20,000 years ago, an alien race made contact with a tribal chieftan. "We noticed you had a large supply of both petroleum and uranium on this world," the alien race said. "What would you like for them?"
"Both are worthless," the chieftan said. "Petroleum is sticky and disgusting. It gets on things and won't come off. Uranium burns anyone who touches it. It is a pox on the world. Feel free to take all of them; we need neither."
The alien race thanked the chieftan, and left him a gift of 200 cuts of bush meat. It then promptly removed 100% of Earth's valueless petroleum and uranium. The chieftan lost no sleep over the loss of these valueless things, and was certain his descendants would never miss them either.
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To consider a unique set of genes assembled over the course of a billion+ years "valueless" shows a great lack of foresight. Each species is a resource of unknown and unstudied adaptations it may take millennia or more to replicate in labs. Our machines now are crude metal things; nature makes the ultimate machines. We're centuries away from catching up, at best. By the time we're ready to benchmark against what nature's already done the work to come up with, it may no longer be there to benchmark against, and we'll waste millions of man hours reinventing species we could formerly have just plucked from the jungle, swamp, sea, or desert.
New apex predators like man reshape the environment and cause extinctions; this is inevitable. Your certainty that this is also inconsequential, however, is misplaced.
Your chieftain story lures us to go wild with speculations about why we don't have more of other useful but rarely naturally occurring resources on our planet.
You have a valid point here, though let's hope that unknown species isn't a key link in some chain in the ecosystem, breaking which could cause an ecological catastrophe in the region.
The unknown, by definition, holds the value of the potential knowledge that can be revealed from it. From this prospective, a living species looses its value only in the moment when we know everything (whatever that means) about it. For now, we're nowhere near that level even for the simple unicellular life like bacterial species.
