This graph shows the known characters of Middle-Earth and Aman divided by race and sex. Some races, such as Ents and Eagles, have been excluded.

A majority of the characters described in Tolkien's works are either Men or Hobbits. Men awoke at the start of the First Age of the Sun and much of the later history of Middle-earth revolves around the doings. Considering how long they had been in Middle-earth, very few Men are known by name. The Hobbits are very well-documented due to their interest in tracing their own ancestry and drawing family trees. Despite this, the origin of Hobbit is unknown and all known characters are from the second half of the Third Age.

This graph shows the average life-span of Hobbits, Dwarves and Men based on characters with known birth and death data.

When interpreting these numbers there are a few things to remember. The Hobbit lifespan of 96.8 years is most likely a very good estimation. There is a relatively large and well-documented sample size and most of them died from natural causes. The average lifespan of a Dwarf is 195 years which is a bit lower than one would expect considering that the age of oldest Dwarves exceeds 250 years. The reason for this is both the relatively low number of dwarves described in Tolkien's works and the fact that many of them died in battle.

This graph shows the distribution of character ages for Hobbits, Men and Dwarves. It is important to understand the underlying data and the characteristics of each race.

There are very few Dwarves with known age at the time of their death and most of the ones that are known died in battle. The longest living Dwarf was Dwalin who lived to become 340 years old, 80 years older than the second oldest Dwarf.

Hobbits lived a very quiet and uneventful life compared to other races and since they had the habit of drawing their family tree their age distribution is fairly narrow.

We will never know exactly how the population of Middle-earth changed over time but we can visualize the characters Tolkien choose to describe. This graph shows the known population as it changed over the years.

The large spike at the end of the First Age indicate the characters mentioned in the Silmarillion. After that, most Men with recorded death and birth date are of royal blood.

This graph shows the age of the various leaders of Men of Nmenorean blood throughout the history of Middle-Earth.

It is explicitly stated by Tolkien that the longevity of Men once granted to the Nmenreans decreased over the years. In Letter #156 Tolkien writes that "a good Nmenrean died of free will when he felt it be the time to do so". With the Shadow and the Downfall of Nmenor this grace was taken away from them and they started dying involuntarily. They continued to live longer than regular Men but their lifespan shortened over the years.

The decreasing lifespan Tolkien mentions can be seen clearly in the graph. The most dramatic change can be seen shortly before the Downfall of Nmenor.