What is a Species?

[morfrain_encilgar]

It is important to define what a species is, to understand what is implied by names like sapiens, neanderthalensis, heidelbergensis or erectus.

Usually, the definition used by anthropologists is that of the biological species, or a unit of animals that can interbreed. Since the inability to breed with related lineages, is unique to a lineage, they can define a species by the lack of evolutionary change, as a grade.

On the other hand, there are others define lineages by evolutionary uniqueness without considering shared features, like interfertility. They often also imply that a distinct lineage is also a biological species, but at least with the earliest members of the lineage, there was interbreeding. This definition gives more restrictive definitions than the other, which as an extreme, places Acheulians as part of the modern species.

[Scoob]

One workable definition of species is a group of organisms with common behavioral and genetic traits. I'd include that to be included within species, organisms must generate species X when it reproduces.

That's very vague and broad.

I'd say with humans, the species we ourselves are dealing with is variations of "Modern Humans". In other words, the behavioral parameters are: humans that are able to thrive and flourish within "civilization." Also, modern humans are able to create and maintain civilization, and possibly advance it (though advancent as a criterion is questionable).

I do not think all of what we call in pop culture "Humans" really qualify as this.

One group in particular that consistently fails to be "modern humans" are most African descended humans. They are not modern, in that sense. Some mixed descendents might qualify.

[morfrain_encilgar]

I'd include that to be included within species, organisms must generate species X when it reproduces.

When deciding wether an archaic is the same species as moderns, that is a problem. There is no way of telling wether hybridisation with moderns was possible, even if DNA is extracted.

I'd say with humans, the species we ourselves are dealing with is variations of "Modern Humans". In other words, the behavioral parameters are: humans that are able to thrive and flourish within "civilization." Also, modern humans are able to create and maintain civilization, and possibly advance it (though advancent as a criterion is questionable).

I wouldn't think that behaviour can be used because a race or a species may be capable of things it shows no sign of doing. Decorative art vanished from Europe at the start of the Mesolithic, but nobody suggests that Azilians were incapable of it, even though there was no evidence. It makes me wonder if earlier the neanderthals lacked the ability, or if they just didn't produce it?

[Dr. Solar Wolff]

A species is a breeding population which NORMALLY doesn't exchange genes outside that group. This can have some twists. For instance, there are physically distince seagull populations surrounding the Artic Circle. Each can breed with the next except at one point in the chain where the two seagull populations do not recognize each other as being in the same species. The question is, are these two populations of seagulls the same species or not? They are since they exchange genes through intermediate populations.

Likewise, early Homo populations have exhanged genes with modern sapiens, almost be definition, since we base our genome on what was given us by them. I my mind, this undermines the concept of the morphospecies or grade destinctions. If bony traits fall outside the range for the modern species, well then maybe, but there is usually a range of continuity between fossil and modern species.

It seems to me that many of the arguments for grade distinctions could be used to maximize racial differences as Coon did with his geographic sub-species idea for what we call the major races. In fact, if we accept Out Of Africa, then why aren't we calling Africans and non-Africans two seperate species? It seems to me that this distinction meets the usual criteria.

[morfrain_encilgar]

Likewise, early Homo populations have exhanged genes with modern sapiens, almost be definition, since we base our genome on what was given us by them. I my mind, this undermines the concept of the morphospecies or grade destinctions.

A lot of biologists would agree. But because of interfertility beng primitive, it ocurred (at least) at the base of each lineage, while it was possible. Hybridisation means that a grade is as real as the lineages.

[Dr. Solar Wolff]

Don't get me wrong. I do believe hybridization took place. In fact, I believe hybridization between sapiens and neandertals is what Europeans are. Likewise, modern Australian Abos. are hybrid Out of Africa sapiens and erectus. Modern Mongoloids, (latter Mongoloids, not American Indians) I believe have aquired non-sapiens genes recently. So hybridization is a big one for me but evolutionary grades are something which should be downgraded and not given biologic status via a Latin name. If, for instance, Homo erectus and Homo sapiens interbred in Australia, then they existed in the same time and space and were interfertile. "Grade" differences, in this case, amount to an admission of Uebermenschen and Untermenschen status but not a biological barrier.

[morfrain_encilgar]

I would generally prefer species to be named as lineages rather than grades. But it could mean creating several species, depending on how similar, more archaic, specimens are related to one another and to later races.

[Dr. Solar Wolff]

The word "linage" sounds better to me. The implication is line of descent yet it carries less baggage from biology as do the words grade, species or morphospecies. Linage has no implications regarding reproductive isolation. Linage in this sense sounds a little bit like clade but with a more extended meaning.

[morfrain_encilgar]

The word "linage" sounds better to me. The implication is line of descent yet it carries less baggage from biology as do the words grade, species or morphospecies. Linage has no implications regarding reproductive isolation. Linage in this sense sounds a little bit like clade but with a more extended meaning.

A clade, is where two distinct lineages share a common ancestor.

[morfrain_encilgar]

A definition I found for clade is "An ancestor (an organism, population, or species) and all of its descendants".