Previously Unknown Population Explosion of Human Species 40,000 Years Ago --Discovered
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October 30, 2012

Previously Unknown Population Explosion of Human Species 40,000 Years Ago --Discovered

 

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DNA sequencing of 36 complete Y chromosomes has uncovered a previously unknown population explosion that occurred 40 to 50 thousand years ago, between the first expansion of modern humans out of Africa 60 to 70 thousand years ago and the Neolithic expansions of people in several parts of the world starting 10 thousand years ago. This is the first time researchers have used the information from large-scale DNA sequencing to create an accurate family tree of the Y chromosome, from which the inferences about human population history could be made.

"We have always considered the expansion of humans out of Africa as being the largest population expansion of modern humans, but our research questions this theory," says Ms Wei Wei, first author from the Wellcome Trust Sanger Institute and the West China University of Medical Sciences. "The out-of-Africa expansion, which happened approximately 60,000 years ago, was extremely large in geographical terms with humans spreading around the globe. Now we've found a second wave of expansion that is much larger in terms of human population growth and occurred over a very short period, somewhere between 40,000 to 50,000 years ago."

There is no obvious archaeological event that would explain why this sudden expansion in the human population occurred. One possible theory is that during the original out-of-Africa expansion, humans moved along the coastlines of the world, settling as they went. Their origins and genetic makeup would mean that these people were suited to coastal life, but not to the demands of living inland. This would have prevented large population growth as the coasts could only sustain a certain number of people.

"We think this second, previously unknown population boom, may have occurred as humans adapted to their new environment after the first out-of-Africa expansion," says Dr Qasim Ayub, lead author from the Wellcome Trust Sanger institute. "We think that when humans moved from the horn of Africa to Asia, Australia and eventually Europe, they remained in small groups by the coasts. It took them tens of thousands of years to adapt to the mountainous, forested surroundings on the inner continents.

However, once their genetic makeup was suited to these new environments, the population increased extremely rapidly as the groups travelled inland and took advantage of the abundance of space and food." The work highlights how it is now possible to obtain new biological insights from existing DNA sequencing data sets, and the value of sharing data. The majority of the DNA information used for this study was obtained from freely-available online data-sets.

Since the Y chromosome is found only in men, its history and evolution are easy to study and interpret. This study also highlights how information generated by other genetic studies, in this case by the company Complete Genomics, can be used to investigate human genetic archaeology. The lengths between the branches and the length of each branch on the Y chromosome family tree provide insights into the evolution of the human population. The closer the branches are, the more rapidly the population was expanding and separating, most likely into different geographic areas. The longer the branch length, the greater the time that group of people have been separated from the other groups.  

"We have provided a nearly ten-fold increase in the number of genetic markers found on Y chromosomes and discovered new historical insights into the evolution of modern humans using DNA sequencing information from just 36 men," says Dr Chris Tyler-Smith, lead author from the Wellcome Trust Sanger Institute. "We now want to look at ten times this number of Y chromosomes in data from the 1000 Genomes Project. Who knows what we will find then?"

For more information: Genome Res. 2012 doi:10.1101/gr.143198.112 Journal reference: Genome Research

The Daily Galaxy via Wellcome Trust Sanger Institute

Image credit: With thanks to bbc.co.uk

Comments

The current human population wave is a result of global warming and of course our technology creating the favourable conditions for the increase in biomass. The conscious development of Technology that is only available to a cognitive species will allow for the enviable ultimate control of its environment and will end its otherwise likely demise that has occurred for so many other species from the recorded cyclic extinction events that have occurred through out earths geologic history. In essence the creative ability of man will allow the biosphere to evolve to a higher state that would otherwise not be possible. Much how the development of our bodies is programmed in our DNA since birth, the needed creative ability of a cognitive species in a biosphere is required and predetermined to evolve to allow it to progress and expand beyond its parent planet. Man has a very important role to play on earth and is not the scourge so many want us to believe, we just have to realize our mission.

I love science

This correlates witht he fact that inland populations are generally more robust; not only in terms of resource availability/utilization but apparently coastal regions are the most adversly affected by environmental changes ... sorry new Jersey, too soon?! another example, once that fish got onto land it wasn't long until various animals moved inland and adapted.

Fascinating. I suppose it makes sense that the retention and accumulation of skills and behaviors in and between groups would be dependant on population size and frequency - the more people you come in contact with, the more opportunities you have to pick up a new skill or pass on one. You'd have to cross a demographic threshold in order to reach a consistent frequency of artifacts in the archaeological record. http://www.nextluxury.com

the assumption seems to be that it was a change in genetic makeup that precipitated the inward expansion, but i see no reason it couldn't have been due to technological advances. Living inland requires a different skill set than living in a coastal area. Advances in clothing, weaponry, food storage, medicine, along with requisite changes in hunting and survival tactics would take time to develop but could spread easily once they were mastered.

You have got to admit that is pretty amazing. Wow

www.ok-anon.tk

Ken, it's people like you that are currently retarding the development of our species. You can't even look at your own comment and realize how daft it is, can you?

God have mercy on us all.

Lee is exactly correct, this is the birth of a new more ordered ecosphere as described in the book Ecophysics, however like any birth this is a dangerous process that could result in the death of the mother if things go wrong so great responsibility is required. The prospect of a hopeful future fills people with horror because it implies nihilistic and hateful attitudes are the result of personal failure rather than being excusable due to cultural failure, and that lives have been wasted not taking the bet that would have payed off. If its all hopeless irresponsible selfishness is validated but if there is any reason for hope irresponsibility and selfishness could not be more of a cause for shame and guilt, the worst possible emotions. Most people have surrendered such that hope represents the greatest possible threat to emotional stability.

We were everywhere is obvious. Now, why did we have to start over so many times? Incidentally, I consider the Neanders and the Denisovians modern humans.
If we did not cause our own demise so many times (and we did not) then what planetary catastrophe did?
This 40,000 very weak magnetic reversal (revealed just before this people blurb) did not cause expansion. We got 'smart' 50,000 ya. I suggest this was due to an energy incursion compressing our heliosphere. Earth was held in a matter-antimatter transform (Majorana),hence the smarts, and not being passed into cosmic space, hence the dumbing down. We managed the onestep forward without the two back.
I suspect the subsequent radon, carbon di,methane bath of E's surface to be claimed to be beneficial (remember what we cannot change we claim is good for us.) It's not. It is from a heated core release. It is why NASA knows bad weather is on the way.

@ Posted by: Lee | October 30, 2012 at 10:46 AM

I don't necessarily agree with your claim that "the current human population wave is a result of global warming and of course our technology creating the favourable conditions for the increase in biomass." And, most of your other claims regarding technology creation, limitation and where you've implied that control of our environment is predetermined, and that, "needed creative ability of a cognitive species in a biosphere is required and predetermined to evolve"... but those are for another conversation.

I think "the current human population wave" is too vague. But, if you're referring to the growth in industry and population from the late 1600s to the late 1800s, the Industrial Revolution, then global warming was not a factor, or has yet not been proven to be one. The discussion for what triggered the industrial revolution is still living, with only a few, general conclusions having been made. Law, Technology and "Energy Conversion" such as coal, steam etc, and other factors all played a part in creating the environment necessary for that kind of growth. I'd reccommend A Farewell to Alms, the math/economics behind it is relatively simple and the concepts are quite elegent.

I do, however, love the optimism and the conclusion. I too believe it is man's duty to leave this planet.

Increased specialization and trade a.k.a capitalism.

I would venture that the technology that supported this expansion is the early symbiosis of human groups with wolf packs leading to more effective hunting and eventually to the domesticated dog.

Bear in mind this is a model,not reality. Results are found and then causes are extrapolated. Extrapolation is always fraught with peril. Look deep enough and someone will come up with an answer just the opposite to the same data.

We'll never really know. We can only surmise. Besides, man is not an ideal species to be seeding other planets. Consider his imperfect genes and the flora and fauna he carries with in him. Enough said.


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