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posted by martyb on Friday August 21 2015, @01:01PM   Printer-friendly
from the we-are-number-one dept.

An article in the LA Times discusses a publication in the journal Science (abstract) on why humans as predators have a much greater ecological impact than other predators.

From the LA Times article, it is because:

... humans have a very different, and problematic, hunting strategy from nature's other successful hunters. Humans tend to pick out adults rather than younger, smaller, weaker members of a species.

The article goes on to use an analogy:

Think of it from a business perspective, the researchers said. An adult female, for example, is like your capital; the young that she produces are the interest generated by that capital. If you kill an adult animal today, it will take years for another to grow up and take her place. But if you kill a young animal, it will (theoretically) take only until the next breeding season to produce another. In other words, it's better to use the up [sic] interest rather than to draw down the capital, because the capital is much more difficult to build back. Once it's gone, it's gone -- and so is the interest.

This has several consequences, including for the evolution of the prey species. For example, killing the biggest or strongest animals (as might be done with trophy hunting) potentially leads to smaller or weaker future generations.


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  • (Score: 3, Interesting) by tibman on Friday August 21 2015, @02:34PM

    by tibman (134) Subscriber Badge on Friday August 21 2015, @02:34PM (#225865)

    Nah, he's not far from the mark. Animals that aren't domesticated are either ignored, vermin (shot when they become a nuisance), or hunted (to keep their population down). Sustainable fishing and husbandry has been around for a long time. The typical unsustainable issue arises when dealing with wild caught animals that an organization is not tracking and managing. People take as much as they can as fast as they can before someone else gets some. Ocean/sea hunting is often uncontrolled because of the huge expanse. Outright banning seems to be the only answer sometimes. Even Japan has skirted banning issues by saying "oh, we're just whaling for scientific reasons!"

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  • (Score: 3, Insightful) by HiThere on Friday August 21 2015, @10:16PM

    by HiThere (866) Subscriber Badge on Friday August 21 2015, @10:16PM (#226062) Journal

    No. Things *called* sustainable hunting, fishing, etc. have been around for a long time, but the sustainability usually fails. Often within a couple of centuries, sometimes sooner.

    Farming we can manage reasonably well, but sustainable harvesting of wild animals we don't have a good record at. It's basically a "tragedy of the commons" kind of problem, with poachers being an added extra that isn't accounted for, or, usually, even measured.

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    • (Score: 2) by tibman on Saturday August 22 2015, @03:13AM

      by tibman (134) Subscriber Badge on Saturday August 22 2015, @03:13AM (#226140)

      If your argument is that it is sustainable until people break the law then i think that is a weak argument against scientists saying humans are unsustainable. Obviously humans can be. Except when they break the law. The law breaking is the exception, not the normal state of things. But you are right that sustainable harvesting of wild animals is incredibly hard. It outright fails in many areas. But i need to point out that even if humans kill off every wild animal on the planet it wouldn't make humans unsustainable. Humans would still have domesticated livestock and grow the herd/flock to meet demands. Which is super sad to even think about : (

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      • (Score: 2) by HiThere on Saturday August 22 2015, @07:40PM

        by HiThere (866) Subscriber Badge on Saturday August 22 2015, @07:40PM (#226363) Journal

        OK, now we get the the problem of reduced genetic diversity leading to single-point-of-failure managed ecosystems. Unless you think that humans are going to manage bacterial, viral, and fungal evolution.

        P.S.: That humans "break the law" (or remain outside the agreements) is something that needs to be factored into the harvest calculations if you want to have a sustainable wild-life harvest. To say they shouldn't is equivalent to closing your eyes and going la-la-la. I'll agree they (usually) shouldn't. But consider different countries that make claims over the same area. Consider insurgent governments, which have different "laws" than the ones they are attempting to overthrow. If those aren't factored in, then you'r "suatainable harvest" isn't going to be sustainable. And often destroying the food supply is an intentional act of aggression. I.e., it's lawful for those who are doing it, even though it "breaks the law" where they are doing it.

        For that matter, people even have trouble managing wild plants. Consider the rate of disappearance of the Amazon rain forest, when it is going to create an economic disaster for EVERYONE in the area when it's disappearance destroys the rainfall. And most, or possibly even all, governments in the area are officially against the destruction of the rainforest. (What they do about it is politics, and a part of what makes humans unsustainable.) Or consider all the people who just close their eyes to global warming when there's new evidence confirming it, it seems, weekly, and any contradictory evidence is weak and poorly understood. (Once it is understood it has, in every case I've followed, turned out to confirm the trend.) But acknowledging it would be economically disadvantageous in the short term. (Well, that's my estimate of the underpinnings, based mainly on who denies it.)

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        • (Score: 2) by tibman on Sunday August 23 2015, @01:20AM

          by tibman (134) Subscriber Badge on Sunday August 23 2015, @01:20AM (#226477)

          I agree with your second paragraph. But what do you mean by "reduced genetic diversity leading to single-point-of-failure managed ecosystems"? Wild animal genetic pool size doesn't factor in to cow, chicken, and other farm raised animals. Look at dogs, for example. The majority of dogs are domesticated and the rare wild ones are often caught (and killed, unfortunately). People have been breeding dogs for so long that they have created even more variety than there was before domestication. Wild animals simply don't matter for dogs anymore.

          Also, i am certain that poaching IS taken into account because most wildlife managers track population size. They don't just issue permits because they saw a few wild animals out there somewhere. They issue enough permits to prevent over-population of a given area, that is all. Often there are further restrictions on gender, or size, or weight.

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          • (Score: 2) by HiThere on Sunday August 23 2015, @02:45AM

            by HiThere (866) Subscriber Badge on Sunday August 23 2015, @02:45AM (#226503) Journal

            Domesticated animals generally have a reduced genetic diversity. Frequently sharply reduced. The Potato is a possible exception, but this is due to its intractable reproductive system. An extreme example is the bananna. I'd include the naval orange except that sexually reproducing oranges still exist. Animals and plants that evolve asexual reproduction generally go extinct rather quickly. (An exception is the bdelloid rotifers, and nobody understands why.)

            Farmers like genetically standardized crops, because they're easy to manage and predict. Unfortunately, if (when?) a disease evolves that kills any of them, it's likely to kill all of them. The ancestral corn plants can no longer be interbred with domestic corn, and domestic corn has a grossly reduced genetic variation WRT maize. Maize (or things called "indian corn") still exist, but:
            a) they are quite rare, so their own genetic diversity has been strongly reduced, and
            b) I'm not sure to what extent current maize even retains the basic characteristics of the ancestral stock. (I.e., you could plant it in a place where it could get enough water, and with a fish buried under it, and wouldn't need to care for it until harvest.) Do note, however, that even maize had been so reduced in diversity that it was genetically dependant on humans to survive. It couldn't disperse its own seeds.

            So. Single point of failure: If a large population is dependant on a single food crop, say corn, rice, or wheat, and something happens that destroys that plant, then the population will starve. This is likely to destroy to social system that said population lives within.

            P.S.: Have you heard that wild triticale, from which we derived wheat, is going extinct? Last I heard efforts were being made to save it, but I haven't heard how effective those efforts have been, and civil war has broken out in that area (the Middle East). When I last heard, a few years ago, the war wasn't in the same area, but is seems to have been spreading wildly, so it's quite likely the project had to be abandoned. That is a single point of failure for additional genes to add back into wheat. Triticale was resistent to many rusts (i.e. fungi) that can destroy all wheat crops.. So far fungicides have sufficed to control them, most of the time.
            And that's another "single point of failure". There are *many* of them. (Perhaps ancestral wheat stocks were transplanted to somewhere safer. If so, I haven't heard.)

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