In tomorrow’s New York Times, I write about what pigeons taught Darwin about evolution, and what they can teach us over 150 years later. The spur for the story is a new paper in which scientists analyze the genomes of forty different pigeon breeds to understand the molecular secrets behind their remarkable diversity. My story is accompanied by some wonderful photos as well as a podcast in which I talk to my editor, David Corcoran, about the research.
Discover, January 30, 2013
Ten thousand years ago, there were just 5 million people on Earth, fewer than live in Singapore today. The population has since soared to 7 billion. This rapid growth has left a mark on the human genome, researchers are finding, drastically increasing the number of very rare mutations in our DNA. That realization casts doubt on the long-standing view that just a few genetic mutations underlie many hereditary diseases. In reality, those diseases are probably caused by a wide variety of extremely rare mutations that vary from one person to the next, complicating efforts to understand and treat them at the genetic level.
We’re made of parts. Our skull is distinct from our spine. Our liver does not grade subtly into our intestines. Of course, the parts have to be connected for us to work as a whole: a skull completely separated from a spine is not much good to anyone. But those connections between the parts are relatively few. Our liver is linked to the intestines, but only by a few ducts. That’s a far cry from the intimate bonds between all the cells that make up the liver itself, not to mention the membrane that wraps around it like an astronaut’s suit. The distinctness of the parts of our bodies is reflected in what they do. In the liver, all sorts of biochemical reactions take place that occur nowhere else. Our skull protects our brain and chews our food–jobs carried out by no other part of our body.
Biologists like to call these parts modules, and they call the “partness” of our bodies modularity. It turns out that we are deeply modular. Our brain, for example, is made up of 86 billion neurons linked together by perhaps 100 trillion connections. But they’re not linked randomly. A neuron is typically part of a dense network of neighboring neurons. Some of the neurons in this module extend links to other modules, creating bigger modules. The brain can link its modules together in different networks to carry out different kinds of thought.
This post was originally published in “Download the Universe,” a multi-author blog about science ebooks edited by Carl Zimmer.
Rough Beasts: The Zanesville Zoo Massacre, One Year Later. By Charles Siebert. Published by Byliner.
Reviewed by Seth Mnookin
January 29, 2013
Continue reading ““Buckeye tigers,” a midnight massacre, and missed opportunities”
In November, I gave a talk at TEDYouth, an all-day event for high school students in New York, about my favorite parasite. The video of the talk is now online, along with extra education material.
Originally published January 29, 2013. Copyright 2013 Carl Zimmer.