[Marika (OP)]

Mike says:

I'm on my holidays and my wife asked why doesn't the skin on my hand and feet tan? I thought it was because the skin is thicker there.

What do you think?

[chris]

It will, but the amount of sunlight exposure there is quite low, and the basal activity of the melanocytes (cells that make melanin) is lower for this reason. Consequently, the skin there tends to be paler (in black and white skinned people) anyway, but would tan up if you were really dedicated about it - sunbathed with your feet in the air and palms uppermost...