Scientists gave old mice a compound called 17-alpha-estradiol when they were already pretty old (like 50-60 human years), and it still made them live 11% longer on average.

Scientists gave old male mice a special compound called 17-alpha-estradiol in their food starting at 20 months old (roughly equivalent to late middle age in humans), and the mice lived about 11% longer than mice that didn't get the compound.

Scientists gave old male mice a special compound called 17-alpha-estradiol when they were about 1.3 years old, and it helped them live about 19% longer - going from an average of about 2 years to over 2.5 years.

Giving male mice a special compound called 17-α-estradiol when they were middle-aged (16 months) helped them live about 7% longer, specifically extending their maximum lifespan.

A special form of estrogen called 17-alpha-estradiol helped male mice live longer when they started taking it in middle age - about 19% longer if started at 16 months old and 11% longer if started at 20 months old. It also increased their maximum lifespan by 7%. But female mice didn't get any lifespan benefit from it at all.

Scientists fed old male mice a special chemical called 17-α-estradiol and found they lived about 19% longer than mice that didn't get the chemical.