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What Makes Humans Unique ?(IV): Shared Intentionality – The Foundation of Human Uniqueness?

What Makes Humans Unique (IV): Shared Intentionality – The Foundation of Human Uniqueness?

Shared or collective intentionality is the ability and motivation to engage with others in collaborative, co-operative activities with joint goals and intentions. (Tomasello et al. 2005). The term also implies that the collaborators’ psychological processes are jointly directed at something and take place within a joint attentional frame (Hurford 2007: 320, Tomasello et al. 2005).

Michael Tomasello and his colleagues at the Max-Planck-Institute for Evolutionary Anthropology in Leipzig, Germany have proposed that shared intentionality and the cognitive infrastructure supporting it may be the crucial feature that makes humans unique.

(You can hear Michael Tomasello talk about shared intentionality in his brief 2009 acceptance speech for the prestigeous “Hegel-Price” here. Transcript here)

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Some Links #13: Universal Grammar Haters

Universal Grammar haters. Mark Lieberman takes umbrage with claims that Ewa Dabrowska’s recent work challenges the concept of a biologically evolved substrate for language. Put simply: it doesn’t. What their experiments suggest is that there are considerable differences in native language attainment. As some of you will probably know, I’m not necessarily a big fan of most UG conceptions, however, there are plenty of papers that directly deal with su ch issues. Dabrowska’s not being one of them. In Lieberman’s own words:

In support of this view, let me offer another analogy. Suppose we find that deaf people are somewhat more likely than hearing people to remember the individual facial characteristics of a stranger they pass on the street. This would be an interesting result, but would we spin it to the world as a challenge to the widely-held theory that there’s an evolutionary substrate for the development of human face-recognition abilities?

Remote control neurons. I remember reading about optogenetics awhile back. It’s a clever technique that enables neural manipulation through the use of light-activated channels and enzymes. Kevin Mitchell over at GNXP classic refers to a new approach where neurons are activated using a radio frequency magnetic field. The obvious advantage to this new approach being fairly straight-forward: magnetic-fields pass through brains far more easily than light. It means the new approach is a lot less invasive, without the need to insert micro-optical fibres or light-emitting diodes. Cool stuff.

Motor imagery enhances object recognition. Neurophilosophy has an article about a study showing that motor simulations may enhance the recognition of tools:

According to these results, then, the simple action of squeezing the ball not only slowed down the participants’ naming of tools, but also slightly reduced their accuracy in naming them correctly. This occured, the authors say, because squeezing the ball involves the same motor circuits needed for generating the simulation, so it interferes with the brain’s ability to generate the mental image of reaching out and grasping the tool. This in turn slows identification of the tools, because their functionality is an integral component of our conceptualization of them. There is other evidence that parallel motor simulations can interfere with movements, and with each other: when reaching for a pencil, people have a larger grip aperture if a hammer is also present than if the pencil is by itself.

On the Origin of Science Writers. If you fancy yourself as a science writer, then Ed Yong, of Not Exactly Rocket Science, wants to read your story. As expected, he’s got a fairly large response (97 comments at the time of writing), which includes some of my favourite science journalists and bloggers. It’s already a useful resource, full of fascinating stories and bits of advice, from a diverse source of individuals.

Some thoughts about science blog aggregation. Although it’s still hanging about, many people, including myself, are looking for an alternative to the ScienceBlogs network. Dave Munger points to Friendfeed as one potential solution, with him setting up a feed for all the Anthropology posts coming in from Research Blogging. Also, in the comments Christina Pikas mentioned Nature Blogs, which, I’m ashamed to say, I haven’t come across before.

What Makes Humans Unique ?(III): Self-Domestication, Social Cognition, and Physical Cognition

In my last post I summed up some proposals for what (among other things) makes human cognition unique. But one thing that we should bear in mind, I think, is that our cognitive style may more be something of an idiosyncrasy due to a highly specific cognitive specialization instead of a definitive quantitative and qualitative advance over other styles of animal cognition. In this post I will look at studies which further point in that direction.

Chimpanzees, for example, beat humans at certain memory tasks (Inoue & Matsuzawa 2007) and behave more rational in reward situations (Jensen et al. 2007).

In addition, it has been shown that in tasks in the social domain, which are generally assumed to be cognitively complex, domesticated animals such as dogs and goats (Kaminski et al. 2005) fare similarly well or even outperform chimpanzees.

Social Cognition and Self-Domestication

It is entirely possible that the first signs of human uniqueness where at first simply side-effects our self-domesticating lifestyle – the same way the evolution of social intelligence in dogs and goats is hypothesised to have come about –, acting on a complex primate brain (Hare & Tomasello 2005).

This line of reasoning is also supported by domesticated silver foxes which have been bred for tameness over a time period of 50 years but developed other interesting characteristics as a by-product: To quote from an excellent post on the topic over at a Blog Around the Clock (see also here):

“They started having splotched and piebald coloration of their coats, floppy ears, white tips of their tails and paws. Their body proportions changed. They started barking. They improved on their performance in cognitive experiments. They started breeding earlier in spring, and many of them started breeding twice a year.”

What seems most interesting to me, however, is another by-product of their experimental domestication: they also improved in the domain of social cognition. For example, like dogs, they are able to understand human communicative gestures like pointing. This is all the more striking because, as mentioned above, chimpanzees do not understand human communicative gestures like helpful pointing. Neither do wolves or non-domesticated silver foxes (Hare et al. 2005).

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Time Travel, Dreams and The Origin of Knowledge

I’ve been attending a weekly seminar on the Metaphysics of Time Travel, given by Alasdair Richmond. Yesterday, he was talking about the way knowledge arises in causal chains. Popper (1972 and various others) argues that “Knowledge comes into existence only by evolutionary, rational processes” (quoted from Paul Nahin, ‘Time Machines: Time Travel in Physics, Metaphysics and Science Fiction, New York, American Institute of Physics, 1999: 312). Good news for us scholars of Cultural Evolution. However, Richmond also talked about the work of David Lewis on the nature of causality. There are three ways that causal chains can be set up:

The first is an infinite sequence of events each caused by the previous one. For example, I’m typing this blog because my PhD work is boring, I’m doing a PhD because I was priced in by funding, I applied for funding because everyone else did … all the way back past my parents meeting and humans evolving etc.

The second option is for a finite sequence of events – like the first option, but with an initial event that caused all the others, like the big-bang.

The third option is a circular sequence of events. In this, A is caused by B which is caused by A. For instance, I’m writing doing a PhD because I got funding and I got funding because I’m doing a PhD, because I got funding. There is no initial cause, the states just are. This third option seems really odd, not least because it involves time-travel. Where do the states come from? However, argues Lewis, they are no more odd than any of the other two options. Option one has a state with no cause and option two has a cause for every event but no original cause. So, how on earth can we get at the origin of knowledge if there is no logical possibility of determining the origin of any sequence of events?

One answer is just to stop caring after a certain point. Us linguists are unlikely to get to the point where we’re studying vowel shifts in the first few seconds of the big bang.

The other answer is noise. Richmond suggested that ‘Eureka’ moments triggered by random occurrences, for instance (Nicholas J. J. Smith, ‘Bananas Enough for Time Travel?’, British Journal for the Philosophy of Science, Vol. 48, 1997: 363-89). mishearing someone or a strange dream, could create information without prior cause.

Spookily, the idea I submitted for my PhD application came to me in a dream.

What Makes Humans Unique? (II): Six Candidates for What Makes Human Cognition Uniquely Human

What makes humans unique? This never-ending debate has sparked a long list of proposals and counter-arguments and, to quote from a recent article on this topic,

“a similar fate most likely awaits some of the claims presented here. However such demarcations simply have to be drawn once and again. They focus our attention, make us wonder, and direct and stimulate research, exactly because they provoke and challenge other researchers to take up the glove and prove us wrong.” (Høgh-Olesen 2010: 60)

In this post, I’ll focus on six candidates that might play a part in constituting what makes human cognition unique, though there are countless others (see, for example, here).

One of the key candidates for what makes human cognition unique is of course language and symbolic thought. We are “the articulate mammal” (Aitchison 1998) and an “animal symbolicum” (Cassirer 2006: 31). And if one defining feature truly fits our nature, it is that we are the “symbolic species” (Deacon 1998). But as evolutionary anthropologists Michael Tomasello and his colleagues argue,

“saying that only humans have language is like saying that only humans build skyscrapers, when the fact is that only humans (among primates) build freestanding shelters at all” (Tomasello et al. 2005: 690).

Language and Social Cognition

According to Tomasello and many other researchers, language and symbolic behaviour, although they certainly are crucial features of human cognition, are derived from human beings’ unique capacities in the social domain. As Willard van Orman Quine pointed out, language is essential a “social art” (Quine 1960: ix). Specifically, it builds on the foundations of infants’ capacities for joint attention, intention-reading, and cultural learning (Tomasello 2003: 58). Linguistic communication, on this view, is essentially a form of joint action rooted in common ground between speaker and hearer (Clark 1996: 3 & 12), in which they make “mutually manifest” relevant changes in their cognitive environment (Sperber & Wilson 1995). This is the precondition for the establishment and (co-)construction of symbolic spaces of meaning and shared perspectives (Graumann 2002, Verhagen 2007: 53f.). These abilities, then, had to evolve prior to language, however great language’s effect on cognition may be in general (Carruthers 2002), and if we look for the origins and defining features of human uniqueness we should probably look in the social domain first.

Corroborating evidence for this view comes from comparisons of brain size among primates. Firstly, there are significant positive correlations between group size and primate neocortex size (Dunbar & Shultz 2007). Secondly, there is also a positive correlation between technological innovation and tool use – which are both facilitated by social learning – on the one hand and brain size on the other (Reader and Laland 2002). Our brain, it seems, is essential a “social brain” that evolved to cope with the affordances of a primate social world that frequently got more complex (Dunbar & Shultz 2007, Lewin 2005: 220f.).

Thus, “although innovation, tool use, and technological invention may have played a crucial role in the evolution of ape and human brains, these skills were probably built upon mental computations that had their origins and foundations in social interactions” (Cheney & Seyfarth 2007: 283).

Continue reading “What Makes Humans Unique? (II): Six Candidates for What Makes Human Cognition Uniquely Human”

What Makes Humans Unique? (I): The Evolution of the Human Brain

Hello! This is my first post here at Replicated Typo and I thought I’d start with reposting a slightly modified version of a three-part series on the evolution of the human mind that I did last year over at my blog Shared Symbolic Storage.

So in this and my next posts I will have a look at how human cognition evolved from the perspective of cognitive science, especially ‘evolutionary linguistics,’ comparative psychology and developmental psychology.

In this post I’ll focus on the evolution of the human brain.

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., Lewin 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’d only 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). All 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).

This is especially important for people who want to come up with an “adaptive story” of how our brain got so big: they 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 in the first place (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 are not simply ‘better’ at thinking than other animals, 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 know universe”, as it is sometimes referred to, we have to acknowledge how preciously little time the evolutionary process had for ‘debugging.’ It could well be that make the human mind is so unique because it is an 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.

In my next post I will have a look at six candidates for what makes human cognition unique.

References:

Aiello, L., & Wheeler, P. (1995). The Expensive-Tissue Hypothesis: The Brain and the Digestive System in Human and Primate Evolution Current Anthropology, 36 (2) DOI: 10.1086/204350

Aiello, L., & Wells, J. (2002). ENERGETICS AND THE EVOLUTION OF THE GENUS HOMO Annual Review of Anthropology, 31 (1), 323-338 DOI: 10.1146/annurev.anthro.31.040402.085403

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., & Shultz, S. (2007). Evolution in the Social Brain Science, 317 (5843), 1344-1347 DOI: 10.1126/science.1145463

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, J. (2006). Human and nonhuman primate brains: Are they allometrically scaled versions of the same design? Evolutionary Anthropology: Issues, News, and Reviews, 15 (2), 65-77 DOI: 10.1002/evan.20095

Some Links #12: What if there had never been a cognitive revolution?

What if there had never been a cognitive revolution? Apparently, nothing would really be all that different according to Nicolas Baumard over at ICCI. It’s all speculative, in a similar vein to alternative history fiction (I recommend: Making History by Stephen Fry and Difference Engine by William Gibson and Bruce Sterling), with Baumard stating:

My point here is that these key ideas would have emerged even without a Cognitive Revolution. Take for instance the idea that the mind cannot be a blank slate. This idea is totally natural to evolutionary biologists. What about the mind as “a complex system composed of many interacting parts”? Without going back to La Mettrie, Hutcheson or Descartes, one can argue that the idea of modularity is at the core of the research program of neuropsychology since its beginning (the same is true, albeit at a lesser degree, for evolutionary biology). We should not forget as well that, with or without the Cognitive Revolution, brain imaging techniques would have emerged and would have joined neuropsychology and evolutionary biology in decomposing the mind. Add the methodological advances of developmental psychology or social psychology – which were not part of the Cognitive revolution – and you get a pretty big part of today’s ‘Cognition and Culture’.

‘Mad Men‘ -ese. Ben Zimmer has a cool article on Mad Men (easily one of the best shows to have emerged in recent years) and its dedication to accurately portraying 1960s dialogue. But with such dedication comes equally dedicated, and pedantic, criticisms of some of the lines used. For example, Zimmer points to Don’s line “The window for this apology is closing” as being tied to the 70s use of window in a metaphorical sense. On another note: the new season of Mad Men begins tomorrow (25th June) in America.

A growing isolated brain can organize itself. Deric Bownds points to an article by Zhou et al (2010) which disconnected a mouse’s neocortex from the rest of its brain to see how the surface map developed. The results:

During these weeks, the mutant mice, despite having disconnected brains, display a variety of behaviors: eating, drinking, walking, and swimming. Thus, “protomap” formation, namely cortical lamination and formation of areas, proceed normally in absence of extrinsic connections, but survival of projection neurons and acquisition of mature morphological and some electrophysiological features depend on the establishment of normal cortical–subcortical relationships.

Things I’d like to see: a nice, simple, colourful website on evidence-based social policy. Being an avid reader of Ben Goldacre’s Bad Science column, and having read his book of the same name, I was surprised to find that he has another blog. Anyway, the linked post is fairly self-explanatory: he’s calling for someone to create a website looking at evidence-based social policy (something he’s been discussing since at least 2007). I’m a big fan of this idea, which would see social policy based on less rhetorical wrangling and more on actual evidence:

There are three key stages in evidence-based practise: you generate evidence; you collate and appraise it, and then you disseminate and implement. It feels to me like the last bit is currently underdone, and often it takes one clear information hub, or an organisation devoted to promoting something, to move things on.

Why money makes you unhappy. Money is apparently not very good at making us happy. Jonah Lehrer writes about a study exploring the experience-stretching hypothesis, and how it relates to money and happiness. Basically, the argument is that because money allows us to enjoy the best things in life, we actually end up lessening our ability to enjoy the mundane aspects of our life. As the mundane aspects are most frequent, then this isn’t necessarily a good thing. This comes on the back of another paper claiming that the United States, currently the richest nation on Earth, is slowly getting less satisfied with life. As the current study states:

Taken together, our findings provide evidence for the provocative notion that having access to the best things in life may actually undermine one’s ability to reap enjoyment from life’s small pleasures. Our research demonstrates that a simple reminder of wealth produces the same deleterious effects as actual wealth on an individual’s ability to savor, suggesting that perceived access to pleasurable experiences may be sufficient to impair everyday savoring. In other words, one need not actually visit the pyramids of Egypt or spend a week at the legendary Banff spas in Canada for one’s savoring ability to be impaired—simply knowing that these peak experiences are readily available may increase one’s tendency to take the small pleasures of daily life for granted.

Language – An Embarrassing Conundrum for the Evolutionist?

Hello! This is my first post on the blog and whilst I didn’t want it to be an angry rant after I found this youtube video there seemed little could have been done to avoid it.

This is a video by a creationist named “ppsimmons” who writes on the front page of his youtube channel that he “apologizes for not knowing enough to scientifically refute the evidence for creation nor for being clever enough to “scientifically” support the theory of evolution.” And yet he feels to be enough of an authority to make videos refuting evolution using ‘science’.

I know I shouldn’t let this annoy me as much as it obviously has, I know that there will always be creationists out there and I know that these creationists will never listen to anything I have to say. However, in this case, I’ve decided to respond mostly to set straight the interpretation of Robert Berwick’s words used in this video.

Continue reading “Language – An Embarrassing Conundrum for the Evolutionist?”

Some Links #9: Sowing the Seed of doubt

This isn’t the first time Seed has sacrificed editorial independence. A worrying article about scienceblogs’ parent company, Seed, and how they restricted the publication of a column on the basis of it being critical of Dow Chemical — someone they were seeking an advertising contract with. As Gaia Vince points out in an email she received from Seed:

We’re not running the bhopal piece, and we’re passing on the Maldive shark ban (a bit late now… Too bad it got caught up in prod week… ). As for Bhopal, it’s a cautionary call on our part as we’re in the midst of advertising negotiations with Dow (who have been inspired by Seed’s photography in their own brand campaigns). RE: the payment, as you’re on a scheduled direct-payment, the bhopal fee covers the Kerry/Carbon trading news piece fee that was outstanding. Let me know if that’s clear.

It’s a great article that’s not only revealing about Seed, but the underlying motivations of the journalism industry in general. I never thought I’d find myself linking to Chomsky’s politics, yet, given the nature of this article, maybe it’s time I dug out my copy of Manufacturing Consent.

Scientific Certainty Argumentation Methods (SCAMs): Science and the politics of doubt. H/T: Ben Goldacre. A good paper looking at what happens when science and politics mix, and how the two have different expectations of what science is. Here’s the abstract:

At least since the time of Popper, scientists have understood that science provides falsification, but not “proof.” In the world of environmental and technological controversies, however, many observers continue to call precisely for “proof,” often under the guise of “scientific certainty.” Closer examination of real-world disputes suggests that such calls may reflect not just a fundamental misunderstanding of the nature of science, but a clever and surprisingly effective political-economic tactic—”Scientific Certainty” Argumentation Methods, or SCAMs. Given that most scientific findings are inherently probabilistic and ambiguous, if agencies can be prevented from imposing any regulations until they are unambiguously “justified,” most regulations can be defeated or postponed, often for decades, allowing profitable but potentially risky activities to continue unabated. An exploratory examination of previously documented controversies suggests that SCAMs are more widespread than has been recognized in the past, and that they deserve greater attention in the future.

The secret history of X and Z. An excellent article from Ed Yong on Chromosome evolution in humans and birds. Key paragraph:

Why the similarities? It’s possible that both X and Z evolved from autosomes with features that made them more likely to become sex chromosomes. Perhaps, for example, their genes were already sparsely distributed. But Bellott ruled out this idea. He compared X to its closest counterpart in chicken, and Z to its equivalents in humans – none of these relatives had any structural features that made them stand out among other autosomes. There’s nothing that singles them out as ideal candidates for the role of sex chromosome.

You are not authorized to see these pictures of the oil spill, citizen… Do not look. Washington’s Blog has some fairly harrowing photos of the recent gulf oil spill and the damage it’s doing to wildlife. Here’s one example:

Some links #8: Are you WEIRD?

We agree it’s WEIRD, but is it WEIRD enough? Greg Downey at Neuroanthropology gives his take on Henrich et al.’s paper The weirdest people in the world? which looks at acronym WEIRD (Western, Educated, Industrialized, Rich, and Democratic) and how we may be extrapolating too much from this particularly narrow data set. Yet, despite this, we continue to use WEIRD individuals in psychological experiments, even though it may not be representative of, say, the large body of Africans. I mean, come on, you wouldn’t take genetic data from Western Europe and then make sweeping generalisations about populations in Western Africa…

The Human Penis Bone. From WEIRD to just weird. Scicurious reviews a very old journal article from 1913, which tells of a guy who actually grew a penis bone. Now, many mammals do have penis bones, but human males generally lack this ossified aid. However, if you’re curious about how to get one, then all you have to do is simply wear a particular type of corset (see below) and, here’s a downside for those of you planning on ditching the Viagra, get syphilis. As Scicurious explains:

The syphilis, combined with the constant irritation of the corset, had apparently caused a build up of desposits, which eventually ossified and turned in to bone. REAL BONE, with marrow and holes in it and everything! […] So the moral of this story is: if you’re a guy, and you’re vain about your appearance, get a flat front corset. You don’t want to be sitting down in something pointy.

Wild cat found mimicking monkey calls. Some clever vocal mimicry from a margay. ScienceDaily reports:

Researchers first recorded the incident in 2005 when a group of eight pied tamarins were feeding in a ficus tree. They then observed a margay emitting calls similar to those made by tamarin babies. This attracted the attention of a tamarin “sentinel,” which climbed down from the tree to investigate the sounds coming from a tangle of vines called lianas. While the sentinel monkey started vocalizing to warn the rest of the group of the strange calls, the monkeys were clearly confounded by these familiar vocalizations, choosing to investigate rather than flee. Four other tamarins climbed down to assess the nature of the calls. At that moment, a margay emerged from the foliage walking down the trunk of a tree in a squirrel-like fashion, jumping down and then moving towards the monkeys. Realizing the ruse, the sentinel screamed an alarm and sent the other tamarins fleeing.

Nongenetic selection and evolution: flies use bacteria to adapt to parasitic worms. Jerry Coyne has a fascinating post about nongenetic evolution occurring in a mushroom-eating fruit fly Drosophila neotestacea. But how is it nongenetic? Well, as Jerry explains:

A new paper by John Jaenike and his colleagues in Science, however, shows a form of biological evolution by natural selection that isn’t based on changes in genes. It’s based on changes in the presence of symbiotic bacteria that protect a species from parasites […] Some flies also carry another organism: the bacterial symbiont Spiroplasma, which is found in many insects. In D. neotestacea, however, the presence of Spiroplasma protects the fly from the sterilizing effects of nematodes. While flies with worms and no Spiroplasma are virtually sterile, the presence of the bacteria confers almost normal fertility on worm-ridden flies. It’s not yet clear how this works, but worms in flies with Spiroplasma are much smaller than those without the bacteria. Presumably the bacteria does something to the worms (or to the flies) that makes the worms grow much more slowly.