Medical students, y u so funny?
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A quiz once told me that the word "sanguine" describes me.
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We eat, excrete, sleep, and get up;
This is our world.
All we have to do after that-
Is to die.
-Ikkyū
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Medical students, y u so funny?
This is pretty damned great.
(Source: dostthouquotethme)
Why don’t our arms grow from the middle of our bodies? The question isn’t as trivial as it appears. Vertebrae, limbs, ribs, tailbone … in only two days, all these elements take their place in the embryo, in the right spot and with the precision of a Swiss watch.
During the development of an embryo, everything happens at a specific moment. In about 48 hours, it will grow from the top to the bottom, one slice at a time — scientists call this the embryo’s segmentation. “We’re made up of thirty-odd horizontal slices,” explains Denis Duboule, a professor at EPFL and Unige. “These slices correspond more or less to the number of vertebrae we have.”
Every hour and a half, a new segment is built. The genes corresponding to the cervical vertebrae, the thoracic vertebrae, the lumbar vertebrae and the tailbone become activated at exactly the right moment one after another. “If the timing is not followed to the letter, you’ll end up with ribs coming off your lumbar vertebrae,” jokes Duboule. How do the genes know how to launch themselves into action in such a perfectly synchronized manner? “We assumed that the DNA played the role of a kind of clock. But we didn’t understand how.”
When DNA acts like a mechanical clock
Very specific genes, known as “Hox,” are involved in this process. Responsible for the formation of limbs and the spinal column, they have a remarkable characteristic. “Hox genes are situated one exactly after the other on the DNA strand, in four groups. First the neck, then the thorax, then the lumbar, and so on,” explains Duboule. “This unique arrangement inevitably had to play a role.”
The process is astonishingly simple. In the embryo’s first moments, the Hox genes are dormant, packaged like a spool of wound yarn on the DNA. When the time is right, the strand begins to unwind. When the embryo begins to form the upper levels, the genes encoding the formation of cervical vertebrae come off the spool and become activated. Then it is the thoracic vertebrae’s turn, and so on down to the tailbone. The DNA strand acts a bit like an old-fashioned computer punchcard, delivering specific instructions as it progressively goes through the machine.
“A new gene comes out of the spool every ninety minutes, which corresponds to the time needed for a new layer of the embryo to be built,” explains Duboule. “It takes two days for the strand to completely unwind; this is the same time that’s needed for all the layers of the embryo to be completed.”
This system is the first “mechanical” clock ever discovered in genetics. And it explains why the system is so remarkably precise.
…
The Hox clock is a demonstration of the extraordinary complexity of evolution. One notable property of the mechanism is its extreme stability, explains Duboule. “Circadian or menstrual clocks involve complex chemistry. They can thus adapt to changing contexts, but in a general sense are fairly imprecise. The mechanism that we have discovered must be infinitely more stable and precise. Even the smallest change would end up leading to the emergence of a new species.”(via From blue whales to earthworms, a common mechanism gives shape to living beings)
This is why developmental biology (and evolution and molecular biology and everything) is awesome.
Eddie Izzard “Stripped”: God and Atheism (2:35)
“If there was a God, don’t you think he would have flicked Hitler’s head off? Don’t you think? You know. ‘Oh, I’m not allowed to do anything’— Well, fuck off, then! If you’re ‘not allowed to do anything’, then what’s the use? Just piss off and stop asking us to mumble things on Sundays!”
Best part. XD
Cancers Are Newly Evolved Parasitic Species, Biologist Argues
Cancer patients may feel like they have alien creatures or parasites growing inside their bodies, robbing them of health and vigor. According to one cell biologist, that’s exactly right. The formation of cancers is really the evolution of a new parasitic species.
Just as parasites do, cancer depends on its host for sustenance, which is why treatments that choke off tumors can be so effective. Thanks to this parasite-host relationship, cancer can grow however it wants, wherever it wants. Cancerous cells do not depend on other cells for survival, and they develop chromosome patterns that are distinct from their human hosts, according to Peter Duesberg, a molecular and cell biology professor at the University of California-Berkeley. As such, they’re novel species.
He argues that the prevailing theories of carcinogenesis, or cancer formation, are wrong. Rather than springing from a few genetic mutations that spur cells to grow at an uncontrolled pace, cancerous tumors grow from a disruption of entire chromosomes, he says. Chromosomes contain many genes, so mis-copies, breaks and omissions lead to tens of thousands of genetic changes. The result is a cell with completely new traits: A new phenotype.
Cancer as evolution in action, which represents a fundamental re-thinking of the disease, has been proposed before — evolutionary biologist Julian S. Huxley first described autonomously growing tumors as a new species back in 1956, according to a Cal news release. But the prevailing view has long been that cancer is the result of genetic mutations.
There are 2 actual creationists in my intro to scientific reasoning class (whyyy are they in that?) and we’re starting to go over Darwin’s evolution. We actually had a very long discussion over the past week about the issues in creationism and how biblical literalists have to denounce every bit of empirical evidence that science presents in order to justify their illogical belief. There is absolutely no support system other than the Bible and people’s imagination to support creationism and yet they take the Bible as fact for everything.
I truly just cannot understand biblical literalism when it comes to creationism. To believe everything that the Bible says as a historical reference is to be very incurious. I don’t care if you pick and choose for your morality unless it conflicts with people’s rights, fine, take the Bible in your religious sense. But in the scientific and historical sense? How could you possibly do that?
The greatest thing about humanity is their ability to think and ask ‘Why?’, in my opinion. Why should anything happen? If you’re a literal creationist, your answer will always be ‘God’. How disappointing is that? It may not be to creationists, sure, but a child with a vivid and wide imagination will ask ‘why?’, expecting answers, as is usually the case. Science provides such profound answers to these questions and to denounce these would be rather… disappointing. Wouldn’t ‘light of a certain wavelength from the sun scattering off of chemicals in the atmosphere’ be a much more interesting answer to ‘Why is the sky blue?’ than just… ‘God made it so’?
To ignore any evidence that has been postulated to stay within a very rigid structure seems to be greatly idiotic. These people in my class do not believe fossils are scientific proof. That God put all the animals on Earth at the same time and eventually, most of these species just died off, even though there are no fossils of humans at the same time as dinosaurs or bacteria. Even though the world shows science and evolution to be so, they reject it forthright. The Earth around the Sun? No. The Earth rotating? No. These kids in my class actually are trying to say that’s wrong.
I asked them how they explained their experiences and they gave me nothing besides ‘God made it so’. To me, that feels rather blind and incurious. Our teacher even told us that most of the people in Darwin’s day did not believe in biblical creationism. How backwards is this country and human rationilising? It’s rather disheartening.
Survivors of the deadly epidemic of prion disease kuru, which was transmitted through cannibalistic rituals, share a particular genetic mutation. Researchers call it a striking example of human evolution in action.
Evolution | KoRn
Somewhat political song with a very strong message.
For the first time, a structure comparable to our cerebral cortex has been found in an invertebrate — a humble marine ragworm.
