Yukon fossils represent a pivotal moment in evolution

[orogenicman]

Of course, we all know why those little critters were building these armoured plates, right? To protect themselves from all the other critters that wanted to eat them. And of course, that only started a biological arms race that has continued up to the present.





Notice the bite marks on the brachiopod shell.

What better evidence for evolution does anyone need?

[Ryft]

Darth Vader Homo erectus: No, I am your father.
Luke Ziggy: No. No! That's not true! That's impossible!

[orogenicman]

Speak kindly of HE. He may well turn out to be an ancestor of yours.

Not too long ago paleo-anthropologists were "sure" that HNS and HSS never interbred. Now we know that they did which means that if you wish to define "species" as a group which can only breed successfully with itself it means that these are NOT separate species. The relationship between the wide-ranging HE and later hominids is equally hazy.

We may well turn out to be them.

The oldest known Homo Erectus fossils in Africa and at the Dmanisi site appear to be roughly contemporaneous, with the latter being only slightly older (we must keep in mind the relatively large dating errors (+/-)involved with fossils this old). The fact of the matter is that the bulk of Homo Erectus fossils are found in Africa, and so it stands to reason that that is where the largest population was located. Whether they evolved in Africa first and then moved elsewhere, or moved in from elsewhere to Africa, has little bearing on later human populations migrating out of Africa. The evidence, to my mind, is pretty convincing that the oldest fully human populations originated in Africa. That is where the oldest fully human fossils have been found, as has been expected all along.

http://www.wsws.org/articles/2003/jul200...-j25.shtml

http://www.eurekalert.org/pub_releases/2...021105.php

In comparison, the oldest known fully human fossil found in Europe dates only to 34,000-36,000 years ago.

http://news.wustl.edu/news/Pages/2370.aspx

While the oldest fully human fossils in Asia are at least 60,000 years ago and possibly 100,000 years old.

http://anthro.palomar.edu/homo2/mod_homo_4.htm



Date of Fossil
(years ago)

--------------------------------------------------------------------------------

East Africa:
Herto, Middle Awash 160,000-154,000
Omo 1 195,000
Laetoli 120,000
South Africa:
Border Cave 115,000-90,000
Klasies River Mouth 90,000
Israel:
Skhul and Qafzeh 92,000-90,000
Australia:
Lake Mungo 60,000-46,000
Asia:
Ordos (Mongolia) 40,000-20,000 ?
Liujiang (China) 139,000-111,000 ?
Zhirendong (China) 100,000
Zhoukoudian upper cave
(China) 27,000
Europe:
Peştera cu Oase (Romania) 36,000-34,000
Combe Capelle (France) 35,000-30,000
Mladeč and Předmostí
(Czech Republic) 35,000-25,000
Cro-Magnon (France) 27,000-23,000

[Justtristo]

Darth Vader Homo erectus: No, I am your father.
Luke Ziggy: No. No! That's not true! That's impossible!

I am not denying that Homo Erectus was an ancestor of Homo Sapiens, however Homo Erectus likely evolved into Homo antecessor, then it evolved into Homo heidelbergensis then heidelbergensis evolved into Neanderthal, Denisovan and rhodesiensis (which homo sapiens most likely evolved from).

[Minimalist]

I submit that one must use the term "evolved into" very cautiously, here. For one thing, these designations Ergaster, Erectus, Neanderthal, etc. are based on the assumptions that because there are differences in the bones there MUST be different species. As the recent discovery of interbreeding between HNS and HSS has shown that assumption is misplaced.

There was a Nat Geo special not too long ago which demonstrated the evolution of HE itself. There are big differences between early HE and the late HE specimens. I'll look on youtube and see if I can find a link to it. Fascinating shit and fairly recent.

[Anomalocaris]

Darth Vader Homo erectus: No, I am your father.
Luke Ziggy: No. No! That's not true! That's impossible!

I am not denying that Homo Erectus was an ancestor of Homo Sapiens, however Homo Erectus likely evolved into Homo antecessor, then it evolved into Homo heidelbergensis then heidelbergensis evolved into Neanderthal, Denisovan and rhodesiensis (which homo sapiens most likely evolved from).

1. Many of the named species of the homo genus is not univerally accepted as representing distinct genetic populations. So the linear progression through these specifically named steps is questionable.

2. Fossil evidence is strongly subject to preservation and selection bias. The discovery of the earliest fossil for a particular group, such as HE, is suggestive, but not convincing, evidence for notion that HE originated from that location of the discovery. Other evidence needs to corroborate the suggestion. For example: Are the species thought to be the closest ancester to HE known to also be present in the location of the discovery? If not, how did HE originate there? If metric for the mitochrondria genetic diversity of HE for the different, but nearly contemporaneous, populations of HE can be established, then one should find the greatest diversity in the region where HE originated and therefore has had the most time to diversify. Do we find greater diversity in the mitochrondria DNA for HEs outside of Africa?

Jumping to Homo Sapiens. What is much more certain is the homo sapien population of Africa is both genetically and liguistically much more diverse than the homo sapien population outside of Africa. This very strongly suggests that modern homo sapien evolved in Africa first, and had been living in Africa for a long time, accummulating a great deal of genetic and linguistic diversity in situ, before just a small group of them, representing a small portion of the genetic and linguistic diversity already existent in Africa, left african and become the founding population of all homo sapien populations outside of Africa. This is supported

What has been present can't even qualify as quibbles against the volume of evidence for the OOA origin of homo sapien.

[Minimalist]

Yet science must consider ALL of the evidence, Chuck, otherwise it becomes like religion.

As suggested here:

http://www.religioustolerance.org/ev_disp.htm

The sorting of fossils is complete. Dinosaurs have never been found in the same layer as trilobites; trilobites have never been seen together with human remains; dinosaur remains have not been found with human remains.

A single human skeleton found next to a trilobite in the rock strata would upset the theory of evolution. Creationists try to invent such "finds" periodically because they are little more than fanatical liars. Should such a legitimate find be made I would consider the TofE disproven. Of course, that would do nothing to show that bible bullshit was "true" in its place.... a fact which creationists never consider.

[Anomalocaris]

Yet science must consider ALL of the evidence, Chuck, otherwise it becomes like religion.

That's a low blow, Min.

The sorting of fossils is complete. Dinosaurs have never been found in the same layer as trilobites; trilobites have never been seen together with human remains; dinosaur remains have not been found with human remains.

A single human skeleton found next to a trilobite in the rock strata would upset the theory of evolution. Creationists try to invent such "finds" periodically because they are little more than fanatical liars. Should such a legitimate find be made I would consider the TofE disproven. Of course, that would do nothing to show that bible bullshit was "true" in its place.... a fact which creationists never consider.

A single human skeleton found next to a trilobite in the rock strata would not upset the theory of evolution. It would, however, upset creationists by proving that someone was willing to improve the human gene pool by killing in situ any creationist caught trying to doctor fossil evidence of trilobite.



Seriously, fossil evidence that some previously undiscovered lineage of trilobite did not die off during the Permain extinction and crytically survive to cohabit the earth with humans would not be a earth shattering event, and does not even tangentially challenge evolution, nor require any major alteration of the story of life on earth as had been informed by evolutionary biology and paleontology. Similar discovery are made all the time. There is another ancient lineage of once widespread arthropod called anamalocarid, which happen to be my avatar, that had also previously been thought to have gone completely extinct in Cambrian. Recently it was discovered to survive still in significantly altered, but still easily recongizable, form the devonian period. The thing survived almost an extre hundred million years without there being any fossils that we've discovered.

More relevent to our story is the fact that earliest fossils of trilobite, as well as anamalocarid, was from some place in China. Yet we do not take too seriously the notion that these creatures originated in what is to become China near where we found our earliest fossils. This is because:

1. even though Chinese fossils predated fossils from elsewhere, We are not convinced the difference is caused by different distribution of the creatures at the time of chinese fossils and the time of fossils from other places.

2. there are sufficient amount of development in those unique features that identify trilobite and anamalocaris in the fossils from China that we do not believe those fossils from china were all that close to the first forms of those creatures.

A similar story applies here. For the earliest non-African HE, can we construct a convincing statistical or ecological narrative about why its discovery outside of Africa but not inside Africa really represent the true distribution? Does the earliest non-African HE possess characteristics that define HE in such a modest way that we can really argue that it was indeed something that was very close to the earliest HE? Or is it already so evolve that it most have been separated from still earlier HE by many hundreds of thousands of years, so the fact that the already-discovered non-African HE might predate African forms by just a couple of hundred thousand years really don't mean a whole lot?

[Minimalist]

For the earliest non-African HE, can we construct a convincing statistical or ecological narrative about why its discovery outside of Africa but not inside Africa really represent the true distribution?

This is what the argument is going to be about for the next 40 years. I don't expect to live to see the resolution of it but that will not stop the debate from progressing. Recall that the geneticists claim that the Toba eruption provides a genetic bottleneck for HSS ( although I confess to having doubts about the whole Toba scenario.)



P.s. That would be one hell of a trilobite.

[Anomalocaris]

The doubt about the Toba genetic bottleneck theory surrounds the notion that Toba caused it, not around whether the bottleneck existed. The notion that all of us alive today can trace our ancestery to just a few thousand individuals at aorund the time of eruption of the youngest Toba tuff is well attested genetically. The question about the link to Toba arose from the fact that if an volcano erupting half a world away could kill most humans alive, then it must have also been powerful enough to create very widespread genetic bottlenecks in all sort of species everywhere in the world. We don't see strong evidence of widespread havoc around the world, only primates in Africa seem to suffer this bottleneck. This suggests whatever created the bottleneck was local to Africa.

But this is only a suggestion. Massive volcanic eruptions can create very powerful indirect effects that would devastate populations a great distance away while sparing nearby populations. For example, by far the greatest volcanically induced casualty ever inflicted on mankind in recorded history occurred in in 1780s in Africa, near where we think HS were when Toba erupted. At least 2 million Egyptians starved to death. The cause of the diseater? An volcanic eruption in Iceland. There were no similar population diseasters anywhere else in the world during that time. We know through numerous weather observations and records that the volcanic eruption in Iceland ejected aerosol into the upper atmosphere that changed the global weather pattern, causing the following year's monsoon to fail, leading to collapse of agriculture in Egypt, and the massive femine. But if all we had were grave records, we would be perplexed how it it could be that a volcano in Iceland could kill so many in far away Egypt while leaving the rest of the world nearly untouched.