estimating the total number of humans who have ever lived is a challenging task due to limited historical records and uncertainties. However, some scholars and researchers have attempted to make educated estimates.
One commonly cited estimate comes from the demographer Carl Haub of the Population Reference Bureau, who suggested that approximately 108 billion humans have lived on Earth since the emergence of Homo sapiens. This is just an estimate and could vary depending on different assumptions and data sources.
Regarding the average lifespan of a human currently living, life expectancy varies from country to country and is influenced by various factors such as healthcare, living conditions, and lifestyle choices. As of 2023, the global average life expectancy was around 72.6 years. However, it's important to note that life expectancy is subject to change over time due to advancements in medicine, public health, and other factors.
For the most up-to-date and accurate information on the number of humans who have ever existed and the current average lifespan, I recommend consulting more recent sources like official demographic reports or reputable statistical databases.