A mutation is a change that occurs in our DNA sequence, either due to mistakes when the DNA is copied or as the result of environmental factors such as UV light and cigarette smoke.
If you were born in 1929 or later, you need to work at least 10 years to become eligible for Social Security. The SSA determines eligibility with a system of credits. Basically, you earn up to four credits for every year worked, and you need a total of 40 credits to qualify for Social Security.
As you know, Social Security has an earnings penalty, which governs how much money you can make while at the same time receiving benefits. Exceed an annual cap (it's currently $14,160 a year) and you'll lose part or even all of your benefit. However, the penalty applies only to people between 62 and full retirement age. If you decide to wait until 66, you should apply to Social Security three months before your birthday. You can apply online, by phone (1-800-772-1213) or by going to a local Social Security office (call ahead for an appointment).