Chimpanzees behave so much like humans they occasionally kill one another.

"I had once thought that chimpanzees resembled humans only in their gentle traits, like holding hands, embracing and kissing," naturalist Jane Goodall said yesterday at a rare news conference here. "The horrifying thing is they bear a strong similarity to humans in other ways. We saw one community of chimps systematically attack and kill another."

Not once did Goodall use the word "murder" to describe the five attacks she saw in the wilds of Tanzania in the last four years, but it was clear from her descriptions that she felt murder was on the minds of the 11 male chimps who annihilated a group of seven male chimps.

"The attacks usually involved young males, who usually used their hands, feet and teeth," Goodall said. "But we saw an old male pick up a rock and throw it at a prostrate victim of another's attack. It showed chimps are closer to humans than I thought."

When she arrived at the Gombe National Park 18 year ago to begin what has become a lifelong study of Chimpanzees. Goodall said she discovered a single community of about 40 chimps living together in what was then harmony. It was largely this harmony that Goodall has popularized in film and books.

In 1970, Goodall said yesterday at the offices of the National Geographic Soceity, the community of chimps began to shwo signs of division, and by 1972 a group of seven males and three females left the community and formed their own to the south of the first group.

Two years later, Goodall said she wtinessed the first attack by five males of the original community on a single male of the splinter crowd. The attack was "brutal and savage" lasted 20 minutes and resulted in the death of the male who'd been attacked, she said.

Goodall saw four more attacks and said she thinks there were others she did not see. All the attacks involved at least three and as many as five males from the original community who terrorized small numbers of the other group. The splinter group apparently did not try to detaliate, Goodall said she saw a gang of males kill an older female in the splinter group and she said she saw another gang attack the last surviving male less than a year ago.

"They broke his leg and beat him up." Goodall said of the last killing. "Nobody's seen his body, but almost surely he's dead. nobody's seen him since the attack."

In attempting to figure out the motive for the murders, Goodall said the only explanation is that the orginal group grew to where there was a preponderance of adult males in the group.

"I think the two groups spilt up because there were too many males," Goodall said. "I think when they gathered together there was too much tension."

In sharp contrast to the newly observed violence among the chimps, Goodall said she also witnessed the first chimpanzee twins known to be born anywhere. She said the twins are still alive at the age of 6 months. They were given the names Gyre and Gible.

"Every time I see them I can't believe they're real," Goodall said of the twins. "You have no idea how difficult it is for a chimpanzee mother of twins to cope with two babies."

Dependent on their mother's milk for the first three years of life, the twin chimps have lived their first six months clingingto their mother's stomach or back. At times, one of the twin clings to the other, and several times Goodall has seen one of the twin fall "because they're so small they just don't cling well."

One of the twins hurt its foot once, Goodall said, making it difficult for the mother (named Melissa) to travel with the babies. When the mother moved through the trees, the injured twin would cry so loudly the mother would stop and make a nest for the twin to rest.

The hardest thing for the mother of twins to do is set aside time for feeding. Normally, adult chimps, and especially breast-feeding mothers, eat for seven or eight hours every day. Melissa ate for only one hour.

"We gave her bananas with antibiotics in them, and this helped them Melissa and the injured twin," Goodall said. "It was only the second time we're interfered medically." The first was to treat a severe fungus on the face of a female chimp.

Goodall is in the United States to start a three-week lecture tour, then it's back to Tanzania and her surviving community of chimps. Why has she done it for 18 years and why will she go on doing it? Because the chimps are still man's closest living relative.

"We've got an abundance of fossils that tell us what early man looked liked and how he walked," Goodall said. "But the only way we can begin to understand early man's behavior is by comparative studies with these chimps. It is only through these chimps that you can begin to understand the evolutionary processes that molded our behavior as it is today."