Cause of Cambrian Explosion – Terrestrial or cosmic? (2018) | Hacker News Reader

Cause of Cambrian Explosion – Terrestrial or cosmic? (2018)

sciencedirect.com

I started reading this with no bias, as I do not know the authors nor their past works, but roughly 1/4 into it I noticed that something was off.

I think this is the passage that made me stop reading with interest:

> Later exploration of several comets, using a variety of space technologies, has strengthened the case for microbial life in comets (and in carbonaceous chondrite residues) but this is not readily admitted in conservative astronomical and meteoritic circles.

"strengthening" the case? "admitting"? Someone is trying to convince the reader here not with evidence but rethorics.

Always with those conservative meteoric circles holding back society and thwarting progress!

What even is a meteoritic circle? Or "a variety of space technologies"?

This is an extensive catalog of wishful thinking, debunked hypotheses, and outright lies. There isn't any new research in it. Whether a couple of stray molecular building blocks of life could have survived inside a comet or meteorite is worth speculating about, but the notion of a continuous stream of "life" raining down, evolutionary biology of cephlapods (oooo they look like aliens) is pretty ridiculous.

Before the Cambrian period, many life forms had soft bodies. These didn't left many fossil evidence of their existence. So, we don't know for sure if the 'Cambrian explosion' was really an explosion or if it was not much different in terms of diversity than the previous period.

> we don't know for sure

To emphasize, we have a pretty good idea, but evidence is a bit limited.

> the 'Cambrian explosion' was really an explosion or if it was not much different in terms of diversity than the previous period

It was certainly an explosion, regardless of what happened before: The first: hard structures (as you note: bones, shells, etc.), vision, legs, metazoa (multicellular animals) - including the ancestors of almost all current species, chordata (phylum containing vertebrates), etc. etc.

In the land of the blind, the trilobite was royalty.

The hypothesis that life is seeded from comets then begs the question - how did it get onto comets in the first place?

Did it evolve on our local comets? In conditions which don't support life, over evolving on earth which does?

Seems unlikely - so I assume we are talking about comets from other systems. Which makes me wonder how life got onto _those_ comets. Which suggests that life can leave a planet and get picked up by a local comet turned wanderer. Given the plethora of life on this planet presumably our comets are well endowed by now...

I guess what I'm saying is that terestial evolution asks me to believe in one set of somewhat unlikely events - whereas cosmic evolution asks me to believe in the same events, just far far away, and then asks me to belive in "random space travel" (leaving as much as arriving) as well.

Consider me sceptical.

I think the argument they're making is that comets aren't as inhospitable as assumed, and in fact were better suited than primordial Earth - so life started there first.

The paper reads as more conjecture than fact. There are a few interesting threads that they are pulling on, but they seem to make a giant leap that

1. There is well established evidence of extraterrestrial microbes in meteorites

2. Earth is constantly bombarded with life bearing rocks, to the point that it is likely that “red rain” is non terrestrial.

3. Evolution events such as the octopus evolving from squid are from injection of genes by extraterrestrial retroviruses

I stopped reading at this point as the conjecture didn’t seem to lead to something substantive. If 1 and 2 are true we should have immediate access to an entire interstellar ecosystem. The space of possible mechanisms for abiogenesis grows exponentially. A distinct set of questions arise like does evolution occur in in asteroids? Do ecosystems on isolated rocks interact every few million years? Are the rocks coming into contact with earth from other life bearing worlds?

The paper answers none of these questions and doesn’t seem to grasp the implications it’s laying out.

Any references? Organic molecules is not life.

That’s the claim of the paper in the TFA.

https://en.wikipedia.org/wiki/Edward_J._Steele#COVID-19

In 2020, Steele, along with researcher N. Chandra Wickramasinghe and others, claimed in ten research papers that COVID-19 originated from a meteor spotted as a bright fireball over the city of Songyuan in Northeast China on October 11, 2019, and that a fragment of the meteor landed in the Wuhan area, which started the first COVID-19 outbreaks. However, the researchers, including Steele, did not provide any direct evidence proving this theory.[1] The pseudonymous science blogger Neuroskeptic, writing in Astronomy magazine, called the meteor origin theory "so remarkable that it makes the others look boring by comparison".[1]

Well that raises the nutjob factor considerably. The core ideas are interesting, it’s a shame some of the authors overreach so much.

So we have 33 smart people and not one was able to double check the facts, read the bibliography, spot the falsehoods and use the most basic level of critical thinking in their own paper. Or just don't cared because boring science will not bring grants to the table.

To start "There are zillions of planets that could have life" equals to "As they are many, there must be a link with earth. Every rock in the galaxy must cross the earth orbit eventually". Do we have a lot of samples of soil from Saturn in the planet? And don't made me talk about the idea of those octopus pointing a luminous tentacle to the sky and saying "my caave". Biologists know that this planet is perfectly able to made things much more weird than that.

"It's all lies, but they are entertaining lies, and in the end, isn't that the real truth?"

If life started on another planet, then how did it start on that other planet? For sure life could have been carried on that other planet from yet somewhere else, but it can't be comets all the way down! At some point, life must have started abiogenetically somewhere.

But if life could start somewhere from non-life, then why do we need panspermia to explain the presence of life on Earth? Isn't it enough to say that life started on Earth from non-life, as it would have to start someplace anyway?

Perhaps there's a less strong position that could be supported? Maybe life did start on Earth abiogenetically, but it was enhanced or enriched with life from outside the Earth? But then, how can we refute that? Is there a "smoking gun" that strongly contradicts the default assumption that life on Earth started on Earth?

Well I'm asking because I don't know those things (I'm lucky that I only have to study non-living systems). I'm grateful for any knowledgeable answers.

I totally agree about octopi, though: they clearly are space aliens.

It is fascinating, and I don't think most people appreciate, just how early life formed on earth. Basically as soon as the lava cooled down and earth wasn't absolutely hostile life popped up.

I believe the current understanding is that life even formed while lava was still around. I think the earliest dating is around 4.1B where the Hadean epoch ended 4B year ago.

IMHO, the key element were 1) foam, 2) warmth. When large bodies of water are formed, wind and earthquakes started to generate waves, waves started to generate foam from floating organic compounds, and warmth start to generate complex reactions, like in a lava tube. We can see similar things at a shore after a tanker spill. Water-organic foam cells are similar to life cells. In a few cubic km of organic foam, short samples of RNA can be formed just by chance. RNA + RNA transferase can produce copies of itself, forming a primitive virus.

This is a repeat, earlier version here:

https://news.ycombinator.com/item?id=30217403

Interesting, I thought the dupe checks would remove the # part of the url.

@dang?

These explanations fail to explain the Avalon Explosion, which was the immediate precursor to the Cambrian Explosion, starting 575 million years ago, roughly 34 million years before the Cambrian:

https://en.wikipedia.org/wiki/Avalon_explosion

The late portion of the Avalon is, arguably, the first phase of the Cambrian, especially after 550 million years ago. This is still under intense discussion.

Theories like "Maybe it was rising oxygen" fail to map to the complex interplay of development that we can see happening at the end of Ediacaran/Avalon-start-of-the-Cambrian.

A better explanation, which might appeal to computer programmers: sometimes you can't do work in a low level language. Sometimes, to do complex work, you need to switch to a high level language. And that is exactly what happened at the end of the Avalon. While you can say "DNA is the language life" what's crucial is the emergence of a powerful new DSL for describing complex body shapes: the Hox genes.

Consider the 3 earliest splits in the animal Kingdom, all happening at the end of the Ediacaran/Avalon:

sponges

Ctenophora

Bilateria

https://en.wikipedia.org/wiki/Bilateria

The first 2 don't have real Hox genes, but all of the Bilateria do, and when we talk about the Cambrian Explosion, we are talking about the explosion of Bilateria.

So we should consider the possibility that the Cambrian Explosion was an innovation in language, a specialization of DNA, the Hox genes essentially offering a specialized language for the description of complex body types. Remember that fish, flies, and humans all have Hox genes, and biology grads getting their PhDs take a certain perverse delight in showing that eyes can be made to appear in many different locations on a fly, by manipulating the Hox genes in the fly eggs.

As an analogy, consider how Alfred North Whitehead, back in 1912, described the benefits of a great math notation:

"By relieving the brain of all unnecessary work, a good notation sets it free to concentrate on more advanced problems, and in effect increases the mental power of the race."

https://en.wikiquote.org/wiki/Alfred_North_Whitehead

It is possible that describing complex body types was simply too much work without the Hox genes, but the Hox genes allowed a simplification, perhaps less actual work for the cells as they reproduced?

Do you happen to know any serious science sources that discuss the Avalon Explosion?

You can start with the references that are listed at the bottom of the Wikipedia page, listed above. I’ll try to post more when I’m back at my regular computer.

> A better explanation, which might appeal to computer programmers [...] a powerful new DSL for describing complex body shapes: the Hox genes

In a similar vein, a talk some years back, IIRC, suggested step-function-like expansions of miRNA repertoires (conserved regulatory small RNA families) at important phylogenetic tree branchings, was fruitfully viewed as "ok, now we have the knobs and dials to take on a new level of metabolic and morphological system complexity".

Sort of vaguely like watching an SPA website's js bundle expand - "ok, looks like it's picked up a reactive programming library, oh, and now it has components, ...".

I wondered if it might fruitfully be used as a theme, to rearrange how the phylogenetic tree is taught to kids. Perhaps gaining a clarity from lower-cardinality deep structure, that's less accessible in sea-of-features detail and stamp collecting.

Helpful article providing a less dense overview:

https://www.sciencealert.com/hoyle-wickramasinghe-thesis-com...

The following is in no way a scientific rebuttal of anything said in the article, and I'm aware of this. That said, the cited Wickramasinghe has some outlandish beliefs, including:

- The belief that various pandemics (flu, covid, etc) have extraterrestrial origin.

- That some fossils such as archaeopteryx is a fake.

- Sided with quasi-creationist views and against the scientific mainstream.

None of this automatically invalidates this theory, but it's at least noteworthy.

The authors could have talked to a geologist or palaeontologist, which would've saved them the time spent on writing a speculative paper like this.

If there is exchange of viable biological material between planets, be it RNA or tardigrades, that would simply be very cool.

I realise a lot of the detailed content of this paper is hyperbolic supposition, which is a shame as the overall idea is really interesting.

Can someone explain how 30 authors, from different institutions wrote the paper?

Good question. I'd like to say "Overleaf" but in standard practice they probably shared via email a zip file with an assortment of .tex and .bib files and their by-products (and including a folder marked "earlier_versions").

Although not fully related, this reminds me of another paper I recently found on astro-ph: https://arxiv.org/abs/2201.08997

This is all conjecture, a sort of a scientific "what-if" that's more suited to some especially woo-woo episode of ancient aliens than a paper.

I’ve wondered for a long time whether “life originated on Earth” isn’t the last geocentrism.

When you paraphrase the statement to "life on Earth originated on Earth" it doesn't sound as geocentric. It doesn't state that all life in the universe originated on Earth.

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