Are you old? Am I? I feel certain that I am.

[mellowtigger]

I've called myself old since age 50. I figure "half a century" is plenty of years for that description.  I'm now 55.

Other people think differently, though, so I've been pondering what objective measure we could use more definitively than that easy-to-identify number. It's more complicated than it sounds. It turns out there are different plausible ways to measure it.

1. Age 45. The typical human begins losing 1% muscle mass per year around age 30. It's a convenient marker for "top of the hill" metabolism. Allowing roughly 15 years as an adult beforehand (following puberty), then add 15 years after that peak, and you've got age 45 as the other terminus for the range of adulthood.
2. Age 50. "Half a century". I still think it sounds as good as any number.
3. Age 65. This is bureaucratic "retirement age" in the USA, qualifying for Social Security benefits.
4. 2% mortality chance per year. This standard is probably the most accurate, but it's also where it starts getting complicated.

See the charts and read the 3 details...

This chart and story provide a good explanation for this standard and how it changes over time. The article provides a similar USA chart for females.

If your chance of dying within the next year is 2 percent or more, Shoven suggests you might be considered "old." The above chart shows that the threshold age for being considered old for men increased from about 55 in the 1920s to 70 today.
- https://www.cbsnews.com/news/what-age-is-considered-old-nowadays/, Steve Vernon, 2016 June 29

So there was a time in USA history a century ago when my current age would qualify as "old".  But if it's situational, depending on how fast everyone around you is dying, then there are other considerations in play too.

1. What about the effects of systemic racism and plutocracy? Pollution is higher in the parts of towns with more black residents. Access to healthcare is lower for poor people. The response of healthcare providers is worse in both cases, and if you're female. The stress of racism and/or poverty increases health problems. The list goes on.
   
   Luckily, the USA has a government program designed to check this kind of stuff at a fine-grained geographic level, the U.S. Small-area Life Expectancy Estimates Project, USALEEP. So I checked the CDC's visual map for life expectancy in my census tract. Sure enough, total life expectancy is quite lower than the rest of my county, state, or country. Here in my little corner of the warzone, we are in the lowest quintile (the bottom 20%).
   


2. And what about the last epidemic? I often oversimplify and state that "half of my demographic died", referring to gay men who were out in the 1980s. The details, while more accurate, are still just as horrifying.

Life expectancy at age 20 for gay and bisexual men ranged from 34.0 years to 46.3 years for the 3% and 9% scenarios respectively. These were all lower than the 54.3 year life expectancy at age 20 for all men.
- https://pubmed.ncbi.nlm.nih.gov/9222793/, "Modelling the impact of HIV disease on mortality in gay and bisexual men" (in Canada)

In other words, I passed the 2% mark into old age a very long time ago. Maybe even in my early 20s when I already knew people around me dying. And if we're going with socially-defined seniority, then here's an article on gay authors teaching us how to "age gracefully", presumably from people who have done it already. They range in chronological age from 54 to 82. They're the elders we have left from the last epidemic.

3. And autistics don't fare any better. We are so much more likely to die from bodily injuries that life expectancy can be as low as 36 years! Seriously, it's that's bad.
   
   One study, published in the American Journal of Public Health in April 2017, finds the life expectancy in the United States of those with ASD to be 36 years old as compared to 72 years old for the general population. They note that those with ASD are 40 times more likely to die from various injuries. About 28 percent of those with ASD die of an injury. Most of these are suffocation, asphyxiation, and drowning. The risk of drowning peaks at about 5 to 7 years old. ...Those with ASD without a learning disability had an average age of death at about 58 years.
   - https://www.psychologytoday.com/gb/blog/caring-autism/201810/early-death-in-those-autism-spectrum-disorder
   
   I noted a decade ago that I try to avoid power tools. This is why. I'm a klutz, and I know it, and I don't want to injure myself any more than the usual range of cuts, bruises, and scrapes would entail. Several years ago, I had a doctor x-ray my foot, because I seriously had no idea how I got the seemingly bruised toe that wouldn't heal quickly. At least he confirmed that it wasn't broken.

So, apparently, "old" is relative, but I qualified decades ago if we use the 2% rule.  There just aren't as many people like me left in the world as there should be.