Preface   The disturbing e-mail arrived on June 16, 2009, its subject header reading,"Decimation of Chimp Population in Tanzania." I agonized for two days before opening it, hoping its contents would not be as devastating as I feared. Finally, it was time. I clicked on it and found an update from the Scientific American website:   Tanzania''s chimpanzee population has plummeted to just 700 today, according to a report from the Tanzania National Parks Authority. The Parks Authority blamed disease and predation--by humans and other mammals--for the dramatic losses. The country''s chimpanzees are located in just two habitats, making them highly susceptible to population-destroying illnesses.   And there it was--exactly what I had dreaded. It appeared that even in Tanzania, home to Dr.

Jane Goodall''s famous research center, chimpanzees are threatened with extinction. If true, it meant that one catastrophic epidemic or even just continued habitat loss could spell disaster for these last Tanzanian survivors.   An e-mail from Dr. James Moore, of the University of California, San Diego, revealed that the faulty estimate of 700 was not that far off from current estimates of 1,000 to 2,600 chimpanzees.1 One hundred of the chimps make up three small adjacent communities at Goodall''s research site in western Tanzania. This is a population so small that it is teetering on the edge of biological nonviability. The others remain in areas to the south where human encroachment is fast approaching. The message hit hard because it cinched the truth--the situation was even bleaker than what we had guessed while visiting Tanzania some months before.

This was final confirmation that it was past time to investigate the full extent to which chimpanzees are at risk across Equatorial Africa.   The truth was tough. One hundred years ago, chimps numbered in the millions, and although an estimated 150,000 to 300,000 remain, their numbers are plummeting even in remote forests. Exponential human population growth means that critical swaths of forest are becoming fragmented or disappearing, and chimps living in unprotected forests--a majority--are in immediate danger every day. In fact, many chimp populations can no longer survive in what little forest area they are left with. Field researcher Matthew McLennan writes,   I just got back from Uganda last week. While it''s good to be back home . I know I''m going to worry about the chimps at my site-- there seems to be no end to the forest clearance, and there really is hardly anything left!   And, so, a 2009 e-mail lent new urgency to a task I already had under way--telling tales of the remarkable chimps and why they matter.

It seemed a sacred debt I owe as one who has been blessed to know chimps. I have experienced the joy of walking with chimps, tickling and laughing with them, even having tears wiped from my eyes by my friend Bandit, the most intelligent and remarkable chimp I have known. I have witnessed their almost human dramas: a female selflessly adopting an orphaned infant, a group rolling a log to keep a lion at bay, an adolescent son mourning the death of his mother. I have seen them lie on their backs to wonder at the night sky, legs crossed, arms folded behind their heads.   My life with chimps dates to 1972, when I arrived at Dr. Jane Goodall''s camp in Tanzania as a Stanford University student, working as a field assistant. As I witnessed the tremendous intelligence and complexity of the chimps, my human-centered worldview was thrown into disarray. They were like children: excitable, curious, and often unable to control their very real emotions.

Unbeknownst to me at the time, my Gombe arrival was the start of a path to working with some of the world''s most fascinating scientists and conservationists, people whose passions would make a difference for chimps and people of Africa. It was also the beginning of a lifelong fascination with chimps, without a doubt the most intriguing creatures on Earth. It is impossible not to be surprised by how human their laughter is as they tickle one another, impossible not to be touched by a usually fierce dominant male joyfully chasing a juvenile around a tree, then reversing and letting the youngster chase him round and round.   This book, so influenced by that e-mail, is both a chronicle of my personal search to learn how chimps are faring across Africa and in captivity and my eyewitness account of a very critical period in their existence. At times, it has been overwhelming to see how imminently threatened chimpanzees are in today''s world. But to allow a world without chimps is unconscionable--so you and I must get involved or risk losing them forever. This book recounts my journey among the inspiring people fighting to save them and is a call for us to join them in order to save humankind''s closest relative, the remarkable chimpanzees. Let us be a voice for the chimpanzees, beings who so deserve to be heard.