Was the Cause of Cambrian Explosion Terrestrial or Cosmic?
sciencedirect.com
sciencedirect.com
https://news.ycombinator.com/item?id=17110874 (82 points/123 comments)
I like to compare it to the evolution of computer games. When they became viable first (home computer revolution), an incredible amount of games was developed. Eventually doom arrived on the scene and every game became a 1st person shooter. (Simplified story, of course). Or the dot com boom maybe - for a while, money was thrown at everything internet related. After a while some winning concepts emerged, and most of the contenders went away again.
I think one needs clear evidence of life on a comet or another planet. Otherwise it is all circumstantial evidence.
A bit like, in a loose analogy the old code was
print "protein"; print "protein"
for i=1 to 2 {print "protein"}
If you take your hypothesis for example, it may explain the explosion (rapidity) of the evolution of new species but it still doesn't offer viable reasons why the explosion was isolated to that period only.
(Just an amusing side note: my God-believing and evolution-denying BIL uses the evidence of the Cambrian explosion to suggest that no scientist can explain why there was an explosion of diverse species is such a short time - it had to be "God's hand". "Only a creator can do such a thing". I must admit, until the arrival of my BIL, the Cambrian period was of mild interest to me. I now read about it with "special interest".
Cheers!
He uses the very same evidence of the existence of the explosion and the absence of evidence to explain the explosion part of the evidence as reason to believe that "it is God". I usually end the dinner conversation when I keep asking "how?". On some very rare but weaker moments he might trip and admit "I don't know". At which point I end it by saying, that's a very scientific thing to say. :-)
He adds colour to our lives.
I'm always perfectly happy when someone calls the big bang the moment of creation. It could have been.
Not really true.
"We don't know exactly how the Cambrian explosion came about, but have a lot of good evidence on how evolution works, which allows us to probe deeper into theories about what happened" is not equivalent to "it's all random chance!"
I do not differentiate between agnostic and atheistic thought. They are both the same thinking/belief systems in my view. An agnostic believes there could be a "god/creator" (but does not pursue this thought any further than "maybe"). An agnostic also believes there may not be a God/Creator given the absence of evidence to justify such a belief. An atheist believes that there is NO god/creator given the absence of evidence to prove the existence of such a being. If evidence had to exist then the atheist will believe the existence of such a being based on such evidence. That sounds exactly the same.
As to your point about "we don't know" - well, not knowing is perfectly fine in science. We cannot ascribe to or embellish and fabricate imagined facts and agents to any unknown phenomenon without evidence.
I find it very interesting that in de US there seem to be a lot of gnostic atheists (they know for certain there is no god, and are very vocal about this), while in Europe most people would be agnostic atheists, and they don't care as much.
My impression is Biblical literalism is more widespread in the US compared to Europe, which in turn is easier to decide for or against. Especially the discussion about evolution vs religion is almost entirely absent in Europe. Framing evolution as opposed to a belief in God means it is pretty easy to become an atheist, since we have overwhelming evidence for evolution.
I think the axioms you need for this kind of argument is that: is God exists, God is human-like, and God loves us.
Why would a cosmic being care more about humans than bacteria? Why would he value things like freedom over slavery? Why would he care if we believed in him or not?
Those are entirely human qualities and concepts.
There is no reason to think that if there is some sort of higher power, it has an any bigger interest in humans than it has with atoms or planets. To assume that is an assumption, which shouldn't be hidden.
These are entirely human concepts only if you've already accepted some different axioms of your own. The Christian argument is that valuing freedom over slavery, and wanting worship, are divine qualities and concepts. And humans share those things because they were made after God's likeness for the sake of being loved (and more importantly, loving God in return).
If this is false, then I think some further axioms may be needed to differentiate the two scenarios.
That's how human brains generally work. He's been conditioned to particular pattern matching and filtering. It's not a rational choice.
Or is he one of those 'micro-evolution' exists, but not 'macro-evolution'.?
Once you reach a certain level of complexity in one lineage you get exponentially more variation possible.
Likewise, compound that from earlier lineage break aways that are now also reaching a tipping point in their own complexity.
In other words, it's just an exponential situation under prime conditions for new species to emerge.
Higher-than-normal levels of radiation would provide the mutagenic effects on all life. Many things would die because of dead-end deviations.
I look at the area around Chernobyl at what radiation can do for evolution. Of course, it's pretty terrible for suffering on a whole, but we're talking about evolution. Life gets messy.
But a quick web search turns up various discussions of recent evolution, e.g. https://www.nytimes.com/2010/07/20/science/20adapt.html
For evolution to happen, a genetic mutation has to endow an advantage that makes its carrier more likely to survive and reproduce. Given that the reproductive selection process (which characteristics are attractive to a mate) is largely driven by cultural norms now, it's hard to see what advantages are going to raise a person's chances of reproducing. Fashion tastes change several times in a single generation.
Women are often said to like taller men. Well we are getting taller as a species [1]. If men prefer a woman with a certain 'look', maybe women are evolving towards that look (it seems like a much harder thing to quantify). Manipulative, cheating males have more sexual partners - maybe we're evolving towards more of that kind of behaviour.
If you're expecting humans to grow extra arms or become super-strong or something, I don't think it's going to happen. Extra limbs is too 'abnormal' and culture doesn't like that. Being physically strong doesn't affect chances of survival in humans any more. Same applies to better vision, hearing... any super-senses. They don't affect our survival. I've heard people posit that maybe we'll lose our little fingers as they don't do anything. Same again though - even if it's true that we don't use them, it doesn't mean that someone born without little fingers is going to have a higher chance of reproducing.
Our development happens at a rate much faster than biological evolution now because of culture (meme vs gene). A lot of what constitutes a modern human is external (as a thought experiment just imagine what a human would be like if he'd never spoken to another human, read anything, or absorbed any culture in any other way). From this point of view, cultural evolution could be seen as evolution v2.0 as it happens and spreads much more quickly that genetic evolution.
[1] https://www.scientificamerican.com/article/why-are-we-gettin...
If humanity in its current state somehow manages not to destroy itself (and much of everything else) the probability of speciation of our survivors is close to a certainty. Not so much as a consequence of natural selection or sexual selection but of human selection.
If we survive another 100 thousand years, we will inevitably see another emergent species genetically superior but incompatible with current homo sapiens. I think that will be an incredible day for humans to acknowledge (the death/extinction of homo sapiens). We had better sort our differences out before that day arrives.
Or sometimes a mutation can survive just by being benign enough not to make much difference to reproductive chances.
Ps choosing your mate is a recent thing for humanity
- white skincolor
- lactose tolerance
http://www.sciencemag.org/news/2015/04/how-europeans-evolved...
- possibly HgbS? Couldn't find much numbers related to its evolutionary history. And it's just one of the independent evolutions for malaria resistance: Thalassemias, Duffy blood groups and a few others seem to provide some level of malaria resistance to malaria
- CCR5-Δ32, while it provides resistance to HIV it's too old to have been selected for it but it's too young to have not been selected for as well (95% confidence that it's 900 to 5000 years old, likely circa 2250, a non-selected random survival would be ~100kY given how widespread it is)
All in all, they are probably more or less going away in the long run.
But then neither has the mosquito "evolved", or the shark. At a genetic level changes are continuous in every organism and genetic changes can even happen as rapidly as from one generation to next. We may not see the molecular changes translate to the phenotype level but the changes are there. (See topic of epigenetics)
Actually, you can see changes at phenotype level too (e.g body morphology of offspring affected by the diet of parents).
"There are only a few groups who diverged at a set time and remained discrete until now. The KhoiSan split off from the rest of us 100,000 years ago, and the Australian Aborigines about 40,000 years ago. Native Americans, who are a sub-set of the East Asian population, became isolated from population-exchange with Eurasia and Africa 12,000+ years ago." [1]
The thing is humans in the modern age intermingle much more so the differences are subtle and much harder to pick out since they don't remain as discrete.
- Humans have evolved. Look at our huge array of characteristic physical appearances. These differences have emerged in spite of the fact that we all share an extremely common same-species common ancestor. And that's just what's on the outside. Our primary divergence from our evolutionary (different species) ancestors has not been what's on the outside, as we've become worse in nearly every way, but what's on the inside. Intelligence > all. Discussing this topic as it relates to humans today is very sensitive.
- Evolution is driven by natural selection and ultimately by who's most successful at breeding. Humanity has socially evolved in a bizarre way in that today those who are least successful tend to breed far more successfully than those are more successful. Lower income, lower education, and higher religiosity are strongly correlated with higher fertility.
The Flynn Effect [1] was the observation that 'real' IQ scores were constantly increasing in developed nations. This was a major issue since IQ is normalized such that for any given population that mean is always 100 with a standard deviation of around 15. That means that somebody in 1960 with an IQ of 100 was probably more intelligent than somebody from 1920 with an IQ of 100. This was convenient for the environmental view of intelligence as improvement in environmental factors correlated with the increases in IQ. However, the Flynn effect in many developed nations has actually reversed, in spite of the continuing improvement in environmental factors. It continues to remain in effect in less developed nations. There are many ways to interpret this, but it's certainly interesting to consider it from an evolutionary perspective.
https://phys.org/news/2011-06-farming-blame-size-brains.html
Essentially there was some chromosome doubling which set the stage for the huge diversity and abundance of flowering plants which quickly dominated the planet. In the Wikipedia article on angiosperms it states, "The evolution of seed plants and later angiosperms appears to be the result of two distinct rounds of whole genome duplication events."
I'm sure something like this is one of the more plausible triggers for the Cambrian.
Anyone heard others?
It seems to be a load of speculation written by people with some sort of agenda and not a lot of actual knowledge.
Ohhhh. Glad I didn't read the paper then. I'm sure he has a lot of knowledge, but he's a bit obsessed by the idea of panspermia.
In my view the only elegant solution is to consider that life can originate a bit everywhere and cross-polinate everytime conditions are there.
On this issue, I think the Vital Question is a great book : https://www.goodreads.com/book/show/23316494-the-vital-quest...
In the abstract of the paper it says "living organisms such as space-resistant and space-hardy bacteria, viruses, more complex eukaryotic cells, fertilised ova and seeds have been continuously delivered ever since to Earth".
Besides from skipping lots of evolutionary steps, if those organisms have been delivered to earth by some cosmic object (a hand of God?), then man ultimately formed from that dust.
I am by no means religious, but it's an interesting thought experiment.
[1] https://www.biblegateway.com/passage/?search=Genesis+2&versi...
"...but it's an interesting thought experiment".
Your story is not a thought experiment of any kind. It's just an unstructured, unverifiable, lacking in continuity idea. It just a "thought" on its own.
I think this is just poetics, but I don't see how panspermia would make us any more cosmic beings than we already are.
All elements heavier than helium were created in the hearts of stars through nuclear fusion. We are all children of supernova remnants.
https://en.wikipedia.org/wiki/DNA
Is composed of hydrogen, oxygen, nitrogen, carbon and phosporus. 4 out of 5 elements there are guaranteed, certified remains of one ancient star or another.
Or. Like Carl Sagan said, "We are made of star stuff".