CHIMPANZEES ARE AMONG OUR CLOSEST RELATIVES - WE SHARE BETWEEN 95 AND 98 PERCENT OF OUR GENES.

AND NOW … RESEARCHERS BELIEVE THIS TROUPE ON THE SENEGAL SAVANNA MAY GIVE US UNIQUE NEW INSIGHT INTO OUR EARLIEST ANCESTORS.

NATIONAL GEOGRAPHIC EMERGING EXPLORER JILL PRUETZ HAS REPORTED NEVER-BEFORE-SEEN BEHAVIOR HERE … INCLUDING MORE THAN A DOZEN INCIDENTS WHERE THE CHIMPS HAVE MADE WHAT APPEAR TO BE WEAPONS FOR HUNTING.

PRUETZ: "This is actually a spear that an adult female named Lucille, we call her Lucille, made to try and obtain a bush baby. So what she did was break off a live branch and then used it to jab into the hole where the bush baby was in and effort to get it, but she was unsuccessful."

OTHER CHIMPS HAVE BEEN SEEN USING THEIR TEETH TO SHARPEN THEIR STICKS INTO A POINT.

IT’S BEEN KNOWN THAT SOME CHIMPS CATCH AND KILL OTHER SPECIES … AND SOMETIMES EAT THEM.

BUT UNTIL NOW … MAKING TOOLS FOR KILLING MAMMALS HAD BEEN CONSIDERED A UNIQUELY HUMAN BEHAVIOR.

THESE CHIMPANZEES IN SENEGAL ARE KNOWN AS THE FONGOLI GROUP …

PRUETZ BELIEVES THEY’RE PARTICULARLY INTRIGUING BECAUSE THEY LIVE ON A SAVANNA … AND SPEND MOST OF THEIR DAY ON THE GROUND …LIKE OUR ANCESTORS DID.

MUCH OF WHAT WE KNOW ABOUT CHIMPANZEES COMES FROM TROOPS THAT LIVE PRIMARILY IN TREES … LIKE THOSE STUDIED FOR DECADES BY JANE GOODALL IN GOMBE.

BUT WHEN OUR EARLIEST ANCESTORS EVOLVED MORE THAN FIVE MILLION YEARS AGO … IT WASN’T IN A RAINFOREST … BUT IN A DRY LANDSCAPE OF GRASSLANDS --MORE SIMILAR TO THIS SENEGAL SAVANNA THAT’S HOME TO THE FONGOLI CHIMPS.

PRUETZ: "I feel like this project is really important to our study of human evolution as well early hominids because …. We know now that apes can do this in this environment."

PRUETZ HAS OBSERVED OTHER INTERESTING BEHAVIORS IN THE FONGOLI CHIMPS.

THEY USE PLANT STEMS AS A FORAGING TOOL TO FISH FOR TERMITES.

THAT’S SOMETHING THAT’S ALREADY BEEN DOCUMENTED IN OTHER CHIMP GROUPS.

BUT SHE’S ALSO SEEN THEM USING CAVES … AS SHELTER WHEN IT’S HOT OUTSIDE.

AND THEN THERE’S THEIR REGARD FOR A LOCAL WATERING HOLE … ON A SWELTERING DAY.

IT’S A SCENE THAT LOOKS OH-SO-FAMILIAR TO HUMANS.

PRUETZ: "The spear use. The water use. And the cave use. And any one of those I would have been happy with seeing any one of those. But to have that, that’s a huge I mean that’s great! I feel really lucky. I mean I just keep waiting for the chimps to do something else who knows."

PRIMATOLOGISTS ARE CAREFUL NOT TO PROJECT HUMAN MOTIVES … OR EMOTIONS … ON THE ANIMALS THEY STUDY.

BUT FONGOLI CHIMPS MAY INDEED EXHIBIT SOME OF OUR VERY EARLIEST BEHAVIORS …

AND WATCHING THEM MAY BE LIKE GAZING INTO A MIRROR THAT REFLECTS OUR VERY DISTANT PAST.