Usually choanoflagellates are considered the nearest non-animal protist to animals. These guys aren't so far off, and maybe shared an ancestor capable of multicellularity, but they're probably not ancestors of animals. So my non-expert guess is that this pattern of embryo-like division is convergent. If not, the evolutionary tree is about to get shuffled big time. https://en.wikipedia.org/wiki/Choanozoa and the containing group, https://en.wikipedia.org/wiki/Holozoa
Edit: folks, there actually is some interesting science here if you can avoid getting hung up on the silly title.
Many choanoflagellates are colonial, so they exhibit a primitive form of multicellularity that differs from true multicellularity by the lack of differentiation between cells.
It is likely that the ancestor of all choanoflagellates was already colonial.
The fact that Chromosphaera is also multicellular for the initial part of its life and it also shows differentiation in at least 2 kinds of cells does not imply that it is more closely related to the animals than the choanoflagellates.
Also in some choanoflagellates, differentiation in 2 kinds of cells has been observed and it has been verified that the same genes are involved in multicellularity, both in animals and in choanoflagellates.
So this new discovery just pushes back the origin of the mulicellularity of the animal type, from the common ancestor of animals and choanoflagellates to the ancestor of all opisthokonts more closely related to humans than to mushrooms.
(Opisthokonts are a group of living beings composed of animals, fungi and their relatives, which are characterized by cells that swim using one posterior flagellum, like the human sperm cells.)
It is likely that the split between the opisthokonts related to animals and the opisthokonts related to fungi has arisen because the former have remained in marine environments while the latter have adapted to continental environments, so in order to survive desiccation the ancestors of fungi have acquired a cell wall made of chitin that has protected their cells but which has caused the loss of their mobility, leading to the difference in lifestyles, where animals move around finding and eating their food, while the fungal spores are spread passively by wind and then they grow into their food.
Multicellularity seems to be the theme of holozoa, for sure, but the article seems to think that this specific cell division pattern is homologous(?) with animals, and that seems unlikely to me, because it should also show up in choanoflagellates and everywhere else if so. (Ed: I think we're in violent agreement on this point)
(That bit about the opisthokont split with fungus is fascinating, thanks.)
As per theory of evolution, current species were created from ancestor species. Since chicken's ancestor species obviously laid eggs. It stands to reason that first chicken came from chicken egg which came from non-chicken!
I assume they're trying to make a joke, as it's too obviously illogical if not. (Admittedly it also seems fairly obviously not funny to me, but that's more subjective than believing that an animal can't "do" anything that it doesn't have a conscious understanding of.)
When we had cattle the cow paths showed up in the pasture, even where there was no obvious destination (for the shortest route to explain it). Legend has it that cattle form these paths along magnetic lines.
Anyway, the veracity of that legend doesn't matter, but it is here merely to illustrate the idea that perhaps we subconsciously build our roads on lines that chickens won't cross, rather than them being aware of the road?
The problem, though, is since the shell of the egg was made by a non-chicken, the chicken's egg is not a chicken egg. So the chicken is first, and that chicken's egg is the first chicken egg.
Actually it's more like trading pokemon. You could probably breed each ancient chicken in a chain all the way up to modern chickens but you just can't breed modern chickens with ancient chickens directly.
Lol whenever you can so casually say that a great scientist is wrong, that might be a good heuristic to know you misunderstood the question. It's a philosophical paradox stemming from our conception of species, not an empirical question about fossil records :)
Very true and well put, but IMHO that's not a productive definition of "scientist". You're definitely on the side of common usage, but this is one of the many hills I'd die on; all scientists necessarily employ intuitive intellectual tools at some point in their process, so it feels silly to cut out those who primarily use them if they're still productively employing systematic thought.
The upside of this is that Mathematicians get to be scientists, too! The downside is that you also have to let the darn philosophers in ;)
The title is XKCD-style Nerd Sniping ;) The body of the article is about how a unicellular species formed multicellular-/animal-like groups via 'polar' division. I don't really understand what the difference between a colony of unicellular organisms and a multicellular organism is, but given the last sentence of the article, I don't think they do either:
This discovery could also shed new light on a long-standing scientific debate concerning 600 million-year-old fossils that resemble embryos, and could challenge certain traditional conceptions of multicellularity.
I literally cannot source this pun, and my ego refuses to believe you can had been this clever.
"Ogres are like onions! They have layers, just like onions. You get it? We both have layers"
We are all just recursive instances of magnitudes of complexity, and the "automata" we dissuade ourselves into denying we are not is just an ironic emergent property of being able to "think".
"Delineation" between these automata is only possible with edges - a membrane, an egg, of sorts.
Sorry for your ego but that came right from my brain as a joke. It wasn't until after I hit submit I paused to think, "that's actually kinda profound for a Thursday morning."
Well I think the original saying could be expanded to something like "Given that chicken birds hatch from chicken eggs, and chicken eggs are layed by chicken birds, how did the cycle get started?"
Or in the case of the article "Given that all egg-layers hatch from eggs and that all eggs are layed by egg-layers how did the cycle get started?"
To answer the former question, we know that a bird can lay mutated eggs, but an egg can hatch into a mutated bird. So a not-quite-chicken layed a chicken egg.
The article deals with the second question.
Returning to your question I guess the answer you are looking for is a watchmaker God? And that if then we continue the analogy the purpose of the universe is to develop into another God?
But where is the cutoff between reptile and chicken? Given how gradual it must've been, we can therefore posit that chicken's ancestors were themselves chicken. What came first, the reptile or the egg?
Also I think by definition a chicken is a bird that hatches from an egg (among other defining characteristics). So th egg must have come first, as a chicken-like creature that didn't come from an egg wouldn't be a chicken.
I'm not sure if this is intended as serious or tongue-in-cheek.
Obviously parents come before offspring.
The earliest form of reproduction is just binary fission - what an amoeba does by splitting itself into two. In it's simplest (origins of life) form this is just a mechanical process of a proto-metabolism (bunch of chemicals) being split into parts that are smaller versions of the "parent", e.g. some proto-cell composed of seashore froth being whipped into smaller versions of itself.
Eventually the division process became asymmetrical with the spawned child being a simpler proto-version of the adult, capable of then independently developing into the adult form. It seems life developed in the oceans before emerging onto land, so the history is probably of multi-cellular fish-precursors reproducing by spawning simpler (conceptually egg-like) versions of themselves, eventually evolving into egg-laying fish, and then egg-laying land-based animals including the dinosaurs from which birds developed.
So, maybe the best answer to "which came first, chicken or egg?" is "fish".
I'm glad you couldn't tell! It's basically tongue in cheek, as the question is silly to begin with.
And of course eggs predate chicken, eggs are seriously old
technology.
Back to the tongue in cheek: there is something easily tautological that chickens come from eggs. At some point a non-chicken laid an egg, and the first chicken was born from it. This is true regardless of which mutation one decides is "the" mutation that makes for the "first" chicken.
The question is asking if the first chicken hatched from a chicken egg (the egg came first) or if the first chicken hatched from an egg of the animal that laid the egg (the chicken came first). Of course, it is just a thought experiment that is ultimately unanswerable. There is no such thing as a distinct chicken or distinct chicken egg.
The koan implies chicken egg, though, not any old egg.
Did the proto-chicken lay a chicken egg which hatched the first chicken, or did the proto-chicken lay a proto-chicken egg which hatched the first chicken?
I guess it depends on whether the crucial mutation that flipped the organism from "non-chicken" to "chicken" happened before or after fertilization!
Or alternatively we can say that the germ line went from 49% chicken to 50% chicken to 51% chicken? Biology is really a continuous state space anyway and trying to push things into categories too hard will break them.
If a chicken egg is an egg laid by a chicken, the chicken came first
If a chicken egg is an egg that hatches into a chicken, the egg came first.
We know that the first case is correct because an unfertilised egg laid by a chicken is called a chicken egg despite by definition not hatching into a chicken.
There is this implicit bias in your question that complexity comes from a discontinuous change which can be noticed at one moment, it’s much more diffuse and gradual. Just like we won’t know we are in World War 3 for another couple years.
Is this just a mindless comment made without even skimming through the article or thinking about the actual meaning and intention behind the question? It's an intended correction I could attribute to a caricature of an autist, taking everything in absurdly literal terms. Typical of HN, in any case... The article talks about the actual origin of embryonic development mechanisms, pointing out that they could've preceded the existence of the animals that came out of them, not literally chickens and eggs (of course, its title uses those terms figuratively):
>"In fact, the study shows that either the principle of embryonic development existed before animals, or multicellular development mechanisms evolved separately in C. perkinsii."
It all boils down to the debate surrounding abiogenesis: the constant egg-chicken (or gamete-organism) loop does not explain how life came to be, emerging from, in principle, no life. It's paradoxical, just like trying to answer "the chicken" or "the egg". Or, as you seem to prefer, "the reptile" or "the egg".
There were eggs long before there were anything like a bird or a chicken.
But if you're on the strict interpretation, the change was so gradual over so many generations it's hard if not impossible to detect. Even when it speciates (becomes unable to produce viable offspring after mating) is hard to tell. There was like likely a long stretch of many generations where sometimes it worked, sometimes it didn't.
TL:DR; How long is a piece of string?
edit: Variation of the same question: Were there radio waves before there radios? Jupiter and thunderstorms produce them, but we had no way of knowing so to us they did not exist.
> Variation of the same question: Were there radio waves before there radios?
I'm not sure that is analogous. The chicken/egg question is about at what point we started identifying an egg as being a chicken egg as opposed to being an egg from another animal. In other words, did the first chicken egg come from a chicken (meaning the chicken came first), or from a proto-chicken (meaning the egg came first)?
A closer variation might be: Which came first, the radio broadcast or the radio broadcaster? Before the radio broadcast and radio broadcaster there was radio and people using radio, but they did not reach a wide public audience. At some point the early small-scale experimental radio use turned into broad utilization, but when and which was earlier on the timeline?
I'd have to go with radio broadcaster. You can make radio waves by touching the poles of a battery together with a wire. BUT, if you don't know you are making radio waves are you still a broadcaster?
> You can make radio waves by touching the poles of a battery together with a wire.
You can. But making radio waves does not imply a broadcast. At least not in the traditional sense. I'll grant you that colloquially we have sometimes come to refer to any radio transmission as a broadcast, but that is not the usage here.
> BUT, if you don't know you are making radio waves are you still a broadcaster?
If you didn't know a chicken emerged from an egg, is it still a chicken? My experience with young children who don't yet understand that process would say yes. No doubt there are career radio broadcasters out there who are not familiar with the science of radio.
It's not about not knowing of the existence of something, though. We know the chicken came from an egg. We just don't know what kind of egg it was. Was it a chicken egg or was it a flibberdoodle egg? If it was a chicken egg, how did the flibberdoodle lay a chicken egg? If it was a flibberdoodle egg, how did a chicken come out?
Usually choanoflagellates are considered the nearest non-animal protist to animals. These guys aren't so far off, and maybe shared an ancestor capable of multicellularity, but they're probably not ancestors of animals. So my non-expert guess is that this pattern of embryo-like division is convergent. If not, the evolutionary tree is about to get shuffled big time. https://en.wikipedia.org/wiki/Choanozoa and the containing group, https://en.wikipedia.org/wiki/Holozoa
Edit: folks, there actually is some interesting science here if you can avoid getting hung up on the silly title.
Many choanoflagellates are colonial, so they exhibit a primitive form of multicellularity that differs from true multicellularity by the lack of differentiation between cells.
It is likely that the ancestor of all choanoflagellates was already colonial.
The fact that Chromosphaera is also multicellular for the initial part of its life and it also shows differentiation in at least 2 kinds of cells does not imply that it is more closely related to the animals than the choanoflagellates.
Also in some choanoflagellates, differentiation in 2 kinds of cells has been observed and it has been verified that the same genes are involved in multicellularity, both in animals and in choanoflagellates.
See e.g. https://www.biorxiv.org/content/10.1101/452185v1
So this new discovery just pushes back the origin of the mulicellularity of the animal type, from the common ancestor of animals and choanoflagellates to the ancestor of all opisthokonts more closely related to humans than to mushrooms.
(Opisthokonts are a group of living beings composed of animals, fungi and their relatives, which are characterized by cells that swim using one posterior flagellum, like the human sperm cells.)
It is likely that the split between the opisthokonts related to animals and the opisthokonts related to fungi has arisen because the former have remained in marine environments while the latter have adapted to continental environments, so in order to survive desiccation the ancestors of fungi have acquired a cell wall made of chitin that has protected their cells but which has caused the loss of their mobility, leading to the difference in lifestyles, where animals move around finding and eating their food, while the fungal spores are spread passively by wind and then they grow into their food.
Multicellularity seems to be the theme of holozoa, for sure, but the article seems to think that this specific cell division pattern is homologous(?) with animals, and that seems unlikely to me, because it should also show up in choanoflagellates and everywhere else if so. (Ed: I think we're in violent agreement on this point)
(That bit about the opisthokont split with fungus is fascinating, thanks.)
Wait, people actually debate this?
As per theory of evolution, current species were created from ancestor species. Since chicken's ancestor species obviously laid eggs. It stands to reason that first chicken came from chicken egg which came from non-chicken!
So, egg came first.
Update: fixed typo
I think a bigger debate is why did it cross the road...
It doesn't. The chicken doesn't know it's a road
A road is not a road if a chicken doesn't know what a road is? That's an interesting rabbit hole to go down.
I assume they're trying to make a joke, as it's too obviously illogical if not. (Admittedly it also seems fairly obviously not funny to me, but that's more subjective than believing that an animal can't "do" anything that it doesn't have a conscious understanding of.)
Or, if a chicken crosses a road and nobody is looking, did the chicken crossed the road?
Yes, I'd say so since the road doesn't have to be perceived by a human to be a road. Does it make a sound?
If a road has not been perceived by a human, what created it?
I meant at the time of the alleged chicken crossing
In practice, the chickens I see along the sides of roads clearly know what roads are. And don't cross them.
When we had cattle the cow paths showed up in the pasture, even where there was no obvious destination (for the shortest route to explain it). Legend has it that cattle form these paths along magnetic lines.
Anyway, the veracity of that legend doesn't matter, but it is here merely to illustrate the idea that perhaps we subconsciously build our roads on lines that chickens won't cross, rather than them being aware of the road?
The problem, though, is since the shell of the egg was made by a non-chicken, the chicken's egg is not a chicken egg. So the chicken is first, and that chicken's egg is the first chicken egg.
Actually it's more like trading pokemon. You could probably breed each ancient chicken in a chain all the way up to modern chickens but you just can't breed modern chickens with ancient chickens directly.
What about when the number of chromosomes changes?
I'm going to call a non-chicken a chocken from now on. :)
A related question would be "what is a chicken", or where is the line between "non-chicken" and "chicken".
There's a gradient of chickenness.
Here it's a joke, I think. Mostly.
Yep, Aristotle was wrong. "Chicken and egg problems" aren't paradoxes, the challenge is to find which is the egg.
Lol whenever you can so casually say that a great scientist is wrong, that might be a good heuristic to know you misunderstood the question. It's a philosophical paradox stemming from our conception of species, not an empirical question about fossil records :)
True in the abstract, but calling Aristotle a "great scientist" is a stretch at best. He wasn't much of an empiricist.
Very true and well put, but IMHO that's not a productive definition of "scientist". You're definitely on the side of common usage, but this is one of the many hills I'd die on; all scientists necessarily employ intuitive intellectual tools at some point in their process, so it feels silly to cut out those who primarily use them if they're still productively employing systematic thought.
The upside of this is that Mathematicians get to be scientists, too! The downside is that you also have to let the darn philosophers in ;)
Almost started discussing this with you. :D
The title is XKCD-style Nerd Sniping ;) The body of the article is about how a unicellular species formed multicellular-/animal-like groups via 'polar' division. I don't really understand what the difference between a colony of unicellular organisms and a multicellular organism is, but given the last sentence of the article, I don't think they do either:
Nice read. Anyways ...
Hindu Mythology: Universe emerged from a "cosmic egg" (Brahmanda).
Greek Mythology: Orphic tradition describes a universe hatching from an egg.
Chinese Mythology: Pangu broke out of a cosmic egg, creating heavens and earth.
Big Bang Theory: Universe began from a dense, hot "singularity," conceptually like a cosmic egg.
Symbolic Parallel: Egg symbolizes unity and potential, akin to the universe's origin.
What's a chicken?
> What's a chicken?
A miserable little pile of secrets.
A vessel to cross the street.
"Delineation" between these automata is only possible with edges - a membrane, an egg, of sorts.
Sorry for your ego but that came right from my brain as a joke. It wasn't until after I hit submit I paused to think, "that's actually kinda profound for a Thursday morning."
Ah, well, neither of our ego's can take credit, then.
Id take the credit for it, but lack the ego.
My ego is in awe. Maybe the credit goes to the Id we found along the way.
Sorry but this sounds and looks like a Crossy Road thing ^^
> What's a chicken?
Well I think the original saying could be expanded to something like "Given that chicken birds hatch from chicken eggs, and chicken eggs are layed by chicken birds, how did the cycle get started?"
Or in the case of the article "Given that all egg-layers hatch from eggs and that all eggs are layed by egg-layers how did the cycle get started?"
To answer the former question, we know that a bird can lay mutated eggs, but an egg can hatch into a mutated bird. So a not-quite-chicken layed a chicken egg.
The article deals with the second question.
Returning to your question I guess the answer you are looking for is a watchmaker God? And that if then we continue the analogy the purpose of the universe is to develop into another God?
^^ This or: God is an egg.
Here is a (professional) philosophical perspective on the problem, with an interesting discussion in the comments http://schwitzsplinters.blogspot.com/2012/02/egg-came-first....
As others have pointed out, this is not the right question to ask now that we know about Darwinian evolution through natural selection.
This is a reminder, however, that the questions we ask are very powerful framing devices that can constrain or liberate our thinking.
First came the reptiles, then the chicken. Eggs are hundreds of millions of years older than chicken.
But where is the cutoff between reptile and chicken? Given how gradual it must've been, we can therefore posit that chicken's ancestors were themselves chicken. What came first, the reptile or the egg?
The egg.
But it looks like phylotypic animal body plans may have originated in cell aggregates before the development of the egg:
https://onlinelibrary.wiley.com/doi/epdf/10.1002/jez.b.21417
Also I think by definition a chicken is a bird that hatches from an egg (among other defining characteristics). So th egg must have come first, as a chicken-like creature that didn't come from an egg wouldn't be a chicken.
I'm not sure if this is intended as serious or tongue-in-cheek.
Obviously parents come before offspring.
The earliest form of reproduction is just binary fission - what an amoeba does by splitting itself into two. In it's simplest (origins of life) form this is just a mechanical process of a proto-metabolism (bunch of chemicals) being split into parts that are smaller versions of the "parent", e.g. some proto-cell composed of seashore froth being whipped into smaller versions of itself.
Eventually the division process became asymmetrical with the spawned child being a simpler proto-version of the adult, capable of then independently developing into the adult form. It seems life developed in the oceans before emerging onto land, so the history is probably of multi-cellular fish-precursors reproducing by spawning simpler (conceptually egg-like) versions of themselves, eventually evolving into egg-laying fish, and then egg-laying land-based animals including the dinosaurs from which birds developed.
So, maybe the best answer to "which came first, chicken or egg?" is "fish".
I'm glad you couldn't tell! It's basically tongue in cheek, as the question is silly to begin with.
And of course eggs predate chicken, eggs are seriously old technology.
Back to the tongue in cheek: there is something easily tautological that chickens come from eggs. At some point a non-chicken laid an egg, and the first chicken was born from it. This is true regardless of which mutation one decides is "the" mutation that makes for the "first" chicken.
QED it's the egg
The question is asking if the first chicken hatched from a chicken egg (the egg came first) or if the first chicken hatched from an egg of the animal that laid the egg (the chicken came first). Of course, it is just a thought experiment that is ultimately unanswerable. There is no such thing as a distinct chicken or distinct chicken egg.
The koan implies chicken egg, though, not any old egg.
Did the proto-chicken lay a chicken egg which hatched the first chicken, or did the proto-chicken lay a proto-chicken egg which hatched the first chicken?
I guess it depends on whether the crucial mutation that flipped the organism from "non-chicken" to "chicken" happened before or after fertilization!
Or alternatively we can say that the germ line went from 49% chicken to 50% chicken to 51% chicken? Biology is really a continuous state space anyway and trying to push things into categories too hard will break them.
If a chicken egg is an egg laid by a chicken, the chicken came first
If a chicken egg is an egg that hatches into a chicken, the egg came first.
We know that the first case is correct because an unfertilised egg laid by a chicken is called a chicken egg despite by definition not hatching into a chicken.
Therefore the chicken came first
There is this implicit bias in your question that complexity comes from a discontinuous change which can be noticed at one moment, it’s much more diffuse and gradual. Just like we won’t know we are in World War 3 for another couple years.
Of course. Communicating that bias in a fun and relatable way is the intent of the question.
Is this just a mindless comment made without even skimming through the article or thinking about the actual meaning and intention behind the question? It's an intended correction I could attribute to a caricature of an autist, taking everything in absurdly literal terms. Typical of HN, in any case... The article talks about the actual origin of embryonic development mechanisms, pointing out that they could've preceded the existence of the animals that came out of them, not literally chickens and eggs (of course, its title uses those terms figuratively):
>"In fact, the study shows that either the principle of embryonic development existed before animals, or multicellular development mechanisms evolved separately in C. perkinsii."
It all boils down to the debate surrounding abiogenesis: the constant egg-chicken (or gamete-organism) loop does not explain how life came to be, emerging from, in principle, no life. It's paradoxical, just like trying to answer "the chicken" or "the egg". Or, as you seem to prefer, "the reptile" or "the egg".
Well I'm glad we've put this age old question to bed
A cheeken laid the egg with the first chicken in it.
There were eggs long before there were anything like a bird or a chicken.
But if you're on the strict interpretation, the change was so gradual over so many generations it's hard if not impossible to detect. Even when it speciates (becomes unable to produce viable offspring after mating) is hard to tell. There was like likely a long stretch of many generations where sometimes it worked, sometimes it didn't.
TL:DR; How long is a piece of string?
edit: Variation of the same question: Were there radio waves before there radios? Jupiter and thunderstorms produce them, but we had no way of knowing so to us they did not exist.
> Variation of the same question: Were there radio waves before there radios?
I'm not sure that is analogous. The chicken/egg question is about at what point we started identifying an egg as being a chicken egg as opposed to being an egg from another animal. In other words, did the first chicken egg come from a chicken (meaning the chicken came first), or from a proto-chicken (meaning the egg came first)?
A closer variation might be: Which came first, the radio broadcast or the radio broadcaster? Before the radio broadcast and radio broadcaster there was radio and people using radio, but they did not reach a wide public audience. At some point the early small-scale experimental radio use turned into broad utilization, but when and which was earlier on the timeline?
I'd have to go with radio broadcaster. You can make radio waves by touching the poles of a battery together with a wire. BUT, if you don't know you are making radio waves are you still a broadcaster?
> You can make radio waves by touching the poles of a battery together with a wire.
You can. But making radio waves does not imply a broadcast. At least not in the traditional sense. I'll grant you that colloquially we have sometimes come to refer to any radio transmission as a broadcast, but that is not the usage here.
> BUT, if you don't know you are making radio waves are you still a broadcaster?
If you didn't know a chicken emerged from an egg, is it still a chicken? My experience with young children who don't yet understand that process would say yes. No doubt there are career radio broadcasters out there who are not familiar with the science of radio.
It's not about not knowing of the existence of something, though. We know the chicken came from an egg. We just don't know what kind of egg it was. Was it a chicken egg or was it a flibberdoodle egg? If it was a chicken egg, how did the flibberdoodle lay a chicken egg? If it was a flibberdoodle egg, how did a chicken come out?
Both - a chicken with a lifetime of eggs. God created the first female chickens with eggs.