When you read the word "nature," what do you think of?

Maybe you imagine a dark wood with sunlight reaching a mottled floor of foliage, thrushes singing and chipmunks hopping. Maybe you peer through grassy dunes at sanderlings running back and forth in the surf , occasionally halting to frantically peck at the sand. Or maybe you see an expanse of cedars bearing a snowfall, deer perusing the bark, and nuthatches hanging from a limb.

In any of these visions, is there a human in sight?

Our species largely views nature as a separate entity from the world we inhabit. We can traverse it on a camping trip, and even bring along our binoculars to better analyze this space so foreign to our own. In heavily populated areas, we visit parks to escape from the city, although we recognize that these spaces are not true "nature," but manicured to our specifications for our greatest enjoyment.

This divide between the two worlds is a fallacy. Its premise is that, before our invasion, ecosystems were static environments that we have, over time, displaced with our buildings and soot and trash. But, while our cities certainly displace the former environment, they also create new ecosystems. And we are intimately involved in these systems, whether we recognize it or not.

The rise of the study of urban ecology and evolution tips a hat to this idea: that, despite our delusions of dominance, other organisms fill and influence our lives as much as we influence theirs. But it doesn't go far enough. Humans still play the role of sculptor in our current versions of urban ecosystems. This rehashes the anthropocentric idea that we stand apart from the rest of the organisms, as laid out in the Bible.

In some ways, this mindset is understandable. The advent of medicine has mostly allowed humans to elude the grasp of natural selection. Society and population overload lift the biological need to pass on our genes and increase our abundance. After all, we now have other ways to extend our individual reaches beyond our deaths, the consciousness to overcome our biological drive, and various exploits to fill our time.

The final nail on the coffin encasing human involvement in ecosystems is our removal from the local food chain, particularly in Western culture. Humans are no longer physically bound to our environments for our daily requirements, instead linked by invisible paths globally. But this still presents a rather limited idea of how ecosystems function. They are based in more than just the food chain, but rather in an endless number of interactions between species and organisms. If we could find a way to highlight, not only how humans influence other organisms, but also how they influence us, we could at least begin to reintegrate our species into a larger ecosystem.

Environmentalism is probably the closest we get to reintegration. Tracing the sources of our food, or considering the impacts of carbon dioxide emissions, overfishing or clearcutting requires thinking about humans as a player in a broader system of species interactions. But, in the end, we still return to the old trope. While environmentalism, at its core, is about preserving resources for our own use, most subscribers articulate it as a desire to take care of nature for its own sake, because we care about nature. And, there it is: that anthropogenic separation rears its head once more.

So how do we do it? How do we reintegrate ourselves into the ecosystems that surround us? It's not easy. I've been working on it for years. I mostly try to think about how the organisms that surround me affect my life, however indirectly, and how my decisions, in turn, affect those organisms -- ad infinitum. Some of these thoughts are rather basic. We provide food for pigeons and, by eating our trash, they clean our streets. (Seriously: imagine how filthy a city would be without its columbine denizens.) White-footed mice, highlighted in a recent article about urban evolution by Carl Zimmer, disperse seeds, and, without plants, my life would be less fresh and far hotter.

These may seem like meager steps in the day-to-day; I'm willing to admit that this idea is a work in progress. Because, in the end, usually my only influence upon these organisms that I can think of is... that I (with my fellow humans) allow their continued existence.

The key may be thinking on a larger scale. An article in New York Magazine from last September highlights the diversity of organisms in the areas we consider the most desolate, and hints at the city as a more integrated ecosystem. (Hat tip to Eric Heydenberk)

Urban ecologists are now taken by the idea of a feedback loop, in which the sullied, mixed-up nature of the city begins to affect the nature of the entire Northeast region. This is what happens when herring planted in the Bronx become food for bluefish in the Gulf of Maine, or when the uncommon trees grown in the NRG’s seed bank in Staten Island are planted in Pennsylvania. But it occurs in less premeditated ways, too. We see the feedback loop in the avian flyway that runs from Alley Pond Park to the little wetland on the brook that runs through the Wykagyl Country Club in New Rochelle and then up through the Hudson Valley into Vermont. Or in the wildlife corridors that connect the Lenoir Preserve in Yonkers through Bear Mountain State Park to the Catskill Forest Preserve. Or in the growing number of green roofs that connect insects across boroughs and counties, slowly turning Google’s satellite view of the city from gray and black to dusty green.

Zooming out puts the smaller decisions made in the city into a larger context, connecting urban ecology to larger ecosystem dynamics. The shellfish in the river that filter contaminants from the water make my bike rides along the Hudson path more pleasant, sure. But they also improve the quality of water entering the ocean, boosting fish abundance for the sake of marine ecosystems, as well as the seafood that I consume.

And, to take it a step further, we can consider the geology of the city. Where did the rock that composes these Brooklyn homes come from? What does that area look like now and how has it changed? How many millions of years ago was the rock formed? What minerals compose it, and when were they formed out there in space? The non-profit research organization Friends of the Pleistocene, whose publication Geologic City I anxiously await, has some answers:

On the way to Prospect Park we passed massive stacked rows of Triassic sandstone. These solid blocks (literally) of geology are installed on the streets as the City’s iconic “brownstones.” This rock is 250 to 200 million years old–that’s pre-dinosaur. Brownstones are one of the most common buildings in Park Slope, but we typically forget that while inhabiting such spaces, we’re living inside the materiality of deep time.

A larger geologic context -- stretching back to the formation of the universe -- helps me to place myself in the context of life's history and larger scale ecology. While our species built these cities, stone by stone, we are still bound by the larger scale workings of the planet and the ecosystems it harbors.

But I'm still not satisfied. The one thing that still irks me is that, despite all my lecturing about anthropocentrism, it's inescapable. I try my best to rearticulate the world to myself holistically, without our species at the central point. And I will continue to fight those battles each day as I walk to the subway, take a nap in a grassy knoll, or sit on my stoop hammering my laptop keyboard. But, in the end, humans are the movers and shakers on this planet, literally. As civilization changes, the ecosystems change as well, and, at this point in time, the power to change them lies primarily with people. So maybe I'm the delusional one after all. Maybe, for now, the greatest influence we have on the white-footed mice or trees that line my street is their continued perseverence.