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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.

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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? – Remi.b Mar 4 '14 at 18:16
Because we are not invasive ones, we expansive ones... – Ilan Mar 4 '14 at 19:53
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-. – Math.StackExchange Mar 5 '14 at 2:12
Haha.. because we are the ones who are setting up the organizations, making categories and writing books. – WYSIWYG Mar 5 '14 at 4:50
@Ilan: history are written by the winners, it's not rebellion, it's freedom fighters, it's not invasive, it's expansive. – Lie Ryan May 4 '14 at 14:38
up vote 4 down vote accepted

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

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