Genes that saved us plague us 3,500 years later (Canada)

"About 3,400 years ago, a plague is believed to have slashed across Europe, killing vast numbers of people. No written records of the unknown disease survive today. But scientists at the University of Ottawa Heart Institute have helped uncover a piece of evidence in the genes of modern Caucasians. A small cluster of genes protected part of early Europe's population against a disease that must have been horrific, perhaps on the scale of the Black Death. But there was a cost: Those genes, still carried by many today, raise the risks of heart disease, diabetes and hypertension." Thirty-four-hundred years ago I think we can imagine that something cataclysmic happened to humans, probably an infection or a plague that wiped out 90 per cent of people," said Alex Stewart, a geneticist and microbiologist at the Heart Institute. "It could have been almost any viral infection. Could have been reminiscent of Ebola. "The people that were able to survive and have children, and have the children survive -- they had to have something really resistant to the infection." A natural disaster or war wouldn't have selected survivors based on their genes. "DNA doesn't protect you against earthquake." But there was a catch. "Nothing in evolution comes for free. Fast-forward 3,400 years later, maybe we're not exposed to those pathogens (causes of infection) any longer." Yet the protective genes are still there, and they're hard on the heart. "All of a sudden, what was beneficial then is detrimental now." Most of the bad effects of this gene cluster occur later in life, when people are in their 50s and 60s. That's too late to prevent them from having children and passing on the gene." - The Province