tonight on "nightline" -- tipping the axis. the rogue leader of a nuclear north korea kim jong-il died. the new leader, a son, barely known, and, as yet, untested. tonight, the looming question -- is the world more or less safe? plus, the daddy effect. is fatherhood bad for men? researchers say there's biological evidence that parenting actually makes a male less macho. abc's nick watts puts the theory to the test. and nip/tuck noel. it's the gift that keeps on giving. how plastic surgery has become the hottest item on some of this year's christmas lists.

good evening, i'm cynthia mcfadden. much of the world is on high alert tonight as the death of north korea's leader kim jong-il raises new questions about nuclear security. the deceased leader gave rise to a cult of personality, as well as chronic poverty and famine conditions within his own country that killed millions. but, might his death be an opportunity for a new kind of north korea? here's abc's david wright in south korea. >> reporter: he was the pint-sized dictator of a pariah country. with his finger on a nuclear trigger. whenever kim jong-il rattled his saber, as he did with some regularity, he'd fire off one of these. remember george w. bush's famous phrase? >> states like these and their terrorist allies constitute an

axis of evil. >> reporter: he was talking about iraq, iran and north korea. and that was before kim jong-il succeeded in building a bomb. today on north korean state tv, the news anchors wept as they broke the news of his death. beneath the giant statue of the dear leader -- a display of abject grief, patriotic mourning. kim jong-il was the absolute ruler of north korea for nearly 20 years. but today, even as the news broke of his sudden death, north korea carried out another missile test. >> they have between six and 12 nuclear devices. we don't think that they are anything that can be put on the end of a missile, but they certainly are a deterrent. >> reporter: over the years, kim jong-il proved very adept at using his nuclear ambitions as a

bargaining chip, outfoxing several u.s. presidents who tried to stand in his way. >> i don't think americans should ever have thought of north korea as a military threat. they know that if they were to attack us, they would be obliterated. they're not crazy. >> reporter: kim jong-il played the crazy card and played it with his own peculiar style. in his elevator shoes. his portly jump suits. and his oversized shades. he looked more like an elvis impersonator than an evil emperor. in movies like "team america world police," he was an easy figure to parody. ♪ i'm so lonely the outlandish stories that built up his cult of personality did little to cultivate respect. the story goes that in 1994, the year he took power from his father, the great leader, kim

jong-il played his one and only round of golf, shooting 38 under par, including 11 holes in one. if anyone in north korea didn't believe it, they didn't dare say so out loud. as abc's diane sawyer discovered in a 2006 trip to north korea, the population was kept almost hermetically sealed from the rest of the world. >> my country, the strongest country in the world. and here are the strongest soldiers. >> reporter: if north koreans know little of the outside world, the outside world knows even less about the young man who was anointed his father's successor. kim jong-un is thought to be in his late 20s, his father's third son. while kim jong-il had been a well-established member of his father's military team, kim jong-un is a virtual unknown. >> here you have a young man of 26 or 27 coming into power with

this very important dynastic role to play. andthink he's not going to want to have anybody rock the boat. and i don't think he is going to rock the boat. >> reporter: what if some other faction in north korea decides to rock the boat? it's not yet clear how much kim jong-un commands respect among the military hard line. this is only the second time in history the hermit kingdom of north korea has had a transition of power. and now there are nuclear weapons in the mix. here in south korea, that is a source of fear and uncertainty. they don't yet know whether they can afford to be optimistic. whether this may finally be a turning point for the better. or whether someone, either the new leader or a potential rival, might lash out in order to prove a point. the devil they know has been replaced by one they don't and that's not much reassurance. cynthia? >> and our thanks to david wright. abc's global affairs anchor christiane amanpour joins us now from london. christiane, good evening. >> reporter: good evening,

cynthia. >> you were in north korea in 2008. what is the death of kim jong-il likely to mean for the people there? >> reporter: well, you know, there's this unbelievable cult of personality as we all know, but this is a country that barely ekes out a subsistence living. this is a place where the prison camps are bursting at the seams. the last of the truly totalitarian regimes. for the people, not much is going to change. because we don't seem to think this new leader, untested, unseasoned, so young, will be able to immediately put any stamp on what happens there. on the other hand, some are saying the very fact that, unlike his father, unlike his grandfather, he actually lived abroad for a while, has seen a different kind of life than just north korea, maybe, just maybe, down the line there may be some reform. >> for an awful lot of people in the u.s. it's all about the nuclear weapons question. the u.s. is in talks with world powers including china and russia to try to address the threat.

what's the next move for the u.s. with regard to nuclear weapons? >> reporter: very difficult because the u.s. was, for a long time now, several months, in direct negotiations with north korea about north korea suspending its nuclear program. and of course with the death of kim jong-il, that is going to probably put that on hold for the foreseeable future. but i was there, as you say, in 2008, and at that time, north korea had suspended its nuclear activities. i watched them dismantle part of the yongbyon facility and stop processing plutonium. i also watched them blow up the cooling tower. that was done in a very careful arrangement with the united states. sort of tit-for-tat diplomatic engagement. so it is possible, it is possible to do. it's just torturous getting both sides back to the table. >> so christiane, with the attempted passing -- it looks like the passing of power here from father to son in north korea, anything to be learned

from the arab spring when we saw the failure of many such transitions? >> reporter: we've seen people power sweep the arab world. it's probably not going to happen in north korea anytime soon. because i cannot tell you how isolated that place is. there's barely any electricity. if you see a satellite picture of the korean peninsula, south korea is exploding in light. north korea is dark. they're barely able to survive, most of the north koreans, so it's unlikely that kind of people power will be manifested anytime soon there. >> christiane amanpour, an important day in the life of the world. and we're very grateful you could join us tonight from london, thank you. still ahead, ever feel he's not the man he used to be? new research says fatherhood fools with men's hormones. we put it to test. [ bird chirping ] [ snoring ]

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well, it's one of the biggest changes in family life in the past 100 years. fathers getting involved with raising the kids. from the breakfast table to bath time, dad is frequently in charge. it may seem like a great piece of news to some mothers but new research suggests there might be a hidden cost for the men. one that goes to the core of their identity. here's abc's nick watt in london on the front lines of fatherhood. >> reporter: that's me and my little boy. his name is myelo. i let him wear his superman outfit 12 hours a day. i give him cake.

i listen to his awesome stories. >> he was sleeping in his bed. a witch came around. he was very naughty. and then superman came. and he was tiptoeing inside. then he had a magic wand. dad, can i have some more? >> reporter: sometimes i might dress him in a dirty fleece. it's got something all over it. oh, well, mommy's not here. it doesn't matter. anyway, i like to think i'm a pretty good dad. oh, good braking. but scientists have discovered something astounding. all this modern man daddying is lowering my testosterone dramatically. what? say it ain't so. this is making me less of a man? >> i think that's absolutely the wrong reaction. although i've been hearing that a great deal from a lot of people. >> reporter: we all see testosterone as manly. aiding sperm production and libido, creating lean, muscular

bodies and assertive, aggressive personalities. testosterone helps a male win a mate. and produce offspring. >> but those same things can get in the way of being a good father. >> reporter: so, like many species of birds, human males have evolved to have two testosterone settings. pumped up babe magnet. caring father. >> if a man couldn't modulate his testosterone, his temper might be shorter. he might be a very bad baby-sitter. >> reporter: researchers from northwestern university studied men in the philippines and conclusively proved testosterone nose-dives when daddyes take care of kids. fathers have on average 20% less testosterone than nonfathers. though right now, 'cause it's the weekend, i'm hanging out with him all the time, my testosterone is rock bottom. what's really clever about this -- >> daddy -- >> reporter: is it's only temporary. and here's the proof. this is london scottish rugby club. an illustrious team in a game

famed for its power and aggression. famed for its testosterone-fueled manliness. that's roman petroskfy, number 14, he's got two little girls at home. >> people say i'm emotional with my children when i'm away. >> reporter: are you a bit of a dirty rugby player? >> other people may say that but it's just a rumor. >> reporter: possibly the truth. during the day when he's with his kids, roman's testosterone will be low. when he's on the field, it's sky high. but why are dads soppy at home? the coach's third kid was born just a few weeks ago. have you noticed any changes in yourself since she was born? >> absolutely shattered. >> reporter: human parenting is easier as a two-person job. our kids are so helpless. and that's why men have evolved to drop the alpha stuff, chill out and muck in. but do you remember the 1970s? dads did nothing. my own dad never made me lunch.

he never changed a diaper. i was sent to boarding school at 6 years old. in the 1970s, men flaunted their bits instead of caring for their kids. and now we know that's not natural. >> always an alpha male, always with high testosterone, always out there seeking mates and so forth. that's a very chimpanzee-like version of humans. >> reporter: and health benefits? low testosterone might cut prostate cancer risks. >> no one's looked at it. we haven't thought to look at it. studies like this suggest we should look at it. >> reporter: bottom line this is, in fact, more manly than leaving wife and kids at home to go sky diving or skirt chasing. on the way, chicken licking lucky ducky draky laky met goosy --

>> goosy lucy. >> reporter: goosy lucy. during the first few months of a baby's life, so they say, a dad's testosterone is at its lowest. and my wife just had another one. baby sebastian. so my testosterone right now is in the basement. no carousing for me. i'm at home in the nest like nature says i should be. i'm nick watt for "nightline" in london. >> what a great dad. nature knows best. next up, botox in a stocking? you won't believe what some folks are asking santa for this year. [ male announcer ] if you're intrigued by the hand-selected wood trim... the 38 1/2 inches of legroom... and the reclinable, heated napa leather seats inside the jeep grand cherokee, just wait until we tell you about the heated and ventilated front seats. ♪ ♪

it's a hot new christmas item this year but you can't put it in a box or wrap it with a bow or stick it under a tree and you'll probably have to ask someone other than santa for it. for abc's abbie boudreau, cosmetic yuletide surgery is tonight's "sign of the times." ♪ >> reporter: it's that time of year to get the perfect gift for your loved one. this year, nicole is showing her older sister tina that she cares a lot. she's getting her botox injections. yes, botox. >> i'm hoping to maybe get a purse from my sister. your sister's, like, excuse me, plastic surgery would be great, thank you. what exactly are you asking for? >> i'm getting botox done. the crow's feet around the eyes, that's what i noticed the most.

between the brows and on the forehead. >> reporter: it cost nicole $650 to treat tina with some plumping injection. >> i think she's a little crazy. i don't think she needs it. but i know that she's been wanting it and it makes her happy. >> reporter: tina franklin as bridal makeup artist who says she needed a pick me up after a breakup with her boyfriend. >> living in orange county, the mecca of plastic surgery, you definitely want to do procedures, including botox, to soften but not freeze. you still want to look like yourself. >> reporter: tina put her face in the hands of dr. tenleylaughton, a newport beach, california, plastic surgeon who's busy this year as housewives of orange county get plastic surgery as christmas gifts. women are asking for everything from breast lifts to tummy tucks to full mommy makeovers. what kind of price range are we talking about? >> for a simple injectable, a few hundred dollars. a full mommy makeover, which

could include a tummy tuck, breast lift, breast augmentation, it could be anywhere from $7,000 to $17,000. >> lift up your eyebrows for me. perfect. >> great. >> i'm just ready to start off 2012 kind of -- >> fresh. >> fresh, thank you. >> reporter: looking hot? >> looking hot, yeah. >> reporter: happy holidays, tina. for "nightline," this is abbie boudreau in newport beach, california. >> ooh, i don't know. abc news has launched a new political website, otusnews.com. it's not just another political site. it's the first of its kind political stock market using breakthrough technology to follow the rise and fall of the stock voters put in each politician. find it at abcnews.com. thanks for watching abc news. remember "good morning america." jimmy kimmel is next. good night, america.