First electronically controlled animals / Study of mothers and their sons / Effects of global warming

This is Sarah Long. And this is Bob Doughty with SCIENCE IN THE NEWS, a VOA Special English program about recent developments in Science. Today, we tell about the first electronically controlled animals. We tell about a study of mothers and their sons. And we tell about some effects of the warming of the Earth on plants and animals.

Scientists have controlled the movements of rats by attaching electrical controls to the animals' brains. The scientists work at the State University of New York's Downstate Medical Center in Brooklyn.

John Chaplin worked on the experiment. He said scientists have controlled the way animals act using other methods in the past. However, this is the first time scientists have been able to directly control another creature with electronic signals. The experiments were reported in the publication Nature.

In the experiments, the team attached wires to areas in the brains of five rats. They also attached very small cameras and communications equipment to the rats. The scientists then sent radio signals to the rats' brains through the communications equipment. The signals caused the rats to move in the direction the researcher wanted to send them.

The electronics were attached to the rats' brains in a complex way. The scientists made two electronic connections to the right and left side of the animals' brains. Those places in the rats' brains control the sense of touch on their whiskers, the long hairs on either side of a rat's nose. The researchers could cause the rats to feel as if their whiskers had been touched. The researchers trained the rats to turn left or right when they felt a signal in their whiskers.

The scientists also made an electrical connection to a place in the rats' brains believed to control enjoyment. The researchers rewarded the rats for going in the right direction by affecting that brain area and making the rats feel good. This process is known as behavior conditioning. It is very similar to giving food to an animal as a reward for doing a desired action. But, in the recent experiment, it was done electronically.

The researchers electronically guided the rats to do several things. Some rats climbed trees even though the rats had never seen a tree before or had ever been outside. Some rats walked through big, bright, open fields, although they normally avoid such areas. Other rats climbed steps and crossed narrow paths in high places. The scientists used computers up to five-hundred meters away to control the animals.

The researchers received support for their experiment from the Army's Advanced Research Projects Agency. Military officials hope that an electronically controlled rat could be used to spy or to find land mines.

The researchers also say that a controlled rat could be used to save lives after events like earthquakes. Rats could find people trapped under wreckage. Rats can move through very small spaces and can carry very small cameras permitting rescuers to look for survivors hidden under tons of material.

Some reports have called these electronically controlled rats living robots. However, the rats are not true robots. That is because the rats were rewarded for doing what the researchers wanted them to do. A robot does not need a reward to act. It simply follows electronic signals.

Many mothers believe that sons are more difficult to care for than daughters. Some mothers have said, "My son will be the death of me yet."

A new study says there may be some truth in what those mothers say. The study examined mothers who lived more than one-hundred years ago. It showed that women who had many sons did not live as long as women who had many daughters. Science magazine published the findings.

Scientists from Finland and Britain examined family records for the Sami (SAH-me) people who lived in northern Europe between the seventeenth and nineteenth centuries. The scientists studied family records kept by church officials between sixteen-forty and eighteen-seventy. They studied three-hundred-seventy-five women who lived to be older than fifty.

One of the scientists was Virpi Lummaa (VEER-pee LOOM-mah) of Cambridge University in England. She says the records contain detailed information on the life events of the Sami. The Sami were a people who traveled from place to place to follow groups of reindeer because they depended on the animals for food. They did not have modern medicine.

She said her team found that the length of a woman's life was not connected to the number of children but to the sex of the children. Women who raised many sons had the shortest lives. The study said that giving birth and raising each son reduced a woman's life by an average of thirty-four weeks.

The study also found that having a daughter increased a woman's life by an average of twenty-three weeks. Among the Sami, women with many adult daughters had the longest lives.

Samuli Helle (SAH-moo-lee HEY-leh) of the University of Turku in Finland helped supervise the study. He says the reason for this difference may be linked to fewer problems giving birth to and caring for a daughter. He noted that daughters often help their mothers with work in the home. He said this could make life easier for women who had many children.

The scientists also noted that there could also be biological reasons for this. Male fetuses produce the hormone testosterone that might suppress the mother's defense system against disease. The scientists also noted that baby boys often weigh more than baby girls. This results in more problems for mothers when giving birth. Baby boys also require more care after birth.

The scientists say the results of the study may not be the same for women in industrial countries today. These women have fewer children, healthier lives and modern medical care. But they said these kinds of effects might still be found among women in developing countries.

Scientists say the warming of the Earth's atmosphere has begun to affect plant and animal life around the world. Scientists from the University of Hanover in Germany say global warming is affecting endangered species, sea life and the change in seasonal activities of organisms. Carbon dioxide and other heat-trapping gases in the atmosphere cause global warming.

Studies show that the Earth's climate has warmed by about six-tenths of one degree Celsius during the past one-hundred years. Most of the increase has taken place in the last thirty years.

The German scientists studied different animal and plant populations around the world in the past thirty years. They say some species will disappear because they can not move to new areas when their home climate gets too warm.

The scientists say one of the biggest signs of climate change has been the worldwide reduction in coral reefs. Rising temperatures in the world's warm ocean waters have caused coral to lose color and die.

In the coldest areas of the world, winter freezing periods are now happening later and ending earlier. Researchers say these changes are having severe effects on animals such as penguins, seals and polar bears.

Changes in temperature in the air can also affect the reproduction of some reptiles and amphibians. For example, the sex of baby painted turtles is linked to the average temperature in July. Scientists say even small temperature increases can threaten the production of male turtles.

In Europe, scientists say warmer temperatures are affecting the spring and autumn seasons. This is affecting the growth of plants and delaying the flight of birds from one place to another.

Scientists also are concerned about invasions of warm weather species into traditionally colder areas. Rising temperatures have been linked with diseases spread by mosquito insects in areas of Asia, East Africa and Latin America.

Britain's Meteorological Office says worldwide temperatures will continue to rise during the next one-hundred years. It says how much these temperatures increase will depend on the success of worldwide policies designed to slow global warming.

This SCIENCE IN THE NEWS program was written by Mario Ritter, George Grow and Cynthia Kirk. It was produced by Cynthia Kirk. This is Sarah Long. And this is Bob Doughty. Join us again next week for more news about science in Special English on the Voice of America.