DNA may tell police the surname of the criminal

[Dave Farber <dave () farber net>]

-------- Original Message --------
Subject: DNA may tell police the surname of the criminal
Date: Wed, 22 Feb 2006 13:09:16 +0000
From: Brian Randell <Brian.Randell () newcastle ac uk>
To: dave () farber net

Hi Dave:

> From today's (UK) Guardian:


> How DNA may tell police the surname of the criminal
>
> Alok Jha
> Wednesday February 22, 2006
> The Guardian
>
> Police will soon be able to predict the surnames of criminals whose 
> DNA is found at crime scenes, according to research published 
> yesterday. The technique would only work in finding men, however, as 
> it is based on identifying similarities in the Y chromosome, which 
> is passed from father to son.
>
> The technique relies on research carried out by University of 
> Leicester scientists into how Y chromosomes have spread through the 
> British population. They analysed these chromosomes in 150 pairs of 
> men with the same surname and found that, in a quarter of cases, the 
> pair had matching Y chromosomes.
>
> When the most common names were excluded from the list - Smith, 
> Jones, Williams and Taylor, for example - the chance that two men 
> with the same surname shared a Y chromosome jumped to 50%. The 
> research appears in the latest edition of Current Biology.
>
> Mark Jobling, a geneticist at the University of Leicester who led 
> the work, said the police would need a relatively small collection 
> of male DNA - around 40,000 people - to allow useful matches to be 
> made. "That sounds big but the national DNA database is nearly 100 
> times bigger," he said. By matching the Y chromosome details of 
> unidentified DNA at a crime scene with the database, police would 
> get a list of potential surname matches.
>
> "That would allow you to prioritise suspects in your investigation," 
> said Dr Jobling. "If you have a lot of suspects - say a whole town 
> or something - you can say we have 50 names, are these names 
> represented here, if so let's go and interview these people."
>
> Y chromosomes are passed from father to son mostly unaltered. Once 
> in a while, they will acquire random mutations as they pass through 
> the generations. Some parts of the chromosome are known to mutate 
> less rapidly than others and, by mapping these differences, 
> scientists can create a tree showing the relationships between 
> different Y chromosomes.
>
> "If men fall in different branches of the tree, there's no way they 
> can be related to a recent male ancestor," said Dr Jobling. "If they 
> lie within the same branch, there is a chance they are, but it 
> doesn't prove it.
>
> "When we do that simple test, we find that a highly statistically 
> significant excess of pairs share a branch of the tree, much more 
> than we expect by chance."
>
> It is a surprising result, since there are plenty of reasons why 
> people might have the same surname but be unrelated: many names were 
> founded by more than one man, for example. There is also the issue 
> of illegitimacy. The researchers predicted that more than 1% of 
> children were illegitimate in each generation. Over many 
> generations, this could have built up a significant error.
>
> "Those two elements would act as a strong force to break any links," 
> said Dr Jobling. "It was a surprise that by choosing just pairs we 
> got a clear signal of sharing ancestors."


http://www.guardian.co.uk/crime/article/0,,1715022,00.html




-- 
School of Computing Science, University of Newcastle, Newcastle upon Tyne,
NE1 7RU, UK
EMAIL = Brian.Randell () ncl ac uk   PHONE = +44 191 222 7923
FAX = +44 191 222 8232  URL = http://www.cs.ncl.ac.uk/~brian.randell/

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