FoxP2: Human Speech Gene Changed the Mouse's Squeak
- Details
- Category: Science & Technology
- Created on Sunday, 31 May 2009 10:00
- Written by Scientific Blogging News Staff
The short story is that one of the unique genes that define human beings, the speech gene known as FoxP2 was grafted into a mouse’s DNA, and the newborne critter started making new and unsual sounds for mice.
This represents an important development by Wolfgang Enard and his colleagues. Nicholas Wade writes in the New York Times:
In a region of the brain called the basal ganglia, known in people to be involved in language, the humanized mice grew nerve cells that had a more complex structure and produced less dopamine, a chemical that transmits signals from one neuron to another. Baby mice utter ultrasonic whistles when removed from their mothers. The humanized baby mice, when isolated, made whistles that had a slightly lower pitch, among other differences, Dr. Enard says. Discovering that humanized mice whistle differently may seem a long way from understanding how language evolved. Dr. Enard argues that putting significant human genes into mice is the only feasible way of exploring the essential differences between people and chimps, our closest living relatives.
Of course, implanting this gene did not enable the mouse to talk. Actual speech requires a cascade of genetic changes in humans from even their close chimp cousins (including brain size, physical throat structures, and more).
It confirms the role of FoxP2 in creating sounds, and it will enhance our ability to understand what that gene does in humans, and it will help us understand more deeply how we became human in the evolution from our earlier chimp-like ancestors.
* * * * **
The following article appeared on Scientific Blogging.
Talking Mice? No, But Their FOXP2 ‘Speech’ Gene Can Tell Us About Our Evolutionary Past
By News Staff | May 28 2009
Following on the heels of ‘missing links’ in the popular media earlier this month, you might expect that research on mice carrying a “humanized version” of a gene believed to influence speech and language will have references to cartoons and mice that talk.
In reality, it’s nothing so outrageous but the research can still teach us about our evolutionary past – even if the mice don’t speak.
Wolfgang Enard of the Max-Planck Institute for Evolutionary Anthropology and colleagues are interested in the genomic differences that set humans apart from their primate relatives. One important difference between humans and chimpanzees they have studied are two amino acid substitutions in FOXP2. Those changes became fixed after the human lineage split from chimpanzees and earlier studies have yielded evidence that the gene underwent positive selection. That evolutionary change is thought to reflect selection for some important aspects of speech and language.
“Changes in FOXP2 occurred over the course of human evolution and are the best candidates for genetic changes that might explain why we can speak,” Enard said. “The challenge is to study it functionally.”
For obvious reasons, the genetic studies needed to sort that out can’t be completed in humans or chimpanzees, he said. In the new study, the researchers introduced those substitutions into the FOXP2 gene of mice. They note that the mouse version of the gene is essentially identical to that of chimps, making it a reasonable model for the ancestral human version.
Mice with the human FOXP2 show changes in brain circuits that have previously been linked to human speech, the new research shows. Intriguingly enough, the genetically altered mouse pups also have qualitative differences in ultrasonic vocalizations they use when placed outside the comfort of their mothers’ nests. But, Enard says, not enough is known about mouse communication to read too much yet into what exactly those changes might mean.
Although FoxP2 is active in many other tissues of the body, the altered version did not appear to have other effects on the mice, which appeared to be generally healthy.
Those differences offer a window into the evolution of speech and language capacity in the human brain. They said it will now be important to further explore the mechanistic basis of the gene’s effects and their possible relationship to characteristics that differ between humans and apes.
They wrote:
“Currently, one can only speculate about the role these effects may have played during human evolution. However, since patients that carry one nonfunctional FOXP2 allele show impairments in the timing and sequencing of orofacial movements, one possibility is that the amino acid substitutions in FOXP2 contributed to an increased fine-tuning of motor control necessary for articulation, i.e., the unique human capacity to learn and coordinate the muscle movements in lungs, larynx, tongue and lips that are necessary for speech. We are confident that concerted studies of mice, humans and other primates will eventually clarify if this is the case.”
People in this conversation
Comments (10)
-
Guest (Eddy Laing)
PermalinkThere are important distinctions between the reductionism displayed in the <I>NY Times</I> headline ('A Human Language Gene Changes the Sound of Mouse Squeaks') and the actual discussion in the report. From Enard <I>et al's</I> paper:
<blockquote>"(...) Foxp2 is expressed in the brain (Campbell etal., 2009,Ferland etal., 2003,Lai etal., 2003,Takahashi etal., 2003) as well as in a wide variety of other tissues (Lai etal., 2001,Shu etal., 2005,Shu etal., 2007). For example, it has been proposed to play a role in combination with Foxp1 during the development of the lung and the esophagus (Shu etal., 2007). Thus, the Foxp2hum allele may have effects in multiple organs. To investigate which physiological systems might be affected by the human amino acid substitutions we analyzed a total of 60 animals, 15 of each homozygous genotype and sex, derived from 17 litters of heterozygous parents in a large standardized phenotypic screen at the German Mouse Clinic (Gailus-Durner etal., 2005) (see Supplemental Data S2 for a detailed description) that assesses morphological traits (Fuchs etal., 2000), hearing, vision, bone morphology and density (Fuchs etal., 2006), various clinical-chemical parameters and hematological parameters, including leukocyte subpopulations and classes of immunoglobulins, metabolism, lung function, blood pressure and heart function. We also studied 24 neurological parameters (Schneider etal., 2006) including forepaw grip strength and nociception as well as motor coordination and motor learning, which were assessed on an accelerating rotarod over 3 consecutive days. Sensorimotor behavior was examined by the acoustic startle response and the prepulse inhibition of the startle response. Locomotor activity, exploration, novel object recognition and frequency of contact with group members was assessed using the modified hole board (Ohl etal., 2001). Finally, 31 tissues were analyzed histologically. Many known sex differences were identified in these tests. For the vast majority of tests, no significant Foxp2hum effects were found. (...)"</blockquote>0 Like -
Coverage of scientific work is often frustrating in the mainstream press -- and even at its best popularization loses some detail and precision.
But I'm not sure what reductionism you are referring to, Eddy. could you break it down a bit:
Is it that the New York Times referred to this gene as a "speech gene" rather than listing the various tissues it affects?
What is the distinction you are pointing to?0 Like -
Guest (Eddy Laing)
PermalinkI apologize for my terseness.
I am referring to the characterization of of a 'speech gene', which implies that there are ultimate chromosomal 'causes' for not only physiology but for behavior. More than that, is the the suggestion of a 'speech gene' which suggests not only the capability for but the outcome of language.
In the except I have cited, note these two sentences:
"Thus, the Foxp2hum allele may have effects in multiple organs"
And not only does genetic material contain instructions that impact the development of multiple and various parts of organismic development, but those instructions are operationalized according to still further developmental variables (for example: temperature, nutrients, other environmental conditions, etc.)
"For the vast majority of tests, no significant Foxp2hum effects were found."
And a good amount of genetic material appears to have no specific causal function at all.0 Like -
Guest (Eddy Laing)
PermalinkLet's try that again.
I am referring to the characterization which implies that there are ultimate chromosomal 'causes' for not only physiology but for behavior. More than that, is the suggestion of a 'speech gene' which suggests the capability and the outcome of language. (Language is a social practice.)
In the except I have cited, note these two sentences:
"Thus, the Foxp2hum allele may have effects in multiple organs"
This is significant. Genetic material contain instructions that can direct the development of multiple and various parts of organismic development, but those instructions are operationalized according to still further developmental variables (for example: temperature, nutrients, other environmental conditions, etc.)
"For the vast majority of tests, no significant Foxp2hum effects were found."
Also importantly, a good amount of genetic material appears to have no specific causal function at all.0 Like -
I'm still not sure if i understand.
I think that what stands out here is that we are understanding better what genetically makes us human... That has real value.
This is a study that focuses on the key areas of chromosomal difference between chimps and humans. They identified FoxP2 as having an important role in human speech.
And this is (from what I understand) confirmed when this genetic material is spliced into another mammal and it affects the sounds made by that mammal. It confirms the association of Foxp2 with speech, and gives us more information on how this genetic material affects speech.
You say that language is a social practice -- which is hard to deny. But we are not discussing language here, but the physical ability to speak. And that physical ability to speak is rooted in genetics. (I.e. the reason humans have the potential to speak and caterpillars can't is rooted in the physical structures rooted in genetics.)
In fact human speech (definitely a behavior, right) is rooted in chromosomal causes (i.e. our larynx, our brains, etc are structured in ways that make speech possible). The reason chimps can't speak is also rooted in chromosomal causes.
the New York Times article is clear that there is a whole "cascade of genes" that made (and make) speech possible (not just one little piece of code.)
you zeroed in on two sentences.... but i'm still not sure how they are important.
In other words, FoxP2 affects multiple organs (presumably including the brain ganglia). Ok. That deepens our understanding of how this particular snippet of code works. But that affects this discussion how?
There are lots of areas where FoxP2 has no effect (and so doesn't effect the tests) doesn't seem to be suprising (I wouldn't assume on piece of code would be influential everywhere in the body). Help us understand how that is relevent to this discussion.0 Like -
Guest (Eddy Laing)
Permalink<BLOCKQUOTE>
In fact human speech (definitely a behavior, right) is rooted in chromosomal causes (i.e. our larynx, our brains, etc are structured in ways that make speech possible). The reason chimps can’t speak is also rooted in chromosomal causes.
</BLOCKQUOTE>
As a point of comparison, one might also argue that speech is rooted in the atomic composition of this sector of the universe as well. (As Carl Sagan rightly noted, for example, we are all made of 'star stuff'.)
All quite true. Nonetheless...
Chromosomes are (metaphorically speaking) more like cookbooks than they are like specific recipes. A cookbook contains instructions for a variety of results. Importantly, the outcomes of a cookbook are not contained within the pages of the cookbook, neither are the ingredients included in a cookbook, nor does the cookbook provide the activities or conditions (e.g. baking, frying, cooling) required to produce the results. Moving out of the metaphor and back into biology...
The point of technical interest regarding FoxP2 may be (has been) as a locus of the ±1% of genetic material that we don't share with all other hominids and perhaps as an indication of how or whether that ±1% is significant. As I read it, the point of Enard <I>et al</I>'s paper is that they think there may be some significance in regard to vocalization on the basis of an observed change (the pitch of the squeak) induced by the transplantation (into mice).
Quite obviously, the anatomy of a mouse and the anatomy of a primate (let alone a hominid) is radically different. The pitch of a squeak is only that. There are several other anatomical features which are important (necessary) to human vocalization, and even so, do not necessarily 'produce' speech.
The current evidence indicates that language (in its most primitive forms) was invented about 50,000 years back, which means that modern humans (<I>Homo sapiens</I>
-- who do have the requisite anatomy -- needed about 125,000 years of social practice to get to that point.
My observation has to do with cautioning against a reductionist and overly-determnist reading of this work. i.e. the "Human Language Gene" as the newspaper reports, which it simply cannot be.0 Like -
Eddy:
I share your caution about the way science is reported -- which at its best is often simplified, and quite often is reductionist. (In this case, the NYT didn't imply that there was only one "human language gene" -- but talked of a necessary cascade of genes for human speech capability. The article in NYT was speaking of A human language gene, in a popular way, not THE human language gene -- and in a loose way they were not mistaken. but still, i believe your caution and points are important.)
<strong>On your point above:</strong>
<blockquote>"The current evidence indicates that language (in its most primitive forms) was invented about 50,000 years back, which means that modern humans (Homo sapiens) — who do have the requisite anatomy — needed about 125,000 years of social practice to get to that point.</blockquote>
Very interesting. Please break this down for us.
Your description of the emergence of speech is a bit at odds with my own (obviously amateurish) sense of how speech must have evolved.
I find it hard to imagine that the physical ability to have speech (brain centers, developed larynx, tongue, and more) evolved, and then over 125,000 years there was practice, after which speech was "invented" about 50,000 years back.
Two points you may choose to help us understand:
1) I am not familiar with <em>any</em> evidence of when speech was "invented." You speak of "current evidence" -- what is that? What evidence gives rise to your assumption that "language (in its most primitive forms) was invented about 50,000 years back." My investigations do not suggest such evidence.
and here we need to differentiate between the evidence of physical speech capabilities and what you are discussin (i.e. evidence of the SOCIAL emergence of actual speech).
There has been the exciting discovery of what the larynx of neanderthal was like (showing important anatomical differences that would have affected the range of possible vocalizations). It is rare for evidence of speech ability because they involve so much soft tissue and cartilage. But in this case it involved a particularly boney part of the larynx.
But (again) is there any evidence on when language of modern humans was socially "invented"?
2) My understanding of the evolutionary process leads me to believe that language (precisely in "its most primitive forms") probably PRECEDED the emergence of modern humans 200,000 years ago.
It is hard for me to imagine the development of this complex physical aparatus for speech in modern humans, if it was not (at many stages in its evolution) impacting on survival. In other words, my understanding would suggest that earlier humans (say, for example Homo Erectus) were likely to be the first humans to have "language in its most primitive forms", and that this powerful emerging capability was part of the advantages with later, more modern humans had over their competitors.
Are you suggesting that there is evidence that neither Homo Erectus nor Neanderthal spoke (in primitive ways)?
My guess is that the physical capability and the social ability emerged in a complex dance -- advances in one spurring development in the other. And that primitive speech far preceded the development of the modern human brain and voicebox.
My previous guess has been that (in contrast to your scenario) our understanding of evolution (and the very very scanty evidence) would suggest that language ("in its most primitive forms") probably emerged over more than a million years, and that when modern humans emerged (with their distinctive voice box) it was not a pre-condition for that emergence, but an evolutionary leap driven by that early emergence of primitive speech.
Part of the question is the differences (and stages) separating vocalization and speech. My dog vocalizes (often in nuanced and sophisticated ways) emotions and desires. But she is incapable of expressing an abstract idea. She can express "let's go." But she can't vocally say "to the park" or "lets walk not drive" (even when, in her brain, she has a clear preference, and even when she might physically find ways to express that preference).
I have no doubt that our earliest primate anscestors (say at the split with chimps) had elaborate vocalizations (alarm, contentment, restlessness, excitement, anger, threat, etc.) But if the creation of implements and the invention of fire started under Homo Erectus, why would we assume that the transition from vocalization to primitive speech didn't also?
And I suspect that speech (and the related mental abilities of abstraction and more sophisticated social action) may well explain the emergence of modern humans over any co-existing hominid species (Neanderthal, and perhaps in some areas Erectus).0 Like -
Guest (Eddy Laing)
PermalinkMike,
You've raised a number of very important points that require examination at length. I'm not sure this thread is the best forum for such a discussion, but I will certainly try to give a preliminary response to your two major questions of my perspective.
<BLOCKQUOTE>
1) I am not familiar with any evidence of when speech was "invented." You speak of "current evidence" -- what is that? What evidence gives rise to your assumption that "language (in its most primitive forms) was invented about 50,000 years back." My investigations do not suggest such evidence.
and here we need to differentiate between the evidence of physical speech capabilities and what you are discussing (i.e. evidence of the SOCIAL emergence of actual speech).
There has been the exciting discovery of what the larynx of neanderthal was like (showing important anatomical differences that would have affected the range of possible vocalizations). It is rare for evidence of speech ability because they involve so much soft tissue and cartilage. But in this case it involved a particularly boney part of the larynx.
But (again) is there any evidence on when language of modern humans was socially "invented"?
</BLOCKQUOTE>
This seems to roll several social processes and anatomical developments together that are better understood in their particularities.
There should be no argument that human anatomy makes a very wide range of voicings possible, even more so than other primates.
However, there is a qualitative difference between signalization and symbolization. Even intentional vocalization -- such as animal alarm calls or your dog whining for food or to be let outside -- does not equate to truly semiotic activity (and symbols arise from and derive importance from representing social practices). Semiotic faculty is itself dialogically created and humans are apparently the only primates who have learned how to learn it. (Michael Tomasello and colleagues who are, like Enard, also at the Max-Planck Institute for Evolutionary Anthropology, have published quite a bit on this. [Tomasello, M. and H. Rakoczy. 2003. "What Makes Human Cognition Unique? From Individual to Shared to Collective Intentionality." Mind & Language 18(2): 121-147.]
Vocalization and speech -- if by that we mean signaling -- are not equivalents, and importantly, neither are they language. It makes rather good dialectical materialist sense that a leap took place -- as a result of social practice -- resulting in the invention of rudimentary semiotics. Symbolizations that represented social relationships and material realties. Thus, we do see the emergence at points in time in the archeological record of physical, written semiotics (about 6000 BCE) and of pre-writing, such as petroglyphs, ivory and bone carvings, etc. (In other words, evidence of qualitative leaps in both cognition and in social practices.)
Yes, we invent our languages, and continually reinvent and extend them. (no scare quotes please.)
<BLOCKQUOTE>
2) My understanding of the evolutionary process leads me to believe that language (precisely in "its most primitive forms") probably PRECEDED the emergence of modern humans 200,000 years ago.
</BLOCKQUOTE>
Here I refer to some contemporaneous work on the same FOXP2 gene.
Another thing we can infer from comparative genetic sequencing (and phylogenetics) is the approximate evolutionary points of common ancestry or divergence (between genera, families, classes, orders, etc). Consequently, one can follow the path backwards. Philip Lieberman, who has a paper in the same issue of <I>Cell</I> with Enard <I>et al</I>, also published a rather thorough report on this second question in <I>Current Anthropology</I> a couple of years ago. [Lieberman, P. 2007. "The Evolution of Human Speech: Its Anatomical and Neural Bases." Current Anthropology 48(1): 39-66.]
Rather than re-phase Lieberman's paper, I will cite the Abstract verbatim:
<I>Human speech involves species-specific anatomy deriving from the descent of the tongue into the pharynx. The human tongue's shape and position yields the 1:1 oral-to-pharyngeal proportions of the supralaryngeal vocal tract. Speech also requires a brain that can "reiterate" -- freely reorder a finite set of motor gestures to form a potentially infinite number of words and sentences. The end points of the evolutionary process are clear. The chimpanzee lacks a supralaryngeal vocal tract capable of producing the "quantal" sounds which facilitate both speech production and perception and a brain that can reiterate the phonetic contrasts apparent in its fixed vocalizations. The traditional Broca-Wernicke brain-language theory is incorrect; neural circuits linking regions of the cortex with the basal ganglia and other subcortical structures regulate motor control, including speech production, as well as cognitive processes including syntax. The dating of the FOXP2 gene, which governs the embryonic development of these subcortical structures, provides an insight on the evolution of speech and language. The starting points for human speech and language were perhaps walking and running. However, <B>fully human speech anatomy first appears in the fossil record in the Upper Paleolithic (about 50,000 years ago) and is absent in both Neanderthals and earlier humans.</B></I>
Lieberman is raising a number of important points in this paper which I will not recap here, but his 50,000 year figure refers to the appearance of FOXP2 and thus the neural basis, which leaves aside the at-least-as-important socio-cultural motivator for engaging that basis. (So in regard my earlier statement: 'sometime after 50,000 years ago' would have been more accurate.)
In reply to this paper, Ian Tattersall (curator of biological anthropology at the American Museum of Natural History, NYC) had this to say (and Tattersall is certainly familiar with <I>Homo neanderthalensis</I>:
<I>"Language is the ultimate symbolic behavior, and the modern human anatomy that permits its expression had long been established by the time that we find any convincing archaeological evidence for symbolic activity among hominids. It is thus permissible to infer that the first anatomically modern humans were not yet the symbolic creatures that their descendants were to become and that the leap to modern symbolic consciousness was achieved via a cultural stimulus (in a creature already exapted to make that leap) rather than by a biological innovation. From this perspective, it is hardly surprising that on morphological grounds Lieberman is able to reject — convincingly — the notion that Neanderthals possessed speech abilities, for only under highly unusual and transitory circumstances is there any association of Neanderthal fossils with symbolic objects."</I> [ibid. p. 57]
All of this is subject to argument, of course. As I said above, a much longer argument. (Which I am more than willing to engage.)0 Like
Sustain Kasama
Latest Comments
he hated blacks, mexicans and gays.....what a guy!!! Castro got rid of him so the United States helped Cuba....but we ar...
Understanding Che Guevara -- 42 Years After His Murder
I am not sure I follow your argument, Nat.
Ending the wage relation would end the exploitation of labor, right? That...
Good piece. Recently I received an article by Maoistroad in response to articles such as the one cited above. Tithi Bhat...
First-tate, informative, engaged and inspirational.
As to your broader point I would only remark that oppression takes many forms. And Communists opposed all forms of oppre...
...clearly China had enough workers for a "genuine revolution..."
According to Mao: A Life by Philip Short, in the earl...
Bravo to Ed Thompson for writing this response piece - a piece which was a long time coming. In an overwhelmingly good a...
Nat,
I think that Althusser's version of the quote from the Grundrisse does a different job in Marx's text (and theory)...
Thanks foryour very thoughtful response HiFi. I responded to your comment in a new thread that you can find here. http:/...
Pampanga: “Nat, you've lost the debate. Learn from it, freshen up your method, and let it go.”
So that’s what this is a...
Latest Open Threads
Kasama is a communist project for the forcible overthrow and transformation of all existing social conditions. We are open to learning, unafraid to admit our own uncertainties. We will not shrink from what we do know: the solutions cannot be found within the current world order or the choices it provides. We are for revolution. We seek to find the forms of organization and action for the people most dispossessed by this system to free themselves and all humanity.
To take this road, we need a fearless, open-eyed debate, discussion and engagement. We need fresh analyses of the rapid changes shaping the world around us. We need to sum up a century of revolutionary strategies and attempts, victories and defeats – instead of the conventional wisdom and facile verdicts that paralyze our movements. We need to re-imagine a radical politics that can take life among people and move mountains.
Dig in.