Once upon a time, we lived life in nature’s tangled bank. Five hundred million years ago, our hearts evolved to pump blood. Their beating was physiological, but nearly every subsequent elaboration on our bodies related to interacting with the rest of life. Four hundred and ninety million years ago, the first eyes evolved in order to detect prey. Later, the first taste buds evolved in order to help us find our food species and avoid toxic species, to urge us toward what we needed and away from what we did not. Our immune systems evolved to detect microscopic creatures and distinguish among them, favoring some and disfavoring others. All of this we share with most of the rest of animal life. In this way, our bodies unite us.
Right now, our biggest barriers remain our brains and their biases, brains that still tell us that a green pesticide-treated lawn is more healthy than one abounding with species, brains that still tell us the same things they told us when we lived in caves and when mammoths still walked along the horizon.
The Pronghorn Principle (The "ghosts" we chase):
Isbell on how Snakes "helped" our vision:
If Isbell was right that the particulars of primate vision evolved in response to the presence or absence of venomous snakes, she would expect better vision with greater exposure to venomous snakes. That is just what she found. Venomous snakes evolved in the Old World, and were relatively recent arrivals (10–20 million years ago) in the New. This matched the differences in primate vision. It fit her theory. But what about Madagascar, where prosimian-present primates have relatively poor vision? From the beginning, Isbell had hoped, in a way, that she was wrong. If she was wrong, she could get back to the life she was living before her idea. Maybe she would find that there are venomous snakes in Madagascar, but just as she predicted, there are not. Madagascar has no venomous snakes, and Madagascar’s primates, the lemurs, have the worst vision of all the primates. They are as likely to find their way by taste, smell, or touch as by sight. In this, they are like Vermeij.
On our hairlessness, disease et al.,:
This theory has been independently suggested by three waves of scientists across more than a century. Each of them has argued that hairlessness evolved because our ancestors were unusually tick, louse, fly, and, more generally, parasite-ridden. This idea was first suggested in the 1800s by the jack-of-all-trades Thomas Belt in his book The Naturalist in Nicaragua.
Fincher compared the individuality scores of people around the world. What they found was that in regions where deadly diseases are more common, people consistently think more about the tribe and less about their own individual fate and decisions. They are also more xenophobic. Separately, Mark Schaller also found that where diseases are more prevalent, individuals are less culturally and sexually open and less extroverted.What Fincher, Schaller, and others observed were correlations. Just because two things, such as disease prevalence and personalities, show the same patterns of variation from one place to another does not mean that one causes the other. But at the very least, the patterns these scientists observed do not rule out their ideas.
Honing the Biophilia Theory:
It is sometimes suggested that what we need to do in cities is to restore “nature.” A body of literature and theory often referred to as “biophilia” posits that we have an innate fondness for nature, and so restoring nature to our lives makes us happier and healthier. I disagree for what might seem to be (but is not) a subtle reason. Namely, by any reasonable definition, the species that have filled in around us in cities are nature. The species that live on our bodies are also nature, as are both smallpox and toucans. What is missing from our lives is not nature, but instead a kind of nature that most benefits us. By that same token, the life we love to have in our neighborhoods and daily lives (bio = life, philia = to love) is not all life, but the life that benefits us in some way. When tigers chased us, we had no innate love for them. When diseases killed our families, we had no love for them either. And so what we need in our cities and suburbs as we move forward is not simply “more nature.” More rats would be more nature, as would more roaches and mosquito-vectored diseases. No, what we need are more of some aspects of nature, its richness and variety and, more pointedly, its benefits.
When we think about benefits, we cannot think simply about what our eyes tell us. The species that benefit us in the future may well include worms, ants, and our gut microbes. They may include, in other words, a much more burgeoning ark of life than we tend to consider when we plan parks and gardens. In our guts, we may really need to give ourselves worms. That we hesitate at this point is largely a function of what our eyes tell us, not of clinical results. We do not yet understand the way worms work as a treatment, but neither do we understand the ways in which most of our modern medicines work. Ask a researcher how Ritalin or pain medication works. In most cases, no one knows. We just know that when taken, a symptom or even a disease goes away. So it is, for now, with the worms.
On Cliff's and Caves:
Larson’s theory was a coming to terms with the similarities between his one life in an office on a campus and his other life, dangling off ledges. It was also the coming together of minds. He formed the theory along with a group of five other scientists* whose thoughts had begun to converge on his own and they wrote an entire book about the idea, The Urban Cliff Revolution: Origins and Evolution of Human Habitats. In the first and most often discussed part of the book, Larson and team argue that the cities we build are like cliffs, populated with cavelike rooms and balconies. We build these clifflike environments even though they are marginal and unproductive, they argue, because through the long years of early human evolution, caves and cliff sides were our refuges from the elements and from predators. We build cities out of cement and up into the sky because they remind us of cliffs and caves. In addition to their big idea about our fondness for caves, the team offered an explanation for the origins of the species—whether dandelions or pigeons—that live with us in our cities. They noticed that the species that make it unbeckoned into our cities tend to be the very same species that originally lived with us in caves or on cliffs. In cities all over the world, we have created a vast network of caves and cliffs into which species that evolved to live under such conditions have moved, as content and successful as they have ever been.
