Only 2bn of 117 bn ppl turned 90 as Fthr

 Short answer: about ~2 billion people in all of human history have reached age 90.

Why this is the rough number:

1. Total humans ever born:
   Demographers estimate about 117 billion humans have ever been born.  
2. Most of history had very short lifespans:
   For tens of thousands of years, average life expectancy was 20–35 years, mostly due to disease, infant mortality, and poor nutrition. Very few people reached extreme ages like 90.
3. Probability of reaching 90:
   
• In modern developed countries: roughly 15–30% of people may survive to 90 depending on gender and cohort.  
• In earlier centuries: estimates suggest well under 1% reached 90.
4. 
   
5. Rough demographic breakdown

Period	Births	% reaching 90	People reaching 90
Pre-1900 (~100B births)	~100B	~0.5%	~500M
1900–today (~17B births)	~17B	~7–10%	~1.2–1.7B

Adding them gives roughly:

≈ 1.7–2.2 billion

So a reasonable single estimate is:

👉 ~2,000,000,000 people have turned 90 in all of human history.

If you want, I can also tell you something surprising: more than half of all people who have ever reached 90 are probably alive today or born in the last ~120 years. That’s because longevity exploded after 1900.