I just read Carl Sagan's
Cosmos for the first time (I was stoked to find it at an English bookstore in Buenos Aires). One of the many interesting things Sagan wrote about was the idea of "Artificial Selection," which is basically rapid evolution caused by human interference. Some manifestations of this phenomenon are intentional: sheep bred to have something like 300x more wool in their coat than occurs naturally, domesticated dogs, etc. There are also unintentional examples of humans changing entire species.
Sagan told a cool (true) story about the Heike crab in Japan. The Heike gets its name from a Japanese legend of a samurai clan (the Heike) who were defeated by another clan. In their defeat, the surviving samurai all jumped into the sea. The legend says that these Heike became crabs and walk the seafloor to this day. For centuries, Japanese crab fisherman have been finding crabs that seem to have a samurai face on their shell (as seen below). They assume these crabs are the Heike and throw them back in the sea out of respect for the Heike.
Of course, these are not mystical samurai crabs. They are simply descendants of a specific species of crab that has passed on its genes for hundreds of years
because it looks like a samurai. Human fisherman
selected which crabs would survive. In fact, they did in a way that the only crabs to survive were the ones that looked most like samurai faces on their shells. Artificial selection.
Recently, a study came out showing how humans are the earth´s super-predators, and how
we have changed the characteristics of 29 different species forever (only 29 were in the study, there are undoubtedly many many more). Big-horn sheep have smaller horns, Atlantic cod are shrinking, and you can imagine how we have affected others.
Cosmos was written in 1980. This study will be published in the July 31 issue of
ScienceNOW. It's just another scary example of how we know we are harming the planet, but most of us just don't give a shit. The next 50 years will be scary. It looks to me like the African elephants, polar bears, and many great whales will go extinct. Maybe everyday Joes can't do anything to stop those inevitabilities. But we can start thinking about what happens to other species and parts of the world when we make everyday decisions; what to eat, what to buy, how to get to work. There are consequences.
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