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Comment by doone on July 21, 2013 at 10:44pm

the-science-llama:

Honeycombs end up hexagonal just from a bit of physics

According to research published in the Journal of the Royal Society Interface, bees initially make circular cells and use their body heat to turn the wax into a viscous liquid. Then the surface tension at the 3-point junctions pulls the wax into a hexagonal shape. Apparently Charles Darwin had come up with this idea before but didn’t have enough evidence to prove it.
Via Nature

Comment by Davy on July 19, 2013 at 3:45pm

Lizards show that evolution is predictable. (click on to read the full article)

If you could hit the reset button on evolution and start over, would essentially the same species appear? Yes, according to a study of Caribbean lizards by researchers at the University of California, Davis, Harvard University and the University of Massachusetts. The work is published July 19 in the journal Science.

The predictability of evolution over timescales of millions of years has long been debated by biologists, said Luke Mahler, a postdoctoral fellow at UC Davis and first author on the paper. For example, the late Stephen Jay Gould predicted that if you "rewound the tape" on evolution and started over, you would get an entirely different outcome, arguing that small events—a storm that wiped out a particular pond, a poor season for insects—could have a disproportionate effect.

On the other hand, there are a number of examples of species in similar habitats that evolve independently into similar-looking forms, such as the cichlid fishes of African lakes.

Read the full article at PHYS-ORG 

 

Comment by doone on July 19, 2013 at 10:10am

Thank a Hominid Near You

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Comment by archaeopteryx on June 28, 2013 at 12:06pm

Evolution in Action: Lizard Moving From Eggs to Live Birth

A yellow-bellied three-toed skink carrying embryos, visible as light orbs inside its body.

Brian Handwerk

for National Geographic News

Published September 1, 2010

Evolution has been caught in the act, according to scientists who are decoding how a species of Australian lizard is abandoning egg-laying in favor of live birth.

Along the warm coastal lowlands of New South Wales (map), the yellow-bellied three-toed skink lays eggs to reproduce. But individuals of the same species living in the state's higher, colder mountains are almost all giving birth to live young.

Only two other modern reptiles—another skink species and a European lizard—use both types of reproduction. (Related: "Virgin Birth Expected at Christmas—By Komodo Dragon.")

Evolutionary records shows that nearly a hundred reptile lineages have independently made the transition from egg-laying to live birth in the past, and today about 20 percent of all living snakes and lizards give birth to live young only.

(See "Oldest Live-Birth Fossil Found; Fish Had Umbilical Cord.")

But modern reptiles that have live young provide only a single snapshot on a long evolutionary time line, said study co-author James Stewart, a biologist at East Tennessee State University. The dual behavior of the yellow-bellied three-toed skink therefore offers scientists a rare opportunity.

"By studying differences among populations that are in different stages of this process, you can begin to put together what looks like the transition from one [birth style] to the other."

Comment by doone on June 19, 2013 at 9:37pm

Necks of Dinos

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Comment by doone on May 16, 2013 at 8:26am

EVOLUTION SHAPES NEW RULES FOR ANT BEHAVIOR

From PhysOrg:

In ancient Greece, the city-states that waited until their own harvest was in before attacking and destroying a rival community's crops often experienced better long-term success. It turns out that ant colonies that show similarselectivity when gathering food yield a similar result. The latest findings from Stanford biology Professor Deborah M. Gordon's long-term study of harvester ants reveal that thecolonies that restrain their foraging except in prime conditions also experience improved rates of reproductive success. Importantly, the study provides the first evidence of natural selection shaping collective behavior, said Gordon, who is also a senior fellow at the Stanford Woods Institute for the Environment.

A long-held belief in biology has posited that the amount of food an animal acquires can serve as a proxy for its reproductive success. The hummingbirds that drink the most nectar, for example, stand the best chance of surviving to reproduce. But the math isn't always so straightforward. The harvester ants that Gordon studies in the desert in southeast Arizona, for instance, have to spend water to obtain water: an ant loses water while foraging, and obtains water from the fats in the seeds it eats. The ants use simple positive feedback interactions to regulate foraging activity. Foragers wait near the opening of the nest, and bump antennae with ants returning with food. The faster outgoing foragers meet ants returning with seeds, the more ants go out to forage. (Last year, Gordon, Katie Dektar, an undergraduate, and Balaji Prabhakar, a professor of computer science and of electrical engineering at Stanford, showed that the ants' "Anternet" algorithm follows the same rules as the protocols that regulate data traffic congestion in the Internet).

More here.

Posted by Azra Raza at 05:50 AM | Permalink

Comment by doone on May 15, 2013 at 9:46am

The Neanderthals’ Handicaps

MAY 14 2013 @ 7:03PM

Priscilla Long presents some theories as to what led to the demise of our evolutionary cousins – shorter lifespans and climate change among them:

Because they had bigger bodies, they required more calories to survive than we do. They may have lacked sewing skills. Neither Neandertals nor Homo sapiens lived long (the rare 30-year-old Neandertal was old), but at some point, for reasons not really understood, the life spans of Homo sapiens began to increase. More longevity provided a grandparent generation to impart knowledge, skills, and more resources to the group.

Another discovery bearing on the subject are the extreme climate fluctuations that occurred between 65,000 and 25,000 years ago. The Neandertals had bodies and cultures adapted to ice and snow. This time of fluctuation involved such rapid climate change that in one lifetime “all the plants and animals that a person had grown up with could vanish and be replaced with unfamiliar flora and fauna,” writes Wong. The environmental stress may have decimated their ranks to below zero population growth.

Comment by doone on May 14, 2013 at 9:40am

Our Asian Origins infographic by Newscientist.

Comment by doone on May 2, 2013 at 5:39pm

Why Do Birds Walk So Weird?

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The crouched stance developed to compensate for the growth of larger forelimbs that eventually made flight possible, according to new research that digitally "fleshed out" fossils to show physical changes over the eons as bipedal dinosaurs evolved into birds.

Comment by doone on April 10, 2013 at 9:18am

EVOLUTION WITHOUT DARWIN

What if a young Charles Darwin, stricken with seasickness, had been washed over the side of HMS Beagle on a dark and stormy night in 1832? Peter Bowler's dramatic opening paragraph, complete with a nod and wink to Edward Bulwer-Lytton, sets a scene that would have averted the far higher drama that ensued from the publication in 1859 of On the Origin of Species. How would biological science's role in history have differed? By 1900, Bowler argues, scientifically informed opinion would have absorbed the idea that living forms evolve, without recognising that this happens through natural selection. In fact, as Bowler has demonstrated in his previous work on the history of evolutionary thought, that is pretty much what did happen. Although Darwin's theory of natural selection transformed the understanding of life by turning all eyes to evolution, the subsequent decades saw a successful effort to sideline it in favour of less disturbing candidates for mechanisms of change. People were ready to accept the idea of evolutionary transformation as long as it seemed orderly, progressive and purposeful. Lamarckian ideas, suggesting that individuals could improve themselves through their own striving and then pass on these improvements to their offspring, were a popular alternative. Other theories proposed that living forms were shaped by inner laws that guided change in beneficial directions.

more from Marek Kohn at Literary Review here.

Posted by Morgan Meis at 08:50 AM | Permalink

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