When compared to a random selection of folk in their middle ages and younger, centenarians have biochemistries that seem better adapted to long term survival. That makes sense, given that few of those random folk would make it to 100 under the same life circumstances as the centenarians. Hopefully researchers can use the identified differences to make faster progress in longevity science. Here is an example:
OBJECTIVES: To analyze several functions and antioxidant parameters of peripheral blood neutrophils from healthy centenarians (men and women) and compare them with those of healthy young (aged 25-35) and middle-aged (aged 65-75) men and women.
PARTICIPANTS: Twenty-one healthy centenarians (8 men), 30 young adults (15 men), and 30 middle-aged adults (15 men).
RESULTS: Neutrophil functions of the middle-aged group were worse than those of young adults and centenarians ... The neutrophil functions of the centenarians were closer to those of the young adults. ... With normal aging, total glutathione levels decrease, but the centenarians in this study showed levels similar to those of young adults. Centenarians showed the highest catalase activity of the three groups.
CONCLUSION: Progressive impairment of the immune system accompanies aging. The better preservation of function and antioxidant systems in the neutrophils of centenarians could play a key role in the longevity of these subjects.
The catalase data is interesting, given the work of Rabinovitch showing that increased catalase expression in mice - if targeted to the mitochondria - extends healthy life. It seems that there might be a fair degree of difference within the human species as to how genetically resistant people are to aging. For more on why catalase - an antioxidant - likely works to extend life when introduced to the mitochondria, you might look back into the Fight Aging! archives.
The catalase soaks up some portion of free radicals before they can attack your vulnerable mitochondrial DNA. Damage to this [DNA] leads to an unfortunate chain of events that causes entire cells to rabidly produce damaging free radicals and export them throughout the body. But stop a fraction of the original mitochondrial free radicals from attacking their birthplace, and you have slowed the rate at which one cause of aging happens - you have slowed down aging, and extended healthy life.