Scientists crack mystery of how MS gene spread

Why are diseases more common in some parts of Europe than others, and why are northern Europeans taller than their southern counterparts?

An international team of scientists say they have unearthed the answer in the DNA of ancient teeth and bones.

The genes which protected our ancestors from animal diseases now raise the risk of multiple sclerosis (MS).

The researchers call their discovery "a quantum leap" in understanding the evolution of the disease.

And they say it could change opinions on what causes MS, and have an impact on the way it is treated.