http://www.guardian.co.uk/science/blog/2013/feb/25/viking-ancestors-astrology

To claim someone has ‘Viking ancestors’ is no better than astrology

Exaggerated claims from genetic ancestry testing companies undermine serious research into human genetic history

You may have missed the latest genetic discovery. As reported by The Daily Telegraph on Friday: “One million British men may be directly descended from the Roman legions”. The story reappeared on Sunday, at the Who Do You Think You Are – Live event at London’s Olympia, when it was repeated by Alistair Moffatt, the managing director of BritainsDNA, the company behind the claims.

Such stories are becoming increasingly common in newspapers, on television and radio. Last week on the BBC miniseries Meet the Izzards we were told that Eddie Izzard is a Viking descendant on his mother’s side and an Anglo-Saxon descendant on his father’s. Last year the Observer reported that Tom Conti has Saracen origins and is a relative of Napoleon Bonaparte.

And for upwards of £150 you too can have your DNA “tested” by any of a number of direct-to-consumer ancestry companies. But how reliable are these claims? The truth is that there is usually little scientific substance to most of them and they are better thought of as genetic astrology.

For some time it has been possible to compare DNA sections among individuals; and in a broad sense greater genetic similarity means greater relatedness. But you have inherited different sections of your DNA from different ancestors, and as we look back through time the number of ancestors you have almost doubles with each generation (it would double exactly were it not for the fact that we are all somewhat inbred).

This means that you don’t have to look very far back before you have more ancestors than sections of DNA, and that means you have ancestors from whom you have inherited no DNA. Added to this, humans have an undeniable fondness for moving and mating – in spite of ethnic, religious or national boundaries – so looking back through time your many ancestors will be spread out over an increasingly wide area. This means we don’t have to look back much more than around 3,500 years before somebody lived who is the common ancestor of everybody alive today.

And perhaps most surprisingly, it has been reasonably estimated that around 5,000 years ago everybody who was alive was either the common ancestor of everybody alive today, or of nobody alive today; at this point in history we all share exactly the same set of ancestors.

What does this say about the descendants of the Roman legions? It says almost everybody in Britain is one, as well as being the descendant of Vikings, Celts, Anglo-Saxons, Arabs, Jews, Saracens, Goths, Vandals, or whatever ethnic group you want to choose in Europe and its vicinity over the last few thousand years. Nobody is pure this, or pure that, and a substantial proportion of human ancestry is common to all of us. Ancestry is complicated and very messy.

more on link

>This means we don’t have to look back much more than around 3,500 years before somebody lived who is the common ancestor of everybody alive today.

I’d say bushwa to that claim.

sibeen said:

>This means we don’t have to look back much more than around 3,500 years before somebody lived who is the common ancestor of everybody alive today.

I’d say bushwa to that claim.

Does seem a bold claim. And physically impossible. 3,500 years ago there was an individual who was the common ancestor of modern full-blood Aussie aborigines and African pygmies and inuits etc etc?

3500 year hey. Was that “common ancestor” named Noah?

i’m a viking. got the disease and everything.

plus viking were renowned to have lots of birthdays.

TMRCA of all living humansEstimating time to MRCA of all humans based on the common genealogical usage of the term ‘ancestor’ is much harder and less accurate compared to estimates of patrilineal and matrilineal MRCAs. Researchers must trace ancestry along both female and male parental lines, and rely on historical and archaeological records.

Depending on the survival of isolated lineages without admixture from modern migrations and taking into account long-isolated peoples, such as historical societies in central Africa, Australia and remote islands in the South Pacific, the human MRCA was generally assumed to have lived in the Upper Paleolithic period. With the advent of mathematical models and computer simulations, some researchers have argued that the MRCA of all humans lived remarkably recently, between 2,000 and 4,000 years ago. Rohde, Olson and Chang (2004), for example, constructed a mathematical model that considered the tendency of individuals to choose mates from the same group, as well as the relative geographical isolation of such groups. The mathematical model with one particular set of parameters showed that the MRCA lived about the year 300 BC and yielded an identical ancestor point (IAP) of 3,000 BC.

The same 2004 Rohde paper also presented results from a computer program based on Monte Carlo simulation designed to overcome some of the limits of the mathematical model. The program took into consideration realistic population substructure and migration patterns, allowing the researchers to simulate historical human demography. A conservative simulation yielded a mean MRCA date of 1,415 BC and a mean IA date of 5,353 BC. A less conservative simulation gave an MRCA date of AD 55 and an IA date of 2,158 BC.

An explanation of this recent MRCA date is that, while humanity’s MRCA was indeed a Paleolithic individual up to early modern times, the European explorers of the 16th and 17th centuries would have fathered enough offspring so that some “mainland” ancestry by today pervades remote habitats. The possibility remains that an isolated population with no recent “mainland” admixture persists somewhere, which would immediately push back the date of humanity’s MRCA by many millennia. While simulations help estimate probabilities, the question can be resolved only by genetically testing every living human individual.

An assumption that there are no isolated populations is questionable in view of the existence of various uncontacted peoples, who are suspected to have been isolated for many millennia, including the Sentinelese who have been isolated from the western world and also from the Asian mainland.

http://en.wikipedia.org/wiki/Most_recent_common_ancestor

This is what my husband looks like. He has Danish and Norwegian ancestry. We think his great-great-great-great-great somebody or other was the model for this :)

>This is what my husband looks like

I’m sure he has his calmer moments.

;)

sibeen said:

>This means we don’t have to look back much more than around 3,500 years before somebody lived who is the common ancestor of everybody alive today.

I’d say bushwa to that claim.

MRCA is a complicated population genetics concept using molecular clock estimates and phylogenetic models and sequence data from particular gene regions – and various assumptions on mating (random vs assortative). Basically, there has been a lot of genetic interchange among the global population, so that you can track haplotypes from widely separated groups back to a source population (genomic coalescence theory) and see the degree of genetic overlap.

http://www.stat.yale.edu/~jtc5/papers/CommonAncestors/NatureAncestorsPressRelease.html

Someone mentioned Aborigines. Many would agree that they had been isolated here for a minimum of 50,000 years. Yet recent papers claim that the last incursion of the human genome to Australia before Europeans was around 5,000 years ago from India. Not that every Aboriginal family would have felt this effect within that 5,000 years?

> Not that every Aboriginal family would have felt this effect within that 5,000 years?

Ooh I don’t know, 5,000 years is a long time :)

Bubblecar said:

> Not that every Aboriginal family would have felt this effect within that 5,000 years?

Ooh I don’t know, 5,000 years is a long time :)

Yeah it is. I wouldn’t argue that but indeed Australia is a difficult place to go spreading wild oats in.

‘Most recent common ancestor’ of all living humans surprisingly recent
New Haven, Conn. — In this week’s issue of Nature, a Yale mathematician presents models showing that the most recent person who was a direct ancestor of all humans currently alive may have lived just a few thousand years ago.

“While we may not all be ‘brothers,’ the models suggest we are all hundredth cousins or so,” said Joseph T. Chang, professor in the Department of Statistics at Yale University and senior author on the paper.

Chang established the basis of this research in a previous publication with an intentionally simplified model that ignored such complexities as geography and migration. Those precise mathematical results showed that in a world obeying the simplified assumptions, the most recent common ancestor would have lived less than 1,000 years ago. He also introduced the “identical ancestors point,” the most recent time — less than 2,000 years ago in the simplified model — when each person was an ancestor to all or ancestor to none of the people alive today.

The current paper presents more realistic mathematical and computer models. It incorporates factors such as socially driven mating, physical barriers of geography and migration, and recorded historical events. Although such complexities make pure mathematical analysis difficult, it was possible to integrate them into an elaborate computer simulation model. The computer repeatedly simulated history under varying assumptions, tracking the lives, movements, and reproduction of all people who lived within the last 20,000 years.

These more realistic models estimate that the most recent common ancestor of mankind lived as recently as about 3,000 years ago, and the identical ancestors point was as recent as several thousand years ago. The paper suggests, “No matter the languages we speak or the color of our skin, we share ancestors who planted rice on the banks of the Yangtze, who first domesticated horses on the steppes of the Ukraine, who hunted giant sloths in the forests of North and South America, and who labored to build the Great Pyramid of Khufu.”

The results can also work backwards, into the future. According to Chang, “Within two thousand years, it is likely that everyone on earth will be descended from most of us.”

http://en.wikipedia.org/wiki/Coalescent_theory

In genetics, coalescent theory is a retrospective model of population genetics. It attempts to trace all alleles of a gene shared by all members of a population to a single ancestral copy, known as the most recent common ancestor (MRCA; sometimes also termed the coancestor to emphasize the coalescent relationship). The inheritance relationships between alleles are typically represented as a gene genealogy, similar in form to a phylogenetic tree. This gene genealogy is also known as the coalescent; understanding the statistical properties of the coalescent under different assumptions forms the basis of coalescent theory.

But as the extract I posted pointed out:

The possibility remains that an isolated population with no recent “mainland” admixture persists somewhere, which would immediately push back the date of humanity’s MRCA by many millennia. While simulations help estimate probabilities, the question can be resolved only by genetically testing every living human individual.

Bubblecar said:

While simulations help estimate probabilities, the question can be resolved only by genetically testing every living human individual.

and it will still be a hypothesis and not a definitive answer (as the analyses go.. you’re plugging data into a model with assumptions and parameters)

Bubblecar said:

While simulations help estimate probabilities, the question can be resolved only by genetically testing every living human individual.

correct.

anyhoo – I think people are thinking about dating time to coalescence in lineages and not the more muddy recent reticulations

http://tedlab.mit.edu/~dr/Papers/Rohde-MRCA-two.pdf

Straight after I posted that it’s physically impossible I realised that it’s not at all physically impossible. But it would be somehow disappointing if it was true :)

i would say it would be interesting to see what they come up with but i would say that it in reasonable terms its the person that decides who they are – not supposed genetic lines.

kii said:

This is what my husband looks like. He has Danish and Norwegian ancestry. We think his great-great-great-great-great somebody or other was the model for this :)

i look like a cross between adam sandler and ben stiller