Million-year-old mammoth DNA rewrites animal's evolutionary tree
DNA from three ancient molars, one likely to be over a million years old, has revealed that there is a ghost lineage of mammoths that interbred with distant relatives to produce the North American mammoth population.
[...] We don't have precise dates for any of the teeth, as they appear to be too old for carbon dating. Instead, dates have been inferred using a combination of the species present in the deposits and the known timing of flips in the orientation of Earth's magnetic field. In addition, the shape of the teeth provide some hints about what species they group with and provide some further indication of when they were deposited. In all, one tooth is likely to be at least a half-million years old, another about a million years old, and a third somewhat older still.
Previously, the oldest DNA obtained from animal remains is roughly the age of the youngest of these samples. But the researchers were able to recover some elephant-like DNA from each of the molars, although it was badly fragmented, and many individual bases were damaged. Researchers were able to isolate the full mitochondrial genome for each of the three teeth, as each cell contains many copies of this genome in each of its mitochondria. Only fragments of the nuclear genome could be obtained, however—at most, about 10 percent of one genome, and at worst under two percent. (Although less than two percent is still tens of millions of individual bases.)
Using the differences between the mammoth and elephant DNA and assuming a constant rate of mutation, the research team was able to derive independent dates for when each of the animals that left a tooth must have lived. Based on the mitochondria genome, the dates were 1.6 million, 1.3 million, and 900,000 years ago. For the two that had enough nuclear genome to analyze, the dates were 1.3 million and 600,000 years ago. The DNA-based dates for these two lined up nicely with each other and the date of the material they were found in. The oldest sample might be older than the deposit it's in, and thus it might have been moved after death.
Million-year-old DNA sheds light on the genomic history of mammoths (DOI: 10.1038/s41586-021-03224-9) (DX)
(Score: -1, Spam) by Anonymous Coward on Friday February 19 2021, @07:01AM
https://archive.org/download/TerryADavis_TempleOS_Archive/videos/2017/2017-07-12T04:47:05+00:00%20-%2008JewishPig.MP4 [archive.org]
(Score: 0) by Anonymous Coward on Friday February 19 2021, @07:52AM (2 children)
What the F is this?
Yes, because, you know, with a known rate of radio decay of isotopes, well at some point they all just get mixed up and we have no idea what we are doing. Ergo, too old for Carbon-14 dating. They call this "science"?
(Score: 3, Insightful) by kvutza on Friday February 19 2021, @12:23PM
After cca 80 thousand years the concentration of 14C is too low, and you cannot use it (reliably) then.
a survey [chcpublications.net]
PS They know what they do.
(Score: 0) by Anonymous Coward on Friday February 19 2021, @12:29PM
Exactly what I thought as well. Carbon dating has been done on way older things, that's why it's used. What they probably wanted to say is that there wasn't enough carbon in the molars for a good determination (read: not method sensitive enough for these quantities). I'm not sure what the requirements are for a carbon dating protocol (never done any), but my best guess is that it's that.
The summary is bad in another way... nowhere they write how it "rewrites animal evolutionairy tree": first the excuse for not being able to determine physical age, then some general things regarding the (mitogontrial) genome and finally they pinpoint the genetic age, nothing regarding the "animal evolutionary tree" (which is much bigger than only the elephant/mammoth part).
(Score: 0) by Anonymous Coward on Friday February 19 2021, @02:11PM (3 children)
I don't think people understand how long a million years is. There aren't going to be bones still sitting around from a million tears ago.
(Score: 0) by Anonymous Coward on Friday February 19 2021, @05:51PM (2 children)
"There aren't going to be bones still sitting around from a million tears ago."
Let's see, there are 6 billion people on earth. If even a million of them cried even once within the last year a million tears ago can't be that long ago.
(Score: 0) by Anonymous Coward on Friday February 19 2021, @05:53PM (1 child)
(well, it's more than 6 billion now, but my brain is still stuck in the past ...).
(Score: -1, Flamebait) by Anonymous Coward on Friday February 19 2021, @10:50PM
That's ok, most of the 1.5 billion new ones are third world scum.