You'd be wrong. Geckos have actually evolved them multiple times.
As with other evolutionary changes, the feet are adaptations to the environment - when in sandy climes, the geckos lose them, because they're a liability there.
"Gecko toepads adhere through a combination of weak intermolecular forces, called van der Waals forces, and frictional adhesion. Hundreds to hundreds of thousands of hair-like bristles, called setae, line the underside of a gecko's toes. The large surface area created by this multitude of bristles generates enough weak intermolecular forces to support the whole animal."
http://phys.org/news/2012-06-sticky-gecko-toes-arose-independently.html
It only takes a look at a jellyfish to realise that the evolution of muscles can occur in the absence of a skeleton - exo or endo - but despite having evolved their muscles in the same way, they did so separately to other animals.
Striated muscles first formed after a myosin motor protein came into existence, consequent to a gene duplication.
Striated muscles are aligned into parallel fibres, and give the possessor a great advantage when it comes to locomotion.
Most muscles around the body are 'smooth', which means they inervate but do not pull in a very controlled way, such as in the eye, blood vessels, bladder, uterus, and vagina.
After the evolution of striated muscles, it would have been a simple and gradual developmental path to cartilaginous and boney skeletons, with which to really ramp up motility.
http://phys.org/news/2012-06-muscles.html
[video] Australopithecus sediba - a human ancestor that lived in South Africa, stands out as one that had a diet more similar to modern apes.
A. Sediba had a diet of harder foods - trees, bushes, and fruits - whereas contemporary relations ate more grasses and sedges.
"What fascinates me is that these individuals are oddballs," said CU-Boulder's Sponheimer. "I had pretty much convinced myself that after 4 million years ago most of our hominid kin had diets that were different from living apes, but now I am not so sure."
http://phys.org/news/2012-06-ancient-human-ancestor-australopithecus-sediba.html
http://www.newscientist.com/article/mg21428712.400-eats-bark-fruit-and-leaves-diet-of-ancient-human.html
[video] 'The physics of going viral: Researchers measure the rate of DNA transfer from viruses to bacteria'
Bacteriophages are viruses that infect bacterial cells, and substitute their DNA for the bacterium's.
What the researchers found was that the DNA int he bacteriophage is held at massive pressure - equivalent to taking 500 metres of cable from the Golden Gate bridge, and shoving them in the back of a truck.
But the pressure wasn't the important variable - the amount of DNA packed in determined how quickly it was ejected into the bacterium, like a molecular-scale harpoon gun.
http://phys.org/news/2012-06-physics-viral-dna-viruses-bacteria.html
'Picking the pig with the perfect pins'
Pig farmers intend to use CCTV to selectively breed with pigs that show no signs of leg problems.
Oh great -- yet another factor decreasing the genetic diversity in livestock populations! I wouldn't be worried if they actually made efforts to compensate for it.
http://phys.org/news/2012-06-pig-pins.html
'Study provides first evidence of co-evolution between invasive, native species'
Evolution is blind. All species mentioned in this study are merely adapting to the environment in which they find themselves, and, apparently, they are doing that with some success.
The idea that 'native' plants will not adapt to the evolutionary pressure applied to them by 'invasive' species is a silly one.
http://phys.org/news/2012-06-evidence-coevolution-invasive-native-species.html
I heard an interview about this, on the Naked Scientists
'Heirloom' varieties are more similar to the older plants, which were more flavoursome, but smaller and uglier, and so sell less well.
This project aims to breed fruit and veg to have the flavour of the 'older' varieties, but with the bulk of the modern varieties.
If you've never tasted an heirloom variety of fruit or vegetable - you don't know what you're missing - they are so much more tasty!
http://phys.org/news/2012-06-discovery-tomato-varieties-vintage-flavor.html
The Naked Scientist's interview:
http://www.thenakedscientists.com/HTML/content/interviews/interview/2111/
Analysis of the rhesus macaque has shown it to have a genetic variance three times that of humans, despite having a population thousandths of times the size.
Chimpanzees and orangutans have populations millionths of times the size, and roughly equal genetic variance.
The reason for this discrepancy is that, historically, humans had a much smaller total population, in the tens of thousands.
Our massive population increase has spread our gene pool very thin, which could be the reason we seem so much more susceptible to epidemics.
http://phys.org/news/2012-06-insights-primate-diversity-lessons-rhesus.html
Elephantnose fish have developed an eye structure that allows them to see through the muddy waters in which they live.
Although they don't have good resolution, they can make out large objects moving through the convoluted gloom, which means they can navigate and detect predators.
http://phys.org/news/2012-06-elephantnose-fish-unique-retina-mud.html
Video diagram of the eyes' structure:
On the subject of eyes: primitive eyes have been grown from stem cells alone, without any frame to grow on. Take that, creationists :D
No comments:
Post a Comment