Earth 1.2 Millions Years Ago: Human Population, 18,500!
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January 22, 2010

Earth 1.2 Millions Years Ago: Human Population, 18,500!

Human_evolution_2 Scientists have calculated that for a period lasting one million years and beginning 1.2 million years ago, at a time when our ancestors were spreading through Africa, Europe and Asia, there were probably between 18,500 to 26,000 individuals capable of breeding (and no more than 26,000). This made them an endangered species with a smaller population than today’s species such as gorillas which number 25,000 breeding individuals and chimpanzees (21,000). 

Researchers have proposed a number of explanations , such as events in which a significant proportion of the population is killed or prevented from reproducing. One such event was the Toba super-volcano in Indonesia that erupted around 70,000 years ago, triggering a nuclear winter. Only an estimated 15,000 humans are thought to have survived. Another explanation is that the numbers of humans and our ancestors were chronically low throughout the last two million years, sometimes with only 10,000 breeding individuals surviving.


The new research is concerned with the entire genome rather than specific genetic lineages studied in the earlier research work. Using a new method of studying genetic markers of DNA in the genome has allowed geneticists to study the genetics not only modern humans, but also our early ancestors such as Homo erectus (thought the most likely to be our direct ancestors), H. ergaster and archaic H. sapiens. Remarkably, they found there was enough information in only two human DNA sequences to estimate the ancient population size.


Human geneticist Lynn B. Jorde and colleagues at the University of Utah studied parts of the genome containing mobile elements called Alu sequences, which are sections of DNA around 300 base-pairs long that randomly insert themselves into the genome. This is a rare occurrence, but once inserted, they tend to stay in place over generations, and act as markers, rather like fossils, for ancient parts of the genome. 


From theirstudies, they calculated there was more genetic diversity in our early ancestors than there is in modern humans. They also came to the conclusion that there had been a catastrophic event around one million years ago that was at least as devastating as the Toba volcanic eruption, and which had almost wiped out the species.


Casey Kazan 


Sources: 


PNAS, the Proceedings of the National Academy of Sciences on January 19.


http://www.physorg.com/news183278038.html

Comments

How ironic that we are now endangered by having too many people. We can't seem to win for losing.


http://ecocosmology.blogspot.com/2009/11/shadow-of-time-governs-earth.html

I found the conclusions suspect given that only two DNA samples were checked. Then this:

"they calculated there was more genetic diversity in our early ancestors than there is in modern humans"

Which even articles here have contradicted, pointing out that genetic diversity is now at a high-point because technology allows people to survive who wouldn't have in ancient times, thus prolonging their genes.

So who is right?

Guess it depends on your definition of "genetic diversity"... and the number of samples you check.

We sure are the "scrappys" of the animal kingdom!

Dredd, I agree.

I really cannot see how they can reach such conclusions.
It just sounds like esoteric speculation masquerading as science.
I may be wrong, I cannot tell. Thats just it.
In order for it to be science, it would need to be verifiable; or at the least be explained in terms of the actual photos of the DNA with some sort of simplified analogy.

The term "genetic diversity" is so wide its meaningless.

We are told that chimps are genetically more similar to us; and yet the horse, cat, and dog, share behaviours and lives and even work with us. Their minds are far more human than monkeys are.

I do realize this is a ridiculous proposal, but funny if you think about it. What if our population level wasn't the only similarity between our ancestors and the modern chimp. What if we too had to contend with an intelligent form of life ruining things for us? Fun thought, might make a good sci-fi novel

Seems that China, a COMMUNIST country, has taken the right attitude towards population control. The U.S. "Progressives" (?) should follow the example and do something about overpopulating America with foreigners, while the native population is shrinking.

Hey Kodiak,

What d'ya mean, "The U.S...should follow the example (of China) and do something about overpopulating America with foreigners, while the native population is shrinking."

We've been there, done that! Native Americans have almost vanished from our landscape now - some estimate as many as 80 million of them were exterminated in the holocaust inflicted by the invading (European) foreigners.

Regards,

AmericanMuse

Kodiak,

What are you talking about "native population"? There isn't a breathing individual in the Americas who didn't get here because, at some time, his family didn't immigrate here.

Even the Native Americans resulted from tribes of people immigrating 20,000-50,000 years ago from what is now Northeast Russia.

" Seems that China, a COMMUNIST country, has taken the right attitude towards population control. The U.S. "Progressives" (?) should follow the example and do something about overpopulating America with foreigners, while the native population is shrinking."

Funny you should say that. I'm partially American Indian, how many of us are left?


Nice talkings.

However nobody has ever believed that branches of the "homo tree" which may or may not include primates monkeys in addition to sapiens-sapiens (us)and quite few other hominide species led "our ancestors some 1.8 Million Y agò to go around from Africa to populate other continents ".

The S2 ancestors 'likely' have moved away from central-east Africa some 70-100 thousand Y agò are supposedly our ancestors and sit on the same branch of the 'homo tree'.


I do not understand what you and them mean by 1.8 million Y agò.

Some monkey like pre-humans were 18K or 25K individuals some 1.8 Million Y agò ?? And so what ?????

FINALLY these fucking genetists must STOP working on " BLACK PROJECTS" for the Military to try to create the 'cloned-perfect warrior'.

We have enough mess even without human-clones on this fucking miniplanet.


More genetic diversity 20,000 years ago ? I wonder what kind of genetic diversity scientists will find 20,000 years into the future with the toxic environment, potential nuclear exchange, above ground and Bikini Atoll atomic testing and the food additives/gm crops. Will mankind, the animals and plants be more or less diverse then than now? Or just a series of like/identical perfect genetic mutations! We are in uncharted territory here and with the BP Gulf Oil spill entering the food chain potentially globally.We may singlehandedly be reducing our population growth through our own HUMAN actions as opposed to NATURAL catastrophes from Earth or space. Survival of the fittest? Maybe it is time we revisit the deeper meaning of that phrase. it seems obese humans with high technology are not the fittest. nor are third world individuals with famine, overpopulation and disease running rampant. Where there is a middle ground there is a way to survive. Where's a time machine when we really need one.

How about all of this is BS and the planet really isn't billions of years old etc? (not 6000) Can't pick at some assumptions and leave others untouched.


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