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Pretty damn likely if we're to judge the future by the red hot now . . . |
Posted on 04/14/2004 6:15:04 AM PDT by Momaw Nadon
I also used to think Human "De-evolution" was impossible. But then we do have a Democratic Party. So there goes that hope.
So, what is the evidence in the fossil record recording the similarly large extinction of multiple species that would also have happened along with this?? At this point, color me largely skeptical.
I reject the premise that morphological stability equals genetic stagnation, or that morphological change necessarily represents huge genetic changes. The fossil record records only morphology, while this "telomere erosion" hypothesis speaks only to genetics.
The eruption of 2,800 cubic km of magma at Toba caldera 75,000 years ago was the largest eruption in the last 2 million years. The eruption may have release as much as 10E12 kg of sulfuric acid, an order of magnitude more than Laki in 1783 and Tambora in 1815, two of the greatest Holocene eruptions. The Toba eruption may have caused about 3 to 4 degree C cooling at the surface but this impact is hard to detect because of concurrent glacial conditions (Sigurdsson, 1990).
Formed by a stupendous prehistoric volcanic explosion, the 100 km long lake is the largest is Southeast Asia and one of the deepest and highest in the world. The drama of that cataclysmic birth persist in 500 meter cliffs dropping into the blue-green waters, Surrounded by steep, pine covered sloped, the climate is fresh and pleasant, with just enough rain to support the lush vegetation.
Smoke Over Lake Toba, Indonesia(NASA Visible Earth)
The super-eruption of Toba, did it cause a human bottleneck? FJ Gathorne-Hardy1, WEH Harcourt-Smith2, 1 Archaeology department, West Street, Sheffield University S1 4ET, 2 Palaeontology department, AMNH, Central Park West 79th Street, NYC, NY10024, U.S.A: It has been claimed that the super-eruption of Toba, Indonesia, about 73.5 Ka, caused a global “volcanic winter” which was responsible for a bottleneck in human populations. We show that the eruption’s radius of direct impact was probably less than 350 km and that the global cooling associated with Toba was not unusual. We argue that at 73.5 Ka humans were adaptable and wide-ranging omnivores, so unlikely to suffer greatly from global cooling. No plant or animal extinction is attributed to the effects of the eruption. Genetic evidence appears not to support the hypothesis of a Toba-induced population bottleneck. We conclude that the Toba super-eruption is unlikely to have caused a bottleneck in human populations.
COMMENT: Above argues against effect of Toba on humans. However ...
URI oceanographers investigate link between last Ice Age and Indonesian volcanic eruptions
January 27, 2004
Approximately 75,000 years ago, a massive explosive eruption from a volcano in western Indonesia (Toba caldera) coincided with the onset of the Earth's last Ice Age.
In the current issue of Geology, University of Rhode Island geological oceanographers Meng-Yang Lee and Steven Carey; Chang-Hwa Chen and Yoshiyuki Iizuka of the Academia Sinica in Taiwan; and Kuo-Yen Wei of National Taiwan University describe their investigation into the possibility that eruptions from the Toba caldera on the island of Sumatra caused a severe "volcanic winter" and the initiation of a glacial period.
The magnitude of the oldest Toba eruptions had not previously been documented due to the difficulty in recognizing their widespread erupted products in marine sediments. Lee and the team of scientists present new data on the distribution of volcanic ash from the oldest Toba eruption in Ocean Drilling Program cores and piston cores in the South China Sea and Indian Ocean. By using high-resolution litho-, magneto-, and oxygen isotope stratigraphic records, the geologists were able to clarify the correlation between distribution patterns in the cores, refine the age of the layers, and reestimate the eruptive volume of the early eruption of Toba.
The results of their analysis indicate that the glass shards from the first Toba eruption 788,000 years ago were dispersed more than 2000 miles from the source. Fallout from the eruption was deposited from clouds that drifted over both the Indian Ocean and the South China Sea, producing an extensive ash blanket that may have been comparable in size to that of the last Toba eruption 75,000 years ago.
Comparing material from the oldest Toba eruption to that of the youngest, or last, Toba eruption, the scientists were able to draw surprising conclusions. The youngest Toba eruption (75,000 years ago) has been proposed as a triggering mechanism for the onset of large-scale glaciation, which brought the last interglacial stage to its end. The coincidence of the oldest Toba eruption with the transition from a glacial stage to an interglacial stage, however, appears to be an opposite effect.
Although the estimated volume of the oldest Toba eruption is not as large as the youngest Toba, they are both enormous eruptions involving discharges of tremendous amounts of magma. However, the warming trend following the oldest supereruption of the Toba appears to suggest that factors other than volcanism have played more influencing roles in governing glacial to interglacial transitions over the last 3 million years.
University of Rhode Island
Genomics, evolution, history, and geography
By polarbearcub , Section Biology
Posted on Mon Apr 22nd, 2002 at 04:04:46 PM PST
Dinosaurs were terminated during KT boundary, which is long long long time ago (65 million years ago). With very limited fossil record and the abrupt extinction of dinosaur, it is difficult and meaningless to study the "evolution" of dinosaur. More interesting is what trigger this event, which is a big unknown, some said asteroid, some said volcano, some said disease.
Human evolution is different, it is recent, there is fossil evidence and genetic evidence and we are not extinct yet =). Genetic evidence (mtDNA, HLA, Y chromosome, Alu sequence) provides us lots of insight about evolution. For example, just by estimate coalescence time and diversity about genetic systems, genetic evidence can tell us about time of human origin, which was around 2 million years ago, and location, which was Africa.
One interesting fact is that human evolution went through a bottleneck event around 75 thousand years ago. And there is evidence that during this bottleneck event, human population went from 100,000 to 10,000. With this short population expansion from a small population after such a recent bottleneck, no wonder we are so similar genetically. So what was going on during this bottleneck? It turns out there was a giant eruption from volcano Toba, in Indonesia. This event was 10,000 more powerful than St. Helen and decreased global temperature by as much as 15 degree Celsius!
COMMENTS: Haven’t found any gene link yet. Found arguments back and forth on the real impact of Toba on human evolution or decrease in population.
Humans DNA dna (lower case) refers the enzymes involved in dna replication. Types dnaA dnaB dnaC dnaG -------------------------------------------------------------------------------- DNA (uppercase) refers to deoxyribonucleic acid. See DNA. -------------------------------------------------------------------------------- Warning: This page may be edited, except for the preamble. The first two paragraphs may not be edited until disputes have been resolved on the discussion page. ..... Click the link for more information. 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.
massive volcanic eruption changed the course of human history by severely reducing the human populations (called a 'bottleneck In population genetics and evolutionary biology, a population bottleneck (or genetic bottleneck) is an evolutionary event in which a significant percentage of a population or species is killed or otherwise prevented from reproducing, and the population is reduced by 50% or more, often by several orders of magnitude. A graph of this change resembles the neck of a bottle, from wide to narrow; hence the name. ..... Click the link for more information. '): Around 75,000 years ago the Toba Lake Toba is a large lake, 100km long and 30km wide, in the middle of the northern part of the Indonesian island of Sumatra. Geology In 1949 the Dutch geologist Rein van Bemmelen reported that Lake Toba was surrounded by a layer of ignimbrite rocks, and was a large volcanic caldera. Later researchers found rhyolite ash similar to that in the ignimbrite around Toba in Malaysia and India, 3000km away. Oceanographers discovered Toba ash on the floor of the eastern Indian Ocean and the Bay of Bengal. ..... Click the link for more information. supervolcano The term supervolcano has no specifically defined scientific meaning. It was coined by the producers of a BBC Popular Science programme in 2000 to refer to volcanoes that have generated Earth's largest volcanic eruptions. As such, a supervolcano would be one that has produced an exceedingly large, catastrophic explosive eruption and a giant caldera. Because there is no well-defined minimum ..... Click the link for more information. in Indonesia The Republic of Indonesia is a large archipelago located between the South East Asian peninsula and Australia, between the Indian and Pacific Oceans. Indonesia borders Malaysia on the island of Borneo, Papua New Guinea on the island of New Guinea and East Timor on the island of Timor. Republik Indonesia (In Detail) (Full size) National motto: Bhinneka Tunggal Ika (Old Javanese: Unity in Diversity) ..... Click the link for more information. erupted with a force three thousand times more powerful than Mount St. Helens Mount St. Helens (MSH) is a volcano in Skamania County, Washington state, in the Pacific Northwest region of the United States. It forms part of the Cascade Range. MSH erupted catastrophically at 08:32 on Sunday, May 18, 1980. Before the eruption, the summit of Mount St. Helens was 9,677 feet (2,950 meters). The eruption reduced its peak to 8,364 feet (2,550 m) in elevation and replaced it with a one-mile-wide (1.5 km) horseshoe-shaped crater. ..... Click the link for more information. .
It's on a 600,000 year cycle and is presently 40,000 years overdue. Recently, portions of Yellowstone have been sectioned off (no public access) because of extreme temperature increases not seen before.
At this rate, you might be...
Depends on what you mean by human. Some of our non-Homo Sapiens ancestors were certainly arboreal, but the hominids that were around 200,000 years ago did not live in trees, AFAIK.
Any honest scientist will tell you that part of the deal of being a scientist is accepting the fact that theories change, are replaced or are disproven over time. That's just the nature of the beast.
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Pretty damn likely if we're to judge the future by the red hot now . . . |
Jumped? I thought they fell...
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