Toba bottleneck illuminated

[Rokcet Scientist]

Ancient Volcanic Blast Illuminates History Of Early Humans

Researchers say that a recent study has yielded “incontrovertible evidence” that a massive volcanic eruption on the Indonesian island of Sumatra some 73,000 years ago wrought massive destruction across much of what is now modern-day India, decimating vast swathes of ancient forests and pushing early human populations to the edge of extinction.

Scientists at the University of Illinois say that their results powerfully corroborate one of the most controversial theories in the natural sciences — the Toba Catastrophe Theory.

The theory — first proposed by Stanley H. Ambrose of the University of Illinois at Urbana-Champaign in 1998 — holds that the supervolcanic event at Lake Toba intensified Earth’s last ice age by releasing so much ash into the atmosphere that sunlight was blocked out for six years. As global temperatures dropped by an average of 28 degrees Fahrenheit, the planet plunged into one its most bitterly cold periods of the last million years.

Ambrose theorized that the crises brought on a severe evolutionary “bottleneck,” reducing the entire human population to between 5,000 and 10,000 individuals and driving several other human-like hominid species to extinction. According to the theory, this vast reduction in the number of humans helps explain the relatively modest genetic diversity present in humans today. [...]

http://www.redorbit.com/news/science/17 ... index.html

Could Toba perhaps have done in a host of hominid species like Erectus (different variants), Antecessor, and Heidelbergensis? Leaving only HSS and HNS?

[kbs2244]

“For the recently released study, Ambrose assembled a team of researchers to look for evidence supporting his theory from two different sources.”

That doesn’t sound very objective.
They started out with an agenda.

[Minimalist]

Leaving only HSS and HNS?

Why leave those two? And what about Peking Man and Java Man? They were a lot closer to ground zero....not that a nuclear winter would matter much there. Why weren't the mammoths wiped out then instead of 50k years later.

I agree with kb. This guy had a agenda.

[Digit]

Plus the Asiatic Rhino, Elephant, Tiger, Orangutans etc all untouched apparently, very odd!

Roy.

[Rokcet Scientist]

Leaving only HSS and HNS?

Why leave those two? And what about Peking Man and Java Man? They were a lot closer to ground zero....not that a nuclear winter would matter much there. Why weren't the mammoths wiped out then instead of 50k years later.

The survivors, man and beast, lived east of Toba. Virtually every higher life form to the west, in the northern hemisphere, was wiped out by the event and its 'immediate' aftermath (a few years of ash and darkness), but the west (of Toba) was repopulated from the east after the 'nuclear winter' subsided.

And it would make sense, in that scenario, that some species of mammoth, rhino, etc. did get wiped out too, just like some species of hominid, leaving only the variants/subspecies we know from later eras. Just like hominids.

[Minimalist]

HNS was west of Toba.

Yet they seemed to survive unscathed.

Perhaps the effects of Toba are being overstated?

[Digit]

Perhaps the effects of Toba are being overstated?

And disputed.

Roy.

[Minimalist]

But of course!

[Rokcet Scientist]

Perhaps the effects of Toba are being overstated?

Perhaps. But hardly likely if you interpret the remains of the event: the size of that crater, and the 14 metres (over 40 feet) of ash layers. Toba was at least two magnitudes more powerful than Krakatoa 1883 (same fault line!).

An full-scale eruption of the Yellowstone supervolcano may be comparable.

[Minimalist]

the size of that crater, and the 14 metres (over 40 feet) of ash layers. Toba was at least two magnitudes more powerful than Krakatoa 1883 (same fault line!).

But - it apparently did not cause extinction on a planet wide basis which suggests that some of this super-volcano (and yes, asteroid/comet impact) stuff is overstated. That would not surprise me. We live in an age where hype is needed to gather attention.

[Rokcet Scientist]

the size of that crater, and the 14 metres (over 40 feet) of ash layers. Toba was at least two magnitudes more powerful than Krakatoa 1883 (same fault line!).

But - it apparently did not cause extinction on a planet wide basis which suggests that some of this super-volcano (and yes, asteroid/comet impact) stuff is overstated. That would not surprise me. We live in an age where hype is needed to gather attention.

Perhaps. But that is all supposition on your part. I like to look at the available facts. The AD 1883 Krakatoa crater can't even be discerned from space, 125 years later. The Toba crater is still clearly visible after 73,000 years and measures 87 kilometers (54 miles) across!

Toba:


Krakatoa:

[Minimalist]

I agree with you, Rok....but it did not wipe out all life on earth even with a blast of that magnitude.

Perhaps the earth is a tad harder to destroy than the harbingers of doom would have us believe?

[Rokcet Scientist]

I agree with you, Rok....but it did not wipe out all life on earth even with a blast of that magnitude.

Perhaps the earth is a tad harder to destroy than the harbingers of doom would have us believe?

If I'm not mistaken this conversation was not about whether or not the earth was destroyed by Toba – it clearly wasn't – but whether Toba was an event big enough to wipe out (a number of) species at the time. Mind you: 1) not all species, and 2) whatever species were wiped out to the west of Toba (earth's rotation) would have been 'replenished' by the survivors to the east of Toba in a few centuries.
So if HE('s variants), Heidelbergensis, Antecessor, etc. lived west of Toba – but had already gone extinct east of Toba – those species could not have been 'replenished' west of Toba...
HN(S) – who lived west of Toba – might have simply been too tough to go extinct from the Toba event, while the others weren't as tough, and thus vanished.
HN(S)' numbers are assumed to have never been much greater than 10,000, in total, world-wide, and at any one time! That might make sense if a large part of HN(S) was wiped out by Toba.

[Digit]

But surely Toba is being sold as causing a bottleneck in HSS, who is supposed to be still in Africa at this time, or did I miss something?

Roy.

[Minimalist]

The nuclear winter scenario is that there is sufficient ash to block out the sun EVERYWHERE.

You're losing me with this East-West stuff, Rok.