Altruism in Chimpanzees

Ed Yong has a nice post up on altruistic behaviour in chimps.

It is also worth it to check out some of his previous posts, such as:

Chimps console each other to reduce stress after fights

Cultured chimps pass on new traditions between groups

An Evolutionary Perspective on the Human Brain

This term I wrote an essay on the topic of human uniqueness from an evolutionary perspective. As I drew on research that is also relevant to this blog, (and to some extent has already been covered here). I'll post some of it here.
In this post I'll have a short look at the human brain from a neuroscientific, a comparative, and an evolutionary perspective:

Human Evolution

We are evolved primates. (As are all other primates of course. So maybe it is better to say that we, like all other primates, are evolved beings with a unique set of specializations, adaptations and features. )

In our lineage, we share a common ancestor with orangutans (about 15 million years ago (mya)), gorillas (about 10mya), and most recently, chimpanzees and bonobos (5 to 7 mya). We not only share a significant amount of DNA with our primate cousins, but also major anatomical features (Gazzaniga 2008: 51f., Lewinn 2005: 61) These include, for example, our basic skeletal anatomy, our facial muscles, or our fingernails (Lewin 2005: 218ff.).

What most distinguishes us as humans on an anatomical level are our bizarre hair distribution, our upright posture and the skeletal modifications necessary for it, including a propensity for endurance running, our opposable thumbs, fat deposits that are unusually extensive (Preuss 2004: 5), and an intestinal tract only 60% the size expected of primates our size (Gibbons 2007: 1558).

Finally, there is also a distinguishing feature that is a much more remarkable violation of expectations – a brain three times the size expected of a primate our size. This is all the more interesting as primates are already twice as encephalized as other mammals (Lewin 2005: 217). A direct comparison shows this difference in numbers: Whereas human brains have an average volume of 1251.8 cubic centimetres and weigh about 1300 gram, the brains of the other great apes only have an average volume of 316.7 cubic centimetres and weigh between 350-500 gram (Rilling 2006: 66, Preuss 2004: 8). In a human brain, there are approximately a hundred billion neurons, each of which is connected to about one thousand other neurons, comprising about one hundred trillion synaptic connections (Gazzaniga 2008: 291). If you would count all the connections in the napkin-sized cortex alone, you would be finished after 32 million years (Edelman 1992: 17).

Expensive Tissue

The human brain is also extremely “expensive tissue” (Aiello & Wheeler 1995): Although it only accounts for 2% of an adult’s body weight, it accounts for 20-25% of an adult’s resting oxygen and energy intake (Attwell & Laughlin 2001: 1143). In early life, the brain even makes up for up 60-70% of the body’s total energy requirements. A chimpanzee’s brain, in comparison, only consumes about 8-9% of its resting metabolism (Aiello & Wells 2002: 330). The human brain’s energy demands are about 8 to 10 times higher than those of skeletal muscles (Dunbar & Shultz 2007: 1344), and, in terms of energy consumption, it is equal to the rate of energy consumed by leg muscles of a marathon runner when running (Attwell & Laughlin 2001: 1143). In all, its consumption rate is only topped by the energy intake of the heart. (Dunbar & Shultz 2007: 1344).

Consequently, if we want to understand the evolutionary trajectory that led to human cognition there is the problem that “because the cost of maintaining a large brain is so great, it is intrinsically unlikely that large brains will evolve merely because they can. Large brains will evolve only when the selection factor in their favour is sufficient to overcome the steep cost gradient“ (Dunbar 1998: 179). We have to come up with a strong enough selection pressure operative in the Pleistocene environment of evolutionary adaptedness that would have allowed such “expensive tissue” to evolve (Bickerton 2009: 165f.).

What About the Brain is Uniquely Human?

If we look to the brain for possible hints, we first find that presently, there is “no good evidence that humans do, in fact, possess uniquely human cortical areas” (although the jury is still out) (Preuss 2004: 9). In addition, we find that there are functions specific to humans which are represented in areas homologous to areas of other primates. Instead, it seems that in the course of human evolution some of the areas of the brain expanded disproportionally, “especially higher-order cortical areas, including the prefrontal cortex” (Preuss 2004: 9, Deacon 1998: 435-438). This means that humans do not only think in a better way, but that they think differently (Preuss 2004: 7). The expansion and apparent specializations of only certain kinds of neuronal areas could indicate a qualitative shift in neuronal activity brought about by re-organization of existing features, leading to a wholly different style of cognition (Deacon 1998: 435-438 Rilling 2006: 75).

This scenario squares well with what we know about the way evolution works, namely that it always has to work with the raw materials that are available, and constantly co-opts and tinkers with existing structures, at times producing haphazard, cobbled-together, but functional results (Gould & Lewontin 1979, Gould & Vrba 1982). Given the relatively short time span for the evolution of the “most complex structure in the universe, we have to acknowledge how preciously little time the evolutionary process had for ‘debugging.’ It could well be that make the human mind so unique is that it is a imperfect ‘Kluge:’ a clumsy or inelegant – yet surprisingly effective – solution to a problem,” like the Apollo 13 CO2 filter or an on-the-spot invention by MacGyver (Marcus 2008: 3f.). It may thus well turn out that what we think makes us so special is a mental “oddity of our species’ way of understanding” the world around us (Povinelli & Vonk 2003: 160). It is reasonable then to assume that human cognition did not just simply get better across the board, but that instead we owe our unique style of thinking to quite specific specializations of the human mind.

With this in mind, we can now ask the question how these neurological differences must translate into psychological differences. But this is where the problem starts: Which features really distinguish us as humans and which are more derivative than others? A true candidate for what got uniquely human cognition off the ground has to pass this test and solve the problem how such “expensive tissue” could evolve in the first place.

References:

Aiello L.C. and P. Wheeler 1995. ”The expensive tissue hypothesis: the brain and the digestive system in human and primate evolution.” Current Anthropology 36:199–221

Aiello, Leslie C. and Jonathan C. K. Wells (2002): “Energetics and the Evolution of the Genus Homo.” In: Annual Review of Anthropology 31:323–38.

Attwell, David and Simon B. Laughlin. (2001.) “An Energy Budget for Signaling in the Grey Matter of the Brain.” Journal of Cerebral Blood Flow and Metabolism 21:1133–1145.

Bickerton, Derek (2009): Adams Tongue: How Humans Made Language. How Language Made Humans. New York: Hill and Wang.

Deacon, Terrence William (1997). The Symbolic Species. The Co-evolution of Language and the Brain. New York / London: W.W. Norton.

Dunbar, Robin I.M. (1998)“The Social Brain Hypothesis” Evolutionary Anthropology 6: 178-190.

Dunbar, R. I. M. and Susanne Shultz. (2007)“Evolution in the Social Brain” Science 317: 1344-1347

Edelman, Gerald Maurice (1992) Bright and Brilliant Fire: On the Matters of the Mind. New York: Basic Books

Gazzaniga, Michael S. (2008): Human: The Science of What Makes us Unique. New York: Harper-Collins.

Gibbons, Ann. (2007) “Food for Thought.” Science 316. 1558-1560.

Gould, Stephen Jay and Richard Lewontin (1979). "The spandrels of San Marco and the Panglossian paradigm: a critique of the adaptationist programme". Proclamations of the Royal. Society of London B: Biological Sciences 205 (1161): 581–98.

Gould, Stephen Jay, and Elizabeth S. Vrba (1982), "Exaptation — a missing term in the science of form," Paleobiology 8 (1): 4–15.

Lewin, Roger (2005): Human Evolution: An Illustrated Introduction. Oxford: Blackwell.

Marcus, Gary (2008): Kluge: The Haphazard Evolution of the Human Mind. London: Faber and Faber.

Povinelli, Daniel .J. and Jennifer Vonk. (2003) Chimpanzee minds: Suspiciously human? Trends in Cognitive Sciences, 7.4, 157–160.

Preuss Todd M. (2004): What is it like to be a human? In: Gazzaniga MS, editor. The Cognitive Neurosciences III, Third Edition. Cambridge, MA: MIT Press: 5-22

Rilling, James K. (2006.) “Human and NonHuman Primate Brains: Are They Allometrically Scaled Versions of the Same Design?” In: Evolutionary Anthropology 15: 67-77

Back to Blogging Soon

Today I handed in my last essay for this term and I really hope I'll be able to post more regularly now.

Meanhwile, both Neurophilosophy and Babel's Dawn have interesting posts up regarding work done by Ofer Tchernichovski, Olga Feher, and her colleagues regarding the tendency of birdsong to converge on the on the standard wildtype-model after a few generations when the first generation was isolate and had no model output they could adopt. (although I find it a bit misleading if birdsong is called language as is done over at the otherwise excellent blog Neurophilosopy)

This happened by small variations the birds made to their input over a couple of generations. These variations accumulated an in the end yielded the wild-type.

In the words of the authors:

"Thus, species-typical song culture can appear de novo. Our study has parallels with language change and evolution. In analogy to models in quantitative genetics, we model song culture as a multigenerational phenotype partly encoded genetically in an isolate founding population, influenced by environmental variables and taking multiple generations to emerge." (Feher et al. 2009).

The question now is inhowfar we can draw a parallel to how human language may be genetically encoded. The topic has been covered previously (here) and although there are also opposing views, (see, for example, Derek Bickerton here), it seems that a consensus is about to emerge that sees language acquisition as the interplay between social learning, innate biases, and more general cognitive capacities. (see, e.g. here and here)

Review of 'The Origins of Human Communication' in Science Magazine

The April 3rd issue of Science Magazine features a review of Michael Tomasello's "The Origin of Human Communication" (see my ongoing summary of the book here, here, and here) by Nick Enfield, who works at the Max Planck Institute for Psycholinguists in the Netherlands and is co-editor of "The Roots of Human Sociality" (part of which I discussed briefly here. See also Enfield's Reviews of James Hurford's The Origins of Meaning and Peter Macneilage's The Origin of Speech here).

Here's how Enfield neatly sums up Tomasello's position on the evolution of language

Requests form one of three classes of social action on which Tomasello builds his account of human communication. The others are informing-helping (e.g., when one person points to keys that another just dropped) and sharing (e.g., when two people's attitudes toward a third person align in the course of a gossip session). He summarizes research showing that all three social motives are fully evident in the communicative behavior of prelinguistic infants and all but absent among our closest relatives, the great apes. Humans have a special combination of cooperative instincts, prosocial motives, high-level intention attribution, and moral propensities (3). Tomasello contends that without this unique psychological wherewithal in the domain

Although he applauds Tomasello's general solution for evolution of complex language, Enfield rightly points out that one of Tomasello's shortcomings is that he doesn't follow through with his idea how we got from a gesture-based shared intentionality inrastructure to full blown syntactic language. In accordance with Paul Bloom's assertion that

"Every species gets the syntax it deserves" (Bloom 2000)

Tomasello links the social functions of requesting, informing and sharing to rising levels of linguistic complexity.

"He dubs these "simple syntax" (strongly dependent on immediate context), "serious syntax" (for making unambiguous reference across contexts), and "fancy syntax" (for organizing long and complex narratives). But this is essentially as far as his links to grammar go, promissory notes notwithstanding."

In this regard, I'm looking forward to the forhtcoming second volume of James Hurford's Language in The Light of Evolution series which focuses on the origins of linguistic form.

What should also be mentioned is that Tomasello has an aversion to telling "fairy-tales," that is, tentative evolutionary scenarios of how exactly language could have evolved during our evolutionary history. This position is directly opposed to that of Derek Bickerton, who in his new book "Adam's Tongue: How Humans Made Language, How Language Made Humans" argues that the only way to get even a faint idea of how language could have evolved is to look at the environment and changing niches our pre-human ancestors lived in.
After having read the book, I have very mixed feelings about Bickerton's proposal and will come back to it in a later post.

Hat tip: Deric Bownds' Mindblog

Immanuel Kant & Mental Time Travel

In my previous post I pointed out that new evidence coming from the chimpanzee Santino's behavior may be crucial for discussions whether 'episodic' planning and prospective Mental Time Travel exist in non-human animals.

This relates to the proposal by Suddendorf & Corballis (1997, 2007) that Mental Time Travel is unique to humans and that from an evolutionary perspective:

"that the crucial selective advantage mental time travel provides is flexibility in novel situations and the versatility to develop and adopt strategic longterm plans to suit individual selected goals."

Mental Time Tavel thene evolved so we are able to plan future behavior based on the recall of past episodes. But our "episodic memory" only provides the "raw material" for future planning, it isn't useful in itself. From an evolutionary perspective, being able to relive past memories may only be a byproduct, and in itself may not very useful. It's only use might be that it provides us with "raw" material.
Acording to this argument, the crux then is is that our ability to recall past episodes is only a necessary design feature of being able to plan flexibly for the future.
The philosophical implications of such a view may be rather bleak, given that it reduces another of our most cherished features of what makes us human - namely our memories and life histories, which give us a sense of having a, a continous, purpose- and meaningful existence - to an accidental spandrel. But what is also interesting from a philosophical point of view is that Suddendorf & Corballis weren't the first to come up with this idea.

Interestingly, I just found a quote from Immanuel Kant in a paper of a friend of mine:
Recalling the past (remembering) occurs only with the intention of making foresight of the future possible […] we look about us from the standpoint of the present in order to decide something or to be prepared for something. Empirical foresight is the anticipation of similar cases […] and requires no rational knowledge of causes and effects, but only tahe remembering of observed events as they commonly follow one another, and repeated experiences produce n aptitude for it" (Kant, Immanuel. Anthropology from a Pragmatic Point of View. Trans. Robert B. Louden. Cambridge Texts in the History of Philosophy. Cambridge: Cambridge University Press, 2006, 79)

Bibliography:

Kant, Immanuel (2006) Anthropology from a Pragmatic Point of View. Trans. Robert B. Louden. Cambridge Texts in the History of Philosophy. Cambridge: Cambridge University Press.

Suddendorf, T. and M.C. Corballis (1997), Mental time travel and the evolution of the human mind, Genetic Social and General Psychology Monographs 123, pp. 133–167.

Suddendorf. T. and M.C. Corballis (2007), The evolution of foresight: What is mental time travel and is it unique to humans?, Behavioral and Brain Sciences 30, pp. 299–351

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Santino the Outlaw & Mental Time Travel

With a lot of essays coming up I have almost no time to blog. But here are some interesting links:

First, there's an interesting story about Santino, a chimpanzee in a Swedish zoo,who stored stones on strategic locations with "malice aforethought" so to speak, in order to throw them at visitors (see, e.g. here and here).
This ties in with a discussion of in how far non-human animals are able to plan ahead, or inhowfar the posses the ability of "Mental Time Travel."
I have briefly mentioned the importance of such an ability for the evolution of language and perspectival mental representations before (here) and Edmund Blair Bolles has a much more comprehensive post on the importance of episodic thinking and communication of episodes for the evolution of language discussing a recent article by Michael C. Corballis on "Mental Time Travel and the Shaping of Language"

How Strong is a Chimpanzee?

John Hawks has a very interesting article in Slate in which he looks at the experiments that have been done to find out how strong chimpanzees really are.
As it turns out, claims of chimpanzees being 5 to 9 times stronger are exaggerated, but they are still about twice as strong as humans.
The short article makes for really enjoyable reading, Go check it out.

I was surprised to read that that a chimp on all fours can easily outrun a human sprinter...