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According to Invasive Species Advisory Committee (ISAC), the definition of the invasive species is “a species that is non-native to the ecosystem under consideration and whose introduction causes or is likely to cause economic or environmental harm or harm to human health.”

But considering the following facts, why is this species not categorized as an invasive species? Homo sapiens:

  • is non-native to the most of the ecosystem which it is inhabiting, since it originated from a certain area of Africa and spread quite recently.

  • has often caused environmental problems by decreasing the local species after its introduction, as it is known that the number of species in the planet is drastically decreasing ever since the advent of Homo sapiens.

  • is likely to cause the same problem after introduced to new environment where homo sapiens hasn't inhabited yet.

http://www.invasivespeciesinfo.gov/docs/council/isacdef.pdf

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    $\begingroup$ Well I bet the answer is as easy as: "Because we just wanted to ignore that Homo sapiens is an invasive species!". Following a strict definition of invasive species (although current definitions are not that strict!) we should add Homo sapiens in the list. Adding Homo sapiens would not change anything to the way conservation actions are performed, we will always consider Homo sapiens very differently than the other species. Do you feel concerned about this issue? Do you think it would change anything adding Homo sapiens to this list? $\endgroup$ – Remi.b Mar 4 '14 at 18:16
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    $\begingroup$ Because we are not invasive ones, we expansive ones... $\endgroup$ – Ilan Mar 4 '14 at 19:53
  • $\begingroup$ Thanks. I didn't know that the definition isn't so strict. Yes, there's actually no special reason for us to call human as an invasive species. Only thing in the real world which it matters with is probably my final grade for the third quarter. If human is an invasive species, I could get A instead of A-. $\endgroup$ – Math.StackExchange Mar 5 '14 at 2:12
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    $\begingroup$ Haha.. because we are the ones who are setting up the organizations, making categories and writing books. $\endgroup$ – WYSIWYG Mar 5 '14 at 4:50
  • $\begingroup$ I'm voting to close this question as off-topic because it does not concern biological classification but classification by governmental or inter-governmental bodies for purposes of husbandry. The question is framed to appear "clever". It isn't. $\endgroup$ – David Oct 28 '18 at 19:47
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Ignoring for the moment the question of politics, let's consider the various definitions of the term "invasive species" that are in use. Colautti and MacIsaac write in their discussion of invasive species terminology (1):

The greatest confusion [among the discussed ecological terms] surrounds the common term ‘invasive’ and its various derivatives (Richardson et al., 2000a). Explicit or implicit definitions for ‘invasive’ include: (1) a synonym for ‘nonindigenous’ (e.g. Goodwin et al., 1999; Radford &Cousens, 2000); (2) an adjective for native or nonindigenous species (NIS) that have colonized natural areas (e.g. Burke & Grime, 1996); (3) discrimination of NIS established in cultivated habitats (as ‘noninvasive’) from those established in natural habitats (e.g. Reichard & Hamilton, 1997); (4) NIS that are widespread (e.g. van Clef & Stiles, 2001); or (5) widespread NIS that have adverse effects on the invaded habitat (e.g. Davis & Thompson, 2000; Mack et al., 2000).

Note that except for #2, all the definitions require that the species is a nonindigenous (non-native) species in the area under consideration. Therefore, while humans may be considered to have been an invasive species for much of our species history, under most definitions of the term we no longer qualify because except in a few places (mainly the arctic, antarctic and marine environments, where human presence is minimal) we are now a native species.

See also http://www.smithsonianmag.com/science-nature/are-humans-an-invasive-species-42999965/?no-ist

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    $\begingroup$ This argument seems to hinge on the pretty arbitrary decision of the point at which an invasive species can be considered indigenous... $\endgroup$ – Armatus Oct 27 '18 at 9:09
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    $\begingroup$ Well, yes. How can it be any other way? $\endgroup$ – jarlemag Oct 28 '18 at 17:34
  • $\begingroup$ That's not what the term native species means, don't confuse the legal term native with the biological term. $\endgroup$ – John Nov 1 at 0:48
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I don't think there is a good answer.

  1. Many people and organisations do not even consider Homo sapiens when making such lists. Why? Because we have been for millennia a narcissistic species (think about religious narrative). This is similar to non-scientifically talking about animals. Homo sapiens is usually implicitly excluded from considerations.
  2. Although Homo sapiens is present on all continents apart from Antarctica, Homo as a genus has been present for millions of years in Eurasia. Homo erectus has been there particularly long. Homo sapiens has outcompeted these species.
  3. Ecosystems do change. Whether or not Homo sapiens is sufficiently long to be a native species is not a well posed question. Any answer would depend on arbitrary cutoffs. For instance if the first migration of Homo sapiens to Americas happened 14k years ago and it took 20 years per generation, then Americas are populated only for 700 generations. Is it a lot or is it little?
  4. However, there are places in the world (mostly islands) where Homo sapiens settled very recently. Mauritius was first settled in 1638. And it is clear that since then many bird species (not only the famous dodo) went extinct and most of the area was converted from forests to sugar cane fields and towns. So yes, in this case there is no doubt the migration was recent and that it drastically changed the ecosystem, therefore it fulfils the definition.
  5. Pragmatism. Probably the most important of it. We define invasive species for a reason: to give them a negative connotation and possibly plan a future removal. Doing these actions against humans are completely different from the legal point.

To sum up: a external observer would classify humans as an invasive species in at least some regions (Mauritius) and not in other (Africa south of Sahara). But people don't classify themselves as such because of political, moral, legal and pragmatic reasons.

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