Feature Article - December 2009
by Do-While Jones

More About Ardi

Evolutionists think Ardi tells us things about teeth, tools, and tottering.

Last month we started a discussion of the Ardipithecus ramidus reports widely circulated in the popular news media. But, as usual, the news media didn’t tell the whole story. There were twelve major articles about Ardi in the journal Science, some of which contained important facts which were overlooked, or given scant mention, in the popular press. This month we want to give those issues the attention they deserve.

Putting Teeth Into It

Ardi had some pretty fearsome teeth, more like apes than humans.

In apes and monkeys, the male's upper canine tooth usually bears a projecting, daggerlike crown that is continuously sharpened (honed) by wear against a specialized lower premolar tooth (together these form the C/P3 complex). The canine tooth is used as a slicing weapon in intra- and intergroup social conflicts. Modern humans have small, stublike canines which function more like incisors. 1

Crown size, proportions, and variation. The Ar. ramidus dentition is approximately chimpanzee-sized (fig. S1 and tables S2 to S4). Mean canine size is comparable to that of female Pan troglodytes [chimps], although the incisors are smaller. Upper and lower first molars (M1s) are P. troglodytes–sized but tend to be buccolingually broader (figs. S1 to S3). The second and third molars (M2s and M3s) are both absolutely and relatively larger (figs. S1 and S4 to S6). Postcanine size and proportions of Ar. ramidus are similar to those of Ar. kadabba and other ~6.0-million-year-old forms (O. tugenensis and S. tchadensis), as well as to many Miocene hominoids (although Miocene ape lower molars tend to be buccolingually narrower) (fig. S3). 2

That’s probably more than you needed to know. The point is, Ardi had much better teeth than modern people do. Ardi didn’t need to invent tools and fire to cut and cook his food to make it tender enough to eat. He could chew anything he wanted to.

The team suggests that Ar. ramidus was "more omnivorous" than chimpanzees, based on the size, shape, and enamel distribution of its teeth. It probably supplemented woodland plants such as fruits, nuts, and tubers with the occasional insects, small mammals, or bird eggs. Carbon-isotope studies of teeth from five individuals show that Ar. ramidus ate mostly woodland, rather than grassland, plants. Although Ar. ramidus probably ate figs and other fruit when ripe, it didn't consume as much fruit as chimpanzees do today. 3

What do evolutionists make of this?

The canine/lower third premolar complex indicates a reduction of canine size and honing capacity early in hominid evolution, possibly driven by selection targeted on the male upper canine. 4

It was previously believed that the common ancestor had puny canine teeth like ours, which evolved into more fearsome teeth in apes. Now evolutionists believe that the common ancestor had sharp canine teeth, but modern humans lost them. This is naturally puzzling. Why would Ardi’s excellent teeth evolve into the inferior teeth we modern humans now have?

Loss of the projecting canine raises other vexing questions because this tooth is so fundamental to reproductive success in higher primates. What could cause males to forfeit their ability to aggressively compete with other males? What changes paved the way for the later emergence of the energy-thirsty brain of Homo? Such questions can no longer be addressed by simply comparing humans to extant apes, because no ape exhibits an even remotely similar evolutionary trajectory to that revealed by Ardipithecus. 5

Of course, such questions can’t remain unanswered, even if there are no answers. So, they have to make one up.

In modern monkeys and apes, the upper canine is important in male agonistic behavior, so its subdued shape in early hominids and Ar. ramidus suggests that sexual selection played a primary role in canine reduction. Thus, fundamental reproductive and social behavioral changes probably occurred in hominids long before they had enlarged brains and began to use stone tools. 6

In other words, girls like boys with small teeth. This explanation might have had more credibility if the article had not come out just a few days before the current box-office hit movie, Twilight. 7 Although the teeny-boppers lined up outside the theater may disagree about who they love more, the vampire and the werewolf both have some really impressive fangs, and the girls love them!

Tooling and Toddling

The articles in Science suggest that Ardi’s skeleton shows that Ardi was very close to using tools and walking around upright, if he wasn’t doing that already.

Ardipithecus also shows that our ability to use and make tools did not require us to greatly modify our hands. Rather, human grasp and dexterity were long ago inherited almost directly from our last common ancestor with chimpanzees. We now know that our earliest ancestors only had to slightly enlarge their thumbs and shorten their fingers to greatly improve their dexterity for tools-using. 8

They didn’t really press this point. They didn’t have any evidence of tools. They just wanted to plant the suggestion that Ardi didn’t use his hands for walking. If Ardi didn’t walk on his hands, he must have walked on two feet.

Does it Stand Up?

We didn’t mention it before, when we were talking about teeth, but the third quote in this essay noted, Ar. ramidus ate mostly woodland, rather than grassland, plants.” This has implications about how upright posture evolved.

This new evidence overwhelmingly refutes the once-favored but now moribund hypothesis that upright-walking hominins arose in open grasslands. "There's so much good data here that people aren't going to be able to question whether early hominins were living in woodlands," says paleoanthropologist Andrew Hill of Yale University. "Savannas had nothing to do with upright walking." 9

The old, old story has been that apes moved out of the jungle into the savannas, and had to learn to walk upright to see over the tall grass. This claim that Ardi unquestionably walked upright in the jungle is bound to start a fight.

But not everyone agrees with the team's interpretations about how Ar. ramidus walked upright and what it reveals about our ancestors. "The authors ... are framing the debate that will inevitably follow," because the description and interpretation of the finds are entwined, says Pilbeam. "My first reaction is to be skeptical about some of the conclusions," including that human ancestors never went through a chimpanzee-like phase. Other researchers are focusing intently on the lower skeleton, where some of the anatomy is so primitive that they are beginning to argue over just what it means to be "bipedal." The pelvis, for example, offers only "circumstantial" evidence for upright walking, says Walker. 10

However, several researchers aren't so sure about these inferences. Some are skeptical that the crushed pelvis really shows the anatomical details needed to demonstrate bipedality. The pelvis is "suggestive" of bipedality but not conclusive, says paleoanthropologist Carol Ward of the University of Missouri, Columbia. Also, Ar. ramidus "does not appear to have had its knee placed over the ankle, which means that when walking bipedally, it would have had to shift its weight to the side," she says. Paleoanthropologist William Jungers of Stony Brook University in New York state is also not sure that the skeleton was bipedal. "Believe me, it's a unique form of bipedalism," he says. "The postcranium alone would not unequivocally signal hominin status, in my opinion." Paleoanthropologist Bernard Wood of George Washington University in Washington, D.C., agrees. Looking at the skeleton as a whole, he says, "I think the head is consistent with it being a hominin, ... [ellipsis in the original] but the rest of the body is much more questionable."

All this underscores how difficult it may be to recognize and define bipedality in the earliest hominins as they began to shift from trees to ground. One thing does seem clear, though: The absence of many specialized traits found in African apes suggests that our ancestors never knuckle-walked.

That throws a monkey wrench into a hypothesis about the last common ancestor of living apes and humans. 11

Who Cares?

Why would anybody care about these things? People care because all these things tie together an important philosophical issue. At various times in the past, evolutionists have speculated about what caused some creature to move from the category of “animal” into the category of “human.” Some said it was eating meat, which allowed us to evolve bigger brains, resulting in higher intelligence, which is the hallmark of humanity. Others said it was upright posture, which led to tool-making and social cooperation, which makes us human.

It all comes down to the nature of humanity. The significant question is whether people are just animals, or are somehow fundamentally different from animals. If people are no different from animals, it poses some logical problems for society. If it is okay to kill animals, and people are just animals, then it is okay to kill people. If it isn’t okay to kill people, and people are just animals, then it isn’t okay to kill and eat animals. If there is no difference between humans and animals, then there is no difference between human rights and animal rights.

Most (but not all) people believe that people are in a separate class from animals. In many cases this belief is rooted in religion (not necessarily a Judeo-Christian religion). If one arbitrarily excludes any religious explanation for the difference between people and animals, then one has to find an objective, quantitative difference.

Evolutionists used to use brain size as the criterion that separates man from animals. If a primate had a brain less than 600 cc, it was an animal. If bigger, it was human.

The reasoning behind this distinction was that it is intelligence that makes man different from animals, and intelligence was thought to be related to brain size. That’s why the science fiction movies in the 1950’s always depicted the more highly evolved aliens from outer space as human-like creatures with super big brains.

The problem with this notion is that animals are a lot smarter than we used to give them credit for. Some insects, such as ants and bees, live in societies of undeniable complexity which requires far more intelligence than their tiny brains would suggest. Then, when the obviously human Homo floresiensis was discovered to have a tiny brain, it blew that theory out of the water. 12

Now, the only difference between apes and humans is that humans habitually walk on two legs. Therefore, it is important to evolutionists to try to figure out how man learned to walk upright. Walking upright is what makes us human. Or so they say (now).

[Ardi] includes most of the skull and teeth, as well as the pelvis, hands, and feet—parts that the authors say reveal an "intermediate" form of upright walking, considered a hallmark of hominins. 13

Now you know why your mother kept telling you to stand up straight! If you don’t walk on two feet, you aren’t human. That’s why evolutionists are so obsessed with figuring out if a fossil primate walked on two feet or not.

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Footnotes:

1 Suwa, et. al, Science, 2 October 2009, “Paleobiological Implications of the Ardipithecus ramidus Dentition” page 69
2 ibid., page 94
3 Gibbons, Science, 2 October 2009, “Ardipithecus ramidus: Habitat for Humanity”, page 40
4 Suwa, et al., Science, 2 October 2009, “Paleobiological Implications of the Ardipithecus ramidus Dentition” page 94
5 Lovejoy, Science, 2 October 2009, “Reexamining Human Origins in Light of Ardipithecus ramidus”, page 74
6 Suwa, et al., Science, 2 October 2009, “Paleobiological Implications of the Ardipithecus ramidus Dentition”, page 69
7 http://www.twilightthemovie.com/worldoftwilight/
8 Lovejoy, et al., Science, 2 October 2009, “Careful Climbing in the Miocene: The Forelimbs of Ardipithecus ramidus and Humans Are Primitive”, page 70
9 Gibbons , Science, 2 October 2009, “Ardipithecus ramidus: Habitat for Humanity”, page 40
10 Gibbons, Science, 2 October 2009, “A New Kind of Ancestor: Ardipithecus Unveiled”, page 37
11 ibid., page 39
12 Disclosure, November 2004, “Homo floresiensis
13 Gibbons, Science, 2 October 2009, “A New Kind of Ancestor: Ardipithecus Unveiled”, pages 36-37