Why would such genes evolve in the first place?

New research has shown that our genes are evolving as we become more industrialized.

But while our genes have not evolved in the last several decades, the obesity rate in America has ballooned.

The genes themselves don't evolve, they merely survive or fail to survive in the gene pool.

Earlier it was believed that genes evolve mainly through the accumulation of small discrete changes in the genetic material.

Hence, it was in these regions that genes for lifelong lactase production first evolved.

The genes of adult lactose tolerance have evolved independently in various ethnic groups.

The genes coding for immune system proteins evolve considerably faster.

Ohno suggested that many unique new genes have evolved this way.

But the genes didn't evolve simply to make organ transplants difficult.