Scientists Set Maximum Lifetime for Ancient DNA
Any DNA found older than this upper limit will cause huge problems for the evolutionary dating scheme.
Researchers have extracted and reconstructed DNA from a mammoth tusk they say is 1.2 million Darwin Years old. This is a new record, they say. It was possible only because the tusk was buried in permafrost. Their conclusions should be remembered if DNA much older is ever found.
Million-year-old mammoth genomes shatter record for oldest ancient DNA (Nature). Ewen Callaway says the DNA extracted is “up to” 1.6 million years old, the “oldest ancient DNA on record, pushing the technology close to — but perhaps not past — its limits.” His spokesman is Love Dalén, an evolutionary geneticist at the Swedish Museum of Natural History (SMNH) in Stockholm.
By crossing the million-year threshold, ancient-DNA researchers might be able to access the early histories of other mammals big and small, says Dalén. Very old permafrost samples of musk oxen, moose and lemmings are now on his lab’s radar.
Is there for a hard limit? Could the technique extract DNA from alleged human ancestors?
The chances of finding million-year-old remains of ancient human relatives in the permafrost are very low, researchers say. But Dalén thinks that the right environment, such as a deep cave, could yield samples that old. Early Neanderthal remains from a Spanish cave dated to 430,000 years ago represent the oldest DNA from an ancient human relative discovered so far. “Finding a hominin in the sort of ideal context for preservation as permafrost would be would be a dream,” says Slon.
As for the likely age limit of ancient DNA, Dalén says that’s easy to determine: “2.6 million years. That’s the limit of the permafrost. Before that, it was too warm.”
The 2.6 million Darwin Year figure is based on evolutionary geological dates for the last Ice Age, not on actual calculations of DNA longevity. Nevertheless, it sets an upper limit on what evolutionists believe is possible for DNA survival – and only if the DNA is frozen.
First million-year-old DNA extracted from Siberian mammoth teeth (New Scientist). Michael Marshall focuses mainly on differences between mammoth varieties, which are minimal because all breeds were interfertile or capable of hybridization.
The older teeth are the first specimens greater than a million years old to have their DNA read. That is far older than the previous record for ancient DNA, a 700,000-year-old horse, although it has proved possible to obtain protein sequences from even older remains, including a 1.9-million-year-old Homo erectus tooth.
“This looks supercool,” says Rebekah Rogers at the University of North Carolina at Charlotte. “It’s bringing together palaeontology and genetics on a deeper timescale than ever before.”
Million-year-old DNA provides a glimpse of mammoth evolution (Nature). This article speaks of “mammoth evolution” and claims that “one species evolved into another.” The differences, however, are very slight between these interfertile breeds. More important is the acknowledgement that “The cold temperatures had lessened degradation of the DNA across geological timescales.” DNA does degrade, and heat speeds up the degradation. Only the belief in the Ice Age dates makes them think it even lasted over a million years.
World’s oldest DNA reveals how mammoths evolved (Phys.org). This article explains that the age of the DNA was not measured directly, but was inferred from “geological data” (stratigraphy based on evolutionary assumptions) and the “molecular clock” hypothesis, which assumes that mutations occur at predictable rates over evolutionary time.
This is the first time that DNA has been sequenced and authenticated from million-year-old specimens, and extracting the DNA from the samples was challenging. The scientists found that only minute amounts of DNA remained in the samples and that the DNA was degraded into very small fragments.
“This DNA is incredibly old. The samples are a thousand times older than Viking remains, and even pre-date the existence of humans and Neanderthals,” says senior author Love Dalén, a Professor of evolutionary genetics at the Centre for Palaeogenetics in Stockholm.
We sequenced the oldest ever DNA, from million-year-old mammoths (The Conversation). Love Dalén himself wrote this article. He tells how difficult it was to piece together the DNA.
The DNA sequences also had another characteristic of very old DNA – they were extremely fragmented. Instead of the longer DNA sequences found in younger, better preserved mammoth samples from the permafrost, we only had short ones.
This caused another problem, because shorter sequences are increasingly difficult to place in their correct position of the genome. They can also be confused with contamination. To avoid this we had to discard all the sequences below a certain length threshold, which was painful but necessary.
He found another surprise; “most adaptations characteristic of the woolly mammoth were already present in its ancestral species that roamed the Siberian steppe over a million years ago.” This indicated to his team that the speciation event that led to the woolly mammoth did not require a fast adaptation rate. The adapted genes were already there. As for time limits,
We think permafrost preserved material holds the promise of even older DNA. However, since the oldest permafrost deposits are dated to the Early Pleistocene – around 2.6 million years ago – this may, sadly, put an upper limit on what is possible.
That’s a number to remember if older DNA is ever alleged.
Source paper: van der Valk, Love Dalén et al., Million-year-old DNA sheds light on the genomic history of mammoths. Nature (2021). https://doi.org/10.1038/s41586-021-03224-9
The DNA in that mammoth is not 1.6 million years old. If you erase the evolutionary assumptions and the dependence on evolutionary geology, it’s no older than the other Siberian animals encased in permafrost that are dated only a few thousand years old (26 Dec 2020). Even those dates are questionable. DNA degrades quickly, even over a few thousand years in permafrost.
Evolutionists love to make reckless drafts on the bank of time, because they never have to pay it back. A million here, a few million there – pretty soon you’re talking real funny. Can anyone really believe that the mammoth tusks and bones just sat there for almost two million years under a steady barrage of UV rays and cosmic rays as the Earth turned and climates changed? 1.6 million years is a belief, not a fact – and an unreasonable one (“a thousand times older than Viking remains”) when you think about it. We know about Vikings; nobody knows a million years. Besides, woolly mammoths are tropical species, not likely to have wandered into Arctic cold during an ice age. The evidence points to a catastrophic burial in a short time frame, not over millions of years.