Message 1 of 30 (387688) 03-01-2007 11:59 PM

I was going to save this topic until I finished my paper, but recent chat discussions bring a feeling in me saying that it should not wait.

Imagine a deck of 52 cards. You must draw one. The probability of you drawing a card is 52/52 = 100% (since you must draw a card, and the card you draw doesn't matter).

Now, suppose you draw the Jack of Clubs. After doing so, you place it back in the deck and reshuffle, etc. Now, you must draw again. The chances of you getting a card are still 100%, but the chances of you getting the same card as before--or in other words, the same card as from a different draw which was itself an independent event--is 1/52 = 1.9%.

In my opinion, this is similar to what we see when looking at present Asian skulls, and H. erectus Asian skulls from so long ago. The skulls have the same features. It is as if H. erectus grabbed the Jack of Clubs, and then H. sapiens grabbed it right afterwards, i.e., extremely unlikely assuming they are independent events. I would first like to point out to the member from chat, that this is not an "argument of incredulity" as the common Creo would put it--life can't evolve because of odds against it, etc.--but this is an argument based on sound reasoning.

In this case, the odds are against the two populations evolving the same characteristics independent of each other. A better explanation is that they interbred, and the traits from H. erectus were passed onto modern Asian populations. Like I said, given they are independent events, it is extremely unlikely to see what we see today. The more likely explanation is that they are not independent events and are closely linked through breeding and gene passing.

Max

Edited by Jonicus Maximus, : grammar & subtitle

Edited by Jonicus Maximus, : message to admins removed

Message 4 of 30 (387702) 03-02-2007 2:12 AM

Out of Africa:

The Out of Africa hypothesis (OOA) states that H. sapiens evolved in Africa about 100,000 years ago, and then migrated outward to where populations of H. erectus and H. neandertalensis were living. The sapiens then out competed/killed off the native populations and took their place. Separate racial characteristics, such as skull features (mentioned in OP), then evolved to what they are today. It claims that mtDNA variation supports the idea.

Multi-regional:

The Multi-regional hypothesis (MH) states that after H. erectus, H. neandertalensis, etc. moved from Africa, their populations, though separated, continued to interact and breed. In a sense, they became a "world population," and not just separate populations in complete isolation. On a global scale then, modern humans--which are considered in MH to be only a variety of the entire H. sapien line that they believe includes erectus and neandertalensis--evolved from these other populations. Evidence for MH comes from the "ginger gene", and fossil similarities between regional skull characteristics, especially those found in Asian H. erectus populations and modern populations.
____________________________

The probability of these skull characteristics arising independently as claimed in OOA is the topic of this thread. Where OOA says they did arise independently, but MH says they are better explained if we accept that earlier "humans" were breeding with local populations of H. erectus (and neandertalensis) and not just replacing them.

I hope this serves to clear up any confusion people may have had regarding the meaning of my post.

Max

Edited by Jonicus Maximus, : conventions & subtitle

Message 5 of 30 (387712) 03-02-2007 6:36 AM

Reply to: Message 3 by Phat 03-02-2007 1:59 AM

TTFN,

WK

Message 6 of 30 (387714) 03-02-2007 7:27 AM

Reply to: Message 5 by Wounded King 03-02-2007 6:36 AM

That's pretty much it, for the Argument from Personal Incredulity anyway.

The Argument from Incredulity "This can't be explained by X, so Y is true", in the broad sense, is identical to the Argument from Ignorance (aka 'Negative Proof') "No evidence against Y, so Y is true", in that the lack of contrary evidence is considered positive proof.

Because Jon is not saying that something is 'certainly true', then I can't see it being that fallacy specifically. He is merely saying which explanation is the most parsimonious, which is perfectly valid. It's very different from positing that "Independent evolution is too unlikely, so it must have been common descent", which is fallacious logic.

See also: EvoWiki: Argument from Incredulity (with a slew of creationist examples)

Edited by Doddy, : fixed formatting

Message 7 of 30 (387723) 03-02-2007 7:58 AM

Reply to: Message 4 by Jon 03-02-2007 2:12 AM

Each having separately evolved in Africa an migrated out.

And that Homo sapiens features evolved in several different locations.

quote:

---

Dr Rosalind Harding, of the Institute of Molecular Medicine at the John Radcliffe Hospital, in Oxford, calculated the age of the ginger version of the gene, known as the melanocortin 1 receptor (MC1R), by using a complex model that looked at its mutation rate.

"The gene is certainly older than 50,000 years and it could be as old as 100,000 years," she said.

---

Because a mathematical model says so? One assuming a constant rate of selection of mutations even though we KNOW this is false? All that is needed is sexual selection for red hair for it to have a higher selection rate.

See Human - Chimp split 4 million years ago? for more on this difference in rates.

See http://www.dmanisi.org.ge/index.html
http://www.dmanisi.org.ge/paleoanthropology.htm

quote:

---

The Dmanisi hominid remains are the first hominids discovered outside of Africa to show clear affinities to African H. ergaster rather than to more typical Asian H. erectus or to any European hominid.

Mandible D-211, is different from all known Homo erectus specimens, but at the same time displays a certain similarity to several African fossils from Koobi Fora and Ileret (e.g., ER 992, and ER 730).

Cranial shape is similar in both specimens, spheroidal in superior view and relatively low and angular in lateral view . Greatest cranial breadth is low at the level of the well-pneumatized mastoid processes. The occipitals are relatively narrow and angular.

The combination of the features of the Dmanisi hominids appear more similar to H. ergaster than to H. erectus sensu stricto (or to any of the habilines). This conclusion is consistent with our studies of the Dmanisi mandible . We thus assign the Dmanisi hominids to Homo ex gr. ergaster.

---

more later ...

ps -- Good start. Nice summary of the positions so far. You'll need more evidence pro and con to flesh it out eh?

One of the arguments for OOH is the modern H.sap. in ethiopia:

http://www.berkeley.edu/news/media/releases/2003/06/11_idaltu.shtml

quote:

---

Because the Herto fossils represent a transition between more primitive hominids from Africa and modern humans, they provide strong support for the hypothesis that modern humans evolved in Africa and subsequently spread into Eurasia. This hypothesis goes against the theory that modern humans arose in many areas of Europe, Asia and Africa from other hominids who had migrated out of Africa at a much earlier time.

---

Enjoy.

Edited by RAZD, : ps added

Message 8 of 30 (387756) 03-02-2007 2:20 PM

Reply to: Message 4 by Jon 03-02-2007 2:12 AM

I want to see the proof that H. sapiens could in fact interbreed with erectus, neandertalensis, and heidelburgensis. Or for that matter, that erectus and neandertalensis could inertreed, or that erectus and heidelgurgensis could interbreed, or any other combination (seeing as how the MRH requires them all being able to interbreed, from what I understand).

If you cannot show that they could, then MRH is dead in the water from the get-go.

Further more, where is the oldest H. sapiens fossil located? The oldest cro-magnon fossil (modern man)? If H. sapiens arose independently through all this interbreeding, shouldn't we find ancient H. sapiens in more than one place?

Did this multiple-region speciation event occur simultaneously? How can you tell? If they didn't, how can you tell that it isn't just H. sapiens replacing the elder species?

Also, if the MRH is true, shouldn't there be more than one line (everyone today is related to a single ancestor, based off of genetic studies)?

What about Y-chromosome data, which shows a similar OOA trend?

" One useless man is a disgrace. Two are called a law firm. Three or more are called a congress" --paraphrased, John Adams

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Message 9 of 30 (387767) 03-02-2007 3:40 PM

Edited by 1.61803, : typos.

Message 10 of 30 (387782) 03-02-2007 5:27 PM

Reply to: Message 9 by 1.61803 03-02-2007 3:40 PM

The biggest problem with MRH? IT requires interbreeding amongst the various Homos. We have no way, as far as I know, to determine if the offspring would be viable, never mind that they actually did cross. A hypothesis is worthless when grounded in such unprovable assumptions.

Message 11 of 30 (387784) 03-02-2007 5:32 PM

Reply to: Message 10 by kuresu 03-02-2007 5:27 PM

Edited by Chiroptera, : No reason given.

Message 12 of 30 (387785) 03-02-2007 5:33 PM

Reply to: Message 10 by kuresu 03-02-2007 5:27 PM

quote:

---

IT requires interbreeding amongst the various Homos. We have no way, as far as I know, to determine if the offspring would be viable, never mind that they actually did cross.

---

Actually, it doesn't require breeding among different species.

What the MH proposes, if I understand it properly (and I don't buy into it myself, by the way -- but I'm not an anthropologist), is that the world-wide population of Homo erectus evolved into H. sapiens. Basically, it proposes that gene flow was high enough throughout the world-wide population that whenever an innovation toward H. sapiens arose somewhere, it spread throughout the world wide H. whatever population. So the world-wide population was, at all times, a single inter-breeding species.

The regional differences (like the modern Asian characteristics allegedly seen in Asian specimens of H. erectus) would be those traits that, because of random chance, never propagated beyond the more-or-less local population.

Message 13 of 30 (387812) 03-02-2007 7:35 PM

Reply to: Message 8 by kuresu 03-02-2007 2:20 PM

Cro Magnon = Homo sapiens

The oldest Homo sapiens fossil (so far) is the set in Ethiopia:
http://www.berkeley.edu/news/media/releases/2003/06/11_idaltu.shtml

quote:

---

160,000-year-old fossilized skulls uncovered in Ethiopia are oldest anatomically modern humans

---

To show the asian link to Homo erectus would only require that Homo erectus and Homo sapiens interbreed - neander would not be necessary.

http://www.dmanisi.org.ge/index.html

quote:

---

The Dmanisi hominid remains are the first hominids discovered outside of Africa to show clear affinities to African H. ergaster rather than to more typical Asian H. erectus or to any European hominid.

---

But H. ergaster is considered ancestral to or an archaic H. erectus

Looking at the typical chart of human development from
http://www.mnh.si.edu/anthro/humanorigins/ha/a_tree.html
or
http://www.handprint.com/LS/ANC/evol.html
we see H. ergaster as the common ancestor to both H. erectus and H. heidelbergensis which is then a common ancestor to H. sapiens and H. neanderthalensis

This makes interspecies hybrids between H. sapiens and H. neander. much more likely to be viable that interspecies hybrids between H. sapiens and H. erectus.

Then we have the genetic data

http://www.pnas.org/cgi/content/full/96/10/5581

quote:

---

The date of divergence between the mtDNAs of the Neandertal and contemporary humans is estimated to 465,000 years before the present, with confidence limits of 317,000 and 741,000 years. Taken together, the results support the concept that the Neandertal mtDNA evolved separately from that of modern humans for a substantial amount of time and lends no support to the idea that they contributed mtDNA to contemporary modern humans.

---

More to the point, there should be genetic evidence of mixing of genes between H. sapiens and other species, evidence that is to date lacking.

Message 14 of 30 (387818) 03-02-2007 8:00 PM

Reply to: Message 8 by kuresu 03-02-2007 2:20 PM

Here you are making the assumption that humans won't stick their member in anything that moves. Also, you sound like a Creationist with that "oh yeah? prove it!" attitude.

Read this from Message 4:

quote:

---

In a sense, they became a "world population," and not just separate populations in complete isolation. On a global scale then, modern humans--which are considered in MH to be only a variety of the entire H. sapien line that they believe includes erectus and neandertalensis--evolved from these other populations.

---

You seem not to realize how few fossils we actually have. Most are nothing but chunky little fragments of skulls, legs, whathaveyou.

You seem to know little to nothing about mtDNA, and I cannot describe everything I know about it here. You will have to read up on it a little and then ask specific questions about how it relates to the two theories.

Max

Message 15 of 30 (387820) 03-02-2007 8:18 PM

Reply to: Message 12 by Chiroptera 03-02-2007 5:33 PM

Max