Currently, the number of languages is estimated to be between 6500 and 7000. 500 years ago, this number was higher because European colonization wiped out many languages in America, Oceania and possibly also in Africa or Asia (there have also been other factors that have reduced the number of languages).
It is possible to speculate on whether the number of languages could have exceeded 10,000 at the beginning of the Neolithic period, although by 10000 B.C. the world population has been estimated at only 2 to 5 million. This would give between 200 and 500 speakers per language, which does not seem far-fetched. However, taking into account known historical facts and current demographic estimates:
- At what point in history should there have been more languages in the world?
- What would be a reasonable estimate for the largest number of languages that existed simultaneously?
Taking into account that about 110 billion people have lived on earth (although the current population is only about 8 billion), and conjecturing that a language only lasts about 1200 to 1500 years (before becoming a distinctly different language),
- How many human languages could we say have existed in total?
Note: I understand that this question is somewhat speculative, and slightly off-topic, but I consider that estimates even on very partial data can be enlightening to understand the history of human languages.