Disappearing Link

Our Evolutionary Ancestors Keep A-Changing

Our human family is obsessed with finding our origins—specifically, with finding our origins in something howling naked in the trees. That makes great special effects for billionaire-backed documentaries . . . but how is it working out in the lab?

The iconic year 2001 featured two promising "earliest humans." Nine skulls of Sahelanthropus, dated between 6 and 7 million years old, were found at various locations in Africa. Orrorin turned up in Kenya, also dated at 6 million years of age. But there wasn't much left of Orrorin, either: an upper femur is the most important fossil.

Ah, but then "Ardi," Ardipithecus ramidus from Ethiopia, burst on the scene in 2009, dated at about 5 million years old. She took the media crown because she still had a skeleton, even though initial reports said it had been "crushed nearly to smithereens."¹ But by 2011, Ardi was also suspect because, as one researcher explained, "We could actually place Ardipithecus in a lineage that's unrelated to humans."²

At Wired Science, Brian Switek chides the whole scene as "ancestor worship" and points out that primate apes of the same period show similar developments.³ Widespread convergent evolution means that researchers shouldn't assume that a fossil is a human ancestor simply because it might resemble humans in one or two ways.⁴

But politicians are not researchers, and when a "first primate," Ida, turned up a few years ago, Mayor Michael Bloomberg of New York held a special ceremony in 2009 to laud her as "the Link." "This changes everything," he said. Arguably, Ida helped Bloomberg's successful reelection bid, and the fact that her ancestor status was shortly thereafter retracted by the science journals made no subsequent difference.⁵

Falling Back on Neanderthal Man

Even if believable screaming-in-the-trees ancestors are currently in short supply, the popular "ascent of man" narrative would survive if we found ape-men—men who never, as a group, made the ascent. But these "missing link" contemporaries are rare, too. For a while in 2006, attempts were made to draft the diminutive Flores people—the oldest of whom date from perhaps 94,000 years ago—into that role, but they never demonstrated any sub-human traits.⁶

Never mind; there's always Neanderthal man. From over 700,000 to about 30,000 years ago, he has been the iconic missing link: stupider and clumsier than us until either we killed him off or his own inferiority caught up with him. Well, along comes genome mapping, and it becomes clear that Neanderthal man intermarried with our own ancestors.⁷ Some think that, in fact, that's how he "disappeared."

Worse, recent excavations have turned up evidence for Neanderthal decorations, carvings, burial practices, and the like, which has forced a reappraisal of the "stupid" role. It turns out that even his tools were not as clumsy as has long been supposed. When modern researchers tried constructing and using Neanderthal tools, they found them to perform about as well as Homo sapiens' tools. One outcome of this discovery is that the editors of the leftwing British newspaper The Guardian have formally distanced themselves from their previous view of Neanderthal man, citing his prehistoric accomplishments.⁸

Just Like Politics

So we are alone again, it seems, except for each other. We either have no ancestors or may as well not have. The long ascent of man might have happened, but it might as well not have.

But such conclusions are not reached quietly, if at all. Svante Pääbo, a Neanderthal genome researcher, has struggled to understand the vicious fights that commonly erupt among scientists who specialize in human paleontology, as opposed to those in molecular biology (his field):

I suppose the reason is that paleontology is a rather data-poor science. There are probably more paleontologists than there are important fossils in the world. To make a name for yourself is to find a new interpretation for those fossils that are extant. This always goes against some earlier person's interpretation, who will not like it very much. . . . It's almost like social anthropology or politics—you can only win by somehow yelling louder than the other person or sounding more convincing.⁹

In which case, Bloomberg's assessment of Ida's value was probably right. •

Endnotes
1. Jamie Shreeve, "Oldest Skeleton of Human Ancestor Found," National Geographic (Oct. 1, 2009); Michael D. Lemonick and Andrea Dorfman, "­Excavating Ardi: A New Piece for the Puzzle of Human Evolution," Time (Oct. 1, 2009).
2. Katherine Harmon, "Was 'Ardi' not a human ancestor after all? New review raises doubts," Scientific American (Feb. 16, 2011).
3. Brian Switek, "Ancestor Worship," Wired Science (Feb. 22, 2011): http://tinyurl.com/7dytekx.
4. "Fossils May Look Like Human Bones: Biological Anthropologists Question Claims for Human Ancestry," ScienceDaily (Feb. 16, 2011): http://tinyurl.com/79gcc3p.
5. See, e.g., Ed Pilkington, "To get a glimpse of the Ida fossil, the media make monkeys of themselves," The Guardian (May 19, 2009): http://tinyurl.com/qm6lm7; also Brandon Keim, "Bone Crunching Debunks 'First ­Monkey' Ida Fossil Hype," Wired (Oct. 21, 2009): http://tinyurl.com/ygcjmjv.
6. See, e.g., "Is the Hobbit's Brain Unfeasibly Small?" ScienceDaily (Jan. 27, 2010): http://tinyurl.com/y89mezp; "Compelling Evidence Demonstrates That 'Hobbit' Fossil Does Not Represent a New Species of Hominid" ScienceDaily (Oct. 9, 2006): http://tinyurl.com/4d7gwmq; "Researchers offer alternate theory for found skull's asymmetry," PhysOrg (Sept. 6, 2010): http://tinyurl.com/36c3rvc; "'Hobbit' Was an Iodine-Deficient Human, Not Another Species, New Study Suggests," ScienceDaily (Sept. 28, 2010): http://tinyurl.com/2g64sre.
7. Michael Marshall, "Breeding with Neanderthals helped humans go global," New Scientist (June 16, 2011): http://tinyurl.com/3tznlo8; "Non-Africans Are Part Neanderthal, Genetic Research Shows," ScienceDaily (July 17, 2011): www.sciencedaily.com/ releases/2011/07/110718085329.htm.
8. "In praise of . . . Neanderthal man" (Editorial), The Guardian (Jan. 13, 2010): http://tinyurl.com/yeq3nt6.
9. "Mapping the Neanderthal Genome: A Conversation with Svante Pääbo," The Edge (Apr. 7, 2009): http://tinyurl.com/n7ggpa.

From Salvo 20 (Spring 2012)
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