By Gautam Naik , Wall Street Journal, April 15, 2011
The world's 6,000 or so modern languages may have all descended from a single ancestral tongue spoken by early African humans between 50,000 and 70,000 years ago, a new study suggests.
Quentin Atkinson, an evolutionary psychologist at the University of Auckland in New Zealand and author of the study, found that the first migrating populations leaving Africa laid the groundwork for all the world's cultures by taking their single language with them—the mother of all mother tongues.
"It was the catalyst that spurred the human expansion that we all are a product of," Dr. Atkinson said.
About 50,000 years ago—the exact timeline is debated—there was a sudden and marked shift in how modern humans behaved. They began to create cave art and bone artifacts and developed far more sophisticated hunting tools. Many experts argue that this unusual spurt in creative activity was likely caused by a key innovation: complex language, which enabled abstract thought. The work done by Dr. Atkinson supports this notion.
Early migrants from Africa probably had to battle significant odds. A founder effect on a breakaway human population tends to reduce its size, genetic complexity and fitness. A similar effect could have limited "the size and cultural complexity of societies at the vanguard of the human expansion" out of Africa, the paper notes.
Palomar Community College Website (likely orphaned course material)
In many species, there have been catastrophic periods caused by rapid dramatic changes in natural selection, during which most individuals died without passing on their genes. The few survivors of these evolutionary "bottlenecks" then were reproductively very successful, resulting in large populations in subsequent generations. The consequence of this bottleneck effect is the extraordinary reduction in genetic diversity of a species since most variability is lost at the time of the bottleneck.
Bottlenecking also occurs at times in human populations as a result of major epidemics and catastrophic storms, earthquakes, and volcanic eruptions. An example of this occurred on the small Micronesian island of Pinegelap in the Western Pacific. In 1775, a typhoon killed at least 90% of its people, thereby eliminating most of the genetic variation. One of the 20 survivors was a man named Nahnmwarki Mwanenised. He had achromatopsia, a very rare genetically inherited recessive eye condition that causes total color blindness and extreme sensitivity to light. Six generations later, nearly 5% of the island's population had achromatopsia. All of those who had it were descendants of Nahnmwarki Mwanenised. By comparison, only 1 in 33,000 people in the United States have it. Not only did the Pinegleapese experience a dramatically reduced genetic diversity as a result of the 18th century storm, but unfortunately that surviving gene pool contained the genes for achromatopsia, making this an example of both the bottlenecking effect and the founder principle.
Jared Diamon in his book Collapse, noted that small isolated groups were at risk when they fell below a certain threshold. The North American Natives were not only at risk to disease because they had been separated from Europe-Asia for so long. But the immunities that they were able to culturally carry along (generally from Mother to child) would have been limited by the founder effect. The smaller the population, the smaller the amount of cultural memory that is allowed. As an example, the typical American may know to much about how to work and operate a modern town or city, but as a group we can do a reasonably good job at it. If a group of modern day Americans "survived" some sort of cataclysm (lets say one of those popularly novelize influenza pandemics) how actual skill would remain within the group to run anything much beyond a small company (60 person) organization?
I suspect that this problem is one of the contributors, beyond the death and devastation, to the depth of the some of the past cultural collapses.