Answers in Genesis have “refuted” this post. I offer a counter-refutation here
Answers in Genesis runs the (in)famous Creation Museum, where they expound the Biblical account of how the earth came to be. From what I hear it is a thoroughly disappointing affair, although not because of it’s kooky premise. Apparently it’s real problem is that it lacks substance, focusing on dioramas and retellings of Biblical stories rather than anything with scientific meat to it. But I shan’t criticise the institution for failings I have not seen but rather, for the very obvious failing I have had the misfortune to stumble across: Lucy the knuckle walking ape.
For some background (those familiar with Lucy feel free to skip ahead a paragraph), Lucy or “AL 288-1” is one of the most famous hominin fossils out there. She’s a member of Australopithecus afarensis, part of the human lineage which lived from 3.8-3 million years ago. This species was either an ancestor of humans or a close relative of that ancestor. Either way, the species is important for showing that even millions of years ago hominins were well on the way to becoming human. They were skilled bipedal walkers (although still probably spent some time in the trees), lived and travelled in family groups and had a generally more “human” anatomy.
Now, I’ve heard the claim Lucy was “just an ape” innumerable times (typically supported by focusing on the ape characteristics an ape/human moasic form necessarily contains) but for some reason I always pictured this as a change of label. I didn’t believe creationists would try and manipulate and mutilate her anatomy to portray her as something she is not; in my mind they accepted all of the anatomical and behavioural conclusions about her and just disputed what she should be called. I suppose I was giving too much credit to the creationists, for they went and created this abomination.
Their justification for producing such a travesty against evolutionary anthropology is that it’s just a matter of interpretation. They often like to claim that their views and science are simply two ways of looking at the evidence, both equally valid. Of course, this forgets that ideas are given more credence when they demonstrate their reliability through hypothesis testing. Whilst science does plenty of that, creationism almost never does; you’ll never see an article with “creationists were surprised by a new finding” because they’re never predicting anything that could be shown to be wrong. As such, science and creationism are far from equally valid ideas.
Anyhoo, on with the show. Starting at the top we run into our first major problem at the base of the skull. The foramen magnum is the hole the spinal cord comes out of and can be used to work out how an animal walked. A biped will want it at the bottom of the skull so the head can sit atop a vertical body whilst a quadruped will want it further back so their head will still face forwards when placed in front of a body. Stick a biped’s head on a quadruped and it would be looking at the ground, which is not particularly useful for survival.
So, is Lucy’s foramen magnum like that of a quadruped or a biped? Unfortunately we can’t say since it wasn’t preserved. Luckily we do have a couple of Au. afarensis specimens with a preserved foramen magnum. So I made a little graph of their foramen magnum “index” (a measurement of its position) and lo, the position of Au. afarensis foramen magnum falls much closer to that of Homo (including humans) than any quadrupedal ape. However, the angle of that foramen is much more similar to an ape than a human. In other words, the hole is close to the human location but the angle of the hole is more like an ape. Could that mean they were quadrupeds? Well, as the second image shows when the location of the foramen magnum is taken into account as well as the angle, we’re still left with a biped.
So, the hole for the spine looks like that of a biped (albeit with the retention of some ape characteristics). The next issue arises with the spine itself. Humans have a curved spine (known as lordosis) which acts as a shock absorber as we walk. Chimps lack this curvature, since they don’t walk like us. What of Au. afarensis? Well, it had that curvature too. And that isn’t the result of bias contained in a reconstruction of the spine, Au. afarensis had the additional lumbar vertebrae which produces lordosis (6 compared to the 4 in chimps; although humans only have 5). You can’t misinterpret the number of vertebrae, that’s an absolute, physical number. And another point in favour of bipedalism.
The next issue is raised by the hand itself. Being used as a limb, knuckle walkers will obviously have a suite of different adaptations to us. Their hand is more robust and sturdy than ours, allowing them to easily walk on it. Naturally, we lack many of these abilities in favour of fine motor control. We can’t support our weight for extended periods of time but we can manipulate things with greater dexterity. And what of Au. afarensis?
Although knuckle-walking cannot be excluded, there is no evidence in the hand of the interlocking surfaces which characterize the hand of African apes and provide stability during knuckle-walking, in the carpometacarpal region and the radiocarpal, midcarpal, and metacarpophalangeal joints (Marze, 1986)
Although some might try and use the fact knuckle walking “cannot be excluded” as a way to weasel out of the fact there’s no evidence they knuckle walked, the fact remains there is no evidence they knuckle walked. Not being able to exclude it is kind of moot when we have no reason to include it in the first place. As such, I’d go further than the paper itself and simply state there’s no evidence of knuckle walking.
Finally we arrive at the hip. In a video associated with their ridiculous reconstruction they try and argue that the gluteus medius of Au. afarensis would not have been able to function properly given the orientation of their hips. Yet numerous computer models of Au. afarensis have shown that their gluteus medius can and does function during bipedal locomotion. Although it has to work a bit harder in Lucy et al. than in us because their hip is not as efficiently built as ours, there is no fundamental difference in the manner by which they move.
Ok, so their reasoning might be wrong. But maybe their observation that Lucy’s hip is like that of a chimp is valid? Well this should be reasonably easy to figure out since human and chimp hips are very distinct. Ours is shaped like a bowl so that our vertical torso can “sit” in it and receive support whilst a chimp hip is a lot taller and flatter to keep their back rigid with minimal effort. I shan’t tell you which one it most looks like, because that would just be my interpretation shining through!
Almost every bit of Lucy’s anatomy points towards bipedalism. Her hip is 3D to support a vertical trunk, her foramen magnum is located on the bottom of the skull to enable her head to sit atop a vertical body. Her hands show know evidence for knuckle walking whilst her spine is curved to best function in a bipedal body. Creationists might cry out about interpretation and bias, but the fact of the matter is that their reconstruction is simply wrong on every major point.
Also, note how in most characteristics she is very similar to a human but not quite human. Many of her attributes also show a significant affinity with chimps such asthe angle of the foramen magnum and her hip not being quite as efficient as ours. It’s almost like Au. afarensis is some half ape/half man form. Like she’s some kind of…intermediate, transitional stage. Funny that.