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Billions of periodical cicadas have emerged in the Eastern United States and everyone and their dog is talking and writing about the mystery behind how cicadas time this event to happen at regular intervals. So I need to be original and mention in my blog something different about cicadas, something that people don’t often talk about; but what? As I was pondering this question, I saw a video by Anna Rothschild of the YouTube channel Gross Science, and I said to myself, "That’s it!" Watch the video below and learn all about butt-less cicadas! As I have mentioned before, one of the defining characteristics of many parasites is that they modify the behavior of their hosts to their advantage. In the case of the fungus, it produces psychoactive drugs that not only make cicadas more sexually active, but also makes males cicadas imitate the behavior of female cicadas so other males will try to copulate with them. All this contributes to the spread of the parasite.
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During a large explosion the air is pushed away from the center of the explosion and compressed into a supersonic shock wave, which creates the loud sound we hear from the blast. Immediately behind the shock wave an area forms of low pressure and temperature. If the explosion is sufficiently strong and occurs in a humid environment, the temperature of the air behind the shock wave can briefly drop below the dew point causing water molecules to rapidly condense into water droplets forming a cloud. In the first atomic bomb tests carried out in the Bikini Atoll in 1946 (Operation Crossroads), these clouds were called Wilson Clouds. They were named after the Scottish physicist Charles Thomson Rees Wilson who won a Nobel Prize (shared with the American physicist Arthur Compton) in 1927 for the development of the cloud chamber which allowed the visualization of radioactivity. In the video below, an atomic bomb named “Baker” is exploded underwater next to unmanned ships to test its power. You can see the large Wilson cloud begin to develop around the huge central column of water 9 seconds into the video. Today Wilson clouds are called “condensation clouds”. Condensation clouds can also form during far weaker explosions under the right conditions such as the one that rocked the port of Beirut in 2020. The white condensation cloud begins to develop 11 seconds into the video. It envelops the central red-colored explosion cloud and then quickly dissipates. However, man-made condensation clouds are not only formed during explosions. Anything capable of generating a supersonic shock wave such as a fighter jet can generate such a cloud, which is this case is called a vapor cone. One of the greatest discoveries of mankind is the discovery of deep time. This is the realization that our planet is billions of years old. This discovery is remarkable because the geological forces that shape our world act on timescales much longer than a hundred human lifespans. Thus understanding geologic time lies outside the regular experience of individuals and beyond the cultural memory of societies. Back in the 18th century, following the analysis of the creation accounts in the Bible, it was believed that the world was a few thousand years old, but the practitioners of the incipient science of geology were finding evidence in the rocks that pointed to much longer time periods. Chief among these practitioners was the Scottish naturalist James Hutton who is considered the father of modern geology. Among the evidence Hutton put forward to argue for an Old Earth is the amazing rock formation found in a rocky outcrop called Siccar Point in the county of Berwickshire off the east coast of Scotland (see figure below).  Hutton's Unconformity (left), and with layers outlined (right) This rock formation is called an “unconformity” (today known as Hutton’s Unconformity: left) because it is made up of layers of rock adjacent to each other that are discontinuous and were formed in different time periods. If you look closely you will see that there are layers of red sandstone on top that are oriented at close to right angles to the underlying layers of grey sandstone which are nearly vertical (see the image at right where I drew white lines to highlight the layers). Hutton understood that the underlying vertical bands of grey sandstone at Siccar Point had once been deposited as horizontal layers of sediments in the bottom of body of water. These layers of sediments were then turned into rock, uplifted, and tilted to acquire their present vertical orientation. The top of these layers then underwent erosion and became shallow enough to be overlaid by new layers of sediments. After this, the new layers of sediments were turned into rock and the land was uplifted and eroded again to attain its present shape. Hutton didn’t have a way to figure out the age of rocks, but he realized that there was no way all this could have happened in just a few thousand years. Such huge changes in the landscape could have only happened over vast intervals. He had discovered deep time! Nowadays, using radiometric dating, scientists have determined that the Earth is billions of years old. The vertical layers of grey sandstone at Siccar Point were deposited 435 million years ago, while the overlying horizontal layers of red sandstone were deposited around 370 million years ago. There is a gap of 65 million years between these two events which represents the time during which the older rocks were formed, forced to the surface, buckled, and eroded. The photograph of Hutton’s Unconformity by dave souza was duplicated and modified by drawing lines to highlight the layers and is used here under Attribution-Share Alike 4.0 International, 3.0 Unported, 2.5 Generic, 2.0 Generic and 1.0 Generic licenses. Again it’s time to spoil your appetite with another video by Anna Rothschild from the YouTube Channel Gross Science. This interesting video about Dracunculiasis, also known as the Guinea Worm Disease, shows that reality is stranger than fiction. What is not explicitly stated in the video is that what the worm does to perpetuate its life cycle is an example of how parasites manipulate their host’s behavior to their advantage. While dracunculiasis is not fatal, removal of the worm is a slow and painful process that can be incapacitating due to secondary infections. Thankfully, the number of cases of the disease, which once numbered in the millions, have been reduced to a few dozen in a couple of countries in Africa. Attempts to fully eradicate the disease through sanitation have been hampered by insecurity and by the ability of the worm to infect animals such as dogs. |
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