[exDemMom]

The East African landscape that Homo erectus walked from about 2 million to 1.5 million years ago was becoming progressively drier, with savanna grasslands spreading in response to changes in the monsoon rains.

Obviously, they weren't walking the landscape; they were driving their SUVs on it to cause all that climate change.

On a more serious note, I wonder why it took humans so long to develop any form of written language. More than a million years between inventing tools and inventing writing seems like a huge lag time.

[Dilbert San Diego]

Didn’t Homo Erectus migrate to San Francisco??????

[seowulf]

I wonder why it took humans so long to develop any form of written language.

Writing came as a result of the need to keep records of commercial transactions especially for long distance trade. Early cuneiform tablets were almost exclusively shipping manifests and such like. Later came diplomatic messages.

Trade develops when there is a surplus, and surpluses come as a result of specialization (i.e. civilization).

So, written languages developed with cities.

[SunkenCiv]

One key to translating ancient (generally unknown) written languages is to find a multilingual inscription. That's how Egyptian hieroglyphic writing (and Demotic) as well as Old Persian was cracked.

In her Plato Prehistorian: 10,000 to 5000 B.C. Myth, Religion, Archaeology, Mary Settegast reproduces a table which shows four runic character sets; a is Upper Paleolithic (found among the cave paintings), b is Indus Valley script, c is Greek (western branch), and d is the Scandinavian runic alphabet.