Population history not yet popular
by Vincent Ciccarello
A
UniSA physicist has thrown a cat among the pigeons with his
genealogy modelling.
John Pattison (pictured) comes across as the shy, retiring type – certainly not one up for some academic biff with UK researchers in an entirely different discipline.
But his latest paper on inbreeding, published in the Proceedings of the Royal Society B (Biological Sciences), has created something of a stir among geneticists and anthropologists from some of England’s leading universities.
"This is a paper that’s not going to die; it’s going to be cited. It’s created interest in the European media, in New Scientist, the Daily Telegraph and on German radio," Pattison said.
The controversy stems from Pattison’s conclusion that long-term, low level migration could explain why about 40 per cent of today’s Britons carry Germanic genes dating from the Dark Ages. His theory debunks a 2006 paper suggesting the results of genetic surveys pointed to the existence of an Anglo-Saxon apartheid.
"But the archaeologists aren’t finding evidence for it," Pattison said. "There’s a lot of things in human nature around the world that I brought into play in my research, and it just seems more likely that the Britons were not enslaved but adopted into the Germanic culture and interbreeding occurred."
Pattison’s results are based on input data about the populations of many countries from a variety of historical sources over 2000 years, analysed using the novel modelling method he created to explain the "genealogical paradox".
"The ‘genealogical paradox’ is, as we go back in time, the apparent contradiction that the number of ancestors doubles while the population of the world actually decreases. Sooner or later, there are more ancestors in a generation than people available in their country or, further back in time, the whole world," he said. "This leads to the idea of inbreeding."
A medical physicist with a strong long-standing interest in human biology, Pattison said it was possible to apply physics, physical techniques and methodology to human systems.
"I do see laws that govern human behaviour, even if many people don’t like that idea," he said. "I thought population geneticists and demographers in the past would have extracted as much information about inbreeding as possible from historical populations, but I found they haven’t."
"In addition to satisfying curiosity, it is of some practical importance to the medical geneticist to have a measure of the inbreeding within a population. This should assist in the estimation of the incidence of certain hereditary and familial diseases.
"Actual census population records only go back about 150 years and thereabouts; beyond that, it’s more speculative. I thought I’d model the British population and see if I can predict what inbreeding values there are for past periods of time when records are less complete."
Pattison’s method, based on methods used by historical demographers to work out populations, has been criticised for relying on speculative data.
"But you’ve got to start sometime; you can’t wait until you have perfect data. Physicists don’t do that; physics got off the ground with all sorts of approximations and rough data back in the 1600s. But they found laws that worked. And they became the basis of all modern science."
Since 2001, Pattison has published five academic papers on inbreeding. He is currently working on another looking at "effective population" sizes.
"Not all people in a given population are breeding – some are too young to breed, and the population includes post-menopausal women. Other people simply choose not to have children. I’m trying to develop another way of finding out what the effective population size has been over an extended period," Pattison said.
A seventh paper is also on the drawing board.