Along a scenic stretch of the Olentangy River, in central Ohio, is a rock jutting out of the water where I like to sit and think. I often refer to this rock and its surroundings as my “office.” As the water rushes past me I can enjoy observing a wide variety of plants and animals while I cogitate about life’s origins and destiny. Where there is water there is life, and within view is a diverse array of life, or rich biodiversity.

Certain of the diverse biological organisms at the office are among my favorites. The damselflies seem to perform...

Change is an integral part of nature. Laws of physics may stay constant, but the only persistent law of biology is that of change. The world we live in is considerably different from what it was about 100,000 years ago, when our species took its modern form. Much of that change has been guided by our own hands. But with or withoutHomo sapiens,change would have been the norm. As one goes back in time to about 2.5 million years ago, when the genusHomofirst arose, the world was even more different from what it is today, with...

The warm and wet tropics are a cauldron of biodiversity, so it is little surprise that the ancestry of humans can be traced to the tropical lands of Africa. The vast majority of our primate cousins, such as monkeys and apes, now live in the tropics. Such was the case sometime between six and three million years ago, when one primate lineage now known as the genusAustralopithecusmade its evolutionary debut and traversed parts of the African continent (fig. 3.1). Given the global spread and domination that characterizes the eventual descendants ofAustralopithecus,one might expect to find evidence...

Foraging was the human occupation for most of the time our species has spent here on earth. Growing our own food is a relatively recent innovation. Before that, generation after generation of our ancestors gathered fruits, nuts, and grains for the bulk of their sustenance, and wood for their fires. Animals were hunted for nutrition from the meat and marrow, as well as for skins to make clothing or shelter; horns and antlers were fashioned into tools. The lives of these foragers involved a lot of travel—every day they walked from their camps to find food and, where necessary,...

Not far from the Chinese fossil site of Zhoukoudian, where we have found the earliest evidence of our ancestors’ spreading into temperate regions, is the modern city of Beijing. It is a sprawling city with an overwhelming number of people—well over fourteen million at the start of the millennium. If you have never been to Beijing, it is worth a visit. Not only can you see the cultural heritage of the Chinese people at places such as the Forbidden City and Tiananmen Square, but you can witness a more universal human heritage: the consequences of our population growth on...

Whenever I go back to South Africa for excavations and research at the fossil sites in the Makapansgat Valley, my thoughts range beyond the changes the world has seen over the past three million years. Much of note has happened since the bones of our distant ancestors became buried in the cave, but the present and future are of concern too. In today’s fast-paced world, anyone who periodically visits this remote location can see significant environmental changes on an annual basis. The valley is rich in species biodiversity, from the insects that my entomologist colleagues were finding and recording to...

Where there is water there is life. Water comprises about two-thirds of our human bodily composition, and accordingly is important in every facet of our daily survival. Most of our world is covered with water, hence the abundance of life on earth. Species are more diverse where there is more water and energy; energy alone cannot support life, hence the paucity of biodiversity in the world’s deserts. The connection between water and all living organisms is why evidence for water on Mars is so important to the search for life on that planet. Yet despite the abundance of water here...

Prior to the current wave of extinctions that is engulfing our planet, the living world has seen five mass extinctions. Despite the precarious imbalance that resulted, life on earth recovered and got back to previous levels of biodiversity, albeit slowly. In some ways this was good for us humans. For example, I’m just as glad that I don’t have to run from a hungryTyrannosaurus rex,although the image provides fodder for exciting cartoons and movies. Moreover, humans almost certainly would not have evolved had the demise of most dinosaurs not left the world open for the small mammals that...

Each weekday morning, before I get down to the day’s writing and research, there is a fairly normal routine to follow. By the time I get cleaned up, dressed, have a chat with my wife, eat breakfast, dress my two boys and get them off to school, about an hour and a half has elapsed. For some people it takes that long just to commute to work; others have routines comparable to mine. The time always seems to go by quite quickly, unless one is stuck in traffic, but meanwhile the fast-paced world of ours churns on.

Here is something...