Dog/Human Alliance: Reading #1


 

Neanderthal Neuroscience [excerpts]

Carl Zimmer

National Geographic |11/14/2011

 

[1] When the Society for Neuroscience gets together for their annual meeting each year, a city of scientists suddenly forms for a week. This year’s meeting has drawn 31,000 people to the Washington DC Convention Center. The subjects of their presentations range from brain scans of memories to the molecular details of disorders such as Parkinson’s and autism. This morning, a scientist named Svante Paabo delivered a talk. Its subject might make you think that he had stumbled into the wrong conference altogether. He delivered a lecture about Neanderthals.

 

[2] Yet Paabo did not speak to an empty room. He stood before thousands of researchers in the main hall. His face was projected onto a dozen giant screens, as if he were opening for the Rolling Stones. When Paabo was done, the audience released a surging crest of applause. One neuroscientist I know, who was sitting somewhere in that huge room, sent me a one-word email as Paabo finished: “Amazing” . . .

 

[3] Paabo then offered a scenario for human evolution: about 800,000 years ago, the ancestors of Neanderthals and Denisovans [Homo heidelbergensis] diverged from our own ancestors. They expanded out of Africa, and the Neanderthals swept to the west into Europe and the Denisovans headed into East Asia . . .

 

[4] At the talk, Paabo described some of his latest work on a gene called FoxP2. Ten years ago, psychologists discovered that mutations to this gene can make it difficult for people to speak and understand language. Paabo and his colleagues have found that FoxP2 underwent a dramatic evolutionary change in our lineage. Most mammals have a practically identical version of the protein, but ours has two different amino acids (the building blocks of proteins).

 

[5] The fact that humans are the only living animals capable of full-blown language, and the fact that this powerful language-linked gene evolved in the human lineage naturally fuels the imagination. Adding fuel to the fire, Paabo pointed out that both Neanderthals and Denisovans had the human version of FoxP2. If Neanderthals could talk, it would be intriguing that they apparently couldn’t paint or make sculptures or do other kinds of abstract expressions that humans did. And if Neanderthal’s couldn’t talk, it would be intriguing that they already had a human version of FoxP2. As scientific mysteries go, it’s a win-win.

 

[6] From a purely scientific point of view, the best way to investigate the evolution of FoxP2 would be to genetically engineer a human with a chimpanzee version of the gene and a chimpanzee with a human version. But since that’s not going to happen anywhere beyond the Island of Doctor Moreau, Paabo is doing the second-best experiment. He and his colleagues are putting the human version of FoxP2 into mice.

 

[7] The humanized mice don’t talk, alas. But they do change in many intriguing ways. The frequency of their ultrasonic squeaks changes. They become more cautious about exploring new places. Many of the most interesting changes happen in the brain. As I wrote in my Discover column, Paabo and his colleagues have found changes in a region deep in the brain called the striatum. The striatum is part of a circuit that lets us learn how to do new things, and then to turn what we learn into automatic habits. A human version of FoxP2 makes neurons in the mouse striatum sprout more branches, and those branches become longer.

 

[8] Paabo’s new experiments are uncovering more details about how human FoxP2 changes the mice. Of the two mutations that changed during human evolution, only one makes a difference to how the striatum behaves. And while that difference may not allow mice to recite Chaucer, they do change the way they learn. Scientists at MIT, working with Paabo, have put his mice into mazes to see how quickly they learn how to find food. Mice with human FoxP2 develop new habits faster than ones with the ordinary version of the gene.

 

[9] So for now, Paabo’s hypothesis is that a single mutation to FoxP2 rewired learning circuits in the brain of hominins over 800,000 years ago. Our ancestors were able to go from practice to expertise faster than earlier hominins. At some point after the evolution of human-like FoxP2, our ancestors were able to use this fast learning to develop the quick, precise motor control required in our lips and tongues in order to speak.

 

[10] I think what made Paabo’s talk so powerful for the audience was that he was coming from a different world─ a world of fossils and stone tools─ but he could talk in the language of neuroscience. As big as the Society for Neuroscience meetings can be, Paabo showed that it was part of a much bigger scientific undertaking: figuring out how we came to be the way we are.


 

Sleeping with the Enemy: What happened between the Neanderthals and us?

Elizabeth Kolbert

The New Yorker | August 11, 2011

 

[1] . . . In 1908, a nearly complete Neanderthal skeleton was discovered in a cave near La Chapelle-aux-Saints, in southern France. The skeleton was sent to a paleontologist named Marcellin Boule, at Paris’s National Museum of Natural History. In a series of monographs, Boule invented what might be called the cartoon version of the Neanderthals— bent-kneed, hunched over, and brutish. Neanderthal bones, Boule wrote, displayed a “distinctly simian arrangement,” while the shape of their skulls indicated “the predominance of functions of a purely vegetative or bestial kind.” Boule’s conclusions were studied and then echoed by many of his contemporaries; the British anthropologist Sir Grafton Elliot Smith, for instance, described Neanderthals as walking with “a half-stooping slouch” upon “legs of a peculiarly ungraceful form.” (Smith also claimed that Neanderthals’ “unattractiveness” was “further emphasized by a shaggy covering of hair over most of the body,” although there was— and still is— no clear evidence that they were hairy.)

 

[2] In the nineteen-fifties, a pair of anatomists, Williams Straus and Alexander Cave, decided to reëxamine the skeleton from La Chapelle. What Boule had taken for the Neanderthal’s natural posture, Straus and Cave determined, was probably a function of arthritis. Neanderthals did not walk with a slouch, or with bent knees. Indeed, given a shave and a new suit, the pair wrote, a Neanderthal probably would attract no more attention on a New York City subway “than some of its other denizens.” More recent scholarship has tended to support the idea that Neanderthals, if not quite up to negotiating the I.R.T., certainly walked upright, with a gait we would recognize more or less as our own. The version of Neanderthals offered by the Neanderthal Museum— another cartoon— is imbued with cheerful dignity. Neanderthals are presented as living in tepees, wearing what look like leather yoga pants, and gazing contemplatively over the frozen landscape. “Neanderthal man was not some prehistoric Rambo,” one of the display tags admonishes. “He was an intelligent individual.”

 

[3] Pääbo announced his plan to sequence the entire Neanderthal genome in July, 2006, just in time for the hundred-and-fiftieth anniversary of the Neanderthal’s discovery. The announcement was made together with an American company, 454 Life Sciences, which had developed a so-called “high throughput” sequencing machine that, with the help of tiny resin spheres, could replicate tens of thousands of DNA snippets at a time. Both inside and outside the genetics profession, the plan was viewed as wildly ambitious, and the project made international news.

 

[4] . . . One way to try to answer the question “What makes us human?” is to ask “What makes us different from apes?,” or, to be more precise, from nonhuman apes, since, of course, humans are apes. As just about every human by now knows— and as the experiments with Dokana once again confirm— nonhuman apes are extremely clever. They’re capable of making inferences, of solving complex puzzles, and of understanding what others are (and are not) likely to know. When researchers from Leipzig performed a battery of tests on chimpanzees, orangutans, and two-and-a-half-year-old children, they found that the chimps, the orangutans, and the kids performed comparably on a wide range of tasks that involved understanding of the physical world. For example, if an experimenter placed a reward inside one of three cups, and then moved the cups around, the apes found the goody just as often as the kids—indeed, in the case of chimps, more often.

 

[5] The apes seemed to grasp quantity as well as the kids did— they consistently chose the dish containing more treats, even when the choice involved using what might loosely be called math— and also seemed to have just as good a grasp of causality. (The apes, for instance, understood that a cup that rattled when shaken was more likely to contain food than one that did not.) And they were equally skillful at manipulating simple tools . . .

 

[6] From the archeological record, it’s inferred that Neanderthals evolved in Europe or western Asia and spread out from there, stopping when they reached water or some other significant obstacle. (During the ice ages, sea levels were a lot lower than they are now, so there was no English Channel to cross.) This is one of the most basic ways modern humans differ from Neanderthals and, in Pääbo’s view, also one of the most intriguing. By about forty-five thousand years ago, modern humans had already reached Australia, a journey that, even mid-ice age, meant crossing open water. Archaic humans like Homo erectus “spread like many other mammals in the Old World,” Pääbo told me. “They never came to Madagascar, never to Australia. Neither did Neanderthals.

 

[7] It’s only fully modern humans who start this thing of venturing out on the ocean where you don’t see land. Part of that is technology, of course; you have to have ships to do it. But there is also, I like to think or say, some madness there. You know? How many people must have sailed out and vanished on the Pacific before you found Easter Island? I mean, it’s ridiculous. And why do you do that? Is it for the glory? For immortality? For curiosity? And now we go to Mars. We never stop.” If the defining characteristic of modern humans is this sort of Faustian restlessness, then, by Pääbo’s account, there must be some sort of Faustian gene. Several times, he told me that he thought it should be possible to identify the basis for this “madness” by comparing Neanderthal and human DNA.

 

[8] “If we one day will know that some freak mutation made the human insanity and exploration thing possible, it will be amazing to think that it was this little inversion on this chromosome that made all this happen and changed the whole ecosystem of the planet and made us dominate everything,” he said at one point. At another, he said, “We are crazy in some way. What drives it? That I would really like to understand. That would be really, really cool to know.”

 

[9] According to the most recent estimates, Neanderthals and modern humans share a common ancestor who lived about four hundred thousand years ago. (It is unclear who that ancestor was, though one possibility is the somewhat shadowy hominid known, after a jawbone found near Heidelberg, as Homo heidelbergensis.) The common ancestor of chimps and humans, by contrast, lived some five million to seven million years ago. This means that Neanderthals and humans had less than one-tenth the time to accumulate genetic differences . . .

 

[10] “If we one day will know that some freak mutation made the human insanity and exploration thing possible, it will be amazing to think that it was this little inversion on this chromosome that made all this happen and changed the whole ecosystem of the planet and made us dominate everything,” he said at one point. At another, he said, “We are crazy in some way. What drives it? That I would really like to understand. That would be really, really cool to know.”

 

[11] According to the most recent estimates, Neanderthals and modern humans share a common ancestor who lived about four hundred thousand years ago. (It is unclear who that ancestor was, though one possibility is the somewhat shadowy hominid known, after a jawbone found near Heidelberg, as Homo heidelbergensis.)  The common ancestor of chimps and humans, by contrast, lived some five million to seven million years ago. This means that Neanderthals and humans had less than one-tenth the time to accumulate genetic differences.

 

[12] Several years ago, Pääbo and a colleague, Wolfgang Enard, became interested in a gene known as FOXP2, which in humans is associated with language. (People who have a faulty copy of the gene— an extremely rare occurrence— are capable of speech, but what they say is, to strangers, mostly incomprehensible.) Pääbo and Enard had some mice bred with a humanized version of the gene, and then studied them from just about every possible angle. The altered mice, it turned out, squeaked at a lower pitch than their un-humanized peers. They also exhibited measurable differences in neural development. (While I was in Leipzig, I watched a graduate student cut the heads off some of the altered mice and then slice up their brains, like radishes.)

 

[13] The Neanderthals’ FOXP2 gene, it turns out, is in almost all ways identical to humans’, but there is one suggestive base-pair difference. When this difference was discovered, it prompted Pääbo to order up a new round of transgenic mice, which, at the time of my visit, had just been born and were being raised under sterile conditions in the basement . . .

 

[14] “We know the end of the story,” he told me. “We know what modern culture looks like, and so then what we do is we want to explain how we got here. And there’s a tendency to over-interpret the past by projecting the present onto it. So when you see a beautiful hand axe and you say, ‘Look at the craftsmanship on this; it’s virtually an object of art,’ that’s your perspective today. But you can’t assume what you’re trying to prove.”

 

[15] Among the hundreds of thousands of Neanderthal artifacts that have been unearthed, almost none represent unambiguous attempts at art or adornment, and those which have been interpreted this way— for instance, ivory pendants discovered in a cave in central France— are the subject of endless, often abstruse disputes. (Many archeologists believe that the pendants were created by Neanderthals who had come into contact with modern humans and were trying to imitate them, but, relying on the most recent dating techniques, some argue that the pendants were, in fact, created by modern humans.) This paucity has led some to propose that Neanderthals were not capable of art or— what amounts to much the same thing— not interested in it. They simply did not possess what, genomically speaking, might be called the aesthetic mutation.

 

[16] Yet it also struck me that so much of what is distinctively human was here on display— creativity, daring, “madness.” And then there were the animals pictured on the walls— the aurochs and mammoths and rhinos. These were the beasts that Paleolithic Europeans had hunted, and then, one by one, as with the Neanderthals, obliterated.


 

FOXP2 and the Evolution of Language [excerpts]

Alec MacAndrew

Proceedings of the National Academy of Science | July 5, 2005

 

Introduction 

[1] This article addresses the history and the significance of the discovery of the relevance of FOXP2 in the development of speech. It is a remarkable scientific detective story that has been in the making for some time.  In its earlier stages, there was serious disagreement within the scientific community about how the scientific findings should be interpreted, and this was set against a background of sensationalist reporting by the popular press.

 

Background

[2] The story goes like this: The KE family were brought to the attention of the scientific community in about 1990. Over three generations of this family, about half the family members suffer from a number of problems, the most obvious of which is severe difficulty in speaking, to such an extent that the speech of the affected people is largely unintelligible, and they are taught signs as a supplement to speech as children.

 

The Disorder is not grammar or speech-specific

[3] They tested affected and unaffected family members and concluded that the disorder had the following characteristics: defects in processing words according to grammatical rules; understanding of more complex sentence structure such as sentences with embedded relative clauses; inability to form intelligible speech; defects in the ability to move the mouth and face not associated with speaking (relative immobility of the lower face and mouth, particularly the upper lip); and significantly reduced IQ in the affected compared with the unaffected in both the verbal and the non-verbal domain.

 

[4] This last finding, about IQ, has been swept under the carpet by some commentators (including Nicholas Wade in the New York Times), who claim that since the ranges of IQ of the affected and unaffected overlap and furthermore that since some of the affected achieve scores above the population mean for non-verbal IQ, then the disorder does not include a general intellectual challenge and is therefore language specific.

 

[5] But, note that the mean of the affected non-verbal IQ is 86 (range 71–111) versus a mean IQ for the unaffected of 104 (range 84–119). Not only is the mean significantly different between affected and unaffected family members but three of the affected had non-verbal IQ scores below 85, which is the normal lower limit for classifying speech defects as `specific language impairment' (that is, any disorder that affects speech only and is not caused by more general cognitive problems). Note, however, that the KE disorder cannot be explained solely by a general cognitive deficiency, because it is present in individuals whose non-verbal IQ is close to or a little above the population average and because it is accompanied by deficiencies in motor control of the face and mouth . . .

 

The molecular evolution of FOXP2

[6] Now let's move on to 2002 when Enard et al (authors include Svante Paabo &Anthony Monaco) published a paper describing work that investigated the evolution of FOXP2. The first thing they note is the extremely highly conserved nature of FOXP2. We have already seen that in all cases, in all species investigated, the amino acid mutated in the KE family is identical . . .

 

[7] However, human FOXP2 differs from gorilla, chimp and rhesus macaque in two further amino acids (and thus differs from mouse in three amino acids out of 715). So, in 75 million years since the divergence of mouse and chimpanzee lineages only one change has occurred in FOXP2, (and that equates to 150 million years of evolution as we don't know whether the mutation occurred in the mouse or the primate lineage) whilst in the six million years since the divergence of man and chimpanzee lineages two changes have occurred in the human lineage . . .

 

[8] The mutation that affects half the members of the KE family is known to cause the problems with speech, but it is in an entirely different part of the gene from the changes that have occurred in the human lineage. What would happen if we reverted FOXP2 in humans to the ancestral form still found in monkeys, chimps and gorilla?  It is an experiment that could probably be done but ought never to be done, being of course, entirely unethical . . .

 

Conclusions

[9] . . . Human mind needs human cognition and human cognition relies on human speech. We cannot envisage humanness without the ability to think abstractly, but abstract thought requires language. This finding confirms that the molecular basis for the origin of human speech and, indeed, the human mind, is critical. Ultimately, we will find great insight from further unravelling the evolutionary roots of human speech— in contrast to Noam Chomsky's lack of interest in this subject.


 

Steven Mithen

Creativity in Human Evolution and Prehistory [1998] Ch.6 [excerpts]

 

[1] One of the most exciting areas of current research in the cognitive sciences is that concerning 'theory of mind'. This refers to an ability to attribute a full range of mental states to other individuals as well as oneself, and then to use such attributions to predict and understand behaviour. A vast literature has arisen regarding this issue, as it seems to be one of the most critical cognitive features humans possess. As such, theory of mind is a central element of what has been termed 'social' and 'Machiavellian intelligence' and is closely related to, perhaps synonymous with, 'mind reading,' and the 'intentional stance.' The importance of theory of mind for human thought and behaviour has been stressed by Simon Baron-Cohen. He lists nine behaviours that depend on the possession of a theory of mind:  

1 Intentionally informing others

2 Intentionally deceiving others

3 Intentionally communicating with others

4 Repairing failed communication with others

5 Teaching others

6 Intentionally persuading others

7 Building shared plans and goals

8 Intentionally sharing a focus or topic of attention

9 Pretending

 

[2] Without these behaviours, human society would be very different. How different might be appreciated by considering that current research strongly suggests that a dysfunctioning of the part of the brain that enables theory of mind may be the root cause of autism (Baron-Cohen 1995). Autistic children do not appear to engage in any of the above behaviours— their lack of a theory of mind has a devastating effect on their abilities to socialise and communicate. It also appears to inhibit their imagination, which suggests that the possession of a theory of mind may provide a critical foundation for creative thinking. From the above list of behaviours, pretence is that which is most clearly linked to imagination and creative thinking. Pretending requires one to hold in one's mind the actual identity of an object, along with the pretend identity. As such, one must have knowledge about one's own mind. If that is lacking, so too will be the ability to pretend . . .

 

[3] The dependency of creative thinking on theory of mind is also apparent from a recent set of drawing experiments that makes a direct link between the experiments by Karmiloff-Smith, described above, and the imagery in the earliest of the Upper Palaeolithic art. This link is the ability to produce representations of unreal things. In Upper Palaeolithic art, imaginary beasts play a significant role. The most dramatic example is the lion/man from Hohlenstein-Stadel, Germany. This is a c.11-cm-high figure carved from a single mammoth tusk about 30,000 years ago, which has the body of a man and the head of a lion . . .

 

[4] A link to the research on the theory of mind from these images is that autistic children appear unable to draw imaginary animals . . . They appear unable to produce just those type of images that we find in the earliest Upper Palaeolithic art, and which we intuitively feel are more creative than those other images of real animals and people. Two explanations were proposed for this deficit. The first is that those suffering from autism are unable to 'fuse' together two primary representations of real objects. Scott and Baron-Cohen give the example of representing a 'flying pig', which involves joining together representations of a real pig, and a real bird, to produce a representation of an unreal animal, the flying pig. An alternative idea relates more directly to an absence of a theory of mind. They argue that 'representing an unreal object necessarily requires pretending, or representing that you (the agent) are holding a pretend attitude (or mental state) towards an object'

 

[5] A second deficit in those suffering from autism appears to be an inability to engage in pretend play. One might also draw links here with the new types of behaviour that emerge with the Upper Palaeolithic. Pretence is a critical feature of ritual in extant hunter-gatherer societies. There can be little doubt that ritualised behaviour was also a critical feature of the earliest Upper Palaeolithic societies. Some of the composite figures in the art seem most likely to be a shaman in costume.

 

[6] In summary, the possession of a theory of mind appears to be a critical requirement for imaginative play and creative thinking; it appears to be an essential prerequisite for the exploration and mapping of conceptual spaces, even if quite why and how are not fully understood. One possibility, therefore, is that the creative explosion of the Upper Palaeolithic is directly related to the evolution of the theory of mind . . .

 

[7] Robin Dunbar has argued that the large brain of our human ancestors implies living in social groups substantially larger than those of existing non-human primates. It is clear from many recent studies that these non-human primates needed to deploy a Machiavellian intelligence to maintain the balance between group fusion and fission and hence maintain an appropriate group size for the efficient exploitation of foodstuffs and predator defence. Theory of mind is most likely to be an essential feature of this Machiavellian intelligence and would have become increasingly important if group size increased during the Middle Pleistocene in the manner that Dunbar claims. In other words, theory of mind appears to have been an essential prerequisite for social life of Early Humans.