When Earth's Human Population Was 18,500!

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

[Allan W Janssen]

We still have letters from my great, great, great, great........... grandfather where he describes the winter of 68,239 B.C.E. as being a "son-fo-a-bitch," and wonders how they get through it!

[Bob Greenwade]

This kind of makes me wonder if any other intelligent species with the potential for civilization had started to develop at some earlier point, and were wiped out by natural disaster.

[Allan W Janssen]

This raises the question of how long it would take all traces of a civilization like ours to disappear!

Anyone?

[doggod]

Yes, I have often wondered-modern man emerged around a million years ago and what were they doing all that time? Something happened but what?

[blah]

allan, i saw one of those discovery channel specials where they explored that very question. major buildings (even skyscrapers) would be gone within 100-1000 years.

major structures like the hoover dam might survive 10,000 years.

and the last thing to go would be mount rushmore, it might last 200,000 years.

they said that animals will occupy different niches. such as domesticated cats, would go wild. but because they are such small predators they would move into the trees and off the ground where large predators would be.

the earth will not miss mankind, and everything we are would be lost in a geologic blink of an eye.

it is up to us to save ourselves.

[Svetlana]

They were scared of global warming so they built their infrastructure on solar, bio, and wind.

And an ice age came.

[Robot Chicken]

The dumbing down of people and uncontrolled breeding is the extinction of 'dumbkind'.

[brandon]

A super-volcano could trigger a volcanic winter, but not a nuclear winter, obviously.

http://en.wikipedia.org/wiki/Volcanic_winter

[Eugen]

"they found there was enough information in only two human DNA sequences to estimate the ancient population size." - maybe someone know, how they get to such conclusion, only by studied two DNA sequences ... for me it's a magic.

[Richard]

The article states there was more genetic diversity in our early ancestors. Is it safe to assume we have evolved into a more refined species since?

[Bob]

Really very informative in nature.
http://funnyandspicy.com/2011-will-witness-7-billion-people-on-earth-brain-picking-video

[Mediamaniac]

This article is just silly. Everyone knows that mankind started only 5,000 years ago in The Garden of Eden! Right?

[Judith]

If another super-volcano (e.g. Yellowstone) started going off, we couldn't do a thing about it. Here comes the nuclear winter.

[Jay Mack]

I guess when it comes down to it, the thing to remember is that nature is in charge of us. We are not in charge of nature. No matter what your belief system is, we are most certainly here for the ride and we are not steering the ship.

[Tom Ulcak]

We see what happens to a species (or breed) which has a small gene pool. There are all sorts of problems: neurological, physical deformities, etc. I think this explains a lot; the overt and extreme violent tendencies of humans, the diseases, and the stunted development socially, culturally and morally.

[John VanDusen]

Remember the story about the Sealacamp fish? Fossilize Sealacamp fish were said to be Millions of years old and was the first fish to walk on dry land. Back in the 70's one was caught and was found to be same as the fossilized fish said to be millions of years old. Round pegs in square holes!!!

[Steven Clark]

You may want to take it up with the Wikipedia page that states - "Humans, known taxonomically as Homo sapiens[3][4] (Latin for "wise man" or "knowing man"),[5] are the only living species in the Homo genus of bipedal primates in Hominidae, the great ape family. Anatomically modern-appearing humans originated in Africa about 200,000 years ago, reaching full behavioral modernity around 50,000 years ago.[6]"

Are you sure humans lived 1.2 million years ago? Really? That's a big jump from 200,000 yrs ago... unless I'm missing something.

[Paul]

This is just more guessing,there is no possible way of knowing how big the piopulation was.They sit around pushing pencils and papers and look as if they have really found something,when it is all speculation. I don't believe Africa was the only "cradle of mankind". I have thought that humans have to have neanderhal DNA,it seems logical,I said this back in the 1960s,now they just came to the same conclusion. I think there were 2 or 3 different groups of neanderthals populating northern Europe ans Asia. I believe that they had white skin,a result of evolving in a colder climate. There closest relatives alive today would be Eskimos and the swedes,,danes andgermanic and slavic peoples. The wave of people out of Northern Africa was a result of the area becoming too arid so they moved into southern Europe and asia.They interbred with the neanderthals and others that evolved in Southeast Asia along with the african group. The black Africans never left subtropical Africa,they had no need to. The reason I think this happened is that I don't think a dark skinned North African can turn into a light skinned Viking or a chinaman unless inbreeding with other unknown hominid groups who were existing at the same time. I think the large populations in India and China were due to a bottleneck effect,they were stopped by the himalayas, than moved south and encountered another hominid group living in what is now malaysia.I think just about anywhere on earth there were apes,their humanlike cousins were also there.

[Cheap Jordan shoes]

Heart and keep pushing, keep the pursuit of progress