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Possible dinosaur DNA has been found

scientificamerican.com

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Re: Possible dinosaur DNA has been found

#81

Post by rurban »

multiplegeorges wrote: post #20
aphextron wrote: post #8

Earlier quoted context omitted.

It's a completely impossible fantasy. DNA has a half life of ~500 years. Mammoths only died out around 10,000 years ago, which is why it's conceivable that one could be brought back, but all dinosaur DNA has been destroyed for millions of years.

You say this as an absolute, but this very article is describing a case where it might have been found. It's unlikely, we'll see.

Extremely unlikely that the DNA they found is really that old. More like some recent dirt DNA.

And they tried really hard to get something out of the really good Mammoth DNA from Siberia. The blood was still liquid. No chance so far.

Re: Possible dinosaur DNA has been found

#83

Post by rcpt »

kuprel wrote: post #77
koeng wrote: post #41

Earlier quoted context omitted.

Possible? Yes. Practical? Not for 2-3 decades when DNA synthesis capacity gets good enough to synthesize full animal genomes. In terms of raw synthesis power, we do have the ability to synthesize billions of base pairs, but you're going to need other infrastructure around it. Also, immune problems I don't think would be a huge issue, the adaptive immune system has been around for a while.

If we could synthesize the dinosaur DNA, would a chicken be able to hatch a dinosaur egg if we injected it in the right place?

http://www.bbc.com/earth/story/20150512-bird-grows-face-of-d...

Some are trying to do this with chickens

Re: Possible dinosaur DNA has been found

#85

Post by gnramires »

Robotbeat wrote: post #59
burtonator wrote: post #49

Earlier quoted context omitted.

There was a paper not long ago saying that the DNA half life is about 500k years or so and that most of the DNA would be degraded. The issue I had with this is why can't we reassemble chunks of DNA like we can with a puzzle. I'm certain specialized algorithms exist within DNA analysis for this reason. This isn't my field and there are already algorithms that exist on the top of my head that could solve this issue. Th…

What does half life of 500,000 years mean? Does that mean any given gene will, on average, split every 500,000 years? Or become unusable in 500,000 years? 65 million years would mean 130 halvings. Basically nothing left, then. ...but this may depend on environmental conditions. this must depend on average environmental temperature, right? Might dinosaur specimens in Antarctic or Arctic regions have experienced signif…

Not sure where his 500k years figure comes from. A cursory search gives 521 years:

https://www.nature.com/news/dna-has-a-521-year-half-life-1.1...

Chemical decay tends to follow Arrhenius equation:

https://en.wikipedia.org/wiki/Arrhenius_equation#Equation

so indeed a difference of maybe 40C should lead to a difference in half life of about 20-30%. I think about 30 half lives (~10^-9 degradation factor) should be the limit of recoverability, so perhaps 521x30 = 15k years in normal conditions up to 521x30x1.25 = 20k years in low temperature.

Of course, other factors such as humidity could contribute as well to the half-life, and reactivity is a lot more complicated than the Arrhenius model in reality. But even then I would be surprised such a vast difference in reactivity outside of true cryogenic conditions (maybe even shielding from radiation?).

edit: your second edit is interesting :) is that curve polynomial or exponential?

Re: Possible dinosaur DNA has been found

#86

Post by Robotbeat »

gnramires wrote: post #85
Robotbeat wrote: post #59

Earlier quoted context omitted.

What does half life of 500,000 years mean? Does that mean any given gene will, on average, split every 500,000 years? Or become unusable in 500,000 years? 65 million years would mean 130 halvings. Basically nothing left, then. ...but this may depend on environmental conditions. this must depend on average environmental temperature, right? Might dinosaur specimens in Antarctic or Arctic regions have experienced signif…

Not sure where his 500k years figure comes from. A cursory search gives 521 years: https://www.nature.com/news/dna-has-a-521-year-half-life-1.1... Chemical decay tends to follow Arrhenius equation: https://en.wikipedia.org/wiki/Arrhenius_equation#Equation so indeed a difference of maybe 40C should lead to a difference in half life of about 20-30%. I think about 30 half lives (~10^-9 degradation factor) should be the…

Looks exponential to me. After all, the Arrhenius equation (whose constants seem different here than your earlier assumptions) is exponential.

Re: Possible dinosaur DNA has been found

#87

Post by roywiggins »

crimsonalucard wrote: post #32
tynpeddler wrote: post #15

Earlier quoted context omitted.

Homology studies. A DNA strand 17 bp long is pretty distinct. If a strand that long or longer was found, we would gain a lot of information about the evolutionary history of dinosaurs that we could never get from fossils. However, the article isn't clear about what they found. It says DNA, then it says there may not be a recoverable sequence. In that case nucleic acids would be a better term than DNA. Without more in…

I think by what "good does that do?" he means like what's the point if you can't use it to create dinosaur clones Jurassic Park style. I literally clicked on the link because that was the only thing on my mind. Not joking.

I mean that a soup of loose nucleic acids can't be sequenced even if we wanted to, we can't learn anything about their genome unless there's actual intact lengths of DNA.

That quote implied the former to me, so- there's not much to be learned from just nucleic acid soup

Re: Possible dinosaur DNA has been found

#88

Post by yesenadam »

RedComet wrote: post #51
echelon wrote: post #23

Earlier quoted context omitted.

> I love how not only the time of existence but also its size and appearance are presented as undisputable facts. All evidence and models across a large variety of disciplines points to the age of the fossils. Geological strata, carbon isotope ratios, phylogenetics, etc. Feel free to present your evidence so that we can weigh in.

Unfortunately, unlike the author of the first reply implied, I don't have a grand religious take on the issue. I'm simply criticizing what passes for "science" these days. Even if someone grants you all of the evidence you presented, we see regularly that discoveries of this sort are false - be it from contamination in the lab or just an overzealous lab coat. That said, I can give you a tasty nugget if you want. I re…

> I'm simply criticizing what passes for "science" these days.

Using scare quotes like that makes me totally confused what you're trying to say. If it's

I'm simply criticizing what passes for science these days.

then why not say so. The scare quotes give an impression you have a problem with all science, not just bad science, which I don't think you meant.

For a discussion of how poisonous to meaning this practice of using scare quotes can be, see David Stove's chapter Neutralizing Success-Words, an analysis of leading 20th C philosophers of science doing it. http://nekhbet.com/popper/chapter-01.html part 3. It's extremely enlightening and pretty funny, as Stove always is.

Re: Possible dinosaur DNA has been found

#89

Post by mod »

dmurray wrote: post #60
BrandonM wrote: post #28

Earlier quoted context omitted.

Bringing back mammoths based only on DNA seems to me to be akin to bringing back a New Yorker based only on DNA, thousands of years after NYC no longer exists. Even with perfect DNA, I think we underestimate the role that social structure and ecological momentum play in even the simplest of creatures. I think humans are the rule and not the exception when it comes to learning after birth. And that's not even getting…

> Even with perfect DNA, I think we underestimate the role that social structure and ecological momentum play in even the simplest of creatures. I don't think that's true. We raise animals without their parents all the time, both on farms and in zoos. The animals we end up with are still recognizably horses or rats or chimpanzees, with unique behavioural traits that could be studied for years. Even if you lose the so…

Was going to comment similarly.

I have 16 chicks in the brooder that have never been around a chicken. They never will be around any but their 15 "siblings."

They're still acting like chickens, and they will continue throughout their lifetimes.

Re: Possible dinosaur DNA has been found

#90

Post by perl4ever »

yesenadam wrote: post #88
RedComet wrote: post #51

Earlier quoted context omitted.

Unfortunately, unlike the author of the first reply implied, I don't have a grand religious take on the issue. I'm simply criticizing what passes for "science" these days. Even if someone grants you all of the evidence you presented, we see regularly that discoveries of this sort are false - be it from contamination in the lab or just an overzealous lab coat. That said, I can give you a tasty nugget if you want. I re…

> I'm simply criticizing what passes for "science" these days. Using scare quotes like that makes me totally confused what you're trying to say. If it's I'm simply criticizing what passes for science these days. then why not say so. The scare quotes give an impression you have a problem with all science, not just bad science, which I don't think you meant. For a discussion of how poisonous to meaning this practice of…

"The scare quotes give an impression you have a problem with all science"

Not to me, it looks like the normal use of scare quotes. You could swap it with so called science. Stuff that people call science, which is not.

If someone doesn't like any science, why would they care about a distinction between science and so called science?

If you don't like that, then you don't like scare quotes at all, but then what's the problem with saying "so called blah"?

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