captioning sponsored by wnet >> sreenivasan: on this edition for saturday, january 11: iran says the downing of a ukranian passenger plane was"er humar." in our signature segment: a new influx of migrants in the crosshairs of shifting immigration policies. and, neuroscientist daniel ley.tin on aging successfull next, on pbs newshour weekend. >> pbs newshour weekend is made possible by: bernard and irene uehwartz. nd edgar wachenheim iii. the cheryl and philip milstein family. rosalind p. walter. pe zuckerberg. charles rosenblum. we try to live in the moment, to not miss what's right in front of us.

at mutual of america, we believe ting care of tomorrow can help you make the most of today. mutual of america financial group, retirement services and instments. additional support has been provided by: and by the corporation for public broadcasting, a private corporation funded by the american people. and by contributions to your pbs station from viewers like you. thank you. from the tisch wnet studios at lincoln center in new york, hari sreenivasan. >> sreenivasan: good evening, and thanks tor joining us. y, iran's revolutionary guard admitted it dcidentally shn the ukrainian jetliner this past wednesday which killed all 176 people on board. iran previously denied the general in charge of iran's plane was misiden as aid the cruise missile, heading toward an iranian military se, hours after iran fired a barrage of missiles at two u.s. bases in

iraq. >> ( translated ): we are sorry abou at this inciden we consider ourselves mournful just like the famalies of these yrs, and sympathize with them. it is as such that we have lost our own loved ones, and we are regretful about it. after all, this is the price of mischiefs, trbulences and actions of america in the region. , that nig were prepared for an all-out conflict. ( chanting ) >> sreenivasan: there were protests in tehran against the government's admission, after days of denial. some chanted demands for the country's supreme leader ayatollah ali khamen to resign. the ukrainian president, volodymyr zelenksy, tweeted," the perpetrators must be held accountable. we look forward to further legal and technical cooperation." both president zanelensk canadian prime minister justin trudeau spoke with iran's president hassan rouhani and asked for a full investigation. get the accountability, justicee and closure that the families

deserve.iv >> sreasan: the u.s. and other nations are sending teams to iran to assist in the investigation. two u.s. service members were killed and two others were wounded by a roadside bomb in southern afghanistan. the taliban claimed responsibility for the attaro in kandaharnce. peace talks between the group and the u.s. ree in stalled. fense department does not release the names of service members killed in action ubeil family memrs are notified. 23 u.s. troops were killed in afanistan last year. a 5.9 magnitude earthquake struck puerto rico this morningo causing power outages and damage along the island's soutrn coast. this follows a magnitude 6.4 quake that struck before dawn on tuesday. erto rico's power authority said that widespread outages are being reported and crews are assessing the damage. tremors continued this afternooncding during my facebook live conversation with cbs news correspondent david begnaud, who is in penuelas, puerto rico. >> it was the scariest

earthquake, so to speak, that i' felt all week. and listen, this is not hyperbole here, right, this was on the tenth floor, it shook for about 20 secon i'd say, and it was felt across the entire island. >> sreenivasan: you can see our full conversation with david begnaud on our pbs newshour facebook page. taiwan's o-independence and pro-democracy president was re-elected for her s lond term in adslide victory today. tsai ing-wen won 57% of the vote, a showing of widespread support for her tough stance against beijing. tsai's democratic progressive party also retained a majority in the 113-seat legislature. tsai warned china usespeech, force to seize control o taiwan, which beijing views as a renegade provinc tsai holds a law doctorate from the london school of economics, and advocates strong relations with the united states. in southeast australia, two wildfires merged and became what firefighters aring a "mega-fire" last night. this new fire has ready burned

more than 1.5 million res. weather conditions were mder day, but there is no heavy fiin forecast. officials say ths are going to continue for weeks since ey began in september, bushfires throughout australia have burned an area larger than at least 26 people have died. >> sreenivasan: iraq' s government is demanding that u.s. tros leave the country in the wake of the killing of an iranian general, an iraqi other iraqis last week.everal yesterday, secretary of state mike pompeo said the u.s. will not wraitbut is open to discussions. there have been violent protests against both the u.s. and iran in the past few days two iraqi journalists were killed covering one of those protests in baa yesterday. joining us now for more on the situation in iraq is the "washington post's" baghdad bureau chief, louisalo

lo. >> it seems the iraqi leaders here are caught between a rock and t hard place. e one hand, you have the united states who is a force who says they're not going to leave erd they have the pf the military, and then anderson, you've got yourneighbor, iran which is also a significant force in the region. >> when thei iraqisnd themselves in an incredibly difficult position right now, and the politics of this are incredibly heated. it's very imptant not to underestimate the anger at the unilateral military action by the united states on iraqi soilv er the last few weeks. there was the killing of multiple itmen in iraqi military bases. and that has really put pressure the prime minister to t the troops out. the question now, really, is whether-- yoknow, a moment to sort of for cooler heads to prevail or the politics to cool down a little bit. but it's very difficult to know which way that is going to go. >> sreenivasan: we shlaould fy there are politicis in iraq, there are people in iraq who do not want want united es to leav

but that's not the way that the vote was reflected in parliament recently. so what kind of ckroo conversations are happening, let's say in the iraqi parliament, to try to say, okay, we made this particular show, this display of ou anger in parliament. two weeks from now,et's calm down and let's figure out a more moderate solution. >> i think it's very important to distinguish between who holds the balance of power in the parliament and who is actually-- what individual parl minitarians think. when you look at the vote that passed last sunday urging the ime minister to expel foreign troops, it was an overwhelmingly shiite troops, heavily influen part by iranian groups. when you look at the people who voted, the parliament reached quorum. sunni lawmakers barely turned up. kurdish lawmakers barelyturned up. there were threats circulating telling people if they dent vote to expel us. troops they would face revenge of the pesle. so thiscertainly something-- a vote that was very politicized

and not representative of all lawmakers. but these groups do representli the prev balance of power in the country right now, and as you say, iraq is caught between ha rock and aard place. has military allies in the united states. has a neighbor and a much stronger partner in ma right now in iran, and certainly the iranians are winning. >> gl what is the practicalil possy of withdrawing all u.s. troops? are military leaders prepared for that? >> that's big question. i think it's a very real possibility that within the space of a year, we will have had the draw-down of some u.s. troops. the coalition is overwhelmingly are many other nations in it.ere and i know there are certainly people behind the scenes it's europeans-- looking at different types of troop presence which could remain. and the bigssueue, of course, is these troops are explicitly in the country to fight islame.c st they have defeated the islamic state and its caliphate.

but the group is regrouping. it's trying to come back. it's only got the capacity to lach small-scale attacks rightno but the iraqi security forces who have been trained through this entire ford, you knokew, rolling back those gains, keep ete force contained, are not y at a stage where international forces feel they could win that fight alone. should the coalition withdrew in a sort of quickd sty manner, i think there's a real possibility that the islamic state militants in so far as they exist could move from the defensive where they are now, on to the offensive, and that's not hang repercussionsorhe of national security of iraq, the national securityf syria, and ultimately the wider region. >> sreenivasan: thanks so mu. >> thank you. s reenivasan: we've paid a lot of attention in recent years to mexican and central american

migrants entering-- or trying to enter-- the united states by crossing america's southern border, but there's an entirely different cohort of migrants from around the world attempting a similar passage. and these days, they find that journey stalled more than a thousand miles away. newshour weekend's special correspondent nadja drost and erviderapher bruno fedico tapachula, mexico.rt from this story was produced with the support of the pulitzer center. >> libertad! libertad! >> reporter: calls for frchdom and ance to leave what migrants are calling an outdoor prison: the city of tapachula in southern mexico. they've beentuck here for weeks to several months, and they want out. >> ( translat ): no one is going to stop migration! >>eporter: but that's what mexico is trying to do: stop migrants from moving northward on their journey to the u.s. and canada. and while shifts in mexican and american immiation policy are largely targeting central americans,re also affecting those from outside the

western hemunphere, from ies as far as cameroon, india, and pistan. they're known as "extra- continental migrants." with nowhere to live, several hundred, mostly from central africa, have been camping out in front of the immigration detentiocenter. there are no batooms, and there's nowhere to bathe. most everyone is hungry; handouts from a church group just aren't enough. >> ( translated ): we arin a prison here. >> ( translated ): you can't go out. you can't work. >> reporter: this couple and their toddler from the delimocratic repof congo are reselling bread to fellow migrants to get by. the ty're afraid to uir real names, so we're calling them isaac and francoise. they fled political persecution after an anti-government milit group paid isaac's family a visit. >> ( translated ): they got angry and called their commander, who gave them the order tndo kill all of us spare nobody. >> reporter: the militia killed isaac's parents and two brothers, but one militia man

who knew isa hped him and his family escape the country. they flew to ecuador and joined a route used by thousands of extra-continental migrants who usually land in ecuador orsa brazil, where equirements are relatively lax.xi on the way to , they must cross a thick, roadless jungle that strades the border between colombia and panama called the "darien gap." >> ( translated ): it was like hell to me. i never thought i would be able to get out of it because i saw other friends dying. >> reporter: they spent 1days crossingungle and rivers, but when they made it to mexico, isaac and francoise hit a roadblock. until recently, mexichad little interest in stopping grants froinental mi traversing the country to reach tht u.s. border. en, in the summer of 2019, the u.s. threatened mexico with tre riffs it didn't drastically stem the flow of

migrants. mexico clamped down, sending 6,000 national guard troops to in effect, the country was doing the american president's bding, says lawyer and activist luis villagran. >> ( translated ): this is where donald tlrump's w starts. for a migrant who flees their country, more so for o carrying kids who are trying to get by day by day, they are seeing that trump's wall starts here.>> eporter: the national guard attempt to intercept migrants withoudocumentation crossing the suchiate river into mexico. some get past the soldiers to reach the city, but for those trying to continue north from tapachula, rseven more barr await. behind me is one of the many checkpoints that surround the city of tapahula, where immigration officials search vehicles and apprehend any migrants and asylum seekers who don't carry the necessary paperwork to cross mexico. the checkpoints are part of expanded immigration enforcement throughout the country, says

luciana gandini, a professor the national aouutonoms university of mexico, who coordinates a center for migration studies. >> ( translated ): on the one hand, they're increasag enforcement the border. but that's not enough, so they're also implementing a containment straty order to comply with some of the strategies the u.s. is asking for. >> reporter: over 13,000 extra-continental migrants registered with immigration authorities last year through november. many more haven't registered. many don't read or spink spanish, meverything from negotiating prices to understanding immigration papers challenging, inot impossible. they try to get by however they can. tembo yumbu t hair for 14 years in his native democratic republic of congo. aw, he's transformed this patch of pavement intooutdoor barber shop. >> ( translated ): most of my clients are congolese, cameroonian, angolese, guinean

and malian bthers. >> reporter:umbu's razor and pair of scissors have given him ans to subsist and carry on the long journey from congo. it's tan him seven months so far. >> ( translated ): but this is the kd of trip that never ends. in order to not overthink and eel a lot of pain, that's why i'm here and doing this. but we hope that one day, we will find so open doors. >> reporter: extra-continental migrants trying to resolveheir status say they come up against administrative delays and confusion at the immigratione cer. >> ( translated since we've been here, migratioid authorities they had no solution for us. >> repor ater: the few interpreters, meaning they often can't understand their options. so, they're shfled, week after week, month after month, from one government office to another. >> ( translated ): you think that thewill give you the documents when you go to the appointment, but it's another >> (itranslated ): it's always another appointment.ep >>ter: mexico's national migration institute, which

applies migration policy down newshour weekend's request for an interview. so did the ministry of external relations, which has negotiated agreements with the u.s. to curb migration. for lawyer villagrán, the delays migrants face aren't justma a er of bureaucracy. >> ( translated ): in the case of people from africa, they tell them they have to leave by thsouthern border. they know they won't leave, so they're stranded here. they're in immigration limbo. >> reporter: the only way extra-continentals can legize their stus is to apply for asylum or permanent residence to stay in mexico, but very few want to stay. osama mahyoub, who says he fled death threats in his native yemen, speaks for many. >> ( translated ): i don't want to ply for asylum in mexico. my goal is to arrive in the u.s.a. here in mexico, we are afraid. the gangs frighten me.

there are a lot of them. there'a lot of mafia in mexico. >> reporter: he pays for a shared hotel room using money he earned working in ecuador before headingor. the longer he stays, the quicker it'll run out, but he doesn't see a way around it. >> ( translated ): i will wait here ummntilration authorities find a solution with the americans for the migrantsin his city. >> reporter: but mexico's stance on migration appears only to be hardening. in an october speech, immigration chief francisco garduño announced thfit-ever deportation of extra-continental migrants, sending home 300 from india. and he warned of more to come. ( translated ): this is a notice for all transcontinental migrati eon, thn if you're from mars, we'll send you back. we'll send you to india, to cameroon, to africa. >> reporter: meanwhile, tapachula has become a pressure-cooker. >> ( translated ): we've been blocked here for four months in terrible living conditions without food, without work!

we've d enough of this story with immigration authorities. these people are demons! >> rorter: some extra- continentals head west to the coast, joining those who resort to paying smugglers take them out of southern mexico by sea. recently, a boat carrying 25 capsized, triggering mexican security forces to carry out a search and rescue mission. one cameroonian was found dead here after fellow migrants had tried to resuscitate him. all told, the ocean waves brought fouread cameroonians to shore. despite the dangers, extra- continental migrants will continue to head out on these waters if it's the only way to reach their destination. >> sreenivasan: it's estimated that 70,000 baby boomers reach

retirement age every week. but life at retirement age is not what it used toe, according to neuroscientist daniel levit. in his latest book, he explores what happens in the brain as we age, and why some of us age better tn others. newshour weekend's christopher booker recently spoke to levitin to learn more. >> reporter: daniel levitin, a neuroscientist and professoryc emeritus of logy at mcgill university, has written extensively about the brain. also a musician, he has written bestselling books examining the tofect of music on the brain, as well as about hohink "straight" in an age of information oveinrload. evitin's latest book, "successful aging," he exor the questions: what happens in the brain as we age, and what are the keys to aging well you set out to write this book, you said, because you had questions of your own. what questions were you looking to answer? >> i looked at people like my rents, who are in their 80s and very active and engaged. they-- they tire me out.

( laughs ) and people like jane glloo or rodney crowell, still only in his 60s but i think doing the best worof his career. paul simon, who i think did the best work of his cinareehe last five years. what are they doing? where-- where does thicome from? i wanted to know. i wanted to get some of that for me. >> reporter: how have your views changed about your own aging process?e >> ime to see aging as not inevitably a period of decline and loss and irrelevance, but a period of potentiallrenewed engagement, energy and meaningful activities. getting older myself-- i'm 62-- i'm spending more time with older people who are just marvelously entertaining, full of life and full of activity.

>> reporter: in researching the about the aging process to everyone from former secretary oftate george shultz to jazz legend sonny rollins to the dalai lama>>. think the main source, main strength is that i'm a you see, every day is filled with praying and thinking. my body, speech and mind, dedicated to wellbeing of other. >> one of the things that emerged in my research is tt, as we age into our seventies and eighties, we're a lot better at some things thanyounger people. and one of them is-- is pattern matching. if you go to see a radiologist, you want a 75-year-old radiologist-- not a 35-year-old raologist-- because they've seen patterns. they're much better at detecting cancers. >> reporter: does the expanded ability to recognize pattern, does it ke it harder for people to change their views or

to maybe look at something differently? >> ican, and you have to fight that. i think that we have to avoid complacency as we get older because we do tend to get set in our ways.we end to want to look at things the same way. we want to go to the same restaurant that we know is going to give us a good meal. we want to hang out with the same friends who we know are not ing to make us feel bad about ourselves. but we havto fight thatux because the inf new ideas and challenging our conventional mos of thinking is important brain food, not just our invidual health but the health of the larger community. >> reporter: your number one recommendation of your top ten things to do, number one was "don't retire." >> yeah. jane goodall said this. you kn, she said, "don't retire. keep going. but," she said, "if you retire,r makeyou have something equally compelling that will engage you you know, that could be philanthropy. it could be education.

>> sreenivasan: for more with daniel levitin, watch here or online at www.pbs.org/newshour. >> reporter: let's talk about sleep. thse's a lot of misconcepti about sleep as we get olde >> the myth is, "oh, old people "don't need as much slee total myth. the fact is, old people do need eight or nine hours of sleep. the dalai lama attributes a lot of his healtto nine hours of sleep every night.bu as we get older, a lot of the hormonal and chemical changes in our bodies make our biological clocks harder to keep regular. so, just staying up an hour or twlater when you're older an affect you for weeks. time every night, waking up atme the same time every morning, particularly after the age of 75, very important. >> reporter: why do some people age better than others? >> some of it is genetic. some of it's environmental. if you had stressors, early

stressors as a child, that's going to play against your fortitude and composition. but the good news is, we can overcome that. genetics is not a-- a prescription. genetics is just an influence, like your childhood, and you can rebuild yourself. >> reporter: because that's one of the other key points, is that essentially it's never too late. >> yoelu can change youat any age. that'd s-- that's the gws. you-- you can look at your life when you're 75 and say, "i'm going to do something different," ant. if you look across the world, across the 60 countrie that have been studied, the peak age of happiness t8ds to be about 2. people get happier. now, there's a neurochemical sis for this. your neurochemistry shifts. but there's also kind of a psychological and very practical basis. you-- you realize you've l tten through ese things that were stressing you out. if you make it tou2, you know, 've managed.

you're-- you're okay! re >>ivasan: that's all for this edition of "pbs newshour weekend." i'm hari sreenivasan. thanks for watching. have a good night. captioning sponsored by wnet captioned by access.wgbhrggroup at wgbh >> pbs newshour weekend is made possible by: bernard and irene schwartz. e and edgar wachenheim iii. the cheryl and philiammilstein y. lter.lind p. wa barbara hope zuckerberg. charles rosenblum. we try to live in the moment, to not miss what's right in

front of us. at mutual of america, we believe acan help you make the most of today. financialf americ group, retirement servis and investments. >> when it comes to wireless, consumer cellular gives its customers the choi. our -contact plans give you as much or as little talk, text and data as you want. and our u.-based customer rvice team is on-hand to help. to learn more, go to wtvww.consumercellula additional support has been provided by: t and corporation for public broadcasting, a private corporation funded by the american people. and by contributions to your pbs station from viewers like you. thank you. you're watching pbs.

nawaz: the oceans swimming in it. rivers are choked with it. coastlines are collecting it. ndfills are clogged with it.tr ouh bags are filled with it. and it's even floating in the a wr:breathe. geye imagine spreading out 9 billion metric tons evenly, we could cover an area the size of argentina or california siximes over. nawaz: it's plastic: the material we can't seem to live without, that also lasts longer than a lifetime. plastic n take hundreds of years to break down, and even then only into micro parties. it's hurting animals, it's in our food chain, plastic, and even then only intois everywhere.. (theme music plays)