When Humans Almost Became Extinct !

In 1967, fossilized human bone remains were found in Ethiopia (Africa) that were clearly identified as belonging to our species (Home Sapiens) and giving an estimated age of approximately 160,000 years ago. Recently however, a new study of that 1967 site (Prof. F. Brown, University of Utah, 2005) has succeeded in pushing back even further that earlier estimate to 195,000 years ago.

"It pushes back the beginning of anatomically modern humans ..."

and

"These are the oldest well-dated fossils of modern humans (Homo sapiens) currently known anywhere in the world ..."

So the above indicates the earliest known members of our species, Homo sapiens, roamed Africa about 195,000 years ago.


The reason that I presented the above was firstly because it indicates the beginnings of "anatomically modern" humans and secondly that it ties in directly with an article that I was reading in the latest edition of Scientific American (Aug. 2010) titled "When the Sea Saved Humanity". The extremely interesting and thought provoking premise of this article was that at some point during a period of approximately 123,000 to 195,000 years ago, the total estimated population size of more than 10,000 breeding individuals crashed to at most just a few hundred ... at which point Homo Sapiens became an endangered species and teetered on the brink of extinction.

According to the SciAmer article, the primary reason for this population crash was that during the above time period, the previously mild African climate deteriorated significantly when the planet entered a long glacial stage approximately 191,000 years ago (referred to as Marine Isotope Stage 6 (MIS6)) that lasted until roughly 123,000 years ago. During this glacial period, Africa's environmental conditions became much cooler and arid and that it's deserts most certainly expanded significantly compared to their modern extents. As a result, much of the African landmass would have become uninhabitable with the exception of the southern coast of Africa being one of the few remaining locations where climatic conditions were stable enough and food supplies readily available, ensuring the ongoing survival of the remaining small numbers of Homo Sapiens.

Additional support for this population crash is also evident in the fact that humans today exhibit very low genetic diversity when compared against many other species having much smaller population sizes and geographic ranges. This phenomenon is best explained by the occurrence of a population crash amongst the emerging Homo Sapiens.


Whilst I found the SciAmer article fascinating reading and opening up a completely unknown period of Homo Sapien history, in my opinion there was a much more significant point being made.

With Homo Sapiens managing to claw their way back from near extinction when the total population numbers amounted to little more than a few hundred individuals ... this means that every single human alive today (me, you, etc) is descended from a small group of people from a single region that managed to survive a climatic catastrophe !


Don't you just love the way that humankind's previously unknown early history, with it's highs and lows, is slowing being discovered and revealed ?

That is quite astonishing information you got there.

I know of another. Approximately 70.000 years ago.

But what about humans? There is one near-extinction event that is fairly well-known, although it remains controversial. Roughly 70,000 years ago, give or take a few thousand years, an enormous eruption occurred in what is now Sumatra, leaving behind Lake Toba (the crater lake pictured above). The eruption coincides with a population bottleneck that is often cited as the reason for the relatively low genetic diversity across Homo sapiens sapiens. Research suggests as few as 2,000 humans were left alive by the eruption and its aftereffects.

Source.

Toba catastrofy Wikipedia.

I just found a link to your story.

When Humans Almost Went Extinct

This amazing !

I understand this is very new information ?


Edit to add :

Does this not explain how us humans have such a small gene pool.

Two events we nearly got wiped out will definitely have left a huge scar.


[edit on 8/14/2010 by Sinter Klaas]

Originally posted by Sinter Klaas
That is quite astonishing information you got there.

I know of another. Approximately 70.000 years ago.

Source.

Toba catastrofy Wikipedia.

Thanks for the above links. I hadn't heard of those particular "population bottlenecks" before so made extremely interesting reading.

Just makes you truly wonder at just how lucky and fortunate we humans really are to have managed to survive for this long !

Roughly 70,000 years ago ... Research suggests as few as 2,000 humans were left alive by the eruption and its after effects.

A recent paper in the Proceedings of the National Academy of Sciences found another population bottleneck much farther back in human history. Genetic studies found that 1.2 million years ago there were as few as 55,000 members of genus Homo, including pre-human hominids like Homo erectus and Homo ergaster.

Looks like we've stared extinction in the eye quite a few times

I might be stating the obvious here but I think creedence is added because both of these time frames correspond with mitochondrial eve (@190,000 years ago) and y-chromosomal adam ( @70,000), respectively,

Originally posted by Hefficide

I might be stating the obvious here but I think creedence is added because both of these time frames correspond with mitochondrial eve (@190,000 years ago) and y-chromosomal adam ( @70,000), respectively,

Just goes to show how posting a thread on a particular topic can lead you along other paths where you learn new stuff ! I wasn't aware that a Y-chromosone study had been done in an attempt to isolate a common male ancestor way back in the past, so your reference to such a study was most welcome.
However, I was actually aware of the mitochondrial study (mitochondrial eve) that helped locate a time frame for our common female ancestor. The interesting thing is that we can now not only state with a degree of certainty that "Eve" existed approx. 160,000 years ago

Today they have sequenced the entire mitochondrial sequence, and the data still points to a recent ancestor in Africa. All mitochondrial DNA, it now appears, came from a single individual who lived 160,000 years ago.

but we may now, courtesy of the SciAm article be able to say that this "Eve" was more than likely one of the surviving females in that group of just a few hundred remaining Homo Sapiens facing potential extinction.
Almost like being able to point a finger at a single individual

reply to post by tauristercus


Ah, my memory was fuzzy and off! Oh well, to be expected with aging I suppose.

I just wanted to take a moment to thank for you this post and your reply. You've been very gracious!

Originally posted by tauristercus
The interesting thing is that we can now not only state with a degree of certainty that "Eve" existed approx. 160,000 years ago

One of the more recent discussions on dating was published by researchers at the University of Leeds back in 2009 and they still peg the date at about 200,000 years ( www.leeds.ac.uk... ).

If you can find a source for 160,000 I'd sincerely appreciate it. =) Thanks.

Hi I just read this link : When humans faced extinction. BBC News

It holds some interesting info. Like the genetic research done to get these findings.


I you really needed a bump. so...

Originally posted by Xtraeme

Originally posted by tauristercus
The interesting thing is that we can now not only state with a degree of certainty that "Eve" existed approx. 160,000 years ago

One of the more recent discussions on dating was published by researchers at the University of Leeds back in 2009 and they still peg the date at about 200,000 years ( www.leeds.ac.uk... ).

If you can find a source for 160,000 I'd sincerely appreciate it. =) Thanks.

The following sources use an estimated time frame of 160,000 years ago.

The oldest DNA evidence from mitochondrial DNA is Scientific Eve (a.k.a. Mitochondrial Eve), some 160,000 years ago

The Human Family Tree on National Geographic

Every person alive today can trace their maternal lineage to a single woman who lived in Africa approximately 160,000 years ago.

Mitochondrial DNA Sequencing

However, I have noticed that there seems to be a lack of overall concensus and that the time frame for "Eve" has varied from as little as 140,000 years ago to as much as 200,000 years ago. I guess an average would be around 170,000 years.


Whilst searching for sources to substantiate my use of 160,000 years, I came across this little gem that makes "Eve" just that little bit more "solid". Imagine being able to make the following definitive statement about one of the earliest Homo Sapiens !

There are a couple of things we can say about the woman who has
the distinction of having copies of her mitochondrial genome
present in every person living today. She lived in Africa ... She had at least two daughters

Mitochondrial DNA Sequencing

Originally posted by tauristercus

There are a couple of things we can say about the woman who has
the distinction of having copies of her mitochondrial genome
present in every person living today. She lived in Africa ... She had at least two daughters

I'm not sure how the researchers came to the conclusion that she must have had at least 2 daughters but impressive to say the least. Here's a female separated from us by almost 200,000 years and scientists can still give us information regarding her and some of her children ... awesome stuff

And just as awesome to know we humans almost hit rock bottom with just a few hundred individuals left to carry on the species. Imagine if things had gone just a little bit more against those remaining individuals and wiped them out completely - what a fluke that they survived !