The discussion centers on estimating the total number of humans who have lived on Earth, starting from a defined point 1 million years ago. Participants debate the criteria for defining a human and the complexities of calculating population growth rates over time. Estimates vary, with one participant suggesting around 100 billion humans have lived, while others express skepticism about the accuracy of such figures. The conversation also touches on the challenges of using fossil records and archaeological evidence to derive meaningful estimates. Ultimately, the question remains complex and largely speculative, highlighting the difficulties in obtaining precise historical population data.