Makes me wonder. The whole genetics or testosterone? Maybe just maybe those early shedders were the first and the most bred? Done, worn out first??? That would be an interesting study. One thing I found while searching....
Testosterone controls the antler cycle. In tests, bucks kept in constant 12 hours of light and dark were unable to shed their antlers and grow new ones, and bucks kept in constant light grew and lost three sets of antlers in two years.
.........Large antlered older bucks typically shed their antlers earlier than young small antlered bucks. This may be due to the large amount of energy they expend during the rut. Similarly, deer in good condition typically hold their antlers longer than deer in poor condition.