovered after each hiatus.

That the fossil bones (of the originals) and the skeletal structure (of the new) are similar, but not identical - let alone the submerged island problem - speaks against your claim that they're the same.

Well, if a swallow can carry a coconut, it can also carry a flightless bird :p

Also important to add it was a flightless bird.

Not saying these all reevolved, but convergent evolution is a thing and pretty common. Without DNA tests of ancient coelacanths and modern ones, how much can we say that it’s the same exact species with little change, vs a related species that evolved to be more like its extinct cousin?

Convergent evolution produces similar phenotypes, not exact ones.

Nothing is stopping this from happening besides chance.

Apparently, they can -- and do -- say whatever they want. It's easy to make up stories.

And, apparently, there will always be a gullible audience.

In this case the mechanism sounds believable to me. There's an ecological niche for flightless rails; going from flightworthy to flightless is presumably an easy step; I expect there'd be pronounced morphological changes associated with adaptation to flightlessness. If the progenitor hasn't changed much, the landlubber adaptations could make the two parallel descendants much more similar to each other than to their parents. Now, whether this is what actually happened I can't say. I have no expertise in the field.

The entire island was under water for tens of thousands of years, it does seem to be a fairly safe call.

what are you citing there? I cannot find any articles that suggest long periods of submersion - only that there WERE submersions

this story doesn't add up - it suggests the birds were there 10,000 years apart while it was submerged for 36,000 years?

I literally cited the first hit from the most obvious google search. You sound curious and dissatisfied with the science reporting. Why don't you look up the paper, possibly use sci-hub if it isn't freely available, and actually read what the scientists say?

I was hoping someone would save me the searching and link me directly to relevant papers. I think the article should have done it itself, as the assumption is rather fundamental to the whole theory.

Similarly I didn't see any mention of intermediate evolutionary stages being found for either a case 1 or 2? If someone sees a paper that does that, it'd be cool

The dissatisfaction is warranted as the article is ONLY noteworthy IFF one assumes there was a complete extinction event on the atol.

Without the assumption of this extinction event, the story is simply this: "There are rails on this island. And, there are fossils of rails on this island."

But did they all “evolve” in the same place?

Seems like evolution would produce mechanisms to foster faster evolution if at all possible. So is there something about DNA that would at a fundamental level prevent saving of previous configurations?

I appreciate this wild vein of thinking, that "junk" DNA (or something else) might contain old data. In America and Americans, John Steinbeck made an even bolder guess he knew might be wrong: that "junk" DNA was partly used to store memories, and pass them on between generations. He imagined that Americans might be better gun-fighters than Europeans simply due to the recent history of gun-violence in the American Old West (which he may have been exaggerating in his head). I don't put any stock in that idea, but I liked it as a thought.

Another mechanism we know is used for allowing more than one pattern to be saved is the methylation of DNA. My understanding (IANABiologist) is that certain chunks of DNA are essentially commented out based on environmental factors. Eusocial insects use this to grow different castes with radically different bodies and behaviors from a shared set of basic DNA; besides the metagenetics, you can't tell the DNA of a worker wasp apart from that of a queen. I'm not saying humans have metagenetic castes to this degree, but it's not hard to imagine some related traits getting commented on and off together through some mechanism. I know some researchers now think there might be a whole other level of commentary, or a different track of information entirely, encoded in how the DNA is folded. That research is still pretty new and doesn't know where it's going, IIRC.

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