In this weeks episode of Sciencism Ross and Dan discuss the Asteroid events of of the past week as well as the asteroid that wiped out the dinosaurs. We talk about a protozoa with thousands of chromosomes, the protein responsible for CJD and the origin of Cosmic Rays. We talk about the issue of gene patents in response to the ruling by the Australia Federal Court. Dan plays science or fiction and the audience gets a chance to take on the science quiz. We finish off with last week in the past.
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The Extinction of the Dinosaurs1
Controversy is a word often misused in science, especially by journalists. Many talk of the controversy over evolution or climate change, but these aren’t true controversies, more the established evidence has arrived at one conclusion, and a certain group of people have refused to accept said conclusions, such as creationists or climate change deniers. However genuine controversies do exist in science and the issue of what caused the extinction of the Dinosaurs is one such example. Was there a catastrophic event that caused a sudden extinction, or was there a gradual decline with the final Dinosaurs going extinct about 66 million years ago? Even within the catastrophe group there is disagreement as to whether an asteroid or super volcano eruption is to blame.
As the years have gone by the evidence has begun to show more and more that a giant asteroid impact at the Yucatan Peninsula, Offshore Mexico is most likely the primary factor in the extinction of the once mighty Dinosaurs. New research by Renne et.al. using argon-argon isotope ratio dating examining 14 samples of material from the impact site suggest the impact occurred around 66 million and 38 thousand years ago and using volcanic ash unearthed in Montana from only a few centimetres above an iridium-rich layer (thought to be deposited by the asteroid collision) and 5cm from rocks which have trapped dinosaur era pollen suggest that mass extinctions occurred 66 million and 43 thousand years ago.
Although these dates aren’t exactly the same what you must consider are the statistical errors involved, or in other word the uncertainty. Taking these values into account it is possible the events occurred at the same time providing counter evidence for the idea that the Dinosaurs suffered a mass extinction 300 thousand years before the asteroid impact.
Was the impact a single asteroid or a double salvo binary asteroid? A separate team earlier this month released research which suggest there may have been double doom for the Dinosaurs.2
15% of all observed asteroids are binary pairs, two asteroids orbiting each other, however only 2-4% of craters on Earth are “doublet craters”. Do binary pairs fall to a planet’s surface less often? Katarina Miljkovic et.al have another explanation, using computer simulations, their research suggests that many binary impacts create only a single crater due to the large size of the impact crater and the comparatively small distance between the binary pairs at the time of impact. The simulations indicate that binary craters should be somewhat asymmetrical, and the Chicxulub crater, the one at the Yucatan peninsula has just those asymmetries. Gravitational data also support the theory that the Yucatan impact was a binary asteroid. Using the geometry and the gravity data it is estimated the two rocks would have had a combined diameter of about 7 – 10km and may have been up to 80km apart.
1 Renne, P. R. et al. Time Scales of Critical Events Around the Cretaceous-Paleogene Boundary. Science 339, 684-687, doi:10.1126/science.1230492 (2013).
2 Miljković, K., Collins, G. S., Mannick, S. & Bland, P. A. Morphology and population of binary asteroid impact craters. Earth and Planetary Science Letters 363, 121-132, doi:http://dx.doi.org/10.1016/j.epsl.2012.12.033 (2013).
More chromosomes than you can beat a cilia at
Chromosomes are a higher order structural arrangement of DNA found in Eukaryotes (animals, plants Fungi etc)
Humans have 23 chromosome pairs, dogs 39
Oxytricha trifallax is a pond dwelling protist, a single celled organism covered in cilia
It has two nuclei, humans have one.
The smaller micronucleus holds a complete copy of the genome but this nucleus is almost inactive.
The larger Macro nucleus contains thousands of whole genome copies that are then broken up into lots of tiny pieces.
Team found ~15,600 nanochromosomes, many containing only a single gene.
On top of this there can be up to 2000 copies of each nanochromosome and then some copies can be broken up into even smaller chunks
Each one of these nanochromosomes is capped with telomeres; the anology given in the NG article is of an encyclopaedia where each page is torn out and hardbound
This week in the past
1937 – Wallace H. Carothers receives a United States patent for nylon.
2001 – First draft of the complete human genome is published in Nature.
1961 – Discovery of the chemical elements: Element 103, Lawrencium, is first synthesized at the University of California.
1633 – Galileo Galilei arrives in Rome for his trial before the Inquisition.
When was the recently discovered particle, thought to be responsible for mass first postulated and by whom?
Science or Fiction
- The overall energy expended during an average mosh pit would enough to power the whole concert.
- Researchers describe a species which grows a new penis each time it copulates
- A new environment-tongue device has been developed which could allow you to use your tongue as a compass