Study finds human population expanded during late Stone Age

July 29, 2009

Genetic evidence is revealing that human populations began to expand in size in Africa during the Late Stone Age approximately 40,000 years ago. A research team led by Michael F. Hammer (Arizona Research Laboratory's Division of Biotechnology at the University of Arizona) found that sub-Saharan populations increased in size well before the development of agriculture.

This research supports the hypothesis that population growth played a significant role in the evolution of cultures in the Late Pleistocene. The team's findings are published in the online peer reviewed journal PLoS ONE on July 29.

Reconstructions of the timing and magnitude of changes in human population size are important for understanding the evolution of our species. There has been a longstanding disagreement whether humans began to increase in number as a result of innovative technologies and/or behaviors formulated by hunter-gatherer groups in the Late Pleistocene, or with the advent of agriculture in the Neolithic. Hammer's research integrates empirical genetics with discoveries in paleontology and archeology to help provide answers to interdisciplinary questions about which kinds of innovations led to the evolutionary success of humankind.

Hammer's UA team, together with their collaborator from the University of California San Francisco's Institute for and Department of Epidemiology and Biostatistics, surveyed the genetic material of ~184 individuals from seven human populations and used a computational approach to simulate the evolution of genetic lineages over time. The researchers found that both hunter-gathers and food-producing groups best fit models with approximately ten-fold population growth beginning well before the origin of agriculture. For the first time ever, Hammer's team was able to investigate the timing of human population expansion by applying sophisticated inferential statistics to a large multilocus autosomal data set re-sequenced in multiple contemporary sub-Saharan African populations.

The team's finely executed experimental design and use of supercomputing power enabled them to determine that this expansion in likely began at the start of the Late Stone Age—a period in prehistory that shows an intensification of archeological sites, an increased abundance of blade-based lithic technologies, and enhanced long-distance exchange. The next step in the project is to gather more data by testing more populations and additional parts of the genome.

More information: Cox MP, Morales DA, Woerner AE, Sozanski J, Wall JD, et al. (2009) Autosomal Resequence Data Reveal Late Signals of Population Expansion in Sub-Saharan African Foraging and Farming Populations. 4(7): e6366. doi:10.1371/journal.pone.0006366

Source: Public Library of Science (news : web)

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3 / 5 (1) Jul 29, 2009
...this expansion in population size likely began at the start of the Late Stone Age, a period in prehistory that shows an intensification of archeological sites, an increased abundance of blade-based lithic technologies, and enhanced long-distance exchange.

Duh! Let's see, what can I do with a flint blade. Better spears for hunting? Check. Spearfishing? Check. Make fishing nets? Triple check. No wonder population soared.

I've often thought that fishing has to have preceded agriculture. Early agriculture would not produced enough additional food to be worth the effort. But once you look at agriculture as an adjunct to fishing (growing vines for nets), everything makes sense. A neolithic community can settle on a river or lake and use agriculture to enhance fishing. Once you do that, growing crops like berries works just fine--the increased cost per calorie of fruit is more than compensated for by the variation in diet.
not rated yet Jul 29, 2009
Just as Microsoft predicted in Age of Empires. (woah)
not rated yet Jul 29, 2009
Well DUH.
not rated yet Jul 29, 2009
i dont get why our species considers ourselves an evolutionary success so far. as far as we know, our specific species has only been around a bit over 200,000 years. FAAAAAR less than most, what I would consider, "successful" species on this planet.

All other species on this planet have many variations among them, whether frogs, or tree swinging primates...except us...were still young on the block, and all of our equal species have already gone extinct....

im thinking that even frogs are more successful than us. we still have much to prove, and much to improve, before we can consider ourselves a successful species.

dont get me wrong, yes we have had success in the form of, oh, say extending the average lifespan, but that isnt evolution. when we grow 7 fingers instead of 5 in response to our environment that involves constant typing daily, THEN weve evolved.... :D
not rated yet Jul 29, 2009
Wow i cannot believe they would have thought to study the impact of stone age technologies on human population growth! Astounding the insight!!!!

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