Do you have a link about the average chest wall thickness? Are you talking the thickness of the chest wall itself or the associated exterior muscle & fat tissues on the outside? Not doubting, just looking for references.
1900 - Average life expectancy (Male) at age 10: 68.59 years
2004 - Average life expectancy (Male) at age 10: 76.30 years
This is different than the "average life expectancy at birth" often used. These figures, at age 10, eliminate early mortality due to childhood deaths from childbirth, childhood diseases and accidents.
People 100 years ago were a lot smaller than they are today. Big Macs have taken their toll. People today are bigger, stronger and healthier than 100 years ago. The average life expectancy was 47 in 1911 to day it is 77. The average chest wall is twice as thick today as in 1911.
Taken at face value, I see contradictions in your comment above. People 100 years ago may have been smaller, but today's "larger" adults are also more overweight and less physically fit than 100 years ago.¹
Most people live longer today because of a number of factors, such as;
- More nutritious diet
- Safer working conditions with fewer farm & industrial accidents.
- Higher survivability in auto accidents.
- Modern medical procedures & antibiotics
- Improved medical diagnosis technologies (MRI, CAT, PET, etc.)
- Broader array of pharmaceuticals
- Better geriatric care (after age 60)
Today's victims of handgun shootings are much more likely to survive than just 50 years ago and enormously more likely than 100 years ago.²
I posit that 100 years ago, people who died of gunshot wounds from handguns likely survived the initial encounter but died hours or days later due more to a lack of timely medical care (bleeding & infections) and less detailed medical knowledge. Further, if our technical capacity was suddenly forced back to around 1900³
then today's modern JHP ammo would prove to be much more lethal than ammo from 100 years ago.
¹ Thanks to modern conveniences like the automobile and other powered machinery from pumped water to vacuum cleaners and farm equipment.
² Between 1900 and about 1950, medical aid took much longer to summon (fewer phones, slower communications). Even then, ambulance attendants were only trained in first-aid as a general rule. In the late 1960's, the first experimental paramedic units showed the benefit of trained personnel and getting people treated within "the golden hour" of their injury. In the 70's, paramedic units started spreading to every state.
³ Such a setback is possible by use of an EMP attack against the U.S. For more information, see: http://www.onesecondafter.com/ or read the novel One Second After by William Forstchen.