Passage 4 But David Quammen says many new diseases,especially viruses,seem to be developing. "Something seems to be different because we've seen a lot of these new diseases,especially viral diseases,emerging over the last five or six decades.And that,of course,raises the question of,why?What's different now?m Mr.Quammen says one reason is that the human population is going deeper and deeper into habitats-or living areas--where humans are finding new creatures. "There are now seven billion of us on the planet.Were going into these diverse ecosystems.Were cutting down trees,were building mines,we're building villages and roads.And we're coming in contact with these animals.And we're giving the viruses those animals carry the opportunity to jump to a new host,to spill over into human populations." Contamination Is A Two-Way Street In the world of diseases,contamination--spreading germs--goes two ways. Peter Walsh says ecotourism has helped protect the living areas of apes But he says people taking those environmental trips are killing the apes 415 Passage 4 4 / 5 But David Quammen says many new diseases, especially viruses, seem to be developing. "Something seems to be different because we've seen a lot of these new diseases, especially viral diseases, emerging over the last five or six decades. And that, of course, raises the question of, why? What's different now?" Mr. Quammen says one reason is that the human population is going deeper and deeper into habitats – or living areas -- where humans are finding new creatures. "There are now seven billion of us on the planet. We're going into these diverse ecosystems. We're cutting down trees, we're building mines, we're building villages and roads. And we're coming in contact with these animals. And we're giving the viruses those animals carry the opportunity to jump to a new host, to spill over into human populations." Contamination Is A Two-Way Street In the world of diseases, contamination -- spreading germs -- goes two ways. Peter Walsh says ecotourism has helped protect the living areas of apes. But he says people taking those environmental trips are killing the apes