involving first lady michelle obama's plane. >> ifill: we update the war in libya. judy woodruff interviews the top u.n. official for humanitarian affairs about the shortage of food and medicines. >> lehrer: and we close with the third in robert macneil's "autism now" series. tonight: deciphering the causes of the disorder. >> i don't think there's any one cause of autism. i would lay money that we will not find one thing. we certainly haven't found one gene; we're finding hundreds of genes. >> lehrer: that's all ahead on tonight's "newshour." major funding for the pbs newshour has been provided by: in 1968, as whaling continued worldwide, the first recordings of humpback songs were released. ( whale singing ) public reaction led to international bans. whale populations began to recover. at pacific life, the whale symbolizes what is possible if people stop and think about the future. help protect your future with pacific life-- the power to help you succeed. >> and by the bill and melinda gates foundation. dedicated to the idea that all people deserve the chance to live a healthy productive life. and with the ongoing support of these institutions and foundations. and... this program was made possible by the corporation for public broadcasting. and by contributions to your pbs station from viewers like you. thank you. >> lehrer: it was a year ago today that the gulf oil spill erupted. when it ended, 87 days later, more than 200 million gallons had spilled into the sea. a few vigils marked the day, while cleanups continued. meanwhile, the people of the region tried to move on. from the skies above louisiana's gulf shoreline today, much of life appeared normal. speed boats raced across the open water and pelicans went about their business. at the same time, crews were still cleaning remnants of oil along the marshes, in a clear reminder of the b.p. spill. and, officials like governor bobby jindal stopped to recall the events of the last year. >> today, should certainly be a day where we take stock of how far we've come, but it also should be a day where we look back and remember the heroes that allowed this state to recover and get back on its feet. >> lehrer: it was april 20th, 2010, when b.p.'s "deepwater horizon" rig exploded, 40 miles offshore, killing eleven workers. b.p. took some of their relatives on a fly-over today. the rig sank two days after the explosion. and at first, officials suggested the threat of an oil spill was relatively small. but within days, a gusher of oil was discovered a mile below the surface at the damaged well- head on the ocean floor. over the ensuing weeks, the oil sullied wetlands and wildlife along vast swaths of shoreline from louisiana to florida. b.p. and its hired crews tried to corral or burn the massive slick. they also scattered dispersant chemicals from the air and injected it into the spouting oil at the well-head. meanwhile, the effort to stop the leak went on in halting fashion. submersible robots tried and failed to shut off key valves or somehow contain the oil. finally, in mid-july, a cap was installed, allowing b.p. to control the spewing oil and pipe it to the surface for collection. and two relief wells were drilled to choke off the damaged well with mud and cement. the well was officially declared dead in september. in all b.p. says it has spent billions of dollars on containment, cleanup and damage payments. but today, governor jindal said it had not been enough. >> certainly, we continue to call on b.p. to fulfill the promises of their ads. we continue to call on b.p. to truly make it right. >> lehrer: in the meantime, new standards have been put in place, including increased preparedness for emergencies and more testing of back-up measures, such as blow-out preventers. but pressure to resume deep sea drilling in the gulf has built steadily. a federal moratorium-- imposed after the spill-- was lifted in october. since then, new deepwater drilling permits have been issued for 11 wells in the gulf. >> ifill: late today b.p. fired a federal lawsuit against maker of the blowout preventer that spaled to stop the spill. the suit charged a faulty design. even a year later, bitter disputes over money and compensation claims remain, as many businesses struggle to recover. "newshour" correspondent tom bearden returned to the gulf coast and filed this report. mayor of gulf shores, alabama. the city's white beaches turned brown before the well was finally capped, and the tourist industry all but shut down for several months. >> with good tourism, we'll survive. >> reporter: robert craft is the mayor of gulf shores. >> we have finished the cleaning of the beaches and obviously the oil is not coming ashore anymore so as you see, we've got tourists back and we're looking forward to a good season. >> reporter: real estate agent emily gonzalez says those condos are filling up, too. >> we're actually cautiously optimistic about our summer. we've seen a rebound from the deficit that we had last year with a lack of rebooking simply because our numbers were down with oil on the beach. >> reporter: people in the seafood industry are also encouraged. that includes keith blalock who runs a retail store and distribution business that supplies seafood to over 30 local restaurants. >> i feel bet they are spring thanive in a long time because it seems like things are starting to get better. >> reporter: just beneath all this optimism, though, is a great deal of anger at the process that was set up to distribute the $20 billion that b.p. put aside to pay damage claims. people say it's arbitrary and completely unfair. the fund was set up after pressure from the obama administration and is meant to compensate people directly affected by the spill. shrimpers, fishermen, restaurant owners, anyone who lost income. >> i'm here primarily to listen to what you want to tell me about this oil spill. >> reporter: kenneth feinberg was appointed by both b.p. and the goverment to administer the fund. he says he is completely independent of both, but some people we talked to didn't think so. among them, walton kraver who attended one of feinberg's meetings last summer at bayou la batre, just across mobile bay from gulf shores. kraver owns several seafood- related businesses. >> we're running out of money quick, ok? and we have already closed one business, ok? >> i will check on that claim, even though i'm not up and running yet, and try and accelerate the payment of that claim. >> reporter: kraver's son, patrick, and daughter-in-law lillie say feinberg promised to personally get back to their family--but never did. >> mr. feinberg promised us personally at a meeting with my dad and he pointed his finger at him and mr. kraver he said you are directly affected we need to get you some money quick. six months later after we had to call him and say look this is getting out of hand we've got to have some money now and we submitted a figure that was correct and then they called back and they lowered the figure and then they called back again and lowered it again and finally they sent him about 40% of what we were supposed to get. >> reporter: we asked feinberg about that recently in his washington, d.c. office. you responded to them by saying i'll look into it and i or somebody else will get back to you. at least four people we spoke to at those meetings said no one ever did. // >> well if that's the case than i've overstated the case and i bear some of that blame. i mean it may be that there are claimants who stood up at a meeting and i made a commitment and i haven't got back to them there may be situations where i failed in that regard. i'm the first one to say i may have failed in that regard. >> reporter: feinberg says people were paid for what they could document, and that $4 billions has already been paid to about 300,000 people. that's out of a total of about 800- thousand claims. pete blalock got emergency funds from the claims office, but says he had to fight every step of the way. >> you battle them, and you battle them, you do the process like they say to do, use their formula, i used accountants from day one and i said take it where the numbers take it whatever the formula is and so you do that and then they'll send you back .50 cents, .25 cents on the dollar. and they won't tell you why >> reporter: we asked asked blalock how he thought the claims process was working. >> you know when mr. feinberg first took over this process i had great faith in him. and more and more i realized that he nothing but an employee of bp. >> reporter: harsh words. >> and i don"t think you will find hardly anybody down here that does not believe that. >> reporter: feinberg rejects the assertion that the process is arbitrary or that he works in any way for bp. >> i think the only way i've said this over and over again the way that you demonstrate credibility and the success of the program just what the justice department asked me to do is the money going out? is it going out quickly? is it going out in a generous fashion in a fair way? i think the answer to that is yes. >> reporter: another consistent complaint is a perceived discrepency in payouts. people with direct claims -- like louisiana shrimper acy cooper -- say they got very little, while oters with only tenuous claims were paid handsomely. >> well we got bellboys in new orleans, we got waitresses, we have all kinds of people in new orleans got money and received money and $20,000 - $30,000 now they give them $25,000 for the final settlement, they probably never lost a penny. stop giving money where it dont belong and give it to the true fishermen the guys that really lost. >> there may be some perceived inconsistency when at waiter who is working next to you get $8,000 and you get $2,000. right away the $2,000 claimant how come. it's arbitrary. it's not arbitrary. that $8,000 waiter has submitted tax returns, or documents confirming what he or she is entitled to and the other claimant has not done that. now there may be some inconsistencies i'm the first one to acknowledge error. when you've got 800,000 claims and out there is bps promise to pay $20 billion everybody files. >> reporter: cooper says most of his members did have the correct paperwork--but still got less money than people whose income didn't come directly from the gulf. feinberg says the emergency claims process ended last november, and has moved on to offering final settlements. if the offer is accepted, the recipient gives up the right to sue bp for future damages. mayor craft says the final settlement offers are too low, and he thinks that's deliberate. >> i do believe its a fact that the businesses here are so stressed down, reserves are gone that i think they are going to be tempted take whatever is put on the table. and i don't know if that was a strategic plan or not but that's what's going to happen im afraid and when they take that money to final payment they've got to release b.p. totally from any past losses and any future events that were to happen. >> reporter: pete blalock agrees. >> what they are trying to do more than anything is just wear you down. and the'yve succeeded i think they've succeeded to a lot of people down here they just so tired of the process that they want to get it done, get past and get them out of their lives. and quite honestly i'm right near that stage in my life. >> i think there is plenty of room to improve the program but this notion that there is a perception that the program is merely designed to prevent people from suing or really is designed by b.p. to hush them up or whatever is absolutely un- categorically not true. i wouldn't be doing it if that was the case >> reporter: going forward, feinberg thinks public perception will change for the better. >> there is a goal in the second year of this program to do our best to modify or alter a perception that there is some hidden agenda here. there really is no hidden agenda. the agenda here is open and transparent $4 billion transparent $4 billion demonstrates it. i think. we want to pay people. we want to pay them promptly. we want to pay them fairly. that's the goal of the program. my credibility is on the line. i mean i'm really determined to continue to do that. >> reporter: but given the hard feelings we encountered in the gulf...that will be a very tough sell. "newshour": transportation >> lehrer: still to come on the "newshour": transportation secretary ray lahood; the humanitarian crisis in libya and the causes of autism. but first, the other news of the day. here's hari sreenivasan. >> sreenivasan: wall street had its best day in a month-- just two days after a warning about u.s. debt caused a sell-off. today, stocks shot higher on strong earnings by intel and others. the dow jones industrial average gained more than 186 points to close at 12,453-- its best finish in nearly three years. the nasdaq rose 57 points to close at 2,802. and the price of oil surged back above $111 a barrel. it's up 20% since the start of the year. thousands of students in syria demonstrated today against the government and organizers planned huge rallies for friday. more than 4,000 students gathered in daraa and surrounding areas. there were also protests at aleppo university in the north. the government of president bashar assad has cracked down on protesters, with more than 200 killed in recent weeks. yesterday, assad ended nearly 50 years of emergency rule, but also warned against more protests. in yemen, gunmen on motorcycles sprayed bullets at hundreds of anti-government protesters in a red sea port city. at least one person was killed and several others were wounded. meanwhile, thousands of people also demonstrated in sanaa, the capital. they chanted slogans demanding again that president ali abdullah saleh step down. later, saleh assured his supporters he won't be ousted by what he called conspiracies or coups. a new terror alert system was unveiled today in washington. it replaces the old five-step, color-coded alerts with two threat levels-- elevated and imminent. the national terrorism advisory system or n-tas will provide details on terror threats and recommend steps the public can take. the secretary of homeland security janet napolitano spoke today in new york. >> we want people to live in a state of alertness and awareness. and we want people to know how they can help themselves, how they can assist their community. and one way to do that is to provide people with more information and more ways to access information. that's what the ntas is designed to help do. >> sreenivasan: officials will begin posting the alerts on facebook and twitter, starting next week. there was word today that millions of dollars in donated malaria drugs have been stolen in recent years. the associated press reported the medicine was taken from the global fund to fight aids, tuberculosis, and malaria. the report cited internal documents from the group. they said drugs have disappeared in 13 countries, mostly in africa. those are some of the day's major stories. now, back to gwen. >> ifill: federal officials set out today to dispel new concerns about the safety of air travel, following a highly publicized episode with the first lady's plane. the latest incident involving air traffic controllers occurred monday. that's when first lady michelle obama and jill biden-- the vice president's wife-- flew from new york to washington after appearing on "the view." as their boeing 737 military jet --- a smaller version of air force one-- approached andrews air force base in maryland, it was allowed to get within three miles of a c-17 military cargo plane landing ahead of it. a five mile distance is required to avoid turbulence caused by the wake of the giant cargo jets. >> if an airplane is too close behind another airplane, the small tornadoes that come off an airplane in front can actually upset the airplane playing behind and cause the airplane flying behind to lose control >> ifill: in this case, the virginia-based civilian controllers' orders were overruled by military controllers at andrews. the first lady's plane was directed to make several turns, circle and make a second approach. officials said neither plane was ever in serious danger. but the attention-getting mishap is the latest in a series of embarrassments for the federal aviation administration. it had already suspended nine air traffic controllers and supervisors over the past month, including some who fell asleep during late-night shifts at washington reagan national and elsewhere and one outside cleveland who was watching movies on the job. >> none of us in this business can tolerate any of this. it absolutely has to stop. i was absolutely infuriated when i heard about the first one or two. but as we began our review it became even more frustrating and more disappointing to me to see what has happened here. >> ifill: over the weekend, the f.a.a. changed their rules to allow controllers nine, instead of eight hours off between shifts. the stories of fatigued and distracted controllers have touched a nerve with the flying public, and the national transportation safety board has now launched its own investigation into the close calls. for more about these aviation troubles, we turn to transportation secretary ray lahood. his job includes oversight of the faa and he joins me now. welcome, mr. secretary. let's clear up first what did and what did not happen with the first lady's plane. >> well, it was too close to the cargo plane and that was disclosed and the controller that was in charge made sure her alleviate any kind of that backup wind that the consultant was talking about. i want to assure everyone that mrs. obama was never in any danger. there other members of the flying public... did other members have reason to worry when they see tail and tail after tail tale after tale after tale about these kinds of mishaps? >> gwen, what i would say to the flying public is that we have the safest aviation system here in the united states anywhere in the world. but we have to do better. we are doing better: we're conducting investigations and i'm prepared to announce tonight that we have fired two controllers after completing two informations. we're also changing proceed yours have having to do with the vice president and first lady's plane when they're flying in and out of washington airspace. so i would say that flying is safe but we need to do more and we are doing more and we'll continue to do more until we make sure that controllers take personal responsibility for the most important safety jobs they have. we're doing a top-to-bottom review of procedures, workplace procedures and other things that you've already announced tonight tonight some of the other things that we're doing and i'm telling the flying public, we take it seriously and that's the reason i'm announcing two controllers have been fired. >> ifill: that's two of the nine who we mentioned in the piece. >> that's correct. >> ifill: do we know where they were? >> miami, florida, where the controller had guided a 737 southwest flight to take a look at a small plane that was out of radio contact to see if something was going on. completely violate prose seed yours. you can't guide a big plane over to look at a small plane. that's not the way that's done. also in tennessee where a controller actually made a bed in the control tower, brought a pillow, brought blankets. he's been fired. we're not going to sit by and let that kind of behavior take place in control towers. >> reporter: how widespread problem is fatigue? that seems to have been a factor in so many of those cases. >> we've extended rest time. we've listened to what controllers have told us and we've expanded rest time for from eight hours to nine hours. our administrator is out around the country talking to controllers, talking about workplace, talking about rest times. if we need to do more, if we need to extend it, we'll do it. we're not going to just sit by and continue to do things the way they've been done in the past. if changes need to be made, we'll make them. >> ifill: are we hearing about these incidents now because they're happening more or because they're being reported more often? >> well, gwen, i've been this this job for two and a half years and the first time i've heard about a sleeping controler is when it happened in washington national airport. and we've had a spike in these reports. >> ifill: the first time you've heard about it but how do you know it hasn't happened? >> because i hadn't heard about it and i think if it had happened we would have heard about it. this is a very serious safety violation when these controllers are sleeping in control towers and i think we would have heard about it. >> ifill: more broadly, are you concerned at all... we are now in 2011. it was in the early 1980s that all of the air traffic controllers were fired and replaced with brand-new folks who now are reaching retirement age. are you worried you're about to lose the experience that you do have? >> well, what we're trying to evaluate is to make sure the training program that these new controllers have been through is the proper training. do we need to do more? that's the top-to-bottom review. and we're also looking at workplace situations like the number of hours they're working, like the rest time which we've expandd from eight to nine hours. we're looking at everything. we will continue to work 24/7 to make sure we get it right and we're working with controllers to help us figure this out. fill fail lot of people who travel a lot-- or even a little-- are far more concerned about things which affect them every single time they travel, like whether they're paying the right amount for their bag fees, whether they're stuck on a tarmac, whether they're getting their money back when their planes are canceled or they're bumped off a flight. today you announced some new rules. could you explain them to us? >> absolutely, if you pay $25, $30, $40 for a bag and it doesn't make it to the destination, you get your money back. that's not the case today. when you go on your web site at home to buy a ticket, we want to make sure all the costs are disclosed: taxes, pillow fee, blanket fee, food fees. they're all there. fill nail will be a long list there on the web site. >> there will be a long list because airlines are charging more for all of these so-called things we've taken for granted. that's number two. number three, if you're on an international flight and are on the tarmac for four hours you go back to the terminal. we implemented that with domestic flights. it's worked very well. we have decreased dramatically tarmac delays as a result of that. if you go to the ticket counter with your ticket, who's ever there at the airline says oh, by the way, we overbooked this flight and you've been bumped, the airlines have to repay you the amount of money that you paid for the ticket plus an additional fee on top of that. those four things we think go a long way to say to the flying public "we felt your pain." all of us fly, and we know that this is a real problem for the flying public. >> ifill: let me ask you about one of those things, which is the tarmac delays. won't that increase cancellations of flights if after four hours rather than sitting there four and a half hours you have to take the plane... they decide to take the plane back to the gate? >> the enforcement we announced was for international flights which is kind of the tip of the iceberg for us was last december when all these flights were delayed. we implemented a domestic tarmac delay three hours and there have been very little delays as a result of it. airlines said there would be, we didn't agree with that, and there haven't been. so the airlines have fit their schedules and people have become accustomed to this idea that we're not going to let people sit on a tarmac for three hours. >> ifill: this all goes into in effect august. >> that's correct. >> ifill: secretary ray lahood, thank you for joining us. >> thank you, gwen. >> lehrer: now, the latest on the fighting in libya. there was more today in the city of misrata, at least five more people killed. government forces have besieged rebels there for nearly two months. we begin with a report from jonathan miller of "independent television news," who is in tripoli. >> reporter: misrata's city center is the front line on the battle for survival. the front line in the war against the dictator colonel moammar qaddafi. ( gunfire ) the detritus of nearly two months of heavy fighting littering the city streets it's their last major stronghold in western libya. many hundreds have been killed. now doctors say the majority civilians of misrata's 300,000 400,000 people life is getting harder by the day. there's a lack of food, medicine, safe water, no electricity. cluster munitions made in spain have been widely filmed and their use documented by human rights groups. these are lethal weapon, each carries 21 high explosive bomblets. today the u.n. human rights commissioner, a former war crimes judge, said their use against a civilan population could constitute a war crime. the libyan government denies they've even got them in their arsenal. as the libyan rebel leader traveled to paris to met president sarkozy who promised to intensify airstrikes on qaddafi's army, we escaped our house arrest in a tripoli hotel to meet a rebel fighter in the capital. we were taken to a safehouse in the city. we cannot verify that this man is who he claims he is, but he took an enormous risk to meet us. >> ( translated ): we have enough guns we have cells in every area of the capital. we make contact with rebels in the east in misratah and zawiyah. when we attack checkpoints, we kill soldiers and take their weapons. our aim is to kill qaddafi. we will get rid of him. >> reporter: responding to an appeal by libyan's foreign minister, the tripoli insurgent said, "no. no more chances. qaddafi had 42 years and it's too late now." ( gunfire ) as the battle rages in misrata, news from libya's western mountains on the border with tunisia that 6,000 villagers, mostly ethnic berbers, have fled heavy shelling by qaddafi's forces. moammar gadhafi pledged to fight to the last bullet. he seems far from running out of those. >> ifill: france said today it would step up air strikes on libya and send military advisers to help the rebels. and the u.s. announced $25 million in non-lethal aid for the rebels. judy woodruff has more on the humanitarian situation in misrata. >> woodruff: for an update on the dire conditions, we go to: valerie amos, the united nations under secretary general and emergency relief coordinator just back from a trip to libya. she is a former cabinet minister in the british government and leader of the house of lords. valerie amos, thank you very much for being with us. you are just back from this trip. what can you add to what ordinary libyans are living with right now? >> well, of course it's a terrible situation in some parts of the country. not just misurata but elsewhere where the violence is very intense, fighting is going on, and we're not able to get aid to the people who need it. i called for a cessation of hostilities, a temporary cessation, so that those people who are feeling really insecure and unsafe could leave so we could get aid in so we could help people who need medical help and we could do an assessment to find out exactly what is happening. that was turned down when i spoke to the prime minister, but i did manage to get agreement to travel to misurata by road. we have not been able to do that because there are checkpoints all along that road and, of course, when you get to misurata the fighting the intense. they've guaranteed our security so we're trying to get a small team into tripoli by this weekend and then to see if we can get to misurata itself. everyone is extremely concerned about the situation there. >> woodruff: so you're saying they gave you permission to get into misurata but you're not able to do that. so what's the meaning of the agreement? >> well, we have to get our people in, our supplies first. we're going to do that this weekend and then we'll try to get misurata from there by road. we will also go in by sea, security situation permitting. but this is a conflict zone. you can see that from the pictures on the television screen so getting in is not going to be easy. we've managed to get aid just into the port area sometimes when the fighting is not as intense and we're able to get in and we've been able to get food and medical supplies in, but they're desperately short of people and we need to be able to go into misurata itself rather than just the port area to find out for ourselves exactly what is going on. so getting the assurances that there will be security guarantees along the road so that our people can get is extremely important. but, of course, the security situation will determine how much we can do. >> woodruff: now, you've also pushed for an end to the use of cluster bombs and other deadly sorts of weaponry. what sort of success did wuf that? >> well, the governments flatly denied that they were using cluster bombs. i made sure that they understood that as a government they had a responsibility to look after the safety and security of their own people and raise the issue of cluster munitions but they flatly denied that they had them or that they had used them. >> woodruff: did you get the sense that you were able to make any head way in your conversations with representatives of colonel qaddafi? >> well, we got an agreement that we could establish a humanitarian presence in tripoli and that there would be security guarantees to ann able us to get to misurata. that's a degree of progress. the test of that will be in its implementation and that's why we're putting together the details of the team to get them in this weekend. we have to do everything we can to get to those people. they are in desperate need and we must remember it's not just misurata, there are other cities and towns that are... where fighting is going on including a town where over 6,000 supreme now fled to the tunisian border. >> woodruff: valerie amos, what else do you need in order to get help to the people in misurata and these other areas or to be able to get them out to safety. >> we need the fighting to stop. people need to appreciate and understand that it is innocent civilians who are suffering. they don't have water; they don't have electricity; they don't have food. they are being held in a situation by the violence. they are too afraid. and you can see why because if they come out, they are under intense shelling. the fighting has got to stop. >> woodruff: and is one side or another more responsible or are they equally responsible at this point? >> my call is on all parties to the conflict. i cannot take sides in this. as someone who is dealing with the humanitarian situation, the important thing is to talk to whoever i need to talk to to try and bring in intense fighting to an end so that we can get aid to the people who need it. that is my goal. that's what i've got to try to achieve. i know that there are others of my colleagues who are working very hard to bring to an end the situation through political means. they have to continue to do that. i have to do my job and try to make sure that people remember that it is innocent children, women, men, families, who are suffering as a result of this violence. >> woodruff: valerie amos, undersecretary-general of the united nations, we thank you very much for talking with us. >> thank you >> lehrer: finally tonight, story number three in robert macneil's "autism now" series. this one is about the search for the causes of the disorder. >> reporter: as we have reported, autism now affects one american child in 110. last month, a committee convened by public health officials in washington called it a national health emergency. the dramatic rise in official figures over the past decade has driven a surge in scientific research to find what is causing autism. one of the centers of such research is the u.c. davis mind institute here in sacramento. here and around the country we have asked leading researchers how that effort now stands. among them were the mind institutes director of research, dr. david amaral. >> well, i think we're close to finding several causes for autism. but there's-- i don't think there's going to be a single cause. >> reporter: the science director for the simons foundation in new york, dr. gerald fishbach, dr. martha herbert, professor of neurology at harvard medical school, and dr. craig newschaffer, professor of epidemiology and biostatistics at drexel university in philadelphia. i asked first how close we are to finding the cause of autism. >> we're much closer now than we were five years ago. there's been a tremendous amount of new information and discoveries but with any disorder as complicated, as multifaceted as autism. i'm reluctant to say how close. >> everything we know about autism is that there are multiple genes that confer risk. the children have various co-morbid problems. and everything we know looks like this is a multitude of disorders all under the umbrella that we call autism spectrum disorders. >> well, to begin with, i think there probably is no cause of autism. we're probably talking about multiple causes. and i think we already have identified some causal components on the genetics front. but if i can interpret your question as a complete understanding of all of these complex causes of autism, i think we're still quite a ways away. >> reporter: some people we've talked to say, "we are on the verge of big discoveries." others say, "we're just scratching the surface." where do you think we are? >> i think we're scratching the surface of big discoveries. ( laughter ) >> i think it's somewhere in between. at the brain level, i think in the last five years, we've figured out that there's a coordination problem of the different parts of the brain not hooking up in as synchronized of a fashion. the question, for me, is why is that happening? >> reporter: the autism puzzle is proving to be immensely complex. but i asked what hunches they have on where the answer will be found? >> clearly, 30 years ago, we didn't know any genes that conferred risk of autism. now, we know that there's at least 20 or more. that seem to be associated with autism. the... the interesting, though, is that any particular gene that you might find that is related to autism, is only related to about 1% to 2% of the cases of autism. so there-- i think what's clear now is that there's not gonna be a single autism gene. but there are many, many. >> well, i think many people feel that autism is a problem in communication between cells in the brain. now that's saying an obvious truth. the brain is a communicating organ. we take in sensory information. we put out motor actions. and in between, there's the whole phenomena of perception, understanding and digestion of that information. it's the phenomenon of synaptic transmission. i-- and my belief is we will find root causes of our autism at particular synapses in the brain. >> well, i think it's going to be a combination of... of... of continued good work on the... the genetic side of things. i also believe, however, that there are going to be causal components that are non- heritable genetics, things that we refer to as environmental causes, with a capital "e," environment encompassing lifestyle factors-- exposures, things of that nature. and those were by the way, we're... we're... we're still at the very beginning stages. >> i think a lot of things. i don't think there's any one cause of autism. i would lay money that we will not find one thing. we certainly haven't found one gene; we're finding hundreds of genes. we're finding boutique genes. we're finding genes that the kids have that the parents don't have-- their own parents. i think that there are a lot of things, environmentally, that are overwhelming our ability to cope, metabolically, that are overwhelming our immune system. and the synergy-- the collective impact of that is to deplete our protective systems. and i think that's what's causing autism. >> but i think the emphasis on genetics probably has been correct, at least as we think about the unfolding of our understanding of what causes autism. and i think over time, we realized that in addition to these genetic components, there is room for and probably just cause for investigating the environmental. so we're swinging around. >> first, there's no question that autism is a genetic disorder. that does not mean the environment is not tremendously important because it is also clear that the genetics are complex. we're looking at the simons foundation for what are called de novo mutations, mutations that arise anew, in the germ cells of one or the other parent, sperm or egg, because it appears that these de novo mutations have a very big effect, a very profound effect. in the jargon of geneticists, if you have the mutation, you have a great risk of developing autism. >> i think that what you have is, yeah, definitely a question of toxics and toxics in our environment, that some of them act like our own molecules, like hormones, for example. that's called endocrine disruption. some of them confuse our neurotrans-- get confused with neurotransmitters. some of them jam up our some of them damage our cell membranes. many, many of them damage our mitochondria or energy factories in our cells. >> something that i think is important in thinking about these complex causes is thinking about the window of vulnerability. when are these causes most likely to act? >> and again, i believe that that prenatal, intrauterine period is going to be very, very important. so things from maternal diet, infections that mothers may be exposed to in pregnancy-- exogenous chemicals, chemicals in the environment that could be neuro-developmentally significant. all these are thing-- i think these things are likely to play a role. how... how... how large, how small, i think, is yet to be determined. >> i don't think this is an either/or effort the issue is ideas and hypotheses. the genetics will facilitate work on the environment. >> reporter: one issue that science has considered settled for years won't go away, a parental belief that vaccines caused autism. public health officials have steadily maintained there is no scientifically valid evidence of such a connection, that all epidemiological studies have been negative. now, bowing to public pressure, the body that sets priorities in autism research, the inter agency coordinating committee, has recommended studies to determine whether small subgroups might be more susceptible to environmental exposures including vaccinations. >> despite many... many... many epidemiological studies, no evidence that current vaccines in their present form have triggered autism. there are two prevalent things going on here: vaccination and the autism. but trying to correlate those two have failed to date. >> i think it's pretty clear that, in general, vaccines are not the culprit. if you look at children that receive the... the standard childhood vaccines. that, if anything, they're-- those children are at... are at slightly less risk of having autism than children that aren't immunized. i-- it's not to say, however, that-- there is a small subset of children who may be particularly vulnerable to vaccines. if the child was ill, if the child had a precondition. like a mitochondrial defect. vaccinations for those children actually may be the... the environmental factor that... that tipped them over the edge of autism. and i think it's-- it is incredibly important, still, to try and figure out what, if any, vulnerabilities, in a small subset of children, might make them at risk for having certain vaccinations. >> i think it's possible that you could have a genetic subgroup. you also might have an immune subgroup there are a variety of subgroups. but the problem with the population studies is, they aren't necessarily designed to have the statistical power to find subgroups like that if the subgroups are small. >> i think, more importantly, what the whole vaccine issue has done. has opened our eyes again to the idea that the immune system is an important component of autism. >> the brain and the immune system and the gut are intimately related. the cells in those systems have common features. they work together seamlessly, and when you deregulate one, you deregulate all the others. and systems biology is a way of looking at how we work as an integrated whole. i think that's a 21st century biology. is the brain mis-wired or is it misrelated? and i've come to think the brain is misrelated. and there are several reasons for that. short-term, dramatic changes in the functional level of people with autism. one of them is the improvements you see with fever. a child who gets a fever will start to make eye contact, will be interactive, will relate. a child who would have been really out of touch will become connected and then it will go away. >> you know, vaccines are only one of the things that we do to ourselves. but there are myriad other kinds of toxic chemicals that we're putting into the environment. >> i don't think there's enough research on environmental factors. frankly, i think it's very expensive. it's difficult research to do. because again, you start trying to develop a list of how many new things there are in the environment now, from 30 years ago. and... and it'll... it'll be a very long list. >> when we were having this explosion of our chemical revolution, we didn't have any way of knowing the subtle impacts on cellular function. we thought, if it doesn't kill you, it's probably okay. but now were learning that it can alter your regulation way before it kills you. >> reporter: there are many other areas of focus that researchers are pursuing. >> the parents are having children at later ages. and there is a lot of evidence that children born of parents in the late 30s and 40s have a higher likelihood of developing autism. >> we're trying to chart of the course of the-- of brain development in autism. and what we've found is that-- there are certain parts of the brain. the frontal lobe, right-- behind the forehead-- in particular. as well as a small structure that's about two inches in from you ear, called the amygdala. both of these structures actually grow too quickly. they get to the adult size too quickly in children with autism. there's a bunch of kids who probably have autism right from the get-go. right-- you know, right from conception or ear-- very early on. there's another group of kids. who, at 12 months old, they look fine. they're... they're communicating, they're having-- engaging socially. but then, some time between 18 and 24 months, they lose social behavior. they lose language. and they regress back into autism. but now, we're showing that the kids who regress into autism, for whatever reason, are the ones who have the rapidly growing brains. so that's a clue. i mean, it... it doesn't tell us all that much. and it doesn't tell us how to treat those two kids differently, but it's beginning to provide evidence that there really are biologically different subsets of kids of autism. and i think, once we actually define that there are different subsets, we can start going after the causes of each one of those subsets. >> reporter: are you at all discouraged that after so much effort, investment, some of the best minds in the world on this, that... that autism is still so baffling? >> i'm not discouraged at all about that. i think we're addressing one of the most profound problems in not only all of medicine, but in all of human existence. the ability to relate to other people, to empathize in a certain way and to comprehend. it's the most worthwhile, most challenging effort in science that i've ever been involved in. so i'm not discouraged at all. >> ifill: tomorrow night, robin examines treatments and the role education plays for children with autism. but you don't have to wait until then to watch it. part four of the series is available right now, in its entirety on our "autism now" webpage, where you can also read extended interviews with those featured in tonight's story. plus, you'll find answers to some of your questions from today's online chat. and you can keep submitting questions to our website. robin will answer some of them after the series ends. >> lehrer: again, the major developments of the day: it was a day of remembrance on the gulf coast, one year after the worst offshore oil spill in the nation's history. the transportation department announced the suspension of two more air traffic controllers for infractions on the job. on "the newshour", secretary ray lahood said investigations are continuing and war photographer and filmmaker tim hetherington was killed today in the fighting in misrata, libya. hetherington directed the oscar- nominated film, "restrepo," based on his time in afghanistan with the 173rd airborne. those troops were also the subject of his book, infidel. jeffrey brown talked with hetherington in november. here's an excerpt. >> i'm there as a witness. and i'm just trying to record what i can in the very kind of frenetic... frenetic environment. and i try and obviously, you know, keep myself out of the way and out of danger, but obviously you're in a situation. and the men kind of really accepted our presence. we became, to all intents and purposes, part of the platoon, although i never carried a weapon, i never pulled guard duty, although i wish-- i think they wished that i did pull guard duty. ( laughter ) and they really opened up to us after a while. they realized that we were going to go to the furthest extents that they would go to. we went on every patrol, into every combat situation. and that made a bond between us and allowed me to document their lives in this very full way. >> reporter: and then, of course, there is the camaraderie, the brotherhood, which you and sebastian junger, to some extent, became part of, right? >> yes. >> reporter: and you tried to capture that. how much do you-- did you feel a part of that, and how much could you sort of capture it as a participant or as a sort of person standing off to the side with the camera? >> well, it's interesting. when we first arrived, obviously, the men were very suspicious of us. after a while, they started to open up to us. and we became, as i said, part of the platoon. i think that they really trusted us to show their world as fully as possible. and that also didn't mean shying away from things. that meant showing both the down time, but also the heat of battle, also the documenting when their friends got killed or some of them got killed. you know, it's a warts-and-all view of the war. and i felt this was important because, you know, often, soldiers and the symbols or representations of soldiers are claimed by the far left or the far right to mean a certain thing. and we do these young men an injustice in not digesting fully their reality. and that's what i wanted to show. >> lehrer: that was photojournalist tim hetherington talking to jeffrey brown last year. hetherington was killed in libya today. he was 41 years old. and now to hari sreenivasan for what's on the "newshour" online. hari? >> sreenivasan: watch all of jeff's interview with tim hetherington, and read more about his career, on "art beat." see a slideshow of images from the b.p. oil spill narrated by an associated press photographer who has covered the story from the beginning and our science unit asks experts what's happened to all the oil in the gulf. plus tonight's edition of "nova" looks at the use of technology to defeat global warming. all that and more is on our web site: newshour.pbs.org. gwen? >> ifill: and that's the "newshour" for tonight. on thursday, we'll look at allied aid for the opposition in libya. i'm gwen ifill. >> lehrer: and i'm jim lehrer. we'll see you online and again here tomorrow evening. thank you and good night. major funding for the pbs newshour has been provided by: >> oil companies have changed my country. >> oil companies can make a difference. >> we have the chance to build the economy. >> create jobs, keep people healthy and improve schools. >> ... and our communities. >> in angola chevron helps train engineers, teachers and farmers; launch child's programs. >> it's not just good business. >> i'm hopeful about my country's future. >> it's my country's future. and the william and flora hewlett foundation, working to solve social and environmental problems at home and around the world. and with the ongoing support of these institutions and foundations. and... this program was made possible by the corporation for public broadcasting. and by contributions to your pbs station from viewers like you. thank you. captioning sponsored by macneil/lehrer productions captioned by media access group at wgbh access.wgbh.org >> this is "c wod news erica." fundg for this presentation is de possible by the freeman foundation onew rk, stowe, vermont,nd holulu. newman's owfoundation. the john d. and cathene t. macarthufountion. and union ba. >> unionank s put its nancial strength to wo for a de range of companies, from small businesses t major corporations. what can we forou? >> and now, bc wld news."