Today’s New Reason To Believe

Posted by Fazale ‘Fuz’ Rana, Ph.D.

Neanderthal Speech Gene May be Due to Contamination

Nobody really likes a potty mouth, including anthropologists. But it looks like these scientists will have to put up with “contaminated” language from Neanderthals, at least if the results of new work are valid. It appears as if the recovery of the so-called language gene from the remains of Neanderthals is not authentic, but instead may be due to contamination from human DNA.

The question of whether or not Neanderthals possessed language capacity has precipitated much controversy. Anatomical studies are ambiguous towards this end. (See Who Was Adam? for a detailed discussion.) To help resolve this issue a team from the Max Planck Institute turned to ancient DNA analysis to probe for the language gene in the Neanderthal genome.

In 2001, a research team from the United Kingdom reported that mutations in the FOXP2 gene cause severe language disorders. Presumably the FOXP2 protein plays a key role in controlling the development of brain and facial structures that support aspects of human language capacity.

An initial evolutionary analysis of the FOXP2 gene, conducted in 2002, indicated that the human variant arose about 200,000 years ago. Subsequent work, published later that year, placed the origin of the human FOXP2 gene at about 100,000 years ago. From an evolutionary standpoint, this is well after the time that humans and Neanderthals allegedly split from a common ancestor. Accordingly, Neanderthals should not possess a human-like FOXP2 gene and, therefore, language ability.

However, to everyone’s surprise, the team from the Max Planck Institute did isolate the human variant of the FOXP2 gene from a recently recovered Neanderthal specimen. This result was interpreted by some as evidence that Neanderthals had language. If so, it creates problems for the RTB human origins model, which predicts that Neanderthals and other hominids should behave in nonhuman ways, and, therefore, should not have the capacity for language.

Did Neanderthals possess language ability? At the time that the recovery of the Neanderthal language gene was announced I wrote:

The very real possibility exists that this result stems from contamination by human DNA. Clearly, the research team went to painstaking efforts to avoid contamination. Anthropologists suited up in clean room gowns and face masks to excavate the Neanderthal remains using sterilized tools. They designed the extraction protocol to avoid isolating any human DNA and ran the appropriate controls to ensure the Neanderthal DNA samples had no human contamination. In spite of these heroic efforts, the possibility of contamination cannot be ruled out. The team from the Max Planck Institute introduced contamination into the Neanderthal genome sample they were previously working with and wrongly interpreted this as evidence for human-Neanderthal interbreeding.

It looks like my initial assessment was right. A research team for the University of Chicago re-assessed the likelihood that Neanderthals possessed the human variant of FOXP2 by looking at the genetic variation associated with this gene among modern human populations. They concluded that the scenario proposed by the Max Planck workers—namely the human variant arose prior to the time that Neanderthal and human lineages diverged from a common ancestor—is inconsistent with the genetic patterns observed among modern humans. They also estimated that the human variant of FOXP2 arose about 42,000 years ago. This result falls in line with earlier estimates, which places the origin of the human variant between 100,000 and 200,000 years ago.

The Chicago scientists suggest two possible scenarios to explain the recovery of the human variant of the FOXP2 gene from Neanderthal remains. First, humans introduced the language gene into the Neanderthal gene pool through interbreeding. They assert that if low levels of interbreeding took place between humans and Neanderthals, this could account for the appearance of the human language gene in the Neanderthal genome. This conclusion is not well supported by other studies, which have failed to find any direct evidence for interbreeding.

The other possibility is that the DNA extracted from Neanderthals was contaminated with modern human DNA. Even though the Max Planck Institute scientists took every precaution to avoid contamination and even ran controls to ensure that their samples were free from contaminants, human DNA, which is ubiquitous, could have easily made its way into the sample. The team from the University of Chicago raises questions about the effectiveness of the control samples. They assert that the controls selected by the Max Planck team do not necessarily ensure contaminant-free Neanderthal DNA samples.

It is really beginning to look like Neanderthals didn’t have language capacity after all—just contaminated language. Now I’d like to know who’s going to volunteer to wash their mouths out with soap.

Posted by Fazale ‘Fuz’ Rana, Ph.D.

New research confirms biological differences between H. floresiensis and modern humans

The way a person walks says a lot about them. For example, someone who is confident will usually walk erect and briskly. Those who amble about with their hands in their pockets and shoulders hunched portray dejection.

Hominid’s various walking styles also say a lot about these creatures. Recently a team of anthropologists from State University of New York at Stony Brook reported on the gait of the hobbit-sized creature Homo floresiensis at the American Association of Physical Anthropology meeting held in Columbus, Ohio. Based on an analysis of a foot taken from the remains of a nearly complete specimen (known as LB-1 and dating around 18,000 years old), the researchers concluded that this hominid ambled about in an unusual manner.

These creatures, which stood just over three feet tall, had unusually large feet. This characteristic forced H. floresiensis to bend further back at the knees (more so than modern humans) when they walked, leading to a high-step march. The research team also noted another difference: The shape of H. floresiensis’ big toe was similar to that of modern humans, but ape-like in size.

The foot structure and gait of this creature represent one more piece of evidence that it was a hominid with strong kinship ties to Homo erectus. This interpretation has been recently challenged by several anthropologists who claim that these animals were actually microcephalic human beings. Other researchers have also suggested that these creatures were insular dwarfs and cretins.

The new analysis of the foot and gait of H. floresiensis, along with an ensemble of additional fossil and archeological evidences indicate that any interpretation of H. floresiensis as a diseased modern human lacks comprehensive support. It is unclear what a high-step march communicates in terms of body language. But for anthropologists it means that H. floresiensis wasn’t a modern human.

The biological and behavioral differences between modern humans and H. floresiensis find ready accommodation in the RTB model of human origins. This scientific theory of creation views the hominids as creatures made by God to possess some level of intellectual and emotional capacity. Still, according to the RTB view, these creatures lacked God’s image. The model predicts that the hominids should be biologically and behaviorally distinct from modern humans, and indeed that appears to be the case for H. floresiensis.

Posted by Fazale ‘Fuz’ Rana, Ph.D.

New research confirms affinity between H. floresiensis and H. erectus

For the last few weeks I have discussed the controversy surrounding Homo floresiensis. (Go here and here to read the past articles.) At times, it seems like anthropologists are all over the place when it comes to determining the identity of this diminutive creature. New research, however, indicates that anthropologists were headed in the right direction all along when they interpreted this creature to be a hominid with close connections to Homo erectus.

The confusion began in the fall of 2004. Australian and Indonesian paleoanthropologists shocked scientists with the publication of evidence for hobbit-sized hominids that coexisted for a time with modern humans. Fossils recovered on the Flores Island of Indonesia indicate that these hominids stood just over three feet tall with a chimpanzee-like brain size (380 cm3). Their cranial and facial features bear resemblance to Homo erectus and their post-cranial skeleton combines characteristics of the australopithecines (like “Lucy”) and H. erectus. The paleoanthropologists who recovered these remains classified them as a new species, Homo floresiensis.

Of the fossils recovered, the most remarkable specimen was a nearly complete skeleton of a female that dates to about 18,000 years in age. Other fossil and archeological evidence indicates that H. floresiensisexisted on Flores Island from about 95,000 to 12,000 years ago, when they became extinct. It appears that H. floresiensis coexisted with modern humans. Still, paleoanthropologists are not sure if the hominids had any actual contact with human beings.

Archeological evidence and animal remains indicate that H. floresiensis hunted and scavenged the dwarf elephants on the island, as well as rats, fish, snakes, frogs, birds, and tortoises.

Due to the coexistence of H. floresiensis with modern humans and their remarkable behavior—given their small brains—a minority of paleoanthropologists argue that these creatures are microcephalic human beings. Others have suggested that these creatures were insular dwarfs and cretins.

These interpretations of H. floresiensis have been met with skepticism by many paleoanthropologists. Since the discovery of the initial H. floresiensis remains, paleoanthropologists have recovered fossils from twelve other individuals, all of which display identical characteristics to the original find. Even though H. floresiensis used tools and hunted, their behavior was still crude when compared to modern humans. Like H. erectus, they used tools reminiscent of the Acheulean industry. Based on these findings, H. floresiensis behaved in nonhuman ways.

Brain shape studies and additional characterization of skeletal features distinguish H. floresiensis from microcephalic humans and confirm its status as a distinct hominid. New work adds support to this interpretation. A team from George Washington University performed multivariate analysis on the external physical features of the H. floresiensis skull, correcting for size difference effects. They concluded that the shape of this hominid’s skull differs significantly from the shape of modern human skulls. Based on skull shape, H. floresiensis appears to relate most closely with H. erectus, and to a lesser degree with H. habilis.

The weight of evidence points anthropologists away from any interpretation that regards H. floresiensis as a diseased or dwarfed modern human and sends them towards the erectines.

How does H. floresiensis fit into RTB’s human origins model? The easiest way to accommodate these creatures would be as diseased or dwarfed humans. But even as hominids, they still find a place in RTB’s creation model.

RTB’s biblical creation model views the hominids as animals created by God. Accordingly, these extraordinary creatures walked erect and possessed some level of intelligence, which allowed these animals to cobble crude tools and even adopt some level of “culture.” The RTB model maintains that the hominids were not spiritual beings made in God’s image, but reserves that status exclusively for modern humans.

The RTB model predicts biological similarities will exist among the hominids and modern humans to varying degrees. But, because the hominids were not created in God’s image, they would be expected to be distinct from modern humans in their cognitive capacity, behavior, “technology,” and “culture.”

Accordingly, H. floresiensis stands distinct from modern humans, not only in anatomy, but in behavior. Remarkable creatures in their own right, but nonetheless creatures that lacked the image of God.