by Michael Dumiak
Volume 59 Number 6, November/December 2006
Will an extinct genome reveal what makes us human?
A computer-generated resin cast of a Neanderthal skull emerges in a Swiss lab. New technologies are allowing scientists to look deeper than ever before into the origins of extinct hominids. (Courtesy of
Christoph Zollikofer and the University of Zurich)
[LARGER IMAGE]
An argument that began 150 years ago with a stunning discovery in Germany's Neander valley may soon come to an end in an ultra-sterile lab at the Max Planck Institute for Evolutionar y Anthropology in Leipzig. Genetic anthropologist Svante Pääbo is teasing the genetic secrets out of bones that have lain buried as glaciers advanced and retreated over Europe. Today, the building is sweltering, the air conditioning is out, but Pääbo is coolly confident that he has found a way to reassemble the genetic code of a
Neanderthal who lived in Croatia 45,000 years ago and who may provide answers to some important questions: Were Neanderthals a separate species from us? Did they interbreed with modern humans? Do their genes survive in modern humans?
"The big picture is that modern humans came out of Africa and replaced Neanderthals," says Pääbo, a bristly browed Swede with a penchant for wearing sandals and goofy socks. "The really important question is what the mutations are that became fixed in
[modern] humans. What are these things that are unique to us with respect to Neanderthals?"
Finding these unique mutations could reveal the biological basis for the way that modern human brains developed, and how we acquired language and art. It may also settle the long-running debate between scientists who believe that anatomically modern humans came from Africa and gradually forced the Neanderthals into extinction, an idea called the Out-of-Africa theory, and those who believe that Neanderthals were among the archaic human species with whom anatomically modern humans interbred as they moved across the globe, an idea called Multi-Regional Evolution.
Nuclear DNA, the prize for genetic sequencing, contains t he Neanderthal's full genetic code. Some of Pääbo's earlier work focused on retrieving mitochondrial DNA from Neanderthal bones. (Mitochondria are the microscopic organelles that provide energy to our cells.) Those studies supported the Out-of-Africa theory by showing that no strains of Neanderthal mitochondria survive in modern humans. Because each cell has several mitochondria and only one set of nuclear DNA, mitochondrial DNA is much easier to find, but it only contains a small portion of the Neanderthal's genes. A new sequencing technique is allowing researchers to piece together the elusive nuclear DNA.
Finding Neanderthal nuclear DNA is like alchemy, only better. A small piece of Neanderthal bone is drilled out and dissolved into a test-tube solution. The sample is flown to a company called 454 Life Sciences in Branford, Connecticut. It is then poured into a machine that sifts through every miniscule fragment of DNA, discarding the 95 percent of recovered genetic material that comes from contaminants such as bacteria or people who have handled the bone. The process is like picking millions of needles out of billions of haystacks.
Even so, Pääbo may have the entire Neanderthal genome sequenced in the next 18 months. As the pieces fall into place the biological differences between modern humans and Neanderthals will come into focus. One interesting marker is a gene labeled
FOXP2, which researchers suspect plays a role in the development of language. By comparing the Neanderthal FOXP2 gene to the modern hu man and chimpanzee versions of the gene, Pääbo believes he can determine whether Neanderthals were capable of developing complex languages, and that could help scientists determine whether language gave modern humans enough of a survival advantage to doom Neanderthals to extinction.

Analysis of 11 different human gene trees suggests that our species arose in Africa, and that there were at least two major population expansions out of Africa; one over 600,000 and another 95,000 years ago (Cann, 2002). Recent fossil finds in norther Spain extend this earliest migration to 1.2 million years ago. An earlier expansion of Homo erectus from Africa occurred 1.7 million years ago (Templeton, 2002). The first corresponds with the movement of Homo neanderthalensis out of Africa and an increase in hominid fossil cranial capacity. Archaeologists have found much physical evidence to confirm this date, such as the 0.73 Mya old fossils with stone tools and bison and other animal bones of a generalised Homo species from Isernia in west central Italy. The other date matches the movement of modern humans, Homo sapiens sapiens out of Africa and the appearance of modern traits in fossil skulls.
Fossil skull traits such as high, rounded skulls, small brow ridges, a vertical forehead and a pronounced chin first appear in Africa about 130,000 years ago. They then appear outside of Africa over 90,000 years ago
(Templeton, 2002). Phylogenetic analysis of Neanderthal mitochondrial DNA leads to a date for the common ancestor of the neanderthal and modern humans at around 465,000 to 600,000 years ago (four times the estimate for the common ancestor of all modern humans) (Disotell, 1999). The common ancestor of the mtDNAs of all living humans lived about 170,000 years ago (Hofreiter et al, 2001). All hominid remains of the last 100,000 years belong to one of these two species (Roe in Waechter, 1990). Ancient remains from a Spanish cave site (La Sima de los Huesos), are a transitional form between Homo erectus and
Neanderthals.
The first Neanderthal remains, discovered in Germany in 1856, were presented to the world of science at a meeting of the Lower Rhine Medical and Natural History Society held in Bonn in February 1857 (Reader,
1988) and named a species, Homo neanderthalensis, by William King in 1864. Some Neanderthal fossils and other remains are in excellent condition, giving a good idea of Neanderthal culture. In 1887, two complete skeletons were found in a cave near Spy in Belgium, and more from sites in France in 1887, 1908 and 1911.
These and other finds showed that the Neanderthals had populated Europe widely from about 130,000 to
28,000 years ago after which they became extinct. Most of these fossils were found in caves. Usually they are associated with cold adapted species such as reindeer, arctic fox, lemming and mammoth. The current conclusion drawn from fossil evidence is that Neanderthals emerged at least 230,000 to 300,000 years ago
(Andrews & Stringer, 1993), (Gore et al, 1996) years and maybe even 350,000 years ago (Bischoff et al,
2003). In the Far East, we first find H. erectus , then a generalised H. sapiens and later H. sapiens sapiens with Mongoloid features, but no Neanderthal presence (Roe in Waechter, 1990). 800,000 year old fossils from northern Spain, has been proposed as the common ancestor to humans and Neanderthals and named
Homo antecessor (Lemonick & Dorfman, 1999). ( H. antecessor may in fact be a variant of H. heidelbergensis ). Others say that Homo heidelbergensis is the more likely common ancestor between humans and Neanderthals, The discovery of such ancient fossils with a mix of modern (tooth development, projecting face, sunken cheekbones) and primitive features (jaw and brow ridges) hints at some surprises as more fossils from this period are unearthed. One line of thought places Homo ergaster as ancestral to Homo antecessor in Africa. A population of Homo antecessor migrated ( see map of migration
from migration article
) via the Middle East to Europe about one million years ago and evolved into Homo heidelbergensis and then into
Neanderthals. The population of Homo antecessor that remained in Africa likely evolved into Homo sapiens
. In this scheme, H. antecessor is ancestral to both H. sapiens and H. neanderthalensis (via H. heidelbergensis ).

March 19, 2007 issue - Unlike teeth and skulls and other bones, hair is no match for the pitiless ravages of weather, geologic upheaval and time. So although skulls from millions of years ago testify to the increase in brain size as one species of human ancestor evolved into the next, and although the architecture of spine and hips shows when our ancestors first stood erect, the fossil record is silent on when they fully lost their body hair and replaced it with clothing. Which makes it fortunate that Mark Stoneking thought of lice.
Head lice live in the hair on the head. But body lice, a larger variety, are misnamed: they live in clothing.
Head lice, as a species, go back millions of years, while body lice are a more recent arrival. Stoneking, an evolutionary anthropologist, had a hunch that he could calculate when body lice evolved from head lice by comparing the two varieties' DNA, which accumulates changes at a regular rate. (It's like calculating how long it took a typist to produce a document if you know he makes six typos per minute.) That fork in the louse's family tree, he and colleagues at Germany's Max Planck Institute for Evolutionary Anthropology concluded, occurred no more than 114,000 years ago. Since new kinds of creatures tend to appear when a new habitat does, that's when human ancestors must have lost their body hair for good—and made up for it with clothing that, besides keeping them warm, provided a home for the newly evolved louse.
If you had asked paleoanthropologists a generation ago what lice DNA might reveal about how we became human, they would have laughed you out of the room. But research into our origins and evolution has come a long way. Starting with the first discovery of a fossil suggesting that a different sort of human once lived on this planet—it was a Neanderthal skull, unearthed in a mine in Germany's Neander Valley in 1856—our species' genealogy was inferred from stones and bones. Fossils and tools testified to our ancestors' origins in
Africa, the emergence of their ability to walk upright, the development of toolmaking and more. But now two new storytellers have begun speaking: DNA and brains.
The science of human evolution is undergoing its own revolution. Although we tend to see the march of species down through time as a single-file parade, with descendant succeeding ancestor in a neat line, the emerging science shows that the story of our species is far more complicated than Biblical literalists would have it—but also more complex than secular science suspected. By analyzing the DNA of today's humans as well as chimps and other species (even lice), scientists are zeroing in on turning points in evolution, such as when and how language and speech developed, and when our ancestors left Africa. DNA can even reveal how many pilgrims made that trek. At the new Hall of Human Origins at the American Museum of Natural
History in New York, DNA gets equal billing with fossils. And by comparing the impressions that brains left on the inside of skulls, "paleoneurology" is documenting when structures that power the human mind arose, shedding light on how our ancestors lived and thought. Whether or not you believe the hand of God was guiding these changes, the discoveries are overturning longstanding ideas about how we became human.
Not that fossils are passé. new discoveries are pruning and reshaping humankind's family tree as radically as bonsai. The neat traditional model in which one species gave rise to another like Biblical "begats" has been replaced by a profusion of branches, representing species that lived at the same time as our direct ancestors but whose lines died out. It's like discovering that your great-great-grandfather was not an only child as you'd thought, but had a number of siblings who, for unknown reasons, left no descendants. New research also shows that "progress" and "human evolution" are only occasional partners. More than once in human prehistory, evolution created a modern trait such as a face without jutting, apelike brows and jaws, only to let it go extinct, before trying again a few million years later. Our species' travels through time proceeded in fits and starts, with long periods when "nothing much happened," punctuated by bursts of dizzying change, says paleontologist Ian Tattersall, co-curator of the American Museum's new hall.
As its exhibits show, humankind's roots are sunk deep in the East African savanna. There, the last creature ancestral to humans as well as chimps—our closest living cousins—lived, standing at a fork in the family tree as momentous as it is contentious. Fossils never resolved when the lineages split. DNA might. Human
DNA and chimp DNA differ by no more than 1.2 percent, and DNA changes at a fairly regular rate. That lets scientists use this rate to calibrate a "molecular clock" whose tick-tocks measure how long ago a genetic change occurred. The fact that the DNA of living chimps and humans differ by about 35 million chemical

"letters," for instance, implies that the two lineages split 5 million to 6 million years ago. That fits with the discovery that Earth became cruelly colder and drier 6.5 million years ago, just the sort of climate change that coaxes new species into being. The apes that stayed in the forests hardly changed; they are the ancestors of today's chimps. Those that ventured into the newly formed habitat of dry grasslands had taken the first steps toward becoming human.
Now the contentious part. In 2001, a team digging in Chad unearthed what it claimed was the oldest fossil of an ancestor of humans but not chimps. If so, it must have lived after the two lineages split. Trouble was,
Sahelanthropus tchadensis (nicknamed Toumai, the local word for "child") lived close to 7 million years ago. The genetic data, pointing to a human-chimp split at least 1 million years later, suggest that Toumai is not the ur-hominid—the first creature ancestral only to human and not our chimp cousins—after all.
If Toumai is not our ancestor, what is he doing with such a humanlike face and teeth, which look like those of species 5 million years his junior? "A 7 million-year-old hominid should be just starting to look like a hominid, not have a trait you see so much later in the fossil record," says paleoanthropologist Bernard Wood of George Washington University. Even if he is not our ancestor, Toumai is valuable because he undermines the "begat" model of human evolution—that Toumai begat Australopithecus who begat Homo habilis who begat Homo erectus who begat Homo sapiens . That model assumes that each biological innovation, whether bipedality or a large brain or any other, evolved only once and stuck. Instead, evolution played Mr. Potato
Head, putting different combinations of features on ancient hominids then letting them vanish until a later species evolved them. "Similar traits evolved more than once, which means you can't use them as gold-plated evidence that one fossil is descended from another or that having an advanced trait means a fossil was a direct ancestor of modern humans," says Wood. "Lots of branches in the human family tree don't make it to the surface."
In fact, starting 4 million years ago half a dozen hominids belonging to the genus Australopithecus called
Africa home. Best-known for the fossil named Lucy, which was discovered in 1974, Australopithecus afarensis had apelike features such as a large jaw and jutting face, and probably scrambled up trees for safety and shelter. But she also strode the grasslands erect, a hallmark of modern humans. Footprints preserved in volcanic ash 3.6 million years old are mute testimony to how one larger afarensis and a smaller companion—woman and mate, or parent and child—walked across a plain in what is now Tanzania.
What triggered this abrupt change—what set us on the road to becoming fully human—has long stumped experts. Where stones and bones were of little help, however, genes and brains have begun to speak. Last summer scientists discovered a gene called HAR1 (for human accelerated region) that is present in animals from chickens to chimps to people. It had changed in only two of its 118 chemical "letters" from 310 million years ago (when the lineages of chickens and chimps split) to 5 million years ago. But 18 letters changed in the (relative) blink of an eye since the human lineage split from chimps', Katherine Pollard of the University of California, Davis, and colleagues reported. That high rate of change is a sign of a gene whose evolution keeps conferring advantages on those who carry it, perhaps starting with Australopithecus.
The brain, more than any other organ, may have reaped those genetic advantages. HAR1 reaches a peak of activity from the seventh to ninth week of gestation in humans, apparently spurring brain growth. And it is plentiful in cells that create the six layers of neurons in the human cortex. "HAR1 is present in neurons that play a role in the geometry and layout of the cortex," says Pollard. It likely helped the cortexes of our ancestors develop the elaborate folds characteristic of a complex brain.
Besides making brain structure more complex, genetic change also advanced the brain's chemistry. In
2005, Matthew Rockman of Duke University and colleagues discovered that a gene called PDYN began accumulating changes 7 million years ago, soon after our oldest direct ancestor appeared. This gene regulates production of a molecule called prodynorphin, which is like the brain's soup stock: depending on what other ingredients are added, it can change into neurochemicals that underlie perception, behavior or memory. "Fossils can tell us a lot, but it is genomes that tell us what was involved in making language possible and in making brains the way they are today," says Rob DeSalle, co-curator of the American
Museum's new hall.

It surely took more than prodynorphin's magic to modernize a brain and thus jump-start the creation of new species. To find what else made us human, scientists led by neurogeneticist Daniel Geschwind of UCLA are examining which combinations of genes are active in the cortex, the seat of higher thinking, of chimps and people. Among the genes turned to "high" in people, they reported last year, are those that influence how fast electrical signals jump from neuron to neuron and therefore how fast the brain can process information, those that enhance connections between the cells and thus learning and memory, and those that promote brain growth. This pattern of gene activity, it appears, began emerging when
Australo-pithecus species did.
And it helps explain why Lucy's kind were the way they were. Afarensis women and men stood three to five feet tall and weighed 60 to 100 pounds. They had small teeth good for fruits and nuts, but not meat. (The available prey was enough to make one a confirmed vegetarian: hyenas the size of bears, saber-toothed cats and other mega-reptiles and raptors.) That suggests that early humans were more often prey than predators, says anthropologist Robert Sussman of Washington University, coauthor of the 2005 book "Man the Hunted." The evidence is as stark as the many fossil skulls containing holes made by big cats and talon marks from raptors.
The realization that early humans were the hunted and not hunters has upended traditional ideas about what it takes for a species to thrive. For decades the reigning view had been that hunting prowess and the ability to vanquish competitors was the key to our ancestors' evolutionary success (an idea fostered, critics now say, by the male domination of anthropology during most of the 20th century). But prey species do not owe their survival to anything of the sort, argues Sussman. Instead, they rely on their wits and, especially, social skills to survive. Being hunted brought evolutionary pressure on our ancestors to cooperate and live in cohesive groups. That, more than aggression and warfare, is our evolutionary legacy.
Both genetics and paleoneurology back that up. A hormone called oxytocin, best-known for inducing labor and lactation in women, also operates in the brain (of both sexes). There, it promotes trust during interactions with other people, and thus the cooperative behavior that lets groups of people live together for the common good. By comparing the chimp genome with the human, scientists infer that oxytocin existed in the ancestor of both. But it has undergone changes since then, perhaps in how strongly the brain responds to it and in how much is produced. The research is still underway, but one possibility is that the changes occurred around the time our ancestors settled into a system based on enduring bonds between men and women, about 1.7 million years ago.
That was a formula for success, and one that may have also left a mark on the brain. Besides revealing the size of a brain, paleoneurology examines impressions of surface features that the brain leaves on the inside of the skull. That yields clues to its organization. Comparing the shapes of the brains of two hominids that lived
2.5 million years ago, Australopithecus africanus and Paranthropus, scientists find major differences in the shape of the frontal lobe, which controls higher cognition. "Paranthropus has a teardrop shape, whereas africanus is more squared off, and africanus has a swooping down on the bottom where Paranthropus is sort of peaked," says Dean Falk of Florida State University. That configuration suggests that africanus had a better-developed region called area 10, which plays a key role in decision-making, taking initiative and advance planning. It may be why africanus evolved while Paranthropus came to a dead end.
Paleoneurology promises to do what simplistic studies of ancient brains—which asked only how big they were—could not: explain our ancestors' great leaps forward. About 2.5 million years ago a new genus, Homo habilis, appeared in Africa. Discovered by the legendary Louis and Mary Leakey, habilis was the first hominid with a brain bigger than a chimp's, and was the first toolmaker: stone tools—sharp flakes of rock— appeared when habilis did. Their direct descendant, Homo erectus, took an equally momentous step: venturing beyond Africa. In the Republic of Georgia at a site called Dmanisi, scientists have unearthed 1.8 million-year-old fossils of erectus, "the first outpost we know of beyond Africa," says G. Philip Rightmire of
Binghamton University. "It looks like these people got out and materialized everywhere in Eurasia," showing up as Java man and Peking man, among others. (None of the original fossils of Peking man survived World

War II. Packed for shipment to the United States for safekeeping, they disappeared in transit; only casts remain.) Ancient humans didn't just walk: they reached Australia 60,000 years ago, across miles of open ocean.
Erectus shows that brain size is too crude a measure of a species' talents. At Dmanisi, the brains range from
600 to 770 cubic centimeters, comparable to the more primitive habilis. But while erectus did not distinguish themselves in brain size, brain structure is more telling. They were the first of our ancestors to have an asymmetric brain, as modern humans do; Australopithecus species do not. Asymmetry is a mark of increasing specialization and therefore complex cognitive ability. Erectus used it to, among other things, discover and tame fire. What they did not use it for is technology. Tools found with the Dmanisi fossils include cutting flakes, rock "cores" from which flakes were made and a chopper, all primitive even for their time. "The old idea that you needed a master's degree in stone tools to leave Africa is crazy," says Bernard
Wood.
Although erectus spread across Eurasia between 2 million and 1 million years ago, DNA makes clear that the species was almost certainly a dead end and not our ancestor, as some scientists had argued. According to this idea, groups of erectus scattered across the Old World all accrued the same mutations and underwent the same natural selection that led to Homo sapiens. The Y chromosome begs to differ. The Y is passed intact from father to son; in that sense, it's like a last name and so can be used to trace ancestries. But like surnames that got Anglicized at Ellis Island, sometimes a Y changes, with the altered version being passed to all male descendants. Peter Underhill, a molecular anthropologist at Stanford University, tracked 160 such changes in the Y's of 1,062 men from 21 populations across the world. Applying the molecular-clock technique, he concludes that the most recent common ancestor of all men alive today lived 89,000 years ago in Africa. The first modern humans—and therefore, unlike the earlier wave of Homo erectus into Asia a million years ago, the ancestors of everyone today—departed Africa about 66,000 years ago.
These pilgrims were strikingly few. From the amount of variation in Y chromosomes today, population geneticists infer how many individuals were in this "founder" population. The best estimate: 2,000 men.
Assuming an equal number of women, only 4,000 brave souls ventured forth from Africa. We are their descendants.
A curious thing about early Homo species is that they looked quite human early on. "By 600,000 years ago everyone had a big brain, and by 200,000 years ago people in Africa looked like modern humans," says archeologist Richard Klein of Stanford. "But there was no representational art, no figurines, no jewelry until
50,000 years ago. Some kind of cognitive advance was required, probably in language or working memory.
But since size hardly changed, the brain change that produced behaviorally modern humans must have been in structure." The source of such structural changes must come, like every aspect of our physiology, from genes. Combing the genome for genes that emerged just when language, art, culture and other products of higher intelligence did, researchers have found three with the right timing.
The first, called FOXP2, plays a role in human speech and language, but it must do something else in other species, because the decidedly nonverbal mouse has a version of it. Using the standard molecular-clock tactic, Svante Paabo and colleagues at the Max Planck Institute estimate that the human version of FOXP2 appeared less than 200,000 years ago—about when anatomically modern humans stepped onto the world stage—and maybe as recently as 50,000. If so, then it is only humans as modern as those in the last diaspora out of Africa who developed advanced, spoken language. Another gene with interesting timing is microcephalin, which affects brain size. It carries a time stamp of 37,000 years ago, again when symbolic thinking was taking hold in our most recent ancestors. The third, called ASPM and also involved in brain size, clocks in at 5,800 years. That was just before people established the first cities in the Near East and is well after Homo sapiens attained their modern form. It therefore suggests that we are still evolving.
The fossils have not finished speaking, of course. These countless postcards from the past surely still lie en-cased in the rocks of the Old World. But now, as ancient DNA and gray matter give up their secrets, they are adding life to the age-old quest to understand where humankind came from and how we got here.

Piltdown man is one of the most famous frauds in the history of science. In 1912 Charles Dawson discovered the first of two skulls found in the Piltdown quarry in Sussex, England, skulls of an apparently primitive hominid, an ancestor of man. Piltdown man, or Eoanthropus dawsoni to use his scientific name, was a sensation. He was the expected "missing link" a mixture of human and ape with the noble brow of Homo sapiens and a primitive jaw. Best of all, he was British!
As the years went by and new finds of ancient hominids were made, Piltdown man became an anomaly that didn't fit in, a creature without a place in the human family tree. Finally, in 1953, the truth came out. Piltdown man was a hoax, the most ancient of people who never were. This is his story.
In 1856 the first Neanderthal fossil discovery was made and the hunt was on to find fossil remains of human ancestors. In the next half century finds were made in continental Europe and in Asia but not in Britain. Finally, in 1912, the sun rose on British paleontology -- fossil remains of an ancient pleistocene hominid were found in the Piltdown quarries in Sussex. In the period 1912 to 1915 the
Piltdown quarries yielded two skulls, a canine tooth, and a mandible of Eoanthropus, a tool carved from an elephant tusk, and fossil teeth from a number of pleistocene animals.
There is a certain vagueness about some of the critical events. Dawson contacted Woodward about the first two skull fragments which were supposedly found by workman "some years prior". Exactly when is unknown. Similarly, the discovery of Piltdown II is shrouded in mystery. Supposedly Dawson and an anonymous friend make the discovery 1915; however the friend and the location of the find are unknown.
The reaction to the finds was mixed. On the whole the British paleontologists were enthusiastic; the
French and American paleontologists tended to be skeptical, some objected quite vociferously. The objectors held that the jawbone and the skull were obviously from two different animals and that their discovery together was simply an accident of placement. In the period 1912-1917 there was a great deal of skepticism. The report in 1917 of the discovery of Piltdown II converted many of the skeptics; one accident of placement was plausible -- two were not.
It should be remembered that, at the time of Piltdown finds, there were very few early hominid fossils;
Homo neanderthalensis and Homo sapiens were clearly fairly late. It was expected that there was a
"missing link" between ape and man. It was an open question as to what that missing link would look like. Piltdown man had the expected mix of features, which lent it plausibility as a human precursor.
This plausibility did not hold up. During the next two decades there were a number of finds of ancient hominids and near hominids, e.g. Dart's discovery of Australopithecus, the Peking man discoveries, and other Homo erectus and australopithecine finds. Piltdown man did not fit in with the new discoveries.
None the less, Sir Arthur Keith (a major defender of Piltdown man) wrote
in 1931:
It is therefore possible that Piltdown man does represent the early pleistocene ancestor of the modern type of man, He may well be the ancestor we have been in search of during all these past years. I am therefore inclined to make the Piltdown type spring from the main ancestral stem of modern humanity...
In the period 1930-1950 Piltdown man was increasingly marginalized and by 1950 was, by and large, simply ignored. It was carried in the books as a fossil hominid. From time to time it was puzzled over and then dismissed again. The American Museum of Natural History quietly classified it as a mixture

of ape and man fossils. Over the years it had become an anomaly; some prominent authors did not even bother to list it. In Bones of Contention Roger Lewin quotes Sherwood Washburn as saying
"I remember writing a paper on human evolution in 1944, and I simply left Piltdown out. You could make sense of human evolution if you didn't try to put Piltdown into it."
Finally, in 1953, the roof fell in. Piltdown man was not an ancestor; it was not a case of erroneous interpretation; it was a case of outright deliberate fraud.
From the chronology and the later reconstruction of events it is fairly clear that there never were any significant fossils at the Piltdown quarry. It was salted from time to time with fossils to be found. Once the hoax was exposed, Sir Kenneth Oakley went on to apply more advanced tests to find where the bones had come from and how old they were. His main findings were:
Piltdown I skull: Medieval, human, ~620 years old.
Piltdown II skull: Same source as Piltdown I skull.
Piltdown I jawbone: Orangutan jaw, ~500 years old, probably from Sarawak.
Elephant molar: Genuine fossil, probably from Tunisia.
Hippopotamus tooth: Genuine fossil, probably from Malta or Sicily.
Canine tooth: Pleistocene chimpanzee fossil.
Originally it had been believed that one skull had been used; later, more precise dating established in
1989 that two different skulls had been used, one for each of the two skull "finds". The skulls were unusually thick; a condition that is quite rare in the general population but is common among the Ona indian tribe in Patagonia. The jawbone was not definitely established as being that of an orangutan until 1982.
Drawhorn's
paper summarizes all that is currently known about the provenance of the bones that were used.
Not only were the bones gathered from a variety of sources, they were given a thorough going treatment to make them appear to be genuinely ancient. A solution containing iron was used to stain the bones; fossil bones deposited in gravel pick up iron and manganese. [It is unclear whether the solution also contained manganese: Millar mentions that manganese was present; Hall, who did the tests for manganese, says that it was not.] Before staining the bones (except for the jawbone) were treated with Chromic acid to convert the bone apatite (mineral component) to gypsum to facilitate the intake of the iron and manganese (?) solution used to stain the bones. The skull may have also been boiled in an iron sulphate solution. The canine tooth was painted after staining, probably with Van
Dyke brown. The jaw bone molars were filed to fit. The connection where the jawbone would meet the rest of the skull was carefully broken so that there would be no evidence of lack of fit. The canine tooth was filed to show wear (and was patched with chewing gum). It was filled with sand as it might have been if it had been in the Ouse river bed.
With few exceptions
nobody suggested that the finds were a hoax until the very end. The beginning of the end came when a new dating technique, the fluorine absorption test, became available. The
Piltdown fossils were dated with this test in 1949; the tests established that the fossils were relatively modern. Even so, they were still accepted as genuine. For example, in Nature, 1950, p 165, New
Evidence on the Antiquity of Piltdown Man Oakley wrote:

The results of the fluorine test have considerably increased the probability that the [Piltdown] mandible and cranium represent the same creature. The relatively late date indicated by the summary of evidence suggests moreover that Piltdown man, far from being an early primitive type, may have been a late specialized hominid which evolved in comparative isolation. In this case the peculiarities of the mandible and the excessive thickness of the cranium might well be interpreted as secondary or gerontic developments.
In 1925 Edmonds had pointed out that Dawson was in error in his geological dating of the Piltdown gravels: they were younger than Dawson had assumed. In 1951 he published an article pointing out that there was no plausible source for the Piltdown animal fossils. Millar (p203) writes:
The older group of Piltdown animals, he said, were alleged to have been washed from a Pliocene land deposit in the Weald. Edmonds thought there must be some misunderstanding. There was no Pliocene land deposit in the entire Weald which could have produced them. the only local Pliocene beds were marine in origin and lay above the five-hundred foot contour line.
In July 1953 an international congress of paleontologists, under the auspices of the Wenner-Gren
Foundation, was held in London. The world's fossil men were put up, admired and set down again.
But, according to Dr. J.S. Weiner , Piltdown man got barely a mention. He did not fit in. He was a piece of the jig-saw puzzle; the right colour but the wrong shape. It was at the congress that the possibility of fraud dawned on Weiner. Once the possibility had raised it was easy to establish that the finds were a fraud. Millar writes:
The original Piltdown teeth were produced and examined by the three scientists. The evidence of fake could seen immediately. The first and second molars were worn to the same degree; the inner margins of the lower teeth were more worn than the outer -- the 'wear' was the wrong way round; the edges of the teeth were sharp and unbevelled; the exposed areas of dentine were free of shallow cavities and flush with the surrounding enamel; the biting surface of the two molars did not form a uniform surface, the planes were out of alignment. That the teeth might have been misplaced after the death of
Piltdown man was considered but an X-ray showed the lower contact surfaces of the roots were correctly positioned. This X-ray also revealed that contrary to the 1916 radiograph the roots were unnaturally similar in length and disposition.
The molar surface were examined under a microscope. They were scarred by criss-cross scratches suggesting the use of an abrasive. 'The evidences of artificial abrasion immediately sprang to the eye' wrote Le Gros Clark. 'Indeed so obvious did they [the scratches] seem it may well be asked -- how was it that they had escaped notice before?' He answered his question with a beautiful simplicity. 'They had never been looked for...nobody previously had examined the Piltdown jaw with the idea of a possible forgery in mind, a deliberate fabrication.'
Why then was the fraud so successful? Briefly, (a) the team finding the specimans (Dawson,
Woodward, Teilhard) had excellent credentials, (b) incompetence on the part of the British
Paleontological community, (c) the relatively primitive analytical tools available circa 1920, (d) skill of the forgery, (e) it matched what was expected from theory, and (f) as Millar remarks, the hoax led a charmed life.
Who did it? Who perpetrated the hoax? When the hoax was exposed nobody knew who the perpetrator was. No one confessed to the deed. For forty odd years people have speculated about the identity of the culprit; over time an impressive list of suspects has accumulated. The case against each

suspect has been circumstantial, a constellation of suspicious behaviour, of possible motives, and of opportunity. In this section we present summaries of the arguments against the principal candidates.
A comprehensive listing of the accusations, when they were made, who made them, and who the accused were can be found in Tom Turrittin's
Piltdown man overview
; it includes details not given here including the particulars of 30 separate books or papers making accusations.
When the hoax was first exposed Dawson, Teilhard, and Woodward were the obvious suspects; they had made the major finds. In 1953 Weiner fingered Dawson as the culprit.
Stephen Jay Gould
argued that Teilhard and Dawson were the culprits. Woodward generally escaped suspicion; however
Drawhorn made a strong case against him in 1994. Grafton Elliot Smith and Sir Arthur Keith were prominent scientists that played key roles in the discovery. Millar argued that Smith was the culprit; Spencer argued that it was a conspiracy between Dawson and Keith. Other candidates that have been mentioned over the years include
Arthur Conan Doyle
, the geologist
W. J. Sollas
, and the paleontologist
Martin Hinton . This is by no means the end of the list; other people accused include Hargreaves , Abbot ,
Barlow
, and
Butterfield
.
This fraud is quite unique. Most scientific frauds and hoaxes fall into a few categories. There are student japes, students concocting evidence to fit a superior's theories. There are confirming evidence frauds, in which a researcher fabricates findings that they believe should be true. There are outright frauds for money, fossils that are fabricated for gullible collectors. There are rare cases of fabrication for reputation, done in the knowledge that the results will not be checked. And, upon occasion, there are frauds concocted simply as an expression of a perverse sense of humor.
The Piltdown hoax does not seem to fit any of these categories well. This was not an ordinary hoax; it was a systematic campaign over the years to establish the existence of Piltdown man. The early skull fragments were created in advance and salted with the foreknowledge that more extensive finds would be planted later. The hoaxer had to have good reason to believe that the salted fossils would be found.
One of the critical factors in any theory is to account for the fact that the perpetrator had to be confident that the salted fossils would be found. That suggests that either Dawson, Teilhard, or
Woodward was involved since they alone made the initial finds. At first sight it would seem that
Dawson must have been guilty since he made the initial find of the first two skull fragments. However he didn't! They were made by anonymous workmen. The "find" could have been arranged for a handful of coins. As Vere pointed out, the labourer Hargreaves, employed to do most of the digging, was also present at the site.
Another critical factor to be accounted for is access to the specimens that were used in the hoax.
Likewise the question of skill and knowledge required for the hoax must be taken into account.

by Zach Zorich
Did our early ancestors walk or climb their way to becoming human?
Volume 60 Number 1, January/February 2007
In a field that typically deals in spans of a million years or more, celebrity can seem especially fleeting. So maybe it was time for the
3.2-million-year-old Australopithecus afarensis known to the world as "Lucy" to step aside as paleoanthropology's reigning diva, an unofficial title she has held since her 1974 discovery when she stunned the world by providing the first solid evidence that humans had evolved from apelike ancestors. Now Lucy is being upstaged by a younger, more complete fossilized superstar: an afarensis skeleton named for the Ethiopian word "peace"--Selam.
"We have captured a moment in the life history of this individual," says paleontologist Zeresenay Alemseged of the Max Planck
Institute in Leipzig, Germany, "but also a moment in the history of the species Australopithecus afarensis ." That moment was frozen by a flood that swept down Ethiopia's Awash River 3.3 million years ago, sealing the bodies of several mammal species in the floodborne sediment. Zeresenay led the team that discovered the child's remains. His analysis shows Selam was only three years old when she died, presumably from drowning in the flood. Her bones show no signs of trauma, being gnawed by scavengers, or abraded by river sediments, indicating she probably had flesh on her bones when the river sealed her off from the world.
Selam's remains are far more complete than two other Australopithecine children found in fossil beds at Laetoli in Ethiopia and
Taung in South Africa. In addition to revealing how afarensis children developed physically, she is giving scientists some new anatomy to obsess over, namely her face, shoulder blades, even the hyoid--a fragile bone from her throat.
" Afarensis was, in a way, a bipedal primitive ancestor." says Zeresenay. "A primitive skull with a small brain, and many primitive features on the upper skeleton were sitting on a more humanlike lower skeleton." Understanding how afarensis evolved from the last common ancestor we shared with the chimpanzee will provide a unique window into how the world of 3 million years ago shaped the ancestors of the human race.
The world's oldest known child has been discovered in East Africa in an area known appropriately as the Cradle of Humanity.
The 3.3-million-year-old fossilized toddler was uncovered in north Ethiopia's badlands along the Great Rift Valley ( map of
Ethiopia ).
The skeleton, belonging to the primitive human species Australopithecus afarensis, is remarkable for its age and completeness, even for a region spectacularly rich in fossils of our ancient ancestors, experts say.
The new find may even trump the superstar fossil of the same species: "Lucy," a 3.2-million-year-old adult female discovered nearby in 1974 that reshaped theories of human evolution. (Related: "Fossil Find Is Missing Link in Human Evolution, Scientists
Say" [April 2006].)
Some experts have taken to calling the baby skeleton "Lucy's baby" because of the proximity of the discoveries, despite the fact that the baby is tens of thousands of years older. (See a historical photo gallery on A. afarensis and more information about
Lucy .)
"This is something you find once in a lifetime," said Zeresenay Alemseged of the Max Planck Institute for Evolutionary
Anthropology in Leipzig, Germany, who led the team that made the discovery. (See a video discussing how the new child skeleton was found .)
A Complete Find
The child was probably female and about three years old when she died, according to the researchers.
Found in sandstone in the Dikika area, the remains include a remarkably well preserved skull, milk teeth, tiny fingers, a torso, a foot, and a kneecap no bigger than a dried pea.
Archaeologists hope that the baby skeleton, because of its completeness, can provide a wealth of details that Lucy and similar fossils couldn't.
The age of death makes the find especially useful, scientists say, providing insights into the growth and development of human ancestors.

"Visually speaking, the Dikika child is definitely more complete [than Lucy]," team member Fred Spoor of University College
London (UCL) said.
"It has the complete skull, the mandible, and the whole brain case. Lucy doesn't have much of a head."
"The most impressive difference between them is that this baby has a face," Zeresenay added. (Ethiopians' first names are their formal names.)
That face, no bigger than a monkey's, was spotted peering from a dusty slope in December 2000. Its smooth brow and short canine teeth identified it as a hominin, a group that encompasses humans and their ancestors.
(See a map of major human ancestor fossil sites .)
Zeresenay's research at Dikika was funded in part by the National Geographic Society.
The find, reported tomorrow in the journal Nature, is also featured in the November issue of National Geographic magazine.
(National Geographic News and National Geographic magazine are both parts of the National Geographic Society.)
(Check out a special "Dikika Baby" Web site with the entire National Geographic article, unpublished photographs, and a video interview with the author.)
New Questions
The fossil child, who died at nursing age, offers important clues to the development of early humans, says Spoor, of UCL.
"It will teach us how our early ancestors grew up," he said. "The only way you can evolve from one type of species into another is by growing up in a different way, because that's how you change."
For instance, a prolonged, dependent childhood allowed later human species to grow larger brains, which need more time to develop after birth.
"As far as we can tell, it is not yet happening [with Lucy's baby]," Spoor said.
While the adult A. afarensis is thought to have had a brain slightly larger than a chimpanzee's, the hominin child's brain appears to have been smaller than an average chimp brain of the same age.
"For the first time we have insights that they may have grown their brains a little bit slower than your average chimp," Spoor said.
"If you take more time to form your brain, it may well be that you make more intricate connections inside," the researcher added.
"Or it may not be a positive thing
—perhaps you live on poorer food or are a bit behind."
Spoor favors the latter explanation in the case of these early hominins.
"They haven't progressed over great apes at all," he said. "They've just changed their locomotion for whatever reason, but they were not necessarily any more clever than chimps were."
The new fossil also supports the theory that A. afarensis walked upright on two legs, but it hints that human ancestors hadn't completely left the trees by that time.
The skeleton's ape-like upper body includes two complete shoulder blades similar to a gorilla's, so it could have been better at climbing than humans are.
"This was a bit of a surprise, and controversial," Spoor said.
Some researchers will say the feature was inherited from an ancestor and reveals little about this hominin's lifestyle, Spoor adds.
"Other people will say it shows they are still using their arms for climbing quite a lot," he said.
"The question is not whether they spent all day swinging around in the trees. But it may be true there was still some climbing aspect, for instance, for building nests at night or to forage in the trees."
A Record Find
Louise Humphrey, a paleontologist at the Natural History Museum in London who wasn't part of Zeresenay's team, describes the find as "an extremely valuable addition to the hominin fossil record.
"The fossil also preserves parts of the skeleton not previously documented for A. afarensis, " she added.

These included a hyoid bone in the throat area that later went on to form part of the human voice box.
"Detailed analysis of the skeleton will reveal a lot more about the [locomotion] and foraging behavior of this young hominin,"
Humphrey said.
How the child died is unclear, though it appears the body was rapidly covered by sand and gravel during a flood.
"It was buried just after it died," Zeresenay said. "That's why we found an almost complete skeleton, so maybe [drowning] could be the cause of its demise."
Like Lucy and many other hominin fossils, the child was uncovered in the low-lying northern end of Africa's Great Rift Valley.
Researchers say the region was once much less arid. Hominins shared the area's lush woods and grasslands with extinct species of elephants, hippos, crocodiles, otters, antelopes, and other animals whose fossils have been found nearby.
For these remains to be preserved and discovered, Zeresenay says, they needed to be covered in sediments and then exposed by tectonic activity, as has happened in the Great Rift Valley.
"These deposited environments were subsequently exposed by tectonics for us to go there and find the hominins," he added.
The Ethiopian paleoanthropologist says several more years of painstaking work will be needed to remove the remaining hard sandstone encasing much of the fossil child's skeleton.