Humans Barely Dodged Extinction----

[indigobusiness]

Humans

DNA evidence suggests that humans today are a legacy of a population bottleneck which occurred 70,000 years ago. This would have had the result of limiting the overall level of genetic diversity in the human species, possibly by a large amount. One theory about this bottleneck is the Toba catastrophe theory, positing that the human population was reduced to a few thousand individuals when the Toba supervolcano in Indonesia erupted and triggered a massive environmental change.

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



Population Bottlenecks and Volcanic Winter

The "Weak Garden of Eden" model for the origin and dispersal of modern humans posits a spread around 100,000 years ago followed by population bottlenecks. Then, around 50,000 years ago, a dramatic growth occurred in genetically isolated, small populations. In a 1998 article, Stanley Ambrose proposed an alternative hypothesis, a volcanic winter scenario, to explain recent human differenciation. The bottleneck was caused by a volcanic winter resulting from the super-eruption of Toba in Sumatra. If Ambrose's hypothesis is correct, modern human variations differentiated abruptly through founder effect, genetic drift, and adaptation to local environments after around 70,000 years ago.

Ambrose points out that the Out of Africa dispersal date of around 100,000 years ago fits the generally warm, humid last interglacial period, 130 -74,000 years ago. An impressive body of paleontological evidence shows an Afro-Arabian biotic community expanded northward during this period. Several such multi-species dispersals out of Africa have occurred during previous interglacial phases. He considers the variants of the Replacement model to be more accurate and realistic than the Multiregional models.

The number of DNA mutations within a population increases temporally. When a population has passed through a bottleneck, the mutation distribution evidences the bottleneck. DNA studies have identified a significant bottleneck (or bottlenecks) during the last glacial period.

The Multiple Dispersals model proposes a population bottleneck occurred when cold, dry climates isolated populations in Africa. Additional bottlenecks occurred through physical bottlenecks such as the Sinai Peninsula. The first dispersal of anatomically modern humans, to the Levant around 100,000 year ago, is evidenced by early modern human skeletons in the Near East. According to Ambrose, this first dispersal apparently failed to permanently establish modern humans outside of Africa. Genetic evidence shows that non-African populations can be divided into southern Australasian and northern Eurasian populations that divided 50-75,000 years ago.

snip

http://www.jqjacobs.net/anthro/paleo/bottleneck.html

Human Evolution

The New Batch - 150,000 Years



How did we escape extinction?

What makes us so special?

How we colonised the world.

With just over 6 billion people living in the world today, human beings are a phenomenally successful animal. But our species, Homo sapiens, once came close to outright extinction.

Social networks spread the risk of survival during the bottleneck
Clues from genetics, archaeology and geology suggest our ancestors were nearly wiped out by one or more environmental catastrophes in the Late Pleistocene period. At one point, the numbers of modern humans living in the world may have dwindled to as few as 10,000 people.

http://www.bbc.co.uk/science/cavemen/chronology/contentpage6.shtml

[purduejake]

1. And we're headed straight for extinction now.

[indigobusiness]

3. I wouldn't argue

with you.

[mhr]

2. Yes, And The Next Extinction Event Will Probably Be Peak Oil

It's probably one minute to midnight as we speak.

Watch the following video for context.

http://edison.ncssm.edu/programs/colloquia/bartlett.ram
http://news.globalfreepress.com/movs/Al_Bartlett-PeakOi...

----
"Facts do not cease to exist because they are ignored" Aldous Huxley.

[pmbryant]

4. I have no clue how peak oil would lead to an extinction event

Especially human extinction. Can you summarize what those links say for us multimedia-challenged posters?

[mhr]

7. Peak Oil Is About The Day When We Will Have Consumed

Half the worlds endowment of oil.

After that, the remaining oil will only become more valuable and the source of ever greater warfare as nations fight for the remaining share.

The second part of this equation is considering how the world can support a population that depends on the products made from oil.

Just consider your life; virtually everything you touch is made from oil. All the food you eat is dependent upon oil. Many of the medicines you need require oil for processing and manufacture. Your daily commute probably relies on oil. Etcetera, Etcetera!

So take all those simple things and now imagine not having them and the chaos that will cause. This all leads to an extinction event.

Here are some websites for further perusal.

http://www.peakoil.net/
http://www.greatchange.org/
http://www.dieoff.org/
http://www.lifeaftertheoilcrash.net/Introduction.html

Enjoy

[pmbryant]

8. Chaos is horrific, but far from extinction

Extinction just doesn't seem like a plausible outcome.

[mhr]

9. Read The Links And You Will Learn That Extinction (Near Extinction)

Is the most probable outcome.

To put it bluntly, many academics believe that we will see world population reduce from 6 billion to 1 billion over the course of a hundred years or so.

I'd say that's chaos on steroids. Your definition may be different.

[pmbryant]

10. That's truly a horrifying scenario

But 1 billion people is far from extinction.

[mhr]

11. Well Okay - That's One Perspective

Read the links and then decide.

[indigobusiness]

13. Your point is well taken (by me at least).

It is hard to anticipate how the chaos will extrapolate.

[mhr]

14. 5 Billion Dead In 100 Years Is 50 Million People Per Year On Average

That is a lot of folks and a lot of chaos.

[Krocksice]

16. not extinction

we'll just have to reach a new, lower carrying capacity.

[Boomer]

5. We may not be so lucky the next time....

Over the last 75 years or so, millions of Humans have replaced the survival techniques developed over thousands of years in favor of a high-tech, high-energy lifestyle.

How many people know enough about gardening to feed their family? How many even know how to preserve enough food for winter? Or how to sew, much less weave cloth?

A few months ago I watched Frontier House and saw how modern families dropped back into life just a century ago lacked the skills possessed by the common man and woman. Despite the best advice and coaching of historians, none of the families succeeded in stockpiling enough wood or food to survive a single winter.

Doesn't bode well for our ability to weather a climate crisis.

[pmbryant]

6. Well, to be fair to the Frontier House people

A hell of a lot of the real pioneers at Plymouth and Jamestown back in the early 1600s weren't able to survive their first winters either.

--Peter

[don954]

12. i think that a huge amount of the population would migrate down to

the southern areas like Florida.

And those of us who have a solar & wind power system would need to hide it or be very well armed.

This is one of the reasons I'm buying a small cruising sailboat and not a power boat.

[indigobusiness]

15. And fight over the last scraps of food.

Before the party is officially over.

[Krocksice]

17. yeah...

plus when everyone goes to the warm places, the resources are gonna run out pretty quick... but we'll have a few more wars over resources before then, so maybe the population will be thinned enough by then that the survivors can live comfortably in the tropical climates.