Friday, 19 September 2008

News Round

Ancient trees recorded in mines

The remains of a tree that grew about 300 million years ago
Spectacular fossil forests have been found in the coal mines of Illinois by a US-UK team of researchers.
The group reported one discovery last year, but has since identified a further five examples.
The ancient vegetation - now turned to rock - is visible in the ceilings of mines covering thousands of hectares.
These were among the first forests to evolve on the planet, Dr Howard Falcon-Lang told the British Association Science Festival in Liverpool.
"These are the largest fossil forests found anywhere in the world at any point in geological time," he told reporters.
"It is quite extraordinary to find a fossil landscape preserved over such a vast area; and we are talking about an area the size of (the British city of) Bristol."

From the BBC.
- - -

Monkey Brains Hint at Evolutionary Root of Language Processing


New research suggests that voice recognition is not as uniquely human as once assumed.

The use of vocalizations, such as grunts, songs or barks, is extremely common throughout the animal kingdom. Nevertheless, humans are the only species in which these vocalizations have attained the sophistication and communicative effectiveness of speech. How did our ancestors become the only speaking animals, some tens of thousands of years ago? Did this change happen abruptly, involving the sudden appearance of a new cerebral region or pattern of cerebral connections? Or did it happen through a more gradual evolutionary process, in which brain structures already present to some extent in other animals were put to a different and more complex use in the human brain?

From SciAm.
- - -


Geologists Dig Up One Of The Largest Lakes In The World, Dammed By Ice During Last Ice Age
Geologists are digging in the bed on the western bank of what was once a 700-800 kilometre-long lake along the 62nd parallel in Russia. Large lakes, dammed up by a huge ice sheet one or more times during the last Ice Age, used to dominate this enormous plain.

They are just beyond the ice margin from the maximum of the last Ice Age, where it has been mapped 100 kilometres north of the town of Kotlas in north-western Russia.

Here, at Tolokonka, in a four kilometre-long cutting beside the River Dvina, an international team of scientists is busy studying the past changes in climate.

"Lakes have probably been situated here in two periods during the last Ice Age. We've found river delta deposits which suggest that the oldest lake formed some 65 000 years ago," Eiliv Larsen, a geologist at the Geological Survey of Norway (NGU) said.

From ScienceDaily.
- - -

Did evolution come before life?


A rudimentary form of natural selection likely existed in the primordial soup even before life arose on Earth. If so, the complex "ecosystem" of prebiotic molecules may have made the eventual arrival of life much more probable.

Most experts presume that life arose from complex molecules such as nucleic acids and proteins, which were assembled from a mix of simpler units strung together with chemical bonds.

To examine how this might occur, Martin Nowak and Hisashi Ohtsuki, mathematical biologists at Harvard University, used simple equations to model the growth of such chains of building-blocks.

The model shows that because longer chains require more assembly reactions, they should be much less common than short chains. And if some assembly reactions run faster than others, then chains built from these fast-assembling sequences of building blocks grow to be most abundant.

Threshold of life

This bare-bones equivalent of natural selection makes the prebiotic soup an interesting place, they say.

"It generates a rich evolutionary dynamic - or what I would want to call a 'prevolutionary' dynamic - where you have diversity, you have information, you have complicated chemistry," says Nowak.

Such a system, full of novel, interacting molecules, would be the ideal milieu to generate a molecule with attributes that would favour the assembly of copies of itself. Nowak's prebiotic selection could then act to refine this ability by ensuring that better replicators become more common.

At some point, Nowak's model predicts, the best replicator may get fast and accurate enough to dominate the population, sucking up all the resources and driving all the other prebiotic sequences extinct. This is the threshold of life.

"Ultimately, life destroys pre-life," says Nowak. "It eats away the scaffold that has built it."

From New Scientist.

No comments:

Post a Comment