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two by two...
opelmanta1900 Offline
#1 Posted:
Joined: 01-10-2012
Posts: 13,954
All modern humans descended from a solitary pair who lived 100,000 to 200,000 years ago, scientists say.

Scientists surveyed the genetic "bar codes" of five million animals - including humans - from 100,000 different species and deduced that we sprang from a single pair of adults after a catastrophic event almost wiped out the human race.

These bar codes, or snippets of DNA that reside outside the nuclei of living cells, suggest that it's not just people who came from a single pair of beings, but nine out of every 10 animal species as well, Daily Mail reports.

The research was led by Senior Research Associate Mark Stoeckle and Research Associate David Thaler of the University of Basel, Switzerland.

Stoeckle and Thaler concluded that 90 per cent of all animal species alive today come from parents that all began giving birth at roughly the same time, less than 250,000 years ago - throwing into doubt the patterns of human evolution.

"This conclusion is very surprising and I fought against it as hard as I could, " Thaler admitted

The new report was published in Human Evolution.

Stoeckle and Thaler mined "big data" insights from the world's fast-growing genetic databases and reviewed a large literature in evolutionary theory, including Darwin.

Stoeckle said: "At a time when humans place so much emphasis on individual and group differences, maybe we should spend more time on the ways in which we resemble one another and the rest of the animal kingdom."

The conclusions throw up considerable mystery as to why the need for human life to start again was needed such a relatively short time ago, especially since the last known extinction we know of was during the time of the dinosaurs 65 million years ago.

This opens up the possibility of an inbuilt human evolutionary process wherein we break down and die out, leaving the need to start from scratch.

We're also surprisingly similar to not just every other human, but every other species.

"If a Martian landed on Earth and met a flock of pigeons and a crowd of humans, one would not seem more diverse than the other according to the basic measure of mitochondrial DNA," said Jesse Ausubel, Director of the Program for the Human Environment at The Rockefeller University.

"Culture, life experience and other things can make people very different but in terms of basic biology, we're like the birds," Stoeckle added.

The "mitochondrial DNA" examined in the research is that which mothers pass down from generation to generation and it showed the "absence of human exceptionalism."

"One might have thought that, due to their high population numbers and wide geographic distribution, humans might have led to greater genetic diversity than other animal species," added Stoeckle.

"At least for mitochondrial DNA, humans turn out to be low to average in genetic diversity."

The study has been misunderstood by some religious parties who thought it meant that we all came into being in some seminal Big Bang-typed event 100,000 ago, but this isn't what the findings actually suggest.

What Stoeckle and Thaler's findings point to is that our species has to revamp far more often than we thought, and we do so in unison with all animals.




https://www.nzherald.co.nz/lifestyle/news/article.cfm?c_id=6&objectid=12166328
Gene363 Online
#2 Posted:
Joined: 01-24-2003
Posts: 30,669
The more we know, the more we don't know. Interesting article, thanks for sharing.
dstieger Offline
#3 Posted:
Joined: 06-22-2007
Posts: 10,889
No, Humans Are Probably Not All Descended From A Single Couple Who Lived 200,000 Years Ago
Michael MarshallContributor
I write about evolutionary biology, earth science and the environment

The idea that humanity started with a single couple has been around for a while

“All humans are descended from just TWO people and a catastrophic event almost wiped out ALL species 100,000 years ago, scientists claim“. “​Scientists Claim Humans Are Descended From Two People“. “New Research Has Concluded That All Humans Are Descendants Of Just One Couple Who Lived 200,000 Years Ago“.


Those headlines give the impression that science has produced evidence to support the story of Adam and Eve. But the study they rest on does not demonstrate anything of the kind, and other lines of evidence strongly suggest that past human populations were always much larger than two.

The study in question was actually published in May and received coverage at the time, but has been picked up again. Its authors were Mark Stoeckle of Rockefeller University in New York and David Thaler of the University of Basel in Switzerland. It appeared in the journal Human Evolution, and it is “open access” so anyone can read it.


The study is about DNA barcoding: the technique of reading a small chunk of an organism’s DNA and using that to identify its species. To identify an animal, geneticists usually look at a gene called cytochrome oxidase 1 (CO1). This gene is not part of the “main” genome held in the nucleus of animal cells, but instead is carried in the mitochondria: tiny sausage-shaped organelles that swarm inside animal cells and provide them with energy.

DNA barcoding is not a perfect method of identifying species, but it works pretty well. That’s because, as the study observes, animals belonging to one species tend to have near-identical CO1 genes, which reliably differ from animals of other species.

Because CO1 genes are so similar within species, regardless of how many individuals there are, Stoeckle and Thaler argue that something must have made them that way. Either evolution is somehow pushing each species to have its own version, which seems unlikely, or each species has had almost all its genetic diversity purged – which implies that its population was once very small.

What’s more, these population bottlenecks seemingly all occurred between 100,000 and 200,000 years ago. This implies some sort of global event, an unspecified catastrophe that slashed the population of pretty much every animal species.

Thaler was quoted by Fox News saying that “all of animal life experiences pulses of growth and stasis or near extinction on similar time scales”. He listed possible explanations: “ice ages and other forms of environmental change, infections, predation, competition from other species and for limited resources, and interactions among these forces”.

This event, whatever it was, also affected humans. The human genetic data, according to the study, is “consistent with the extreme bottleneck of a founding pair”.

The idea of humans being reduced to a population of two, who then had to repopulate the planet, has understandably drawn people’s attention. But this idea is almost certainly wrong, for a host of reasons.

First, we should always be hesitant about drawing big conclusions from mitochondrial DNA, and especially from a single gene – even if that gene has been examined in hundreds of species. Mitochondrial DNA is only inherited from one’s mother, so it necessarily only tells us about the female line. More importantly, because there is so little of it, it often misleads us. When the mitochondrial genome of Neanderthals was sequenced, it showed no sign that humans and Neanderthals had interbred. The interbreeding was only revealed when the Neanderthal nuclear genome was read.

Second, there is no trace in the geological record of any such global event in the last 200,000 years. Any event that slashed populations that significantly would surely have led to a noticeable spike in the extinction rate, and there isn’t one. There are of course the extinctions linked to humans, but those occurred at separate times and locations, not simultaneously across the planet.

Indeed, the study’s finding that the event occurred between 100,000 and 200,000 years ago is so vague as to be meaningless. It’s a bit like saying that the Napoleonic Wars happened after the fall of Mycenaean Greece but before 9/11. The suggested timespan is so vast, there is no reason to invoke a single event at all.

The whole pattern can be explained much more easily by saying that a lot of new species evolved over the last few hundred thousand years. That would not be surprising, because most species are indeed fairly young.

We don’t know for sure how long the average species lasts, partly because the fossil record is imperfect and partly because we don’t have a firm definition of what a species is anyway. But it’s been estimated that species typically last somewhere between 500,000 and 10 million years. It follows that a lot of species on Earth must have originated in the last few hundred thousand years. For instance, polar bears have been estimated to be about 400,000 years old as a species.

Stoeckle and Thaler’s findings would have us believe that 90 per cent of species are less than 200,000 years old. I don’t think their mitochondrial DNA data is enough to show that, and studies of whole genomes and fossils will give us more reliable dates that I would expect to be older. But they won’t be that much older. Given that the planet has been in and out of glacial periods over the last 2.5 million years, plus all the upheavals caused by humans and our extinct relatives, the finding that most species alive today are fairly young shouldn’t surprise us.

What about our own species? First, Stoeckle and Thaler only ever said that their data was “consistent” with the existence of a founding pair. That doesn’t mean much, and they immediately conceded that the same pattern could have arisen “within a founding population of thousands that was stable for tens of thousands of years”. The fact is, genomic data doesn’t do a great job of revealing the sizes of past populations except in broad-brush terms. The human population was probably pretty small for a long time, but there is no reason to think it was two.

Finally, the archaeological record tells a different story. It used to be thought that our species was about 200,000 years old, which would fit Stoeckle and Thaler’s data. However, in 2017 fossils uncovered at Jebel Irhoud in Morocco turned out to belong to our species, and they were around 300,000 years old. What’s more, our lineage split from that of the Neanderthals (our closest extinct relatives) roughly 500,000 years ago, so arguably our species is 500,000 years old. 200,000 years ago does not appear to have been a particularly special time in the history of our species.

https://www.forbes.com/sites/michaelmarshalleurope/2018/11/26/no-humans-are-probably-not-all-descended-from-a-single-couple-who-lived-200000-years-ago/#34e3d557cd8e

dstieger Offline
#4 Posted:
Joined: 06-22-2007
Posts: 10,889
I haven't thought hard about any of the points in either article. But just thought opposing words from 'respectable' pub might be worth putting alongside the other
DrafterX Offline
#5 Posted:
Joined: 10-18-2005
Posts: 98,508
But what about the Trogs..?? Nobody ever thinks about the Trogs... Sad
Gene363 Online
#6 Posted:
Joined: 01-24-2003
Posts: 30,669
dstieger wrote:
I haven't thought hard about any of the points in either article. But just thought opposing words from 'respectable' pub might be worth putting alongside the other


There is a constant stream of DNA associated discoveries and our understanding is constantly being expanded. As our understanding expands there will be various conclusions and suppositions, but I don't think we know the whole story yet.
opelmanta1900 Offline
#7 Posted:
Joined: 01-10-2012
Posts: 13,954
dstieger wrote:
No, Humans Are Probably Not All Descended From A Single Couple Who Lived 200,000 Years Ago
Michael MarshallContributor
I write about evolutionary biology, earth science and the environment

The idea that humanity started with a single couple has been around for a while

“All humans are descended from just TWO people and a catastrophic event almost wiped out ALL species 100,000 years ago, scientists claim“. “​Scientists Claim Humans Are Descended From Two People“. “New Research Has Concluded That All Humans Are Descendants Of Just One Couple Who Lived 200,000 Years Ago“.


Those headlines give the impression that science has produced evidence to support the story of Adam and Eve. But the study they rest on does not demonstrate anything of the kind, and other lines of evidence strongly suggest that past human populations were always much larger than two.

The study in question was actually published in May and received coverage at the time, but has been picked up again. Its authors were Mark Stoeckle of Rockefeller University in New York and David Thaler of the University of Basel in Switzerland. It appeared in the journal Human Evolution, and it is “open access” so anyone can read it.


The study is about DNA barcoding: the technique of reading a small chunk of an organism’s DNA and using that to identify its species. To identify an animal, geneticists usually look at a gene called cytochrome oxidase 1 (CO1). This gene is not part of the “main” genome held in the nucleus of animal cells, but instead is carried in the mitochondria: tiny sausage-shaped organelles that swarm inside animal cells and provide them with energy.

DNA barcoding is not a perfect method of identifying species, but it works pretty well. That’s because, as the study observes, animals belonging to one species tend to have near-identical CO1 genes, which reliably differ from animals of other species.

Because CO1 genes are so similar within species, regardless of how many individuals there are, Stoeckle and Thaler argue that something must have made them that way. Either evolution is somehow pushing each species to have its own version, which seems unlikely, or each species has had almost all its genetic diversity purged – which implies that its population was once very small.

What’s more, these population bottlenecks seemingly all occurred between 100,000 and 200,000 years ago. This implies some sort of global event, an unspecified catastrophe that slashed the population of pretty much every animal species.

Thaler was quoted by Fox News saying that “all of animal life experiences pulses of growth and stasis or near extinction on similar time scales”. He listed possible explanations: “ice ages and other forms of environmental change, infections, predation, competition from other species and for limited resources, and interactions among these forces”.

This event, whatever it was, also affected humans. The human genetic data, according to the study, is “consistent with the extreme bottleneck of a founding pair”.

The idea of humans being reduced to a population of two, who then had to repopulate the planet, has understandably drawn people’s attention. But this idea is almost certainly wrong, for a host of reasons.

First, we should always be hesitant about drawing big conclusions from mitochondrial DNA, and especially from a single gene – even if that gene has been examined in hundreds of species. Mitochondrial DNA is only inherited from one’s mother, so it necessarily only tells us about the female line. More importantly, because there is so little of it, it often misleads us. When the mitochondrial genome of Neanderthals was sequenced, it showed no sign that humans and Neanderthals had interbred. The interbreeding was only revealed when the Neanderthal nuclear genome was read.

Second, there is no trace in the geological record of any such global event in the last 200,000 years. Any event that slashed populations that significantly would surely have led to a noticeable spike in the extinction rate, and there isn’t one. There are of course the extinctions linked to humans, but those occurred at separate times and locations, not simultaneously across the planet.

Indeed, the study’s finding that the event occurred between 100,000 and 200,000 years ago is so vague as to be meaningless. It’s a bit like saying that the Napoleonic Wars happened after the fall of Mycenaean Greece but before 9/11. The suggested timespan is so vast, there is no reason to invoke a single event at all.

The whole pattern can be explained much more easily by saying that a lot of new species evolved over the last few hundred thousand years. That would not be surprising, because most species are indeed fairly young.

We don’t know for sure how long the average species lasts, partly because the fossil record is imperfect and partly because we don’t have a firm definition of what a species is anyway. But it’s been estimated that species typically last somewhere between 500,000 and 10 million years. It follows that a lot of species on Earth must have originated in the last few hundred thousand years. For instance, polar bears have been estimated to be about 400,000 years old as a species.

Stoeckle and Thaler’s findings would have us believe that 90 per cent of species are less than 200,000 years old. I don’t think their mitochondrial DNA data is enough to show that, and studies of whole genomes and fossils will give us more reliable dates that I would expect to be older. But they won’t be that much older. Given that the planet has been in and out of glacial periods over the last 2.5 million years, plus all the upheavals caused by humans and our extinct relatives, the finding that most species alive today are fairly young shouldn’t surprise us.

What about our own species? First, Stoeckle and Thaler only ever said that their data was “consistent” with the existence of a founding pair. That doesn’t mean much, and they immediately conceded that the same pattern could have arisen “within a founding population of thousands that was stable for tens of thousands of years”. The fact is, genomic data doesn’t do a great job of revealing the sizes of past populations except in broad-brush terms. The human population was probably pretty small for a long time, but there is no reason to think it was two.

Finally, the archaeological record tells a different story. It used to be thought that our species was about 200,000 years old, which would fit Stoeckle and Thaler’s data. However, in 2017 fossils uncovered at Jebel Irhoud in Morocco turned out to belong to our species, and they were around 300,000 years old. What’s more, our lineage split from that of the Neanderthals (our closest extinct relatives) roughly 500,000 years ago, so arguably our species is 500,000 years old. 200,000 years ago does not appear to have been a particularly special time in the history of our species.

https://www.forbes.com/sites/michaelmarshalleurope/2018/11/26/no-humans-are-probably-not-all-descended-from-a-single-couple-who-lived-200000-years-ago/#34e3d557cd8e




nice opinion piece I suppose...
Ewok126 Offline
#8 Posted:
Joined: 06-25-2017
Posts: 4,356
DrafterX wrote:
But what about the Trogs..?? Nobody ever thinks about the Trogs... Sad


Piss on the Trogs, they are raciest!Speak to the hand

Morlocks for the win! fog
tailgater Offline
#9 Posted:
Joined: 06-01-2000
Posts: 26,185
DrafterX wrote:
But what about the Trogs..?? Nobody ever thinks about the Trogs... Sad


Wild Thing!
DrafterX Offline
#10 Posted:
Joined: 10-18-2005
Posts: 98,508
Laugh
RMAN4443 Offline
#11 Posted:
Joined: 09-29-2016
Posts: 7,683
DrafterX wrote:
But what about the Trogs..?? Nobody ever thinks about the Trogs... Sad

Wild Thing...fog
frankj1 Offline
#12 Posted:
Joined: 02-08-2007
Posts: 44,211
tailgater wrote:
Wild Thing!

follow up hit could not have been more different...Love is All Around
tailgater Offline
#13 Posted:
Joined: 06-01-2000
Posts: 26,185
RMAN4443 wrote:
Wild Thing...fog


echo
Mattie B Offline
#14 Posted:
Joined: 12-12-2005
Posts: 6,350
Old News

I’ve known this since hearing about Adam and Eve in 4 yr old Sunday School.
DrafterX Offline
#15 Posted:
Joined: 10-18-2005
Posts: 98,508
That Bitch..!! Mad
tonygraz Offline
#16 Posted:
Joined: 08-11-2008
Posts: 20,175
They shoulda locked her up ?
DrafterX Offline
#17 Posted:
Joined: 10-18-2005
Posts: 98,508
There was no they back then... Mellow
Whistlebritches Offline
#18 Posted:
Joined: 04-23-2006
Posts: 22,127
Mattie B wrote:
Old News

I’ve known this since hearing about Adam and Eve in 4 yr old Sunday School.


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