Your uncle wants to create a dog small enough to fit into a purse. Of the hundreds of dogs on his farm, he breeds only the smallest 10% of them. He then breeds only the smallest 10% of their offspring, and continues to breed only the smallest 10% of each generation. Over 20 years, he observes that his group of dogs did become smaller (though not small enough to fit into a purse). Which line of support does he have that his dogs have evolved?.