Because languages leave behind no fossils, it is difficult to put our finger on the exact time when human language originated. Some scientists dubiously attempt to guess the sophistication of primate communication based on the complexity of the tool industry at the time. We may never know for sure when language originated, until we are able to use preserved DNA from ancient homonids to recreate them and observe their language capacities.
Rather than evolving abruptly, it is likely that language as we know it developed over a long period of time. Some scholars believe that the advent of bipedalism 3.5 million years ago brought anatomical changes, such as a more L-shaped vocal tract, which would have expanded the range of possible sounds. Whether primates at this time actually used this anatomy to make more sophisticated sounds is not known. These "missing links" are now all extinct.
Research of homonid skulls has found that about 400,000 years ago, Neanderthals had a hypoglossal canal similar in size to that of modern humans. The hypoglossal canal is a bony channel that routes nerve fibers associated with the production of speech, although some studies have found an inconclusive link between the size of this canal and speech capabilities. Neanderthals possessed a tool industry significantly more sophisticated than earlier homonids, and had large brains. Many scholars suspect that Neanderthals had some rudimentary form of language, and tentatively believe that modern language originated around 400,000 years ago.
Although the precise time when language originated remains unknown, it was certainly in use 200,000 years ago, when modern humans evolved in Africa. These humans were modern anatomically, but behaved similarly to some of the simpler homonids that came before them until about 100,000 years ago. About 50,000 years go, a small group of humans left Africa. Some scholars argue that this departure signifies that humans had reached some threshold level in their capacity to communicate, which made them capable of leaving, although this hypothesis is quite doubtful.
Most scientists believe that all modern language originates from a single source, rather than having developed independently on all continents. If so, it must have come from a source at least as far back as the common ancestor of all living humans. All modern humans are ancestors of "Mitochondrial Eve," a female that lived in Africa approximately 150,000 years ago. Modern language may date back to this era, or may be more recent. About 70,000 years ago, the human species experienced a severe population bottleneck when the total number of individuals may have been as low as 2,000. The global language might also date back to this period.
Michael is a longtime WiseGEEK contributor who specializes in topics relating to paleontology, physics, biology, astronomy, chemistry, and futurism. In addition to being an avid blogger, Michael is particularly passionate about stem cell research, regenerative medicine, and life extension therapies. He has also worked for the Methuselah Foundation, the Singularity Institute for Artificial Intelligence, and the Lifeboat Foundation.