(THEME)
VOICE ONE:
This is SCIENCE IN THE NEWS, in VOA Special English. I'm BobDoughty.
VOICE TWO:
And I'm Sarah Long. On our program this week -- making a mousewith two mothers, no father required.
VOICE ONE:
A monkey society where females teach males to be less aggressive.
VOICE TWO:
And a theory why people have a bigger brain but a smaller mouththan early humans.
(THEME)
VOICE ONE:
There is a mouse in Japan with two mothers and no father. Howcould this happen? Scientists explain how in the magazine Nature.However, the process they used to create this small animal is notnew. It is called parthenogenesis.
Parthenogenesis is development with an unfertilized egg orreproductive cell. Some plants and animals reproduce this way. Amongthem are a number of fish and birds. Scientists thought mammals hadto have an egg from a female and sperm from a male to reproduce.
VOICE TWO:
Tomohiro Kono of Tokyo University of Agriculture led a team ofJapanese and Korean scientists. They used only female mice in theirexperiment. They joined the nucleus of an egg from one mouse withthe nucleus of an egg from a second mouse.
They combined a young egg with an older egg. The young egg hadnot yet gone through an important part of development. Its geneswere not yet imprinted. During this process, some genes are orderedto work and others are not.
VOICE ONE:
The imprint depends on whether the gene comes from the mother orthe father. Eggs and sperm have similar sets of genes. But theimprint decides which gene in a set should be active and whichshould not.
The young egg came from a genetically engineered mouse. Thismouse was made to lack two genes linked to the growth of a fetus.
Tomohiro Kono says he thinks the young egg acted more like asperm because of the missing genes. The older egg was alreadyimprinted. It had all the normal genes.
In their experiment, the scientists produced hundreds of embryos.They placed them inside female mice to grow. Only ten live mice, allfemale, were born. Just one of these survived to grow into an adult.
VOICE TWO :
The scientists named her Kaguya, after a princess in a Japanesestory. Kaguya is now more than a year old. She has already hadbabies through the way mice normally reproduce.
The team says the results of the experiment suggest thatimprinting with genes from the father prevents parthenogenesis. Thiswould make sure that the father has a part in the development.
Scientists say this experiment should not worry men. They sayparthenogenesis will not replace them anytime soon. But experts ingenetics and biology say the experiment did teach a lot about themysterious process of imprinting.
And Tomohiro Kono has other plans. He told Nature magazine thatnext he wants to make pigs.
(MUSIC)
VOICE ONE:
This is Science in the News, in VOA Special English.
Biologists have reported about a group of male baboons that areunusually nice. The biologists are Robert Sapolsky and Lisa Share ofStanford University in California.
Their work involves a group of olive baboons at the Masai MaraReserve in Kenya. Mister Sapolsky began the study innineteen-seventy-eight. The baboons slept in the trees near thevisitors center. So Mister Sapolsky called them the Forest Troop.
In the early nineteen-eighties, workers dug a large hole near thebuilding to throw trash away. Members of Forest Troop began tosearch through the waste for meat and other food. However, anothertroop of baboons had already claimed the area. They became known asthe Garbage Dump Troop.
VOICE TWO:
Adult male baboons are not known for their ability to share. TheGarbage Dump males and the Forest Troop males often fought. So, onlythe most aggressive males from Forest Troop would go. These were thehigh-ranking baboons in the troop. Such males are at the top of thesocial order.
In nineteen-eighty-three, however, tuberculosis began to spreadin the garbage dump area. All the high-ranking Forest Troop malesgot sick with the lung disease and died. Only the least sociallypowerful males remained.
After that, Mister Sapolsky observed that aggressive actionswithin Forest Troop greatly decreased. He ended his observation innineteen-eighty-six. He began to study another troop of baboons.
Then, in nineteen-ninety-three, Mister Sapolsky again observedthe Forest Troop. This time he went with Lisa Share. They found thatthe males were still much more gentle compared to other baboons. Butthe scientists also found something else. All the adult males inForest Troop at that time were from other troops.
All the ones that were in Forest Troop in nineteen-eighty-six haddied or moved on. Male baboons move into other troops when theybecome adults. The scientists wondered why the new members of ForestTroop were not aggressive like other male baboons.
VOICE ONE:
They say it appears that the females are teaching cooperation tomales that enter the troop. They say the females present themselvesto the new males sooner than females of other troops. The femalealso begin to care for the males by cleaning insects from their hairsooner than normal. The males also groom the females this way.
Robert Sapolsky and Lisa Share say adult males in Forest Troop dohave some things in common with other male baboons. For example,those at the top of the social order stay at that level for about ayear. High-ranking Forest Troop males mistreat lower-level males,just like in other troops. However, the mistreatment is less severe.
VOICE TWO:
The scientists took blood from lower-ranking members of ForestTroop. They did this to measure levels of hormones produced bytension. They say the blood tests found lower levels of thesestress-related hormones than usual.
The two biologists plan to continue to watch the Forest Troop inKenya. They note that some animals pass along culture by teachingthings like tool making or communication. They say the baboons inForest Troop pass along their unusual social rules as part of theirculture. And the scientists suggest this is mainly thanks to femaleguidance.
The findings appear in PLoS (pronounced ploss) Biology. PLoS isthe Public Library of Science. Internet users can read thisscientific journal free of charge. The Web site ispubliclibraryofscience-dot-o-r-g. Again, the address ispubliclibraryofscience -- all one word -- dot o-r-g.
(MUSIC)
VOICE ONE:
Modern humans have a bigger brain and a smaller jaw than ourancestors. Some scientists in the United States have a theory toexplain why. They say this may all have been the result of a changein one gene.
The scientists are from the University of Pennsylvania inPhiladelphia. Their report is in Nature magazine. Hansell (HAHN-sul)Stedman and Nancy Minugh (mi-nyew)-Purvis led the team.
The team studied a protein called myosin. Myosin is what providespower to muscles. It permits them to tighten for movement.
The scientists say they found that a change took place in amyosin gene about two-and-one-half-million years ago. This change,or mutation, prevented the gene from producing a form of myosincalled M.Y.H.-sixteen. The scientists tested genetic material ofpeople from all over the world. They found this change in all cases.
VOICE TWO:
The scientists also looked at D.N.A. from seven other kinds ofprimates besides humans. These included the chimpanzee and macaquemonkey. The scientists did not find the mutated gene in any of them.All of these animals have the gene that produces M.Y.H-sixteen. Thescientists found that this kind of myosin is involved mainly inbiting and chewing.
Two-point-five-million years ago was just before a period ofmajor change in the human head. The fossil record shows that ourjawbones shrank and brains grew larger beginning around two-millionyears ago.
Nancy Minugh-Purvis offers a possible explanation: Without themyosin, jaw-muscle size and force decreased. This removed pressureon the skull. And that freed the brain to expand. Something to keepin mind.
(THEME)
VOICE ONE:
SCIENCE IN THE NEWS was written by Caty Weaver. Cynthia Kirk wasour producer. This is Bob Doughty.
VOICE TWO:
And this is Sarah Long. Listen next week for more news aboutscience, in Special English, on the Voice of America.