in a place called hell Valley an ancient tribe relies on each other to survive a monkey's position in the group is inherited from its mother bloodline determines rank and every member knows their place but in this world of tradition there are opportunities to change your fate one quiet moment can have great significance when a young monkey bonds with the leader of the troop in this plan nothing goes on gnosis it's all part of the drama unfolding deep and the Japanese out long ago one hearty tribe made an epic journey traveling thousands of miles crossing treacherous mountain passes and deep snow bound valleys by the time they finally settled down these macaques have traveled farther north than any other primate on earth aside from us over time they adapted to the extremes of the seasons and rightfully earned their name snow monkeys to this day the descendants of that ancient tribe still roamed the mountains of central Japan and this is where our story begins it's early winter in the Japanese Alps but already the temperature is well below freezing here boiling volcanic waters feed the Yukon River keeping it ice-free all winter long snow monkeys take advantage of the subterranean heat by huddling over thermal vents higher up in the trees families cling tightly together in the frigid morning air no one is quick to rise well almost no one hero is just eight months old and as he watches the juveniles play he's anxious to start his day as well hero and his friends are determined to get the rest of the trip on their feet no easy task and a family this size the troop is 160 members in all mostly females and their offspring males usually leave home before they reach sexual maturity but a handful of adult males may stick with a troop ensuring its safety hero's mother is a lower ranking female the status he'll likely share until he's old enough to leave the troop and short his own path his rambunctious play has even roused the troops leader Cureton has a reputation for being ill-tempered with little tolerance for youngsters the clan roosts high in the mountains but every morning they heed a familiar call a whistle from the valley below beckons him down the mountain hero and his cousin are still busy playing but the rest of the family is already on the move and this is why they were in such a hurry grain has been scattered to supplement the troops meter winter diet and no one wants to be late for breakfast but someone is missing hero and his cousin have lagged behind and his cousin is no help at all just one familiar face is all it takes and they are back on track keeping up of the troop is vital for snow monkeys family is survival but there's something else drawing them down the mountain Shikoku Danny or hell Valley is famous for its hot springs and some 50 years ago one was built exclusively for the held valley troop it became an overnight sensation and snow monkeys have been soaking up the warm volcanic waters ever since it's a communal affair open to all regardless of rank every member of the troop is a unique individual some a little more unique than others take bubbles for example she loves making bubbles in the water surface and seems completely engrossed in the task and there's hero Sam he's a lover of the hot spring even earning the nickname hot springs uncle he's supposed to be pure Oh Sam's right-hand man when trouble breaks out but he spends most of his days lounging with the ladies kuroh son rarely enters the hot spring instead he spends his days alone he still new to the job of trip leader and perhaps the added stress has made him more withdrawn than normal but that doesn't stop Hiro maybe it's the bitter cold or maybe he thinks kuru son needs a little company kuru son ignores Hiro's gesture he'd rather be alone yet it seems no matter where he goes he is surrounded by little ones as evening approaches the troupe must seek shelter deeper in the forest but kuro-san seems reluctant to lead maybe it's all too much for him the late day flurries are a reminder the worst of winter is yet to come a fresh bed of snow fills the forest floor and the troop text of the trees to avoid the deep drifts on a steep hillside a gang of juveniles is playing king of the mountain play fighting is how young monkeys test each other's strengths and weaknesses sorting out a delicate balance of power this is not a battle yet but a dance one young gang leader decides to turn this into a more serious contest the juveniles caught downhill feel threatened by his aggression and call for reinforcements but their brother at the top of the hill is unaware the game has changed the belligerent youngster tries to assert his dominance but the lower Hill gang refuses to back down now as backup arrives the troublemaker realizes he may have overplayed his hand with all forces converging on them his only option is to flee finally he wriggles free and makes a dash for safety but the point of this battle has already been made this little gang of juveniles has a new leader at least for now and a family more than a hundred strong learning to play with others is the most important thing heroes made a snowball and tries to get his cousin to play along the relationships he forges through the simple act may one day tipped the scales in a more serious game but for Hiro being playful comes as naturally as the newly fallen snow it's getting late and the snow was growing thicker by the minute suddenly heroes games cut short there is a sense of urgency in the air a storm is coming the trip must seek shelter for the night and this time corrosion leads the way but as they climb hero falls father and father behind his mother scans the area for her son as the others move on heroes desperate corals are swallowed up by the wind his mother continues her search but fast-moving snow has erased his tracks finally his mother hears his faint cries now a hero holds on tight he was lucky this time second chances don't come along often inhale Valley storms like this can last for days during winter more snow falls in the Japanese Alps than almost anywhere else on earth snow monkeys have learned to keep friends and family close it is truly a matter of survival without the warmth the companionship of others the bitter cold sinks into their bones the troop is drawn down the mountain knowing the hot spring awaits them one by one families gather in the water to soak each seeking the warmth so desperately needed sheera son was one of the first to arrive but now the little pool is getting packed Kiko is a lower-ranking female but a regular to the hot spring in her eagerness to squeeze in she's managed to annoy higher-ranking tomorrow Kiko tries again but tomorrow won't budge zero son is hoping this little spat doesn't get out of hand but finally he steps in to break up the fight as things settled down Kiko takes a different tack and finds an opening behind her sister yet tamaño isn't ready to leave Keiko alone but strangely she's not back to fight she slides over and grooms Keiko for snow monkeys grooming is an act of reconciliation a way of making up after a fight in a community that depends upon one another for survival grooming is that loo that binds the troupe together it's partly a free meal partly good hygiene beneficial all-around in fact that may be better to give and receive the very act of grooming leads to many benefits and the more equally you distribute this act of kindness the calmer and healthier you become kuroh son the troop leader sits alone he hobbles with no one as he shivers in the cold but with his less than sunny disposition most of the troop have given up on him the only one who still seeks him out his hero so far Jerusalem doesn't seem to mind him hanging around too much it's possible that heroes plucky nature is slowly chipping away at Kura Suns icy facade for on this quiet snowy afternoon something is about to happen that will surprise everyone suddenly chorus unfolds hero into his arms though he isn't quite sure he's made the right move well at least they are both a little bit warmer and honestly that's how some relationships begin it's always sort of a dance really and awkward jerky odd-looking dance but eventually every pair of figures out the moves and then they're on their way this is all highly unusual seeing any male with a youngster perched on his back is oughta nuff but for a reclusive leader like Khorasan it's even more surprising and the spectacle isn't lost on the rest of the troupe either now Oscar asam leads the troop hero has a first-class ticket the chance to see the world through the eyes of a leader hero watches his new mentor intently as they shred bark together heroes confidence grows with his air of loneliness lifted purusam as a new energy garrison has found a spot to bask peacefully in the Sun well sort of with Hiro now at his side the day's never seemed to slow down much but we'll list fragile relationship lasts or melt away with the winter snow it won't be long now spring is on its way with help from the troupe the ornaments of winter are taken down one by one the river surges with the new snowmelt the warm rains washed the forests clean and filled the river to its banks slivers of spring like fiddleheads and peat moss or peeking out preparing their takeover snails emerged from hibernation stretching out from their shells to search for young green shoots the troop moves through the forest like explorers of a new and verdant land stopping now and again to soak up the warm air laden with the intoxicating sense of spring in Japan cherry blossoms are the symbol of the ephemeral nature of life the troupe takes advantage of these sweet flowers while they last the forest is a buffet and Hiro hardly knows where to begin after eating bark and twigs or winter this is paradise but an unfamiliar cry has gotten his attention rina has a brand-new baby boy just hours old and she's not the only one the forest has been turned into a nursery with babies everywhere newborn snow monkeys are small enough to fit in the palm of your hand but these little bundles of energy can't be contained for long for mum keeping them safe is a full-time job they're intensely curious but are blissfully unaware of true politics wandering up to a stranger can be a dangerous lesson unless she's your aunt but this constant exploration is how babies learn about their world so it's a good thing snow monkeys are such patient mothers both Rina and her sister have given birth just a week apart during the short spring the troop will have around 20 infants Riina's sister is an experienced mom and her eldest daughter is always close at hand keeping a watchful eye on her little brother especially now he's beginning to wonder if mom's busy schedule it's always good to have a little help around every day is a new lesson and by sticking close to mom all the tiny secrets of the forest will be revealed like how to find insect larvae under the bark of cedar trees this time of year a monkeys diet is mostly greens so it's important to look for protein wherever they can find it it's a bit like rummaging through the kitchen cabinets eventually you find what you're looking for like all kids they learn by watching others and Hiro now one year old is eager to do everything grown-ups do like most things there's a bit of a learning curve clearly there's a skill to this peeling business that Hiro has yet to master maple trees are a troop favorite and Riina's sister is busy plucking fresh new shoots now four weeks old the babies are already learning to climb but confidence well that comes with practice there you go safe and sound on the valley floor the troop relaxes in the sunshine but a cry of distress is upsetting the calm of the forest it's a brand new baby with no mother in sight Rena forages with her young baby cuts to her just steps from the infant uncertain what to do rina mines the first rule of snow monkey motherhood look but don't touch but clearly something is wrong here and she can't ignore the desperate baby in front of her the new infant is still a bit shaken but is slowly realizing she is no longer in danger Rina on the other hand may not appreciate what she's taken on having two mouths to feed is quite a challenge the new baby can't see months beyond her reach just yet but somehow she seems to know she's found a new mum summer rains come early to help Valley for the babies the downpour is something entirely new while Rina nurses her adopted baby her son is busy exploring the new playmate and bubbles is transfixed as rain creates magic on the water's surface kuroh sons unusual relationship with hero continues to blossom while all around them japanese wisteria is in full bloom Oscar asam gently grooms his little buddy the juveniles well they're up to their usual antics in a sly move they have commandeered the hot spring instead of the heated waters of winter cool river water is now piped into the pool it's the perfect summer swimming oh maybe it's just the weather or maybe it's hero's influence whatever the case Khurasan seems more relaxed than ever but while the juveniles are playing the mothers have their hands full for rena the job is twice as hard with each passing day nursing and carrying two infants is becoming more of a burden she can barely manage to keep up with her sister but her son is growing stronger every day her adopted baby remains weak struggling just to keep a grip on mum as the days pass it becomes clear that there is something very wrong with Remus adopted daughter as possible Rena could not produce enough milk to feed both infants or maybe the adopted baby was already the old there is nothing Rina can do now Rena's son has yet to realize his adopted sister is gone summer gives way to autumn once again hell valley is transformed but it's not just the color of the leaves that has changed the usually quiet reserved kuro-san is now loud and aggressive hero takes refuge with his mother kuroh sans faces flush his body taught his eyes wild this is not the affectionate leader that gently groomed him in the Summer Sun it's mating season and he'll Valley and kuru son has only one thing on his mind but he's got competition males from outside the troop have come to help Ally to mate and they're making their presence known kuro-san keeps a close eye on the intruders but he stayed they age a little closer awesome days are shortened hell Valley and bulking up for winter is the going concern some strip bracket fungi from the trees while others dig up the last of the seasons chestnuts as the troop is busy foraging one of the outside males silently slips past Khurasan he's tracking down a female or crossing the valley which he tries to run he gets aggressive he tries to separate her baby from her but she rushes in to protect it as the baby makes a dash for safety her eldest daughter tries to help but she is pushed aside by the large male cool son and the other males Russian and the intruder makes a run for it but kuro-san and show us on our hot in his tail they pin him down at the river's age but the intruder breaks free and uses the river as a shield with the icy river between them the male scales the steep cliff to make us escape his scar will be a permanent reminder of the troops strength his comrade what is from the cliff above if he wants to mate he'll need a different approach Garos on now turns towards heroes mum grooming are affectionately Piro wants to nurse but for once it's her turn to be pampered mating as a dance and the females often lead one of the outside males has made an impression on heroes and she's chosen a secluded patch of forest for a romantic rendezvous the cries are mating calls attraction is a difficult thing to define but her interest in this exotic foreigner does make genetic sense he represents fresh genes from outside of Hell Valley by breeding with this male she will ensure that her own troupe will stay strong wind sweeps across the mountains taking withered autumns colors soon the valley will be under a blanket of snow with autumn behind them the troop settles into their winter routine a diet of twigs and bark here on nibbles on the buds of a maple not far away kuroh son is doing the same even after the trials of autumn it's clear their relationship hasn't skipped a beat in fact it seems stronger than ever the troop moves across the valley each member of keeping close tabs on their mothers and sisters ensuring no one is left behind and like family hero and Khurasan stick close as they braved the winter together their unusual relationship may have started out of convenience each seeking comfort that first hard winter but it has grown into something more a friendship that has lasted through the seasons by the following spring kuro-san has grown into a confident and caring leader and hero is always by his side he's already two years old and even has a brand-new baby sister like every spring there's new life in the troupe last year's babies are now the curious one-year-old hero once was hero may have come from humble beginnings but this bright-eyed youngster has lit a spark in a once lonely leader their unlikely friendship has already begun to reshape their future to learn more about what you've seen on this nature program visit pbs.org