photographer, gerald herbert. >> there's whole sections of this island that are not even recognizable from what it was before. so, where there was mangrove, now it's dead. pelicans are now nesting on the bare earth. >> lehrer: that's all ahead on tonight's "newshour." major funding for the pbs newshour has been provided by: >> okay, listen. somebody has got to get serious. >> i think... >> we need renewable energy. >> ...renewable energy is vital to our planet. >> you hear about alternatives, right? wind, solar, algae. >> i think it's got to work on a big scale. and i think it's got to be affordable. >> so, where are they? >> it has to work in the real world. at chevron, we're investing millions in solar and biofuel technology to make it work. >> we've got to get on this now. >> right now. and by the alfred p. sloan foundation. supporting science, technology, and improved economic performance and financial literacy in the 21st century. and with the ongoing support of these institutions and foundations. and... this program was made possible by the corporation for public broadcasting. a

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. >> repo