I think that rather than ask whether humans are “more important than other species,” we have to explore the human-nature dichotomy itself. Unfortunateley, discussions on environmental issues seem to start from an assumption that one exists. These discussions, which put humans at odds with nature, generally lose me on three points (though, again, this is not my field of expertise):
1) The intense focus on large mammals. If we are going to convince ourselves that “nature’s” needs are more important than our own (or simply worth considering) we have to eliminate the idea of a hierarchy of species and consider all living things as equally important. It often seems that conversations become less holistic and more mammal-centric. Given that we are mammals and hard wired to like cute and furry things (particularly those small and weak), this is to be expected. However, the urge to protect things like ourselves makes it impossible for humans to objectively rank the importance of living things.
How often do you hear about people screaming to save snakes? Perhaps it happens and I just don’t hear about it. Clearly, big furry animals are an easy sell.
2) The idea that “species” are distinct entities, the number of which needs to be maximized at any cost. Preserving more species is seen as a goal, when in fact, the word itself is not uncontroversial. “Species” is a rough and artificial concept created by humans to assist in our understanding of the world. Even scientists can’t agree on what a species is, given that the situation that determines how a species is defined differs by type of animal and context (and history).
Take the Zebra, which comes in three main flavors, though I’ll focus on two. The Grevy zebra is Equus grevyi and the plains zebra is Equus quagga, different “species” by classification, but able to breed with one another and create offspring which are able to reproduce. The two “species” are distinct from one another only in superficial morphological features (stripes and size) and behavior.
Gravy’s, though genetically indistinct from plains zebras, are listed as endangered, which gives them certain benefits and allows Kenya (for example) to legally restrict grazing for Maasai goat herders, with the support of international groups. It’s a simplistic example, but it makes little sense to me to ask that humans make sacrifices based on a flawed concept of what makes a “species.” It also makes little sense to create policy which impacts the lives of Africans based on a false paradigm created by 19th century Europeans (“Gravy” was a French President). Yet, here we are.
An aside, but I often think that people really believe that “species,” particularly large mammals, are individuals with distinct personalities and collective thought patterns. From the animals’ standpoint, extinction isn’t an issue. Rhinos don’t hold regular meetings and worry collectively about extinction. Individual rhinos are merely concerned with eating enough grass and mating when necessary.
3) The concept that nature is a fragile and static entity which would be ultimately benefit from our non-existence. This stems from traditional dichotomies of “man” and “nature” where man operates in his (male) world and nature operates in an entirely separate and unchanged sphere. In the West, this goes all the way back to Genesis. It is a simplistic and useless concept and does more harm than good.
Nature is a dynamic and constantly changing system of which we are one part. We create nature “reserves” which are thought to “preserve” the “natural” state of “nature” but even these are artificial, human constructed spaces, as we have dictated the location and killed all our large wildlife. We approach them are “preserves”, but forget that we have altered the system (by, for example killing the wolves or cutting all the pine trees in Michigan). Thus, arguing for the “preservation” of nature is somewhat disingenuous, since even by advocating for what part of nature needs to be preserved, we are writing its rules.
The question of whether the world would be better or worse off without us is fairly moot since humans are defining the terms of “better” and “worse.” Moreover, from the German cockroach’s (Blattella germanica) standpoint or the Black rat (Rattus rattus), humans could be considered a great thing as we tend to migrate and take our pests with us. If it could, Plasmodium falciparum should worship us like a God, since it wouldn’t exist without us.
I don’t see man as separate from nature. For better or for worse, we are a part of it. But after we have run our course, the world will go on without us. “Nature,” however it may be defined, has shown itself to be a tough beast in the past. Even if the entire planet became desertized (is that a word?), life would continue to exist. One day, with or without us, all life on Earth will cease to exist.
The most salient questions should revolve around how our environmental impacts affect our long term survival for humans. Focusing on our own needs is the only sustainable strategy (though I despise the word).