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Natural Environment How Human History has been impacted by the environment, science, nature, geography, weather, and natural phenomena


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Old May 10th, 2012, 05:05 PM   #351

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Not Always Safety in Numbers When It Comes to Extinction Risk


"..ScienceDaily (May 8, 2012) — A basic tenet underpinning scientists' understanding of extinction is that more abundant species persist longer than their less abundant counterparts, but a new University of Georgia study reveals a much more complex relationship. A team of scientists analyzed more than 46,000 fossils from 52 sites and found that greater numbers did indeed help clam-like brachiopods survive the Ordovician extinction, which killed off approximately half of Earth's life forms some 444 million years ago. Surprisingly, abundance did not help brachiopod species persist for extended periods outside of the extinction event....

...
"Many recent studies of extinction by paleobiologists are coming out with findings that are contrary to what we see in modern environments and sometimes even contrary to what other paleontologists see in other geologic eras," he said. "I think this is why paleobiology is so important-it's the only way for us to examine ecology at multiple points in the Earth's history, when perhaps the environmental and biological settings were different enough that even our most intuitive expectations don't hold."
In a related study published in the same edition of Paleobiology, Holland tackled another widely held theory about extinction -- that rising sea levels encourage the diversification of new species by increasing the amount of available shallow-water habitat. He modeled nine diverse global locations and found that sea level rise does not consistently increase habitable area, with different coasts and different habitats displaying substantially different changes in area for the same amount of sea level fluctuation.
Holland admitted that his findings are a bit disheartening. The planet is currently in the midst of an extinction event caused by human-induced habitat loss and global warming, and scientists would like to be able to predict which species are most at risk so that scarce resources can be put toward their conservation.
"You really want to be able to make some predictions about extinction risk so that you can guide policies," Holland said, "and if the selectivity of extinction is much more complicated, it makes it harder to generate those rules."..." Not always safety in numbers when it comes to extinction risk
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Old May 18th, 2012, 10:03 AM   #352
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As a believer in evolution, I have one question that I cannot find an answer to that frustrates me because the DNA line seems illogical in that we can only trace our line to one first human.

Part of medical science is all about the ability to recreate a given condition over and over again consistently involving germs, viruses, etc. Labs can set up multiple Petri dishes with mold, exposed them to the same conditions, and wa la, they have lots of penicillin made at the same time. So, how is it that scientists cannot prove that we evolved from multiple beings? Consider that whatever condition that created the first human had to have happened out in the open and not in some lab somewhere. So the likelihood of multiple first humans evolving at once should be a possibility. All the creatures in the specific region or area were exposed to the same conditions, at the same time, so why can't scientists prove an entire community of these first humans were created within a given time period? If they were, I guess we could make the assumption that disease and other factors killed off many, if not most, of these first humans and that only two survived long enough to produce and raise offspring and a genetic trend the tracks all mankind.
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Old May 30th, 2012, 07:30 PM   #353

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ScienceDaily (May 30, 2012) "Evolution of Birds Is Result of a Drastic Change in How Dinosaurs Developed"

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Researchers from Harvard University, The University of Texas at Austin and elsewhere have found evidence that the evolution of birds is the result of a drastic change in how dinosaurs developed. Scientists have long understood that modern birds descended from dinosaurs. Rather than take years to reach sexual maturity, as many dinosaurs did, birds sped up the clock -- some species take as little as 12 weeks to mature -- allowing them to retain the physical characteristics of baby dinosaurs.

The results of the study appeared May 27 in an online edition of the journal Nature.

"What is interesting about this research is the way it illustrates evolution as a developmental phenomenon," said Arkhat Abzhanov, associate professor at Harvard and study co-author. "By changing the developmental biology in early species, nature has produced the modern bird -- an entirely new creature -- and one that, with approximately 10,000 species, is today the most successful group of land vertebrates on the planet."

While it's clear simply from looking at the skulls of dinosaurs and modern birds that the two creatures are vastly different -- dinosaurs have distinctively long snouts and mouths bristling with teeth, while birds have proportionally larger eyes and brains -- it was the realization that skulls of modern birds and juvenile dinosaurs show a surprising degree of similarity that sparked the study. . . .

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Skulls of three types of archosaur—alligator, primitive dinosaur, and early bird. The left column represents juveniles and the right column represents adults. (Credit: Image courtesy of The University of Texas at Austin)
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Old October 28th, 2012, 11:02 AM   #354

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ScienceDaily (Oct. 25, 2012) "Fossils of First Feathered Dinosaurs from North America Discovered: Clues On Early Wing Uses"

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The ostrich-like dinosaurs in the original Jurassic Park movie were portrayed as a herd of scaly, fleet-footed animals being chased by a ferocious Tyrannosaurus rex. New research published in the journal Science reveals this depiction of these bird-mimic dinosaurs is not entirely accurate -- the ornithomimids, as they are scientifically known, should have had feathers and wings.

The new study, led by paleontologists Darla Zelenitsky from the University of Calgary and François Therrien from the Royal Tyrrell Museum of Palaeontology, describes the first ornithomimid specimens preserved with feathers, recovered from 75 million-year-old rocks in the badlands of Alberta, Canada.

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This is an artistic reconstruction of feathered ornithomimid dinosaurs found in Alberta.
(Credit: Julius Csotonyi)

The Guardian (26 October 2012) "A new feathered dinosaur shows we still have lots to learn: The latest in a long line of feathered dinosaurs shows the predictive power of evolution and heralds a bright future for further discoveries"

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. . . this paper has a near perfect scientific hat-trick, it fulfils a scientific prediction about evolution, confirms a previous hypothesis with more information, and it also provides good evidence that we can expect more find[s] and more data.
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Old November 9th, 2012, 09:03 AM   #355
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If not evolution, then...?


if you do not believe in evolution, then what do you believe?<> that a fully developed human just ''appeared' or 'energized'?
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Old November 9th, 2012, 09:05 AM   #356

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I think this might be one for the Religion subforum. It's been discussed on many occasions on the site.
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Old November 9th, 2012, 09:21 AM   #357
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Originally Posted by Naomasa298 View Post
I think this might be one for the Religion subforum. It's been discussed on many occasions on the site.
I'm sorry--yorkshire??
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Old November 9th, 2012, 10:01 AM   #358

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Originally Posted by Mulligan View Post
if you do not believe in evolution, then what do you believe?<> that a fully developed human just ''appeared' or 'energized'?
You just need to look at different mythologies to see what they believed, made from clay (middle east), made of wood (Norse), baked in an oven (Hopi), etc.

I think early man assumed that things were created in the manner that we create things. Early man created the stories. Modern people that don't believe in evolution do so because they believe it conflicts with their religion.
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Old November 9th, 2012, 10:36 AM   #359

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Quote:
Originally Posted by Naomasa298 View Post
I think this might be one for the Religion subforum. It's been discussed on many occasions on the site.
It is and has. Thread merged.
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Old November 12th, 2012, 03:41 AM   #360
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Quote:
Originally Posted by Rasta View Post
You just need to look at different mythologies to see what they believed, made from clay (middle east), made of wood (Norse), baked in an oven (Hopi), etc.

I think early man assumed that things were created in the manner that we create things. Early man created the stories. Modern people that don't believe in evolution do so because they believe it conflicts with their religion.
thank you for a common sense answer. I just like to learn of the many different ideas there are
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