It was inevitable that science writers all over the world would screw up the story of Ardipithicus ramidus as reported in a series of papers published in Science [see the special Science webpage: Ardipithicus ramidus].Everyone will have their favorite example. Mine comes from today's issue of The Toronto Star in an article by Joseph Hall titled Did apes descend from us?
Man didn't descend from apes.We did not descend from apes—humans are apes. Modern humans and other modern apes share a common ancestor. It's silly to say that humans descend from monkeys, or apes, and it's just as silly to say that chimpanzees descend from humans.
What is closer to the truth is that our knuckle-dragging cousins descended from us.
That's one of the shocking new theories being drawn from a series of anthropology papers published Friday in a special edition of the journal Science.
Scientists say a 4.4-million-year-old fossil called Ardi – short for ardipithecus ramidus – is descended from the "missing link," or the last common ancestor between humans and apes.
The 4-foot, 110-pound female's skeleton and physiological characteristics bear a closer resemblance to modern-day humans than to contemporary apes, meaning they evolved from humanlike creatures – not the other way around.
The second part of the quotation is pretty accurate but it's overshadowed by the unnecessary hype in the first few sentences. There are no "shocking new theories" being promoted.
C. Owen Lovejoy is one of the authors on several of the papers just published (e.g. White et al. 2009; Suwa et al. 2009). He is quoted in the Star article, presumably from a 'phone interview by the author. "It's transformative. This is a lot closer to anything that you'd call the missing link than anything that's ever been found," says Lovejoy, a biological anthropologist at Ohio's Kent State University.Can you blame the reporter when this is what one of the authors says? Yes you can, because, as Carl Zimmer points out, it's up to science reporters to do a bit of digging to find out the real story behind the scientific papers and the press releases.
Among other things, research on Ardi suggests humans are far more primitive in an evolutionary sense than today's great apes – like chimps and gorillas – which have continued to evolve from the missing link.
"In a way we're saying that the old idea that we evolved from a chimpanzee is totally incorrect," he says. "It's more proper to say that chimpanzees evolved from us."
But we also need to blame scientists for the sorry state of scientific literacy. That was a remarkably stupid thing for C. Owen Lovejoy to have said to a science journalist. As a scientist he should have known that the "old idea" (we evolved from a chimpanzee) is wrong and the "new idea" (chimpanzees evolved from us) is also wrong for the same reasons.
Maybe Lovejoy was misquoted? After all, he's a member of the National Academy of Sciences so he must know what he's talking about. Let's look at the Kent State University press release [Kent State University Professor C. Owen Lovejoy helps unveil oldest hominid skeleton].
KENT, Ohio -- Oct. 1, 2009 -- Throw out all those posters and books that depict an ape evolving into a human being, says Kent State University Professor of Anthropology Dr. C. Owen Lovejoy. An internationally recognized biological anthropologist who specializes in the study of human origins, Lovejoy is one of the primary authors who revealed their research findings today on Ardipithecus ramidus, a hominid species that lived 4.4 million years ago in what is now Ethiopia.Not much better, although Loverjoy does emphasize the fact that "people often think we evolved from apes." However, he doesn't do much to dispel this way of thinking when he says, "apes in many ways evolved from us."
"People often think we evolved from apes, but no, apes in many ways evolved from us," Lovejoy said. "It has been a popular idea to think humans are modified chimpanzees. From studying Ardipithecus ramidus, or 'Ardi,' we learn that we cannot understand or model human evolution from chimps and gorillas."
I don't think we can blame our reporter for this one.
What about the scientific papers? What do they say? Remarkably, the papers actually address the idea that humans might have evolved from chimpanzees as though this was a real scientific belief held by real scientists. Here's the conclusion of the White et al. (2009) paper.
Conclusions. Besides hominids, the only apes to escape post-Miocene extinction persist today as relict species, their modern distributions centered in forested refugia. The markedly primitive Ar. ramidus indicates that no modern ape is a realistic proxy for characterizing early hominid evolution—whether social or locomotor—as appreciated by Huxley. Rather, Ar. ramidus reveals that the last common ancestor that we share with chimpanzees (CLCA) was probably a palmigrade quadrupedal arboreal climber/clamberer that lacked specializations for suspension, vertical climbing, or knuckle-walking (24–27). It probably retained a generalized incisal/postcanine dentition associated with an omnivorous/frugivorous diet less specialized than that of extant great apes (22, 23). The CLCA probably also combined moderate canine dimorphism with minimal skull and body size dimorphism (22, 23), most likely associated with relatively weak male-male agonism in a male philopatric social system (22, 23, 31).Hmmm ... I'm not that familiar with the scientific beliefs of anthropologists. Maybe they really did think that humans evolved from chimpanzees! That's pretty scary.
Ardipithecus reveals the first hominid adaptive plateau after the CLCA. It combined facultative terrestrial bipedality (25, 26) in a woodland habitat (28–30) with retained arboreal capabilities inherited from the CLCA (24–27). This knowledge of Ar. ramidus provides us, for the first time, with the paleobiological substrate for the emergence of the subsequent Australopithecus and Homo adaptive phases of human evolution. Perhaps the most critical single implication of Ar. ramidus is its reaffirmation of Darwin’s appreciation: Humans did not evolve from chimpanzees but rather through a series of progenitors starting from a distant common ancestor that once occupied the ancient forests of the African Miocene.
Owen Lovejoy has a single author paper where he makes the case for just such a mistaken view of human evolution (Lovejoy 2009). It's a good read. He might be right that his colleagues tended toward a ladder-like view of evolution.
Not all of the reporting is bad. Yesterday I linked to the article by Carl Zimmer [Ardipithecus: We Meet At Last] and today we get to see the reports in Science. One of these reports, A New Kind of Ancestor: Ardipithecus Unveiled by Ann Gibbons, is particularly good. It contains important bits of information like this ...
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. But however the debate about Ardi’s locomotion and identity evolves, she provides the first hard evidence that will inform and constrain future ideas about the ancient hominin bauplan.It's important to remember that the scientific papers are promoting a particular view of human evolution and the importance of the very fossils that the authors have been working on for many years. They have a big stake in this. There will be biases that creep into the conclusions. It would be wrong to conclude that everything we today hear about Ardipithicus ramidus will stand up to subsequent scrutiny.
If I had to guess, I'd say that the most significant finding is the evidence that Ardipithicus lived in a woodland environment and not on a savanna [see Habitat for Humanity]. This could change the way we think about how humans evolved. If early humans were more likely to lived in wooded areas than in open savanna, then many adaptationist explanations for certain characters will have to be revised. (See the Lovejoy (2009) paper.)
Such a result will make it difficult to explain our supposed instinctual preference for savanna-like terrains, for example [E.O. Wilson in New York]. Why would our ancestral population have fixed alleles making us admire savanna when our ancestors lived in the woods?
[Image Credit: The map of the Afar Rift is form The View from Afar]
Lovejoy, C. O. (2009) Reexamining Human Origins in Light of Ardipithecus ramidus. Science 326:74e1-74e8. [doi: 10.1126/science.1175834]
Suwa, G., Asfaw, B., Kono, R.T., Kubo, D., Lovejoy, C.O., and White, T.D. (2009) The Ardipithecus ramidus Skull and Its Implications for Hominid Origins. Science 326:68e1-68e7. [doi: 10.1126/science.1175825]
White, T.D., Asfaw, B., Beyene, Y., Haile-Selassie, Y., Lovejoy, C.O., Suwa, G., and WoldeGabriel, G. (2009) Ardipithecus ramidus and the Paleobiology of Early Hominids. Science 326:75-86. [doi: 10.1126/science.1175802]
