Henry Gee

"The cause of extinction is usually a delayed reaction to habitat loss. ...H. sapiens might ...already be a dead species walking."

"[O]ver the past few decades, the quality of human sperm has declined massively... Pollution... is one possible factor. Another might be stress... triggered by living in close proximity..."

"To take a line of fossils and claim that they represent a lineage is not a scientific hypothesis that can be tested, but an assertion that carries the same validity as a bedtime story—amusing, perhaps even instructive, but not scientific."

"The intervals of time that separate the fossils are so huge that we cannot say anything definite about their possible connection through ancestry and descent."

"[T]he human population is set not just for shrinkage but collapse—and soon. To paraphrase Lehrer, if we are going to write about human extinction, we’d better start writing now."

"There is more genetic variation in a few troupes of wild chimpanzees than in the entire human population. Lack of genetic variation is never good for species survival."