28 Sept 2012

The Anniversary of Silent Spring

By Claire Eamer

Rachel Carson in 1944.
U.S. Fish and Wildlife Service photo
This week marks an important anniversary. Fifty years ago yesterday - September 27, 1962 - was the official publication date of Rachel Carson’s book, Silent Spring. It was a ground-breaking, impeccably researched, and lyrically written chronicle of the damage being done to the environment by excessive use of synthetic chemicals, especially DDT. And it’s generally credited with launching the environmental movement.

Even before Silent Spring reached bookstore shelves, its friends and foes were lining up to do battle. The book had been serialized in the New Yorker magazine over the previous summer, so its contents were no secret. One of the big chemical companies threatened a lawsuit in an attempt to block publication, but Carson’s publishers went ahead anyway. With thousands of pre-orders and a spot on the Book of the Month Club roster, Silent Spring was heading for the best-seller list.

And Rachel Carson was heading into battle. She was an unlikely environmental warrior. Born in 1907, Carson was a biologist who had worked for the United States government until her successful books about the ocean made it possible for her to quit and write full-time. She was a quiet, private person who had worked hard all her life, supporting her parents, sisters, nieces, and an adopted son. Walks along the seashore and peaceful hours of writing were what she wanted – not a public platform.

Rachel Carson and Bob Hines conduct marine biology
research in Florida, 1952.
U.S. Fish and Wildlife photo
But the public platform is what she got. As soon as the book appeared, it was attacked by spokesmen for the big, powerful chemical companies, by agriculture departments, by scientists who had tied their reputations to the chemical revolution of the 40s and 50s, and by a lot of politicians who knew where their campaign funds came from. The problem facing her opponents, however, was that Carson had done her homework. Her research was solid, and she had consulted the leading experts in the United States and beyond. She had facts on her side.

Stymied in their attempts to attack the book’s content, Carson’s opponents turned to attacking its author. She was called a hysterical woman, a fanatic devotee of bird-huggers and organic gardeners, even a tool of subversive (read Communist) forces that were threatening America’s food supply by trying to ban all pesticides (a position Carson never took). It was the kind of firestorm of personal attacks that American climate scientists face today.

Through it all, Carson remained calm, polite, and eminently rational – all the more remarkable because she was desperately ill. In fact, she was dying of breast cancer, although very few people knew it. Her words, both written and spoken, won her plenty of supporters, including the American President, John Kennedy. By the time she died, just 18 months after the publication of Silent Spring, Carson knew she had made a difference and that the first steps were being taken to control the use of pesticides and other chemicals and limit their environmental impact.

For more about Rachel Carson and Silent Spring:




21 Sept 2012

Evolution - Not Just for Carbon-Based Organisms

by L E Carmichael

For about twenty years now, scientists have been studying evolution using a new kind of life form - a digital one.

Digital organisms are programs designed to replicate their own code, and were originally inspired by computer viruses.  Their computer-based habitats are restricted in space (RAM) and restricted in energy (the CPU time required to run the program).   As the organisms reproduce, errors are introduced into their codes at a fixed frequency - the mutation rate.  This results in a genetically variable population which is competing for resources.  And because some variants in the population can reproduce faster, while randomly-chosen organisms are periodically deleted from the system (simulating death), the composition of the population shifts over time.  In other words, the digital species evolves.

There are major advantages to using digital organisms in the study of evolution.  For one thing, complex carbon-based life forms tend to have long generation times, making it difficult to observe evolution in action.  With some exceptions, such as Darwin's finches, scientists are usually restricted to studies of the fossil record, or relationships between living species.  This research is therefore largely observational.  Experiments on evolution can normally be done only on carbon-based bacteria and viruses, and even then, it takes years to propagate the population through enough generations for evolution to occur.  In contrast, digital organisms can go through thousands of generations in just a few hours.

More importantly, because digital organisms share no history with life on earth, they are a completely independent example of evolution.  This allows scientists to distinguish general principles of evolution from quirks that might be specific to DNA-based organisms.

Some of the most interesting results to come out of this research relate to complexity.  In most cases, digital organisms develop faster replication rates by losing code - stripping themselves down to the essential instructions required for reproduction.  In other words, they get simpler over time.  Under computational scenarios, however, simple organisms can obtain numbers from their environment (equivalent to necessary chemicals or food resources).  If they have the right code (genes), they can perform calculations using these numbers (just as carbon-based life forms use enzymes to transform nutrients).  They then release the products of the computation back into the environment.  If those products are deemed beneficial, the organism is rewarded with an increase in fitness - the ability to replicate more quickly.    As mutations which allow new computations are rewarded, what results is a spontaneous increase in complexity over time.  In fact, over the course of several hundred generations, digital organisms evolve that can perform up to 50 distinct calculations.

Another mind-blowing result of this research is the spontaneous evolution of parasites - digital organisms with stripped-down genomes that piggy-back on more complex organisms, using the code of their hosts to copy themselves.  This is exactly what the average cold virus does when it infects a human nose.  What's even more incredible is that the host organisms begin to evolve parasite resistance, launching a digital arms race analogous to that between influenza and annual flu shots!

Digital organisms are a powerful model system, but there is also scientific interest in studying them as life forms in their own right.  I suspect Isaac Asimov would approve.

14 Sept 2012

Science Plus Kids TV Equals Fun!

Written by Helaine Becker

For the last three years, alongside my other writing projects, I've been the staff writer for a science- and environment-themed television show for children called Planet Echo (You can see it on APTN, or watch it on line.). The segment I write is called Dr. Greenie's Mad Lab. It mixes serious, science-y information with an abundance of fart jokes. Hey, what's not to like?

Dr. Greenie mixing up something gross  - and educational! - in his lab.
The Mad Lab segment has indeed proven so popular with viewers that we are spinning it off into a stand-alone show. Some sample footage from the new show was submitted recently to the Juried competition at MIP Junior, the preeminent international trade show for children's television.
And guess what! Dr. Greenie's Mad Lab has been selected as a finalist!

The awards will be given out at a chi-chi red carpet gala in Cannes on October 7. Alas, a plane ticket to attend the event is not in my pay package; I will have to get the news of the winner via a tweet from producer Chris Greaves.

In the meantime, I'm adding tweaks to the all-new webisode for the show, an exciting project that includes both a fun plot and three interactive games kids can play on their tablet or phone.

Watch this space for news of the award winners, and wish us luck!

7 Sept 2012

It’s an Animal! It’s a Plant! No, It’s a Slime Mold!

by Jan Thornhill

Dog Vomit Slime. Pretzel Slime. Wolf’s Milk Slime. Insect Egg Slime. These are just a few of the wacky names people have come up with to describe different species of myxomycetes, a group of peculiar miniature “critters” commonly known as slime molds.

A variety of slime mold fruiting bodies, including
Pretzel Slime (the snakey one) and Wolf’s Milk Slime (the pink cushions).
Photo credits: Laurence Acland, John Carl Jacobs, Jan Thornhill
Slime molds make me happy – and not just because of their wacky names. They make me happy because almost everything about them is odd. One of their oddities is that they spend part of their lives behaving like animals and another part acting like plants or fungi.

To see slime molds, it helps to get down on your knees in the woods, especially beside rotting logs in places were it’s damp and dimly lit. This is where many types of slime mold begin their lives as a loose sack of liquid, a huge single-cell with multiple nuclei. In this slimy form, called a “plasmodium,” the organism oozes slowly over and under dead leaves like a mammoth amoeba, speeding along at about a millimeter an hour. While it moves it feeds by engulfing and digesting bacteria, fungal spores, and even other slime molds. What’s really impressive is that this network of slippery muck behaves as if it has intelligence. It makes choices, veering towards food as if it’s hunting. In the lab, some slime molds are even able to figure out the shortest path to escape a maze. Stranger still, if the plasmodium is chopped into bits, the separated pieces will slowly migrate back together again!

When food runs out, or the environment becomes too dry, slime molds search out a high spot, such as a log, to do their plant-like trick of sprouting fruiting bodies and releasing spores. This is the stage where they get fancy. The giant plasmodial cell divides itself into innumerable single cells that then form the fruiting bodies. In many species, some of these cells seem to sacrifice themselves for the good of the others by creating a stalk that will hold the spore-producing structures high enough to catch a breeze. When mature, the structure bursts open and the powdery spores are carried away by wind or passing animals.

In only 7 hours, the slimy yellow plasmodium of Insect
Egg Slime(Leocarpus fragilis) transforms itself
into hard-shelled orange fruiting bodies.
More than 1,000 different slime molds have been identified, and they come in a startling variety of shapes and colors. Some look like mini wieners-on-a-stick or ice-cream cones or pretzels, though at a size only a cricket could enjoy. Others have shimmering, metallic coats, or are encased in a cracked white crust. Yet others look like delicate coral. One of my favorites, Wolf’s Milk Slime, will squirt pink goo at you if you poke it with a stick. There’s even one that can grow so large, and is so ugly, that some people blame their neighbor’s dog for its appearance in their garden or on their woodpile. That one’s scientific name is Fuligo septica, otherwise known as – you guessed it – Dog Vomit Slime.

A small, mature Dog Vomit Slime (Fuligo septica) releasing its spores.

Check out:
Artist Heather Barnett’s video-taped experiments with slime molds:

Tons of pictures of slime mold fruiting bodies at: