The Cooked and the Raw
Recalling the discussion about big heads a few days ago, I was drawn to theory that cooking is the secret to humans having big brains. Richard W. Wrangham, the Ruth B. Moore Professor of Biological Anthropology at Harvard University’s Peabody Museum, responds to a Q & A in the December 19th Scientific American:
I tend to think of the advent of cooking as having a huge impact on the quality of the diet. In fact, I can’t think of any increase in the quality of diet in the history of life that is bigger. And repeatedly we have evidence in biology of increases in dietary quality affecting bodies. The food was softer, easier to eat, with a higher density of calories—so this led to smaller guts, and, since the food was providing more energy, we see more evidence of energy use by the body. There’s only one time it could have happened on that basis; that is, with the evolution of Homo erectus somewhere between 1.6 [million] and 1.8 million years ago.Homo erectus is the species that has the biggest drop in tooth size in human evolution, from the previous species, which in that case was Homo habilis. There wasn’t any drop in tooth size as large as that at any later point in human evolution. We don’t know exactly about the gut, but the normal argument is that if you reconstruct the ribs, you have reduced flaring of the ribs. Up until this point you have ribs that went out to apparently hold a big belly, which is what chimps and gorillas are like, and then at this point [when Homo erectus arose] the ribs go flat, meaning you’ve got now a flatter belly and, therefore, smaller guts. And then you have more energy being used; people interpret the locomotor skeleton as meaning that the distances traveled every day are much farther. And the brain has one of its larger rises in size.
My own speculation about big brains and cooked food does not go much further, though it does lead me to reflect on whether—-genetically altered mice that are used for scientific studies aside—autism is something that only humans can have.
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POSTED IN: Animals, Food and Diet, Neuroscience
7 opinions for The Cooked and the Raw
Emily
Dec 22, 2007 at 10:27 pm
I would say that given the feature of impaired social interaction skills shared by most people on the spectrum, the ideas people have about empathy and theory of the mind, and other factors that might be involved in complex social interaction…this may well be something confined only to species that rely on complex social communication within complex social structures. We combine looks, gestures, body posture, words, facial expressions with multiple subtle meanings, a host of cues to parse and understand, often in a split second and requiring both an awareness of self and an awareness of how others think. We have identified only a few species that approach this level of social communication, awareness, and social structure (elephants? dolphins? and us), and they all, as it happens, are also species with relatively the largest brains. At any rate, for it to be “impaired,” it must exist in the population in the first place; thus, humans are probably *it* when it comes to autism as we currently characterize it. That doesn’t mean we can’t try to tease out some of the genes that influence specific traits characteristic of autism. I know that some researchers focus on the chromosomal mutation in Williams syndrome as a starting point because people with Williams share some traits with people on the spectrum. I think there’s a “mouse model” of Williams used in such research.
joycemocha
Dec 23, 2007 at 12:10 am
I’ve known horses in training that could be exhibiting an equine version of autism. In many cases, though, it’s the upbringing and lack of training in herd communication either through a dysfunctional dam or by being orphaned and brought up by humans.
Kristina Chew, PhD
Dec 23, 2007 at 2:42 am
And then there’s this book on all cats have Asperger Syndrome. I always wonder about language: Animals communicate but is what they use “language” as we use the term in regard to humans?
RAJ
Dec 23, 2007 at 10:29 am
” I know that some researchers focus on the chromosomal mutation in Williams syndrome as a starting point because people with Williams share some traits with people on the spectrum”.
Williams Syndrome people could be described as being on the opposite side of the Bell Curve of autistic “traits”, they are hypersocial. The autistic ‘traits’ commonly described by autism experts are actually non-specific to autism. Cognitive theories, deficits such as impairments of Theory of Mind and Executive function are commonly found in mental retardation, schizophrenia, Down Syndrome etc. Developmental language impairments such as pronoun reversal are also found in a host neurodevelopmental disorders, including those with a specific developmental language disorder and even in a transient phase in Alzheimer’s. The behaviors of Williams Syndrome people are opposite of what the polygenic theorists describe as the ‘Broad autism phenotype”, namely that the parents of autistic children are autistic themselves, cold and rational, anti-social creatures who have managed to defrost just long enough to have produced a genetically defective child.
The following in depth article published by Mount Sinai is one of the more excellent and readable pieces about Williams Syndrome:
http://www.cnsspectrums.com/aspx/articledetail.aspx?articleid=1382
Emily
Dec 23, 2007 at 10:53 am
Oh, boy. Big question. My mother is a linguist and we talk about these things all of the time. My gut answer for most animals is, “no.” There are some complex communications for some animals–whales, for example–that qualify. But much of what animals vocalize (like birds) is pretty programmed. That, of course, leads to the argument of whether or not we start with the programming–files for parts of speech, etc.–and modify it with culture and heredity. Anyway…HUGE question.
Emily
Dec 23, 2007 at 6:14 pm
“Williams Syndrome people could be described as being on the opposite side of the Bell Curve of autistic “traits”, they are hypersocial. The autistic ‘traits’ commonly described by autism experts are actually non-specific to autism. Cognitive theories, deficits such as impairments of Theory of Mind and Executive function are commonly found in mental retardation, schizophrenia, Down Syndrome etc. Developmental language impairments such as pronoun reversal are also found in a host neurodevelopmental disorders, including those with a specific developmental language disorder and even in a transient phase in Alzheimer’s.”
I actually am very close to a child who has Williams syndrome, and he shares many traits with my oldest son, traits that are “supposed” to be autism traits, but I am wholly aware of the fact that these traits are not actually confined to children on the spectrum, having literally written the book on the things you list. It may be helpful to use specific models to trace these phenotypes, but I’m talking about social interaction when it comes to the William’s deletion. It’s not the manifestation of “hypersociability” vs being “antisocial” as much as it is “impairments in social interaction” in general that make the model attractive for some researchers. There was a great piece in the New York Times in July that touched on this very subject and that can be found here (if you have an account): http://www.nytimes.com/2007/07/08/magazine/08sociability-t.html?_r=1&oref=slogin
“The behaviors of Williams Syndrome people are opposite of what the polygenic theorists describe as the ‘Broad autism phenotype”, namely that the parents of autistic children are autistic themselves, cold and rational, anti-social creatures who have managed to defrost just long enough to have produced a genetically defective child.”
I don’t buy the “broad autism phenotype” any more than I buy that people with autism don’t want to interact socially with others or that there is a “bell curve” that applies to such a mixed construct of action and desire. My son would love to interact with other people–sometimes–if he could just figure out how to do it. It’s his manifest inability to finesse socially that is his impairment, not a missing desire to do so. Also, I’m just enough like him that I can’t tell if you’re arguing with me or not here, but at any rate, I am not a “polygenic theorist” when it comes to autism, I am a “multifactorial theorist” of my own making, and as the parent of a child on the spectrum I know that he and I both are warm and occasionally social and even sometimes irrational.
Emily
Dec 23, 2007 at 6:22 pm
And this also from the NYT:
http://query.nytimes.com/gst/fullpage.html?res=9907E1DA1531F931A3575BC0A962958260&sec=health&spon=&pagewanted=1
The idea is that these genes influence some traits, one way or the other, and may serve as guides to an improved understanding of the pathways they determine and regulate, pathways involved in–for example–autism spectrum disorders.
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