Human evolution and phylogeny: what we are, and what we aren't.

Intro.

Having spent under a month haunting this particular forum, it has come to my attention that a lot of arguments concerning the validity of "the theory of evolution" are actually based on a specific evolutionary hypothesis concerning human origins, namely that we are a member of the goup "primates", also including the great and lesser apes, old world and new world monkeys, lemurs, tarsiers, and so on.

While the body of evidence supporting this particular hypothesis is sufficient to convince me that it is true, that is not my concern here. Rather, I have noticed that a good many people, on both sides of the "evolutionist" argument, are misrepresenting our (hypothesized) position within the primates. I intend to rectify this.

A Couple Of Words on Phylogeny

Just so you know what I'm talking about, there are a couple of terms that will need to be explained: First off, "monophyly" and "paraphyly". If a term - for example, "monkey" is to be treated as monophyletic, it has to include all descendants of the most recent common ancestor of all groups described as monkeys. If it does not, it is considered to be "polyphyletic", which effectively makes it biologically invalid.

As a less obscure example, imagine a group of people known by the name of "The Smith-Joneses", who all share one great-great grandmother. For the term to be monophyletic, everyone descended from this great-great grandmother must be included in the group known as "the Smith-Joneses". If those who have, for example, married and changed their names, are not included, "the Smith-Joneses" becomes polyphyletic

Another issue is with the levels of phylogeny. Basically, every organism exists within a species, within a genus, within a family, within an order, within a class, within a phylum, within a kingdom, within a domain.

Because evolution doesn't tend to happen in neat, regular units, a number of intermediate "clades" are added - those above gain the prefix "super-", and those below gain either "Sub-", "Infra-" or "Parv" - giving us such terms as parvorders within infraorders within suborders within orders within superorders, et cetera. The term "tribe", although not used here, is employed to describe a group between subfamily and genus.

What we are

Homonins
Homo sapiens - that's us - are in the subfamily Homoninae. Also within the Homoninae are the African Great apes - that is, members of the genus Pan (chimps and bonobos), and, at the base of the group, members of the genus Gorilla.

Assuming the arrangement of the groups within the hominins is correct - with gorillas splitting off before chimps and humans diverged - the term "african apes", to be monophyletic, would include humans. Our ancestry, at any rate, is considered to be with the group "african apes".

That is not to say that we evolved from chimpanzees, or that they evolved from gorillas. While the common ancestor was an african ape, it would not be considered the same species as any one of the modern species.

Homonids

Homonids, or "great apes", describes the members of the family Homonidae. Within this group are the subfamilies "Homoninae" and "Ponginae". "Ponginae" currently includes only the genus "Pongo", the Orangutans.

To be monophyletic, as such, "great apes", including chimps, bonobos, gorillas and orangutans, must also include humans.

Hominoids

Hominoids, or "apes" describes members of the superfamily Hominoidea. Within this group are the families "Homonidae" - the great apes - and "Hylobatidae" - the gibbons, or "lesser apes". To be monophyletic, therefore, "Apes" must include not only gibbons, orangutans, chimps, bonobos and gorillas, but also ourselves.

Catarrhines

The parvorder Catarrhini contains two groups - the previously discussed Hominoidea, and the Cercopithecoidea, or old world monkeys - old world monkeys describing the - mostly tailed - monkeys native to Africa and Asia.

Simian

The infraorder Simiiformes, or simians, describes the "ape-like" primates, consisting of the two parvorders "Catarrhini" and "Platyrrhini (the new world monkeys).

What this means is that the two lineages currently known as "Monkeys" diverged before the old world monkeys separated from the apes.

What this, in turn, means is that "monkeys", from an evolutionary perspective, includes the apes. Certainly, the apes have an ancestor that would be described as a "monkey".

Haplorrhines

The Haplorrhines, or suborder Haplorrhini, is made up of the infraorders "Simiiformes" and "Tarsiiformes", or tarsiers. Along with Strepsirrhini, which includes the more divergent primates such as lemurs and lorises, it makes up the group primates.

The Point

My purpose in starting this thread is not to debate human origins. I am not a primatologist, and as far as the vertebrates go, I think the only group I have less interest in are sheep. I do not definitively "know" if this phylogeny is correct - everything in science is always subject to change. However, if people are going to discuss human evolution, I feel it that they will be best able to deny ignorance, wherever they find it, if they know what we are actually said to have evolved from. We can be said to have evolved from a primate, we can be said to have evolved from a monkey, we can be said to have evolved from an ape, we can be said to have evolved from a great ape, and we can be said to have evolved from an african ape.

We cannot, however, be said to have evolved from any modern species of any of these any more than they can be said to have evolved from us.

We are Homo sapiens, a homonin, homonid, hominoid, catarrhine, simian, haplorrhine primate.


[size=-3]While it doesn't name all the nodes that I have discussed here, and does name a couple incorrectly, the basic structure of the described phylogenetic tree can be found at the Tree Of Life Web project (primates).

i have read your argument and as much as i would like to pick it apart (i love a good intellectual brawl), i cannot.

but what i can say is that i cannot understand why, at the level of discourse of ATS, do you think this level of semantics is relevant to the discussion?


i TOTALLY get what you are saying, but i still see nothing wrong with simply stating that we "evolved from monkeys". it is an overall simpler abstraction and thus allows us to handle the complexity of the concept of evolution with more agility.

bluntly: whats your point?

Originally posted by tgidkp
i TOTALLY get what you are saying, but i still see nothing wrong with simply stating that we "evolved from monkeys". it is an overall simpler abstraction and thus allows us to handle the complexity of the concept of evolution with more agility.

bluntly: whats your point?

I believe this statement to be incorrect, it is misleading and not correct science...

I would have to say we have evolved along side of the apes and Humans are their own individual species.

this is where alot of the misinterpretation and representation comes into play, even down at the museums.

simpler maybe but totally non acceptable as we are our own species, Apes being our cousins.

Originally posted by Cosmic.Artifact
Apes being our cousins.

Apes being our cousins and still in a state of evolution at this moment in time, I believe the philosophy behind "The Planet of the Apes" series of movies revolves around this ?

Evolution is real-time, something that is happening currently and not to be spoken of as past-tense, it is happening at this very moment in the natural world.

reply to post by tgidkp

I think the reason for the OP is to explain why the common creationist strawman argument of "we've never seen a monkey turn into a man" isn't a valid one. There seems to be a misconception that evolution states that humans literally evolved from chimpanzees or gorillas, rather than a common ancestor.

reply to post by tgidkp


The point is two-fold: first, a lot of people demand to know why there are apes or monkeys still around if we evolved from them - which we didn't any more than they from us; second, a lot of responses are "we didn't evolve from apes, we and apes share a common ancestor", or "we didn't evolve from monkeys", often imbedded in posts that I otherwise agree with, when they should, more correctly, state that "we didn't evolve from any modern ape, we share a common ancestor with them".

So I'm not saying "we evolved from monkeys, discuss", I'm saying "By the way, as much as we did not evolve from any modern monkeys, we did evolve from an ancestral monkey"

reply to post by Cosmic.Artifact


If I understand what you're saying, thanks, that is a good way of putting it. However, please do note that while modern apes are more properly considered our cousins than our grandparents, some are currently considered much closer cousins to us than they are to other apes (hence, we did evolve from an ape, just not current ones.

reply to post by iterationzero


That, and those who are arguing - as is appropriate - that we share a common ancestor rather than a monkey-gives-birth-to-human scenario, often say "nobody says we evolved from monkeys", when... we do say that.

Originally posted by TheWill
reply to post by iterationzero

 

That, and those who are arguing - as is appropriate - that we share a common ancestor rather than a monkey-gives-birth-to-human scenario, often say "nobody says we evolved from monkeys", when... we do say that.

Agreed. I think the problem lies in the fact that those seeking to debunk evolution mean modern monkeys, not a common ancestor.

reply to post by Cosmic.Artifact


...you are demonstrating a lack of understanding of what the OP of this thread states.

We are apes, but we are our own species.

Apes belong to the family homonidae, but are further divided by subfamilies, genus, and species.

We are apes, but we are our own species. Just like tigers are cats but are still their own species.



As for this thread, great job!
I starred and flagged it when I first read the OP.

reply to post by Cosmic.Artifact

Originally posted by Cosmic.Artifact

Originally posted by Cosmic.Artifact
Apes being our cousins.

Apes being our cousins and still in a state of evolution at this moment in time, I believe the philosophy behind "The Planet of the Apes" series of movies revolves around this ?

Every living organism is currently in a state of evolution., it is an unending process. Of course, that doesn't mean that the rest of our ape family members are going to become human like. It all depends on the selective pressures they're introduced to.

Evolution is real-time, something that is happening currently and not to be spoken of as past-tense, it is happening at this very moment in the natural world.

And in the human world. We're evolving, but only very slowly. There have been changes in our allele frequencies over successive generations and there will continue to be such changes unless our branch of the 'tree of life' withers and dies.

Originally posted by tgidkp
i have read your argument and as much as i would like to pick it apart (i love a good intellectual brawl), i cannot.
but what i can say is that i cannot understand why, at the level of discourse of ATS, do you think this level of semantics is relevant to the discussion?
i TOTALLY get what you are saying, but i still see nothing wrong with simply stating that we "evolved from monkeys". it is an overall simpler abstraction and thus allows us to handle the complexity of the concept of evolution with more agility.
bluntly: whats your point?

I agree. Maths has never been my thing, so it's confusing when people who understand numbers insist that pi is a never-ending number that I can't remember.

What would be wrong with just saying pi = 3?
It's much simpler and that's how I understand it.
And, as Madness has previously pointed out, the bible proves pi = 3.