Naked Science Forum
Life Sciences => Plant Sciences, Zoology & Evolution => Topic started by: alancalverd on 02/04/2020 17:11:04
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I've never accepted the idea that the dinosaurs were wiped out by climate change. A sudden shift of temperature, sunshine, or whatever, might eliminate several land-based species, but unless all the oceans froze (for which we have no evidence) the seagoing dinos (of which there were plenty) would simply have migrated to somewhere warmer or colder that suited them.
However the rapid spread of this year's killer virus does provide a plausible model for the sudden disappearance of a whole raft of related species.
Any thoughts (or better still, actual knowledge)?
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Like Covid, a virus might have knocked out a few percent of one species.
But that's obviously not the same as a mass extinction of many different species.
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There are significant differences between human behavior and that of other species - long range communication and collaboration, active medical intervention, extraordinary resilience due to being omnivores, avoidance of cannibalism (we learned a lot from kuru), and so forth. Without these, I think COVID infection would be even more rapid and widespread and long-term could make a significant dent in the population.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2738515 Infectious agents that can infect more than one host species are ubiquitous. Indeed, 62% of all human pathogens are classified as zoonoses (1), and 77% of livestock pathogens and 91% of domestic carnivore pathogens infect multiple hosts. Fifty seven of the 70 animal diseases considered to be of greatest international importance infect multiple hosts (2). The ability of pathogens to infect a wide range of hosts has been demonstrated as a risk factor for disease emergence in both humans (1) and domestic animals (2). (Virtually all recent outbreaks of disease in endangered wildlife have been caused by pathogens that can infect other, more abundant host species [3,4]).'
So given a few million years to adapt to one widespread species, it is entirely possible that a particularly agile virus could mutate over a few thousand more to infect several others. And we must remember that "species" doesn't actually have a scientific basis - it's merely a convenient label that we attach to things that appear to be related. It's entirely possible that all the dinosaurs were in fact more similar and thus susceptible to lethal zoonoses than all the present-day species. Then the virus made the mistake of killing all its hosts, and thus died out along with them.
Admittedly it's stretching credibility a bit, but it would at least explain the geologically "sudden" disappearance of the marine dinos.
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There are significant differences between human behavior and that of other species - long range communication and collaboration, active medical intervention, extraordinary resilience due to being omnivores, avoidance of cannibalism (we learned a lot from kuru), and so forth. Without these, I think COVID infection would be even more rapid and widespread and long-term could make a significant dent in the population.
And a hundred years ago we didn't know what a virus was. Essentially we had no effective medical treatment.
Covid's cousin made a mess of us, but we survived. 97% of us got by
"Indeed, 62% of all human pathogens are classified as zoonoses "
which means they infect the species we care about (us) and at least one other.
But "dinosaurs" is a very broad category.
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A sudden shift of temperature, sunshine, or whatever, might eliminate several land-based species, but unless all the oceans froze (for which we have no evidence) the seagoing dinos (of which there were plenty) would simply have migrated to somewhere warmer or colder that suited them.
The funny thing about climate is that it applies to the *whole planet.*
Obviously many creatures did survive (on land and in the water). As I understand it, the survivors are not related by biochemistry or genetics (as might be expected for pathogen-driven evolution), but by position in their respective food chains (the only apex predator I am aware of that survived this period was sharks, and they can eat pretty much anything), and flexibility in resource/habitat needs (omnivores > carnivores or herbivores).
The extinction at the K-T boundary appears to have included microbes, plants, fungus, vertebrates, and invertebrates. This seems atypical of a virus, to say the least!
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There are significant differences between human behavior and that of other species - long range communication and collaboration, active medical intervention, extraordinary resilience due to being omnivores, avoidance of cannibalism (we learned a lot from kuru), and so forth.
What's kuru?
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...............avoidance of cannibalism (we learned a lot from kuru), and so forth.
What's kuru?
It’s worth Googling. However, my search also threw up restaurant ‘Kuru Kuru Sushi’ which apparently also offers vegetarian options! ;)
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...............avoidance of cannibalism (we learned a lot from kuru), and so forth.
What's kuru?
It’s worth Googling. However, my search also threw up restaurant ‘Kuru Kuru Sushi’ which apparently also offers vegetarian options! ;)
Googled that and conclude that the only part unsafe to eat from a human is their brain? But brains are my favorites... Of course I only did chickens, ducks, geese, cows, and goats so far... Their brains are delicious!
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the only part unsafe to eat from a human is their brain?
Kuru is a prion disease, somewhat like "Mad Cow Disease" which shut down parts of the UK meat industry in the decades around the 1990s.
- And resulted in a significant reduction of eating brains in the UK
- And resulted in a ban on UK residents donating blood in Australia, for fear of passing on Mad Cow DIsease in blood transfusions
Mad Cow DIsease became widespread in cattle because of the practice in the UK of feeding calves the unwanted remains of cows and sheep (including the brains).
- There was a well-known disease in sheep called "scrapie" (although scientists didn't know what caused it until after Mad Cow Disease was finally diagnosed).
- It also affected some humans (in the hundreds)
- But like viruses, there is a species barrier that means a disease affecting one species is less likely to affect a different species, because their DNA and proteins are slightly different.
- Sheep and cow proteins are more similar to each other than to humans
- It's a reminder to avoid eating your own species (or closely related species - think of ebola and monkey meat)...
See: https://en.wikipedia.org/wiki/Bovine_spongiform_encephalopathy
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So, as long as I'm not eating a brain of a species which eats their own species' brain, I'm going to be fine?
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I've never accepted the idea that the dinosaurs were wiped out by climate change
Back to the original assumption....
These days, scientists are not suggesting that climate change (or dino flatulence) was the primary cause of the dinosaur extinction.
The leading theory today is that the Earth was struck by an asteroid perhaps 10km across, which landed offshore where the Yucutan peninsula is in modern Mexico.
This would have produced a global catastrophe, stretching far beyond the blast radius of what was effectively an explosion of 100 million megatons of TNT-equivalent
- some physicists calculated that just 1 or 2 hours later, the far side of the Earth would have approached pizza-oven temperatures as vaporized rock blasted into space from Mexico re-entered the Earth's atmosphere as a heavy rain of tiny meteorites.
- This event is marked around the world by a layer containing iridium (common in asteroids) and tiny spheres of glass representing the condensed meteorite rain.
The dust in the atmosphere and sulphate minerals blasted into the atmosphere would have changed the global climate for a few years, but this was a secondary effect.
- The primary cause was the asteroid impact
See: https://en.wikipedia.org/wiki/Cretaceous%E2%80%93Paleogene_extinction_event
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The asteroid fallout is superficially persuasive but if the impact cooked the oceans, that would explain the disappearance of the marine dinosaurs, but not the survival of other complex aquatic species.
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So, as long as I'm not eating a brain of a species which eats their own species' brain, I'm going to be fine?
Not necessarily true. Bovine spongiform encephalopathy, commonly known as mad cow disease, was caused by cattle being fed meat and bone meal from cattle with the disease or scrapie infected sheep parts. More than one pathway.
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When I was a boy a common expression for a fidgeting child was that he had the collie wobbles presumably a brain disorder of a shepherd's dog fed on scraps from dead sheep.
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if the impact cooked the oceans, that would explain the disappearance of the marine dinosaurs, but not the survival of other complex aquatic species.
Water has a very high specific heat. It would take an extended period of high temperatures to "cook the ocean" (today we are heating it up gradually, over centuries).
I think that marine dinosaurs would have had a fairly high metabolic rate, and would have to come up for oxygen pretty regularly. Air at pizza-over temperatures would destroy their lungs.
- The intense period of debris re-entry would have lasted a few hours
- But the large amount of sulphate aerosols would have led to acid rain and global cooling due to reflecting away sunlight.
The creatures that survived were:
- fish, which don't need to come up for air
- turtles and crocodiles, which have a very low basal metabolic rate, and can remain underwater for long periods of time
- 4-legged animals with masses < 25kg. Presumably some of these lived in caves or burrows, and could shelter from the heat, surviving on whatever oxygen was in their burrow
- Ancestors of the birds
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When I was a boy a common expression for a fidgeting child was that he had the collie wobbles presumably a brain disorder of a shepherd's dog fed on scraps from dead sheep.
That's not what it meant where I grew up
https://www.phrases.org.uk/meanings/97050.html
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We never cease to learn from the internet that interpretation of the term was my own idea I have no evidence that any one else thought it but as a child my mother from Bakewell often told me I had the collie-wobbles
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I've had the same thought today, that current corona virus outbreak can be connected to dinosaur eggs fossils. Specifically this has jumped out in my memory: www. thestar. com.my/news/nation/2019/07/29/china-boy-scores-big-find-with-dinosaur-egg-fossil . Time period between this discovery and outbreak is only 4 month. Since calcium is vital for virus survival, these egg fossils could be carriers of the virus. China is the place where most of the dinosaur fossils are found. Every year when there were disease outbreaks there were discovery of fossils, of course, not all fossils were in suitable conditions to become carriers or not all dinosaurs were infected. It seems quite convincing that current virus can not be traced to any other corona virus that is circulating in animal kingdom. It could be well worth to research further.
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these egg fossils could be carriers of the virus
- It is true that disease researchers have been able to sequence the 1918 flu strain from the graves of people who died of it.
- And researchers have been able to reconstruct the genome of the black death, from the 1500s.
- But genetic material degrades rapidly over time; the best preservation comes from uninterrupted frozen conditions
- Sequencing this old DNA is like a jigsaw puzzle; the DNA is broken up into small fragments, which have to be pieced together, often using a modern relative as a template (like solving a jigsaw puzzle with the help of the picture on the front of the jigsaw box)
- Protein survives a bit longer; again, best preservation is by freezing
Despite occasional claims that intact protein has been recovered from dinosaur fossils, it seems unlikely that intact and viable genetic material would survive that long.
- And that it would then jump the significant species barrier from dinosaurs to humans seems even more unlikely
Which path seems more likely for a species jump into humans?...
- A virus which survives for perhaps a day or two on surfaces, lying buried in fossils for ages
- Or many live bats (and other exotic mammal species) actively shedding billions of live virus particles in crowded animal markets
See: https://www.nationalgeographic.com/science/phenomena/2011/10/12/scientists-sequence-the-full-black-death-genome-and-find-the-mother-of-all-plagues/
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Yes, it is very slim chance that all conditions align favorably. But since virus can make mineral shell it can become spore like. https ://newsroom.wiley. com/press-release/angewandte-chemie-international-edition/virus-eggshell-mineral-layer-around-avian-flu-
I've seen a study, where it assumes that corona virus can substitute their own proteins or even RNA strands, without protein capsids, is capable to move from one host to another and maintain the activities of transcription and replication.
And the question, why would virus jump from dinosaur to human, I would think that we have similar receptor for it to attach.