Humans and Chimps: What's the Difference? / Thousands of Ancient Remains Found in Peru / Rice Genes Mapped
This is Doug Johnson. And this is Bob Doughty with SCIENCE IN THE NEWS, a VOA Special English program about recent developments in science. Today, we tell about some genetic differences between humans and chimpanzees. We tell about the discovery of the remains of thousands of ancient people in Peru. And we tell about the genetic map of rice.
Humans are more closely related to chimpanzees than any other animal. Humans and chimpanzees have more than ninety-eight percent of the same genetic material. Yet scientists have had trouble explaining why humans and chimps are so different if they have almost all of the same genes.
A new study has provided information to explain some of the differences. Scientists from Germany, the Netherlands and the United States used genetic tests to get their answer. Svante Paabo of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany led the study. The publication Science reported the findings.
The scientists used modern genetic technology to study tissue from chimps and people who had died of natural causes. They measured and compared the activity of genes that both species share. Genes send messages to cells. These messages direct the cells to make proteins and other substances used by the body.
The European and American scientists examined blood, liver and brain cells from the humans and chimps. They found that humans and chimps are genetically similar, except for the gene activity in their brains. Gene activity levels in the human brains were greatly different from those in the chimp brains. For example, the scientists showed that a gene might produce a lot of proteins in human brain cells but few proteins in chimp brain cells.
However, the genetic activity in the blood and liver cells of humans and chimps looked similar. The report said this suggests that the human brain grew quickly after the two creatures developed separately from a common ancestor millions of years ago. Humans developed a brain that is about two times the size of a chimp's brain.
Ajit Varki is a professor of medicine at the University of California at San Diego. He helped write the study. He said the genetic comparison of chimps and humans might lead to better treatments for diseases. He said scientists may learn more about the genetics of diseases that harm humans but not chimps. For example, he noted that chimps can become infected with H-I-V, the virus that causes AIDS in humans. However, the animals almost never get sick from the disease.
Doctor Varki said the study does not mean that chimps should be used in laboratory experiments. He said chimps and humans are so closely related that future research on chimps should obey the same rules as research on humans.
Peruvian archeologists have discovered thousands of human remains under a town near the Peruvian capital, Lima. The remains were recovered from a burial area that may contain as many as ten-thousand bodies. The bodies are about five-hundred years old. This is when the Inca ruled the area.
Experts say the discovery may change their understanding of Inca society. The Inca once ruled large parts of South America, from what is now Colombia to Chile. However, invading Spanish explorers defeated them in fifteen-thirty-three.
Peruvian archeologist Guillermo Cock led the members of the team. They made the discovery in the small, coastal town of Tupac Amaru at an area called Puruchuco. Mr. Cock says his team found at least two-thousand-two-hundred bodies of men, women and children. They are believed to be from the fifteenth and sixteenth centuries, when Spanish explorers began arriving in the area.
In the past, information about Inca culture has come from a limited number of burial places. The recent discovery includes rich and poor people of all ages, from babies to old people.
Many of the bodies were found wrapped together in many pieces of cloth material. These are called mummy bundles. Some mummy bundles held as many as seven individuals and their objects. These mummy bundles weighed as much as one-hundred-eighty kilograms. Several bodies still wore clothing that showed the person's importance in Inca society. About forty of the large mummy bundles had false heads on top. Such heads were attached to mummy bundles that included leading members of Inca society.
The archeologists also found more than fifty-thousand objects along with the bodies. They include personal valuable objects, food, cloth materials, pottery and cooking equipment.
The archeologists say nothing special was done to protect the bodies before burial. Thick pieces of cloth around the bodies trapped any body fluids. The dry, sandy soil also helped protect the bodies. As a result, there was little damage over the past few centuries.
The greatest damage, however, came from human wastes and other fluids left by people who lived in Tupac Amaru. The wastes and liquids sank into the ground, damaging the bodies. In addition, earth-moving equipment destroyed other burial areas in Nineteen-Ninety-Eight.
The research team worked quickly during the past three years to save what it could. Peru's government and the National Geographic Society in Washington, D.C., provided money for the project.
Mr. Cock says this is one of the most important discoveries in the history of Inca archeology. He says it will take years to study all of it. He says archeologists will learn much about the lives, health and culture of the Inca people as well as their social, economic and political systems.
The discovery has already disputed some beliefs about Inca life. For example, Mr. Cock says it disputes the idea that common people were not involved in Inca culture. He says even the poorest individuals show strong ties to the Inca.
The archeologist says he has no plans to dig again in the area. Yet he remains concerned because hundreds of other bodies remain buried underground. Small buildings cover most of the unexplored areas. School children play on the dusty field where many of the remains were found. Their feet crush tiny pieces of Inca corn and human hair that remain on the surface.
Scientists have identified almost all the genes found in rice. Two teams published separate versions of the genetic information for rice plants last month. This is the first time scientists have mapped the genes of an important crop. The scientists say this genetic information could lead to improved kinds of rice and better rice production in developing countries. They also expect the information to be useful in improving other grains, such as corn and wheat.
Rice feeds more than half the world's population. However, weather conditions, disease and insects can restrict its production. That may change because of the efforts of the scientific teams. They reported their findings in the publication Science.
One group was led by Jun Yu of the Beijing Genomics Institute in China and the University of Washington in Seattle. His group studied indica, the rice most commonly grown in China. The group says it has identified more than ninety percent of the genes in indica rice.
The other scientists work for the Syngenta company based in Switzerland. They did the research at the company's Torrey Mesa Research Institute in La Jolla, (La HOY-ah) California. They created a map of japonica, a short-grain rice grown in warm climates. Syngenta claims its map is more than ninety-nine percent complete and ninety-nine percent correct.The chief editor of Science magazine said he believes the rice genome could prove more important in the next few years than the human genome. He noted that more people depend on rice than any other crop.
This SCIENCE IN THE NEWS program was written and produced by George Grow. This is Doug Johnson. And this is Bob Doughty. Join us again next week for more news about science in Special English on the Voice of America.