I sometimes see people citing humans being at the "top" of the food chain as justification for doing anything they want to those "lower" on the food chain. This argument often goes hand in hand with the claim that humans are "more evolved" than other animals. However, these arguments are based in a binary moral system of "better" and "worse" which simply doesn't exist in nature. Not in the way the arguments are used, at least.

"Evolution" is a very neutral word. It means "change over time," through incremental adaptation and mutation. Since all life on Earth shares a common ancestor (as far as we know), our genome has gone through the same amount of "time," even if species have gone through different amounts of "change." If there is such a thing as "more evolved" in the biological sense, it would be measured by the number of mutations your DNA has been through.

There is no universally objective measure of "better" or "worse" in evolution. The efficacy of adaptation and mutation is relative to the conditions an individual finds themselves in. Someone highly adapted to life in a warm climate would probably die that much quicker in a cold climate, someone specialized to life in a forest wouldn't fare well in a desert, and vice versa. As conditions change, those most successful under the old conditions will likely be at a disadvantage, even compared to some who were less successful before.

Likewise, "survival of the fittest" doesn't mean "might makes right." There are a great many factors that influence survival, and they boil down to how we interact with our environment and with each other. A ruthless "every man for himself" attitude is often counter-productive since it creates enemies and alienates allies, whereas community bonds and altruistic behavior often strengthens the chances of survival - especially for social animals (such as humans).

This means that all life in an ecosystem is interdependent. A wolf, eagle, or shark can be thought of as a "top predator" in an ecosystem, but this doesn't make them better than a deer, rabbit, or seal. On the contrary, it makes them the most vulnerable. Those at the "top" of a food chain are the ones most affected by changes in the ecosystem, since they depend on the health of everyone "below" them. Not only would they die from a shortage of prey, they are also hardest hit by pollution. Individual blades of grass may be contaminated, but deer eat many blades of grass, and wolves eat many deer. Toxins accumulate in ever-greater concentrations the farther "up" the food chain you go. The toll on "top predators" is devastating, as can be seen by the thinning of egg shells from DDT or the heavy metals in fish.

This is why those at the "top" of the food chain can't do whatever they want. Instead, they have a greater degree of responsibility to everyone "below." Not in any superior or condescending way, but because their very survival depends on it. Harm to those "below" inevitably harms those "above." Perhaps the most important role of "top predators" is to benefit those below. Benefit to those "below" likewise benefits those "above." Carnivores help maintain healthy herbivore populations by hunting the weak and the sick; they help to control herbivore population growth to prevent overgrazing, which benefits the plant life that benefits herbivores; they help increase biodiversity by giving other species more room to play their roles, such as leaving carrion for scavengers and rejuvenating plants around waterways. A harmonious ecosystem benefits everyone in it because all are interdependent.

Modern humans do not play the role of a "top predator." Industrialized farming methods have the paradoxical effect of being both isolated from natural processes and imposing themselves upon them. We do not benefit cows, pigs, chickens, and other "livestock" animals by breeding and eating them. We do not eat the sick or the weak, and instead actively breed genetic monstrosities adapted to nothing beyond pleasing human palates after a miserable life in artificial confinement where they are denied every natural instinct. Factory farms also spew a staggering amount of pollution into our air and water, contaminating everything in their vicinity and poisoning everyone who depends on it.

"Free range" is no better. The small percentage of "free range" animals who actually get to roam the outdoors do nothing but wreak havoc on existing ecosystems. In most cases, "livestock" animals are not native to the land, and so are an invasive species. To make matters worse, ranchers do everything in their power to prevent predators from controlling the "livestock" population. Historically, this has resulted in the systematic extermination (often through indiscriminate poisons, with far-reaching consequences) of wolves, coyotes, cougars, bears, and other wild carnivores, triggering a catastrophic domino effect within their ecosystems culminating in plagues of rats, locusts, and dust storms. Unchecked "livestock" overgraze, trample the topsoil, destroy waterways, drive out wildlife, and leave a wasteland in their wake.

Modern humans are not "on top" of the food chain. They're not even part of a food chain in any sane sense of the word. And if you still want to call it a food chain, you have to admit that humanity's role in the greater ecosystem acts against all factors evolved to long-term sustainability. The modern "ecosystem" created by humanity provides none of the benefits while reaping all of the harm. There are better ways.