In many parts of the book, Coyne repeatedly states that humans are responsible for the extinction of many species either directly or indirectly through our actions. Indeed, nowadays, you can’t find a newspaper without an article about going green, or saving the environment and stopping the destruction of rain forests, etc. However, if humans are so destructive, than what would the world be like without humans?
Pretend that the human race met with a biological dead end early in their evolution from our most common ancestor and became extinct. How would the world look like today? What species, if any, has the presence of humans suppressed that would be more numerous in a world without humans? Has the presence of humans actually helped other organisms in some ways and if so, what would the lack of humans do to this species? You may focus on and describe a general view of the world (but don’t be too vague, include examples) or focus on the development of a specific species that has been greatly impacted by humans and how that development would be changed without the presence of humans. Be sure to relate to biological themes.
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Human influence is clearly seen throughout pretty much all of the planet’s biomes, but I’ll focus on the oceanic biome. It’s pretty clear that humans have had a hugely negative impact on the oceanic biome; I can’t really see many aspects regarding the ocean that humans have actually helped. The ocean is an extremely important biome, and is the most productive biome on the planet.
ReplyDeleteWithout humans, both species richness and species abundance would be drastically increased. Species richness is just the number of species while species relative abundance is the amount of organisms alive from a particular species(Campbell 1215). One example of humans’ negative influence on the ocean is the manatee. The manatee has become endangered and the most common reason for manatee death is collision with human boats and human capture(http://www.theinsite.org/earth/earth_es_manatee.html). Human pollution has also been a major problem; this experiment http://www.jstor.org/stable/25472597?&Search=yes&term=synergistic&term=salmon&term=pacific&list=hide&searchUri=) details how human contaminations have a hugely negative effect on pacific salmon. Surely, pacific salmon aren’t the only fish species affected by this pollution. In addition, humans are destroying coral reefs very quickly. One example of this is the effect of sunscreen on the coral and fish that live on the coral(Sunscreen on Coral Bleeching Causes viral infection on Jstor). Clearly, these are various aspects in which humans have a negative impact on the ocean. And there are a plethora of other examples that I have not mentioned.
Without humans, the ocean would be massively more successful. There would be less pollution/contamination, which would help decrease physical deformities of various fish. Also, less pollution and cleaner water would provide a much safer advantage for offspring to reproduce, which would obviously increase the evolutionary success immensely. Commercial/contest fishing would be nonexistent, so fish populations would be more diverse and prosperous. Human intervention hugely alters the food web of the ocean(as seen in the destruction of coral, which is the primary producer of the ocean). Without humans, coral would be more common, and the base of the food web of the ocean would be restored. This would have a hugely positive impact on the whole food web, because the primary producers of a biome are crucial to that biome’s success.
Like I mentioned previously, there aren’t any obvious ways in which humans help the oceanic biome. Humans increase pollution, increase the amount of extinct or endangered species, and decreases reproductive success. This topic relates to the theme of interdependence in nature. That theme is basically how the actions of one species affects other species or populations around the world. In this case, human intervention is destroying one of the most important biomes on the planet. Without humans, the ocean would be in much much shape.
I think that without humans there would be both positive and negative effects for certain species. For example, there are (or were) many species that have become extinct or endangered at a very fast rate due to the invovlement of humans. The Dodo is just one example of many. It is possible that the Dodo may have become extinct regardless of human involvement, but poaching definately accelerated the process.
ReplyDeleteOn the other hand, humans and our effects on the environment do help some species. Rats that live in urban areas are helped by the shelter that buildings and man made objects supply as well as the food and garbage leftover. It has been proven that rats thrive in this environment, but it is also possible that they could survive perfectly fine without us.
I also agree with what Kevin said about humans having an overall negative effect on aquatic biomes. Commercial fishing, trawling, and run-off are all human related threats that are damaging this specific biome.
Another negative effect humans have had is introducing foreign species. This is generally bad for an ecosystem because often times the newly introduced species has no natural enemies. If the species has no natural enemies to control the population, they will grow out of control and take up resources and fill niches held by native species. This concept is discussed in chapter 56 of Campbell.
As Kevin also said, this prompt relates the most to the theme of interdependence in nature because all species, including humans, play some role in an ecosystem.
As Kevin stated, human influence is seen affecting organisms throughout the world. I'd like to focus on hunting though. Hunting is a method through which the human race has driven many other species to extinction/near extinction. In fact, the bald eagle, the symbol of American, was almost hunted to extinction in the late 1800s, when settlers began moving to areas that had bald eagles and began altering the environment. Actions such as cutting down trees and actually hunting he eagles led to a significant decrease in the population of bald eagles in America (http://www.essortment.com/all/theamericanbal_rykh.htm). Also, the use of DDT, a pesticide, also had a detrimental effect on the population of bald eagles. When humans used DDT, the pesticide would run off into streams and lakes, where fish would become intoxicated with DDT. When birds, such as the bald eagle, ate these fish, they too would become intoxicated. However, the birds got the brunt of the blow, because of a phenomenon called biological magnification. Campbell defines biological magnification as toxins being particularly harmful because they "become more concentrated in successive trophic levels of a food web" (Campbell 1238). Closely related to biological magnification is the theme of energy transfer, where "energy flows from producers to consumers in an ecosystem" (COB 16). Because birds such as the bald eagle must eat the fish for food, the toxins, along with energy, are passed up to the birds from the fish. However, concentrations of DDT increase exponentially through the trophic levels, while the energy transferred decreases exponentially. Rachel Carson was a noteworthy person with relation to DDT. She wrote a book titled Silent Spring which told of the dangers of DDT on the environment.
ReplyDeleteHumans really have changed the environment and the ecosystem negatively. Actions such as hunting. fishing, and even negligent use of pesticides can cause detrimental effects to countless organisms on Earth. To answer your questions directly, Earth would look incredibly different, as there would be no cities, roads, buildings, etc. on Earth. As mentioned already, the bald eagle would be much more plentiful had humans not been there to destroy the eagles' habitats and homes. Brendan is correct in saying that there are some positive effects of human intervention on certain species. For example, using artificial selection on organisms has developed and can help develop organisms that are better adapted to environmental pressures/threats.