Mutations Are the Ultimate Source of All Genetic Variation

A Debate Over How The Universe Began

Even though it’s commonly accepted today, the Big Bang theory was not always the universally accepted scientific explanation for how our universe began. In fact, the term ‘Big Bang’ was coined by a prominent physicist in 1948 to mock the idea.

In the middle of the 20th century, researchers in the field of cosmology had two warring theories. The one we would come to call the Big Bang suggested the universe expanded rapidly from a primordial, hot, and ultra-dense cosmos. Conversely, the so-called ‘Steady State’ theory held that the universe, at any given point in time, looked roughly the same.

The story of how the Big Bang became the accepted theory of physics is also a story of two men. One, Fred Hoyle, was a steady state supporter who thought the universe would last forever. Meanwhile, George Gamow, the major public advocate of the Big Bang, begged to differ. They debated in the pages of Scientific American and in competing popular books, as both dedicated scientists and earnest popularizers of their field.

And while Gamow ended up winning the debate, for the most part, the two men managed to come together in one way: They accidentally explained the origins of every element of matter by being part right, and part wrong. The truth, it turned out, would lie in the middle.

Ira talks to physicist and science historian Paul Halpern about this story, detailed in his book, Flashes of Creation: George Gamow, Fred Hoyle, and the Great Big Bang Debate.

 

The World According To Sound: Listening To Black Holes Collide

In this piece, you can actually listen to gravitational waves, the ripples in spacetime made by the tremendous mass of colliding black holes. It is possible to hear them, because their wavelengths have been shifted all the way into the human range of hearing by MIT professor Scott Hughes.

Drawn together by their immense gravity, nearby black holes will swirl faster and faster until they are finally absorbed completely into one another. When the pitch rises, it means the force of gravity is increasing as the black holes collide.

Not all black holes come together at the same rate or release the same amount of gravitational waves, so each combining pair has its own particular sonic signature. Some black holes collide quickly. Others slowly merge. Some produce relatively high pitches, because of the intensity of the gravitational waves, while others have a low bass rumbling. Some even make the sound of a wobbling top as the two black holes swirl around each other, before eventually meeting and becoming totally absorbed into one another.

 

Is There A Method To Plant Mutation?

Mutation is one of the cornerstones of evolutionary biology. When an organism’s DNA mutates thanks to damage or copying error, that organism passes the mutation on to its offspring. Those offspring then become either more or less equipped to survive and reproduce. And at least until recently, researchers have assumed that those mutations were random—equally likely to happen along any particular snippet of a piece of DNA.

Now, scientists are questioning whether that’s actually true—or if mutation is more likely to occur in some parts of the genome than others. New research published in the journal Nature this week looks at just that question, in a common weed called Arabidopsis thaliana. After following 24 generations of plants for several years and then sequencing the offspring, the team found that some genes are far less likely to mutate than others. And those genes are some of the most essential to the function of DNA itself, where a mutation could be fatal. Conversely, the genes most likely to mutate were those associated with the plant’s ability to respond to its environment—potentially a handy trick for a highly adaptable weed.

Lead author Grey Monroe talks to Ira about his group’s findings, why this skew in mutation likelihood may benefit plants like Arabidopsis, and why it may be time to think differently about evolution.

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