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May 13, 2006
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Ongoing evolutionary debate...

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MokeleMbembe Featured By Owner May 13, 2006
Ok, to be honest I just found this thread on a random google search, I don't know how old it is, and I suspect the post I am responding to is way way up there, but when I read it I couldn't let it go:

Australopithecus africanus Famously known as Lucy, detailed studies of the inner ear, skulls and bones have suggested that ‘Lucy’ and her like are not on the way to becoming human. For example, they may have walked more upright than most apes, but not in the human manner. Australopithecus afarensis is very similar to the pygmy chimpanzee. A study done at University College, London, showed they did not walk habitually upright. (Nature Oct 1994 )

Incorrect. First of all, Lucy is a member of the species Australopithecus afarensis. In addition, your assertion about walking habitually upright is wrong. I do have a webpage citation for that, but hear me out first. If you have ever seen the fossils, pictures of them, or casts of them you can see that the lower legs of australopithecines have a carrying angle to them: below the knee, the legs angle inwards. This is a feature found also in modern humans that allows the feet to support the center of gravity more efficiently while standing and walking bipedally, without the creature having to walk bowlegged like chimps do when they move around on two legs. A carrying angle is an ontogenetic feature, meaning that the creature (say, a human or a chimp) is not born with it but that it develops from continued use in a certain way. Human babies are not born with carrying angles, but acquire them after they start to walk. So the carrying angle is a good indicator for bipedalism, as the creatures would have to have been habitually walking upright in order to acquire one.

The pelvis of an australopithecine like Lucy is much wider, relatively, than a modern human's. However, it is much, much more similar to a human's than to a chimp's. Chimp pelvises are tall, and oriented side-to-side. In Australopithecines and modern Homo sapiens, the pelvis forms a sort of bowl shape that allows it to hold up the guts. Australopithecines retain an apelike chest shape, wide and shallow, rather than a barrel shape like moderns. This may be related to why their pelvises are wider - they needed to be in order to support the more apelike thorax. In any case, they didn't walk completely like moderns, but it's not as if they were knuckle walkers like modern gorillas (in addition to the fact that their legs clearly show a carrying angle, their hands look almost modern).

Also, 3.6 million year old footprints (falling in line with dates when australopithecines were around, and in the same area) are known at an African site called Laetoli, in an ash layer (which I presume was dated with K/Ar or Ar/Ar dating, since that would give good results with volcanic materials). The prints are clearly made by bipedal creatures, with feet that are shaped like hominid feet.

Here’s a good site that handles the claim also: [link] .

PS. Also, wanted to point out: what difference does it make if australopithecines looked apelike, or bonobolike, as you put it? They should look like that, since they are just bipedal apes, same as us. They look more apelike than we do because they are closer in time to the split between the chimps/bonobo lineage and the hominid lineage. One wouldn’t expect a chimp to one day give birth to a human looking baby, right?

PPS. Almost forgot – there are differences between chimps and early australopithecines too… off the top of my head, the canine teeth in chimps are used in intimidation displays, in australopithecines they are smaller, while the teeth in general have thicker enamel. Also, australopithecines were bipedal at least some of the time, as I showed above (and had anatomical adaptations for it like bowl-shaped wide pelvises, s-shaped spines like us, more lumbar vertebrae than apes – allowing for more flexibility like us, carrying angles), have more modern-looking hands than chimps… There are more differences but that’s what I remember right now.

Homo habilis After a CAT SCAN (performed by Dr. F Spoor, Professor of evolutionary anatomy at University College, London) of the inner ear of a Homo habilis skull known as Stw 53 show that it walked more like a baboon than a human, Today most researcher (including Spoor) regard Homo habilis as ‘a waste-bin of various species’, including bits and pieces from Australopithecus and Homo erectus, and not as a valid category. In other words, it never existed as such, and so cannot be the supposed link between australopithecine apes and true man

Way to misrepresent what Dr. Spoor actually said. Really, bravo to the creationists. Check out this page for his actual response (it’s about halfway down on my browser) [link] . Stw 53 and the semicircular canal issue are also dealt with in the page I linked up above.

Homo erectus They are smaller than the average human today, with an appropriately smaller head (and brain size). However, the brain size is within the range of people today and studies of the middle ear have shown that Homo erectus was just like us. Remains have been found in the same strata and in close proximity to ordinary Homo sapiens, suggesting that they lived together. So it begs the question of are the a version of early humans, or a simple variants of human.

Incorrect. A juvenile (we can tell he’s a juvenile from his pattern of tooth eruption – not all wisdom teeth are in, etc) Homo erectus (WT—15000) found a Nariokotome in West Turkana is 5 feet 3 inches tall. If he had matured he probably would have been at least 6 feet tall. Modern people living in that area are also very tall and lanky, as having a body plan like that allows for minimum surface area with maximum heat dispersal… something very necessary when living in the tropics. As for the claim that erectuses had modern-size brains, that just isn’t true. Average size for a Homo erectus’ brain is about 900cc. Modern humans have brains about 1300cc, usually. There is some fluctuation, but the point is that Homo erectus had smaller brains.

I don’t know where you got the claim of Homo erectus living with modern humans, but going back to Nariokotome again – that skeleton was found between two ash layers, which are accurately datable using either K/Ar or Ar/Ar methods. Nariokotome is known to be around 1.6 million years old. To my knowledge, no Homo erectus finds are known from less than about 100,000 years ago.

Your claim that they are “just like us” is flat wrong. In addition to the brain sizes, the craniofacial morphology is different, with bigger brow ridges, less of a forehead, no chin, a pulled out (prognathic) midface, and a longer, lower skull than is found in modern Homo sapiens. The postcranial skeleton of Homo erectus is very similar to modern humans, but not the same. The femoral neck is longer, and the vertebrae have smaller spaces in them for the spinal cord to pass through.

Homo sapiens neanderthalensis 150 years ago Neandertal reconstructions were stooped and very much like an ‘ape-man’. It is now argued, even amoung evolutionists, that the supposedly stooped posture was due to disease and that Neandertal is just a variation of the human kind. Even it's voice box/larnyx (hyoid bone) had explicitly predicted what a Neandertal hyoid would look like, many were surprised when it turned out to be a slightly enlarged version of a human hyoid and nothing like an ape or transistional hyoid

The “supposedly stooped posture” is because the most complete specimen known at the time, the one the reconstruction was based on (the old man of La Chappelle) had severe arthritis, as well as other injuries. Many other neandertal skeletons have been found, and they all show a much more robust morphology than modern humans, as well as archaic features of the skull similar to Homo erectus but even more pronounced. In addition, your claim about the hyoid makes no difference in this discussion. So a hypothesis about what the bone might be like was shown to be wrong by evidence. That’s why we don’t use that hypothesis anymore. Also, it’s not only the shape and size of the hyoid that is important, but its placement in the throat. Baby humans obviously have human hyoids, but our voices (men and women both) don’t mature until the Adam’s/Eve’s apple descends in the neck (obviously this affects men’s voices more than women’s, however). And even if neandertals DID have modern hyoids, what difference would that make as far as how they are classified? I already described their clearly outside-the-modern-human-range suite of anatomical features… if you ever compared a modern human skull/skeleton to a neandertal, you’d immediately see a big difference.

At the end of the paragraph there you say “the hyoid was nothing like an ape or transitional hyoid.” Well, it shouldn’t look like either of those, as neandertals were not ancestral to moderns, but rather a split-off group from a previous group of hominids (still in the genus Homo, but not anatomically modern humans) living in Europe. We know they are not ancestral to moderns through mtDNA mapping. All the similarities in hyoid shape between moderns and neandertals suggest is that the bone and voicebox had begun acquiring its modern shape at some time before the split between archaic hominids ancestral to neandertals, and archaics ancestral to modern Homo sapiens.



My suggestion? Stop getting all your info from AIG and other creationist sources and take a look at the actual evidence. TalkOrigins is an excellent resource, for example. Check out their list of hominid fossils and such. I’ve heard people say the site is “biased”… in reality it’s only “biased” towards real empirical thought, not distortions made specifically to induce doubt where it doubt is undeserved. If you don’t wanna go there (I strongly suggest you do though), go to your local college campus and look for the anth department, or just go to a natural history museum. Honestly. There’s no reason for people to be so misinformed.




PS. I wish I had sourced everything really nicely, but it’s 5 AM where I live. Google this stuff if you have more questions, or better yet, go to [link] and see if you can get any real scientific papers on hominids or whatever else this thread has moved on to.

PPS: In response to “no-angel” above me there, I don’t want to sound too rude (tired) but you fundamentally misunderstand what a scientific theory does. It doesn’t “prove” anything but rather takes the evidence and tries to fit it together in a way that makes sense – scientific theories can never be proven 100% conclusively, but they can be disproven or modified by newly discovered data and evidence.

Among the pieces of evidence for human evolution there are fossil remains from populations of apelike bipedal animals which, over immense stretches of time, look and behave more and more like modern humans. We know that humans share something like 98% of our genome with chimps – and while we apparently do share large percentages of our genes with all other living things, like bananas, for example, is that not perfect evidence for the common descent of all living things? The fact that we share more genes with chimps than bananas shows that chimps and humans had a more recent common ancestor than chimps+humans and bananas did.

We know that DNA does change over time in populations, and that survivability of creatures with a given feature (say, light skin) is often determined by the creature’s environment. Imagine a white lion being born in Africa (due to a simple genetic mutation – I have seen pictures of a lion like this)… not very easy to hide and hunt, right? What if that same mutation had taken place in a population of lions living further north in a snowy area, as we know they did thousands of years ago? That white lion would have a serious advantage over others and might thus become a leader in his group, and have access to lots of mates. His white gene gets passed on more than the other lions’ brown gene, and we might have polar lions in addition to polar bears in that case. Now imagine that every trait is malleable in this way, over a long time, through the passing of the genes from one generation to the next. Why wouldn’t it be possible for enough changes to accumulate over time that we would say “hey look, those are two different species!” So in addition to being logically sound, it has also been observed in several instances. Speciation has been observed in several species (gonna use TO again: [link] , [link] .)

All of the empirical evidence supports evolution. Maybe a god directed it from some metaphysical behind the scenes place, or maybe not, but regardless, the theory of evolution is far and away the best fit to the observed evidence from the natural world.
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