We punish based on intent, not on victim type.
On the perpetrator side, the punishments themselves are in the context of current lifespan. If the life expectancy jumps to 150, is 36 the new 18?
On the victim side:
"A Denver Post analysis of five years of state sentencing data found that those convicted of child abuse resulting in death between 2007 and 2011 got prison sentences 25 percent shorter than those who killed adults and were sentenced for the comparable felony charge of second-degree murder."
http://www.denverpost.com/failedtodeath/ci_21996958/inequity...