Please note: this is a rough draft and work-in-progress that is far from finished yet. Footnotes and references will be added later.
This topic will address the issues raised by creationists regarding Homo Erectus' relationship with modern humans (Homo Sapiens Sapiens).
This image was taken from Harun Yahya's "Atlas of Creation" website. Images of partial Homo Erectus skulls and what we are told is a Malaysian tribesmen are juxtaposed to suggest that H. Erectus really could have been just another race of modern human.
We are also not provided with any other information about this man. Are there others who look similar? It is possible he may just have some individual variance that does not reflect the rest of his group. According to Wiki, the native aboriginals of Malaysia are collectively known as the Orang Asli, divided into three main tribal groups -- Semang (negrito), Senoi, and Proto-Malay (Aboriginal Malay)
Now here's another jpeg from Yahya's site, arguing that skull "variance" only shows differences between geographical races and does not imply different species (implying that more ancient hominin forms were just variations of modern humans).
Since humans are so widely distributed, it should be expected that there can be some allowance of facial variation. But they also have certain similarities...
Here I have lined them all up so we can see the proportional similarities shared by modern humans. All share a certain symmetry in which the eyes are roughly in the center of the face. This is not shared by H. erectus and similar ancient hominids, and it is due to the proportionally higher forehead that houses an enlarged cerebral cortex.
Let's examine this further:
From The Smithsonian Institute's anthropology website:
Homo erectus exhibits many features particular to the species, including a long skull shaped with thick cranial walls. The back of the skull is marked with a protruberance known as a transverse torus. Over the eyes is a large and prominent browridge, or supraorbital torus, which joins the rest of the frontal bone at a depression called the sulcus. Cranial capacities of Homo erectus average around 1000cc, which is far greater than earlier australopiths and even early Homo. The dentition of Homo erectus is nearly identical to modern humans, although the cheek teeth do remain larger, and the mandible is generally more robust.
This side view diagram shows the differences in bone structure and brain volume between H. sapiens and H. erectus.
Below are photos of the Turkana Boy skeleton at the Kenya National Museum - one of the most complete hominin fossils found to date (click on image for larger version). It was determined to be around the age of 12, based on skull and dental features. Its skeleton is identifiably human -- almost modern in appearance. The discovery of this skeleton caused creationists to re-think their position on H. erectus.
Its skull is not quite modern, however. A comparison between this skull and the skull of a modern 12-year-old H. Sapiens would quickly bear that out. Moreover, unlike modern humans, it does not have the anatomy associated with complex speech vocalization.
Here I have drawn a sketch around the photo of the skull (leaving out details one might need to imagine) but giving a basic sense of facial proportion. Keep in mind that this is a juvenile -- so as an adult, the cranium would appear smaller in proportion to the face. Although it looks human in a broad sense, a child with these facial proportions would probably be looked upon as freakish if alive today.
Below is a photo of an Australian aborigine boy. Children of all races of Homo sapiens have a characteristically very high forehead, which is not shared by Turkana Boy, which has a sloping forehead and much smaller cranium.
Now let's take a look at some other skull similarities and differences...
Older hominin forms have robust cheek bones that transition more evenly into the maxilla (upper jaw bone). Modern humans, on the other hand, have more refined facial bones with an undercut zygomatic arch (cheekbone), creating a typically "hollowed out" area around the mouth. This is where the intricate muscles used for speaking and expression are attached. One can see these features on any modern H. sapiens skull, including Australian aborigines (shown below):
These facial bone refinements are not found in the older hominins...
(I highly recommend viewing this video in which a professional reconstruction artist shares the same observations about the Turkana's Boy's skull anatomy).
What obviously occurred in the time period between H. erectus and H. sapiens is an enlarging brain and a regression of face and jaw area. According to the "use it or lose it" principle, evolution predicts something like this would happen based on the evidence that hominins became more reliant on tools and weapons instead of relying so much on powerful teeth and jaws for survival, as is the case with apes and other animals. Wisdom teeth, which sometimes must be surgically removed due to impaction, are evidence of these distant ancestors and their larger jawbones. So the trends that led the way towards our more modern form were as follows:
1. Walking upright and having opposable thumbs
2. Learning to use fire and learning to cook food
3. Cooperation instead of conflict among males
4. Sexual selection based on visual appearance and social strategy becomes the primary evolutionary force,
Evolutionists that creationists often quote out of context:
Creationists often like to quote evolutionary biologists out of context in order to make it appear as if "evolutionists" are conceding that H. erectus is merely a different race of our own species. ( And of course, they usually just focus on these very few while ignoring the others who disagree).
1. Richard Leakey. In www.hyahya.org/definitivereply05.php Yahya disingenuously writes, "Even the evolutionist Richard Leakey states that the differences between Homo erectus and modern man are no more than racial variance:" Really? Here is the actual quote, where Leakey describes the Turkana Boy:
"One would also see differences in the shape of the skull, in the degree of protrusion of the face, the robustness of the brows and so on. These differences are probably no more pronounced than we see today between the separate geographical races of modern humans. Such biological variation arises when populations are geographically separated from each other for significant lengths of time."
Leakey was comparing the Turkana Boy TO OTHER H. ERECTUS -- not to modern humans! He was talking about "races" AMONG H. Erectus! For its time, H. erectus range was widespread and found on more than one continent, so it followed that an African H. erectus might look different than an Asian one. This is just one of many examples where Yahya dishonestly takes quotes out of their original context.
2. Alan Thorne et al proposed that H. erectus was on a trend towards evolving bigger brains no matter where it migrated to, whereas the prevailing idea was that H. Sapiens came from one branch in Africa while H. erectus died out. In other words, they're saying that the smaller-brained fossils previously classified as H. erectus (which they do not dispute are different) was just a very archaic form of H. sapiens -- not a "race" as we define it today. His theory was based on the finding of a fossil hominid in Australia, originally dated 60,000 BP. (However, it has since been found that the fossil isn't as old as was originally claimed to be.)
3. Milford Wolpoff : this has more to do with classification than disputing evolution. The reason has to do with there not being a clear demarcation point between where H. erectus ends and H. sapiens begins - in other words, gradual transitions! He does NOT dispute the fact that there are distinct physical differences between the two. You can read Wolpoff's quotes and additional sources here.
...So basically, what he's saying is that because of the smooth transition he doesn't really know where H. erectus ends and H. sapiens begins - that it is a cladistic issue related to the way we classify things, similar to why some biologists classify birds as dinosaurs and humans as apes.
Ironically, the creationists seem to take issue with these transitional fossils although they've posed the rhetorical demand for "missing links". These fossils DO show a gradual transition - how else do they think it ought to be? (And ironically, few if any creationists are also citing the biologists who classify humans as apes or chimpanzees as hominids, even though the reasons are the same.)
It's quite possible that these anthropologists were following the proposal of Stephen Jay Gould, a proponent of the neoteny theory. The human skull over time seemed to undergo a "juvenilization" process in which the proportions of the brain became larger while the proportions of the face and jaw shrunk (as in a juvenile primate).
Neoteny is a documented fact -- as evidenced by its effect on domesticated animals. They are technically the same species as their wild ancestors, but they retain certain juvenile characteristics, such as playfulness, trusting personality and cuter faces. Humans may have inadvertently self-domesticated themselves over time by selecting more cooperative mates, which in turn created stronger family units and better chances for their children to survive to maturity.
However, despite skull changes, domesticated animals do not have more highly developed brains, as modern humans do. So despite this being a possibility, it could be only a piece of the puzzle -- not the entire answer.
What is "race"?
The biological definition of "race" is the following:
a. An interbreeding, usually geographically isolated population of organisms differing from other populations of the same species in the frequency of hereditary traits. A race that has been given formal taxonomic recognition is known as a subspecies.
In layman's terms, "races" come after the population established themselves in various locations and acquired certain characteristics due to local interbreeding. If Thorne is correct, Homo Erectus did the opposite -- it migrated and distributed its populations. If Homo Erectus was the group from which modern man stemmed from it therefore would not be considered a "race" as we define modern "races" today, but an ancestral archaic form that gave rise to later forms.
What is "species"?
According to Wiki:
Biologists view species as statistical phenomena and not as categories or types. This view is counterintuitive since the classical idea of species is still widely-held, with a species seen as a class of organisms exemplified by a "type specimen" that bears all the traits common to this species. Instead, a species is now defined as a separately evolving lineage that forms a single gene pool. Although properties such as genetics and morphology are used to help separate closely-related lineages, this definition has fuzzy boundaries.[1
But just as different-looking skulls can be of the same species, similar-looking skulls can be of different species (such as the lion and the tiger). In fact, the morphology of lions, tigers and leopards share even more similarities among them than do the skulls of H. sapiens and H. erectus. And even though lions, tigers and leopards can produce hybrids, they are still considered separate species -- not different "races". So skulls alone do not really give a complete picture of species differences.
One thing is generally agreed upon -- that even though more archaic forms of humans existed, the characteristic that truly distinguished modern humans was a far more developed ability for abstract thinking, as evidenced by art, ornamentation and sophisticated language ability, among other things. Evidence of this more sophisticated level of intelligence has not been found among the remains of earlier hominids.
Recent studies in molecular biology point to changes in a gene controlling speech that occurred about 200,000 years ago, which coincides with the rise of modern humans. This ties in quite neatly with language-related features such as an expanded cerebral cortex and refinement of facial bones and muscles.
Researchers investigating the roots of language have discovered a gene variant that appears to be essential for speech and that is not shared by our closest animal relatives.
The mutation appeared at the same time that modern humans emerged in Africa.
FOXP2 was identified last year using data from the Human Genome Project and the study of three generations of a family suffering from severe difficulties with speech and grammar.
They found that the human FOXP2 gene contains two significant changes that appear to be involved in the control of facial muscles, an ability crucial for speech. They believe it conferred an advantage to our human ancestors and that it was "fixed" in human DNA during the last 200,000 years.
Unfortunately for the creationists, they keep forgetting that the study of evolution is not seen as scripture frozen in time, but a continuously unfolding detective scenario -- and citing references written 30 years ago simply doesn't cut it. New information is always being added to the scenario, sometimes supplanting older speculations. Creationists, who once viewed earlier H. erectus fossils as "just another ape", but with the discovery of Turkana Boy, were forced to adjust their thinking and accept that H. erectus was indeed a human, but in their black-and-white scope of thinking, wish to now classify it as simply a variation of modern human, which leaves them to try to dismiss H. Habilis and Australopithecus as "just another ape."
New World Encyclopedia: Homo Erectus
Homo erectus 'to' modern man: evolution or human variability?