Category: pseudo-explanation

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Keith S. Taber

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What is it like to be a mosquito? At the risk of an early spoiler, I admit I do not know. But I know of a couple of professors who might think they do. I have learned from Prof. Leslie Vosshall (Chief Scientific Officer of the Howard Hughes Medical Institute at Rockefeller University) that mosquitoes actually enjoy the experience of piercing human skin to feed on blood, but according to Prof. Sarah Reece (Professor of Evolutionary Parasitology at the University of Edinburgh) they feel rubbish if they gorge on blood too soon after waking up or just before going to sleep.

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• blood feeding mosquitoes have figured out how to get a giant protein-rich meal
• mosquitoes feel rubbish if they eat a massive meal just after waking

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How can we know what it is like to experience the world as another?

I cannot deny these claims, but I am sceptical we can justifiably make them.

The philosopher Thomas Nagel famously posed the question of what it is like to be a bat. He could have substituted a cat or a dolphin or a pigeon. Bats are mammals, like us. But they are quite different from humans in many respects. They are nocturnal, unlike most of us; and they eat more insects than most of us. They tend to sleep hanging upside down, which we generally do not. Perhaps more significantly, they fly in a way humans unaided do not, and in flying around in the dark navigate by echolocation – which again is quite unlike us.

The point is that the bat's sensory apparatus is so different from ours that we have no experience of what it might be like to be a bat. But this is jut one example. Almost a century ago the biologist Jakob von Uexküll proposed the term 'umwelt' to describe the environment as perceived by an organism, and attempted to imagine how the organism's scale and habitat and sensory and cognitive apparatus would influence its perception of the world. Being a spider 'tuned in' the vibrations of a the threads of a web is quite different to being a bat, but also quite different from being the fly using its compound eye to avoid the spider's web.

The issue is not just the array of sensory organs, but the cognitive system that has evolved to function with it. How can we appreciate what it is like to be a dolphin which sleeps half a brain at a time? How can we understand what it might be like to be an octopus which has a central brain that delegates to subsidiary organs in each tentacle, so they work as somewhat autonomous units. Imagine only finding out you are going for a walk 'second hand' – the octopus head must be a bit like a traveller on a train who notices when pulling out of a station but has no direct input into the action. 'A bit like', but we can never really know what it is actually like to be an octopus.

Qualia-tative experience

Some birds and insects have differently tuned colour receptors in their eyes, so for example some can see into what we call ultraviolet. So some insects see lines on petals that lead to the nectar – lines that we just do not see. Their visual world is simply different to ours.

But why stop there? My father was colour blind. He saw the same objective world as me, but could not make the same red-green distinctions that I can. This never bothered him – he had no idea what he was missing (and, critically, it did not seem to affect his golf). We might say his umwelt was different to mine because of these differences in our sensory apparatus.

Yet this touches upon the notion of qualia, the word used to describe our direct sense experiences. I have an experience of red – something I experience when I look at a red object. I have a different qualia if I see something green. That is, I have a subjective experience when I perceive a particular colour.

Physics tells us that colours are not objective properties of objects, rather our visual system processes the reflected spectrum from an object, and somehow does a comparison with the rest of the visual field to 'allow' for overall viewing conditions (so the light at midday compared with the light when the sun is setting makes a great difference to the spectrum of light being reflected from an object for example) and usually maintains a reasonable continuity in the qualia – the colour as perceived in a person's consciousness. (Questions of the processing in terms of chemistry and physics and cell biology are clearly scientific questions – but it is less clear if natural science can ever fully explain the subjective experiences.)

Presumably, my father did not experience red and green as I do – perhaps he experienced what I see as green when looking at red as well as when he looked at something green – or perhaps he saw my yellow in both cases, or perhaps he had completely different colour qualia that I have never experienced. And, this might be true of people with 'normal' colour vision. What I experience as red is not (as far as we know) inherently directly linked to anything physical about red objects but perhaps is something that emerged from my developing sensory-cognitive system as it interpreted perceptual data when I was very young. Maybe another person, with a different unique selection of genes, and with a different developing brain, and somewhat different early visual experiences, will experience my red when they see something that is blue? Or again, perhaps what they experience is something different to any of my colour qualia?

After all, if we agree on what is red and what is blue and what is green (and let's face it, we do not always even agree on that) this would be just as true if we are experiencing different subjective colours, as long as the qualia are consistent within each person. How could we ever know? Perhaps those people mocked for having poor taste in colour combinations (mea culpa) are seeing wonderful juxtapositions when their mockers see clashes? Again: how could we ever know?

Our brains do not arrive fully formed, but develop in response to our experiences. So, how we hear sound develops in relation to the early sound environment – certainly in relation to speech. We often find it difficult to discriminate the sounds of a very unfamiliar language as repeated early exposure to our specific native language has led to modifications in the way we process sounds.¹ It is like the brain grows its own filters and interpretation algorithms to make best sense of what is experienced in early life.

And the somewhat mysterious sense of smell is likely much more individual than sight or sound, such that it varies much more according to one's personal genetic profile, much like our immune systems.

So perhaps we can never really know how another person experiences the world, let alone how a bat, a dolphin or an octopus experiences their lives. Or, surely, a mosquito.

Now to be totally clear, I am not suggesting that because other organisms may not experience the world as we do, we can treat them as though they do not have experiences. The Cartesian distinction between humans as having minds and everything else being mere machinery is not convincing when we consider the common evolutionary basis of life on earth.

I imagine that bats and dolphins and octopuses have rich lived experiences, just that these are incommensurable with our human experiences. I am not convinced that there is anything it is like to be a bacterium or a protozoan (they have senses, but surely not consciousness), but I would not rule out spiders, flies and mosquitoes having some kind of conscious experience – even if, surely, with their tiny brains, this would be much less rich than ours. And that is what leads me to be sceptical of some of what I heard from Profs Vosshall and Reece.

The curious case of the reflective mosquito

What sparked these thoughts was listening to an episode of the BBC Radio 4 programme/podcast 'Curious Cases', a popular science programme aimed at a general audience. The episode was about mosquitoes that bite people, and why they seem to prey on some people more often than others.

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In discussing those species of mosquitoes that bite humans, the guest scientists made a number of claims that I considered it would be difficult to justify.

Prof. Sarah Reece told listeners that,

"We feel rubbish if we eat a massive meal just before we go to bed or immediately if we wake up. The same is going to be true for mosquitoes as well."

Perhaps she is right – but does that seem likely?

Reece compared the mosquito feeding (we might say gorging) on blood to be like a human drinking a bath of soup. Excessive eating before bedtime is unwise for humans. But then we are not mosquitoes. Modern humans in many contexts are able to engage in eating behaviours that are not healthy, but which would have matched a sensible strategy (i.e., eat whenever food is available) during most of human evolution when food was not as abundant. The modern standards of living allowing over-consumption experienced by many people today have not existed long enough for natural selection to have changed our eating behaviours. Perhaps mosquitoes have evolved to feed in the way they do because they, as mosquitoes, have different life-cycles, and experience different environmental affordances and constraints, to us.

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Perhaps they do feel something after talking a blood meal, and perhaps it feels different according to the time of day – but who knows? I do not, and I am not convinced by the justification that what is true for a human must be the case for an insect. (Humans may feel guilt or regret or shame afer eating an immoderate meal – so do mosquitoes? Humans often belch after excessive eating: so does this mean mosquitoes will burp after engorging themselves on human blood?)

Prof. Leslie Vosshall made a number of claims I found questionable:

"They love everything about humans…they like the feeling of piercing skin"

"The blood-feeding mosquitoes have figured out how to get a giant protein-rich meal mostly from humans and they need that to make eggs….They're being good mums, they want to provision their offspring with the biggest meal possible

"The mosquitoes say like 'haha, you are all like sleeping under these nets where we can't get at you' and so slowly the population moves to day biting…because they realise that we are not going to walk around wearing bed nets, as we go about our day."

Mosquitoes enjoy piercing skin

So, according to Prof. Leslie Vosshall mosquitoes enjoy the experience of piercing the skin of people they feed off. Now on the face of it I do not think this is unreasonable. Humans enjoy eating, as well as other activities that support species survival – sexual activity, a good sleep, being with a pair-bonded partner, keeping young children close at hand and petting them…. I expect chimpanzees enjoy grooming each other as they remove parasites. It makes sense that evolution would lead to people and other complex organisms enjoying essential activities. Natural selection for finding eating unpleasant or for being indifferent to human offspring would not work out so well.

But does a mosquito have a sufficiently complex neural system for this kind of experience to evolve, or is biting people no more than an instinctive behaviour? Do mosquitoes have a subjective experience we can reasonably describe as liking the feeling of piercing skin? I cannot be certain that they do not, but I am doubtful; and I wonder how Prof. Leslie Vosshall thinks she knows they do.

Mosquitoes want to be good mums

I can understand how a good blood meal may allow a female mosquito to provide the nutrients needed for healthy eggs. But then as an adult human being I have the ability to engage in abstract thought – what is known as 'formal operations'. I have abstract concepts relating to nutrition, and reproduction, and I am able to link these concepts in patterns to see how sucking blood relates to a healthy brood (such as understanding how proteins from the blood can be broken down into the amino acids used to build up new proteins in the egg).

But does a mosquito really know it is to be a mum, and does it have any idea at all that its feeding activity is related to its reproductive activity? I really would take some persuading (by argument that is based on evidence, as is the way in science) that mosquitoes want to provision their offspring with the biggest meal possible.

I have seen it claimed that:

• female fish want males who can last until the babies are grown

I doubt this is literally true. Does a female fish have any concept of males, and does she actually know that she will spawn eggs that develop into 'baby' fish that (if not predated first, as most are) will grow into adults like herself? I am pretty sure the fish has no understanding of any of this, and simply follows instincts that have evolved, rather than having a preference based on a deliberate mothering strategy.

Could I be wrong about the fish?

Could I really be wrong about the mosquitoes?

Mosquitoes work things out for themselves

Two other claims here seem even more extreme. If I take Prof. Vosshall's comments literally then she thinks that mosquitoes worked out that (a) feeding off humans rather than plants was a good way to access dietary protein; and also that (b) humans sleep under mosquito nets which make them inaccessible, but that the humans will leave the nets behind when they go about daily activities, and so will then be more susceptible to 'bites'.

No, I am sorry – but I do not think that mosquitoes have any kinds of mental experiences that we would reasonably describe in these terms. We are reflective beings, that analyse situations in abstract terms; imagine possible futures; make plans, and (sometimes at least) act deliberately in accord with our reasoning. Our large, highly evolved, brains and the cultural representational tools – language and other symbol systems, that we, in effect, 'load up' as 'apps' during our extended development and enculturation – allow us to do this.

By contrast, an adult mosquito has a tiny brain, is not social, and lives to feed and breed for about a month if it is lucky. I do not think any mosquito has ever figured out anything about its nutritional requirements or the behavioural patterns of other species. I am happy to accept a mosquito has some kind of subjective experience, but not that it has abstract thought or reasoning. It reacts to behavoural stimuli, and perhaps engages in some level of learning – but it does not reflect on experience and reason things out.

It is just anthropomorphism

Do Profs Vosshall and Reece really think that a mosquito can have this level of awareness of its physiology and environment, and this reasoning power? Perhaps they do – they surely know a great deal more about mosquitoes than I do. But I suspect not. I suspect they are speaking figuratively – either deliberately or inadvertently.

'Curious Cases' is aimed at a general audience, not science specialists. It is possible that Profs Vosshall and Reece are deliberately seeking to use language that will engage and be accessible to the target audience. Alternatively, perhaps these scholars are so used to using this kind of language that they have fallen into habits of speech (and thought?) which were originally meant as a kind of shorthand, and so it does not occur to them that their audience may not share that assumption.

Is this a problem?

Anthropomorphism is one way of engaging young people with science – after all, all teachers seek to make the unfamiliar familiar by relating it to what learners find familiar. What we all find most familiar is being human – human experience. We experience the world as a human um965674welt, and we understand through human-developed concepts. We can help learners relate to other species by presenting them as if human-like beings in different bodies.

So, we are told that some bees realised meat was available and decided to stop being vegetarian; that butterflies can be shy; that a monkey is concerned about lack of protein in diet ; that some moths thought switching to eating clothes would offer a better life, and so on and so forth. (See Examples of anthropomorphism).

The problem is that these types of accounts are pseudo-explanations. They appear to explain natural phenomena, but they surely cannot be true. Yet we know learners often adopt these anthropomorphic accounts as if they are formal scientific explanations (so, a chemical reaction occurs because the atoms want to get full electron shells). Anthropomorphism may help introduce unfamiliar ideas about other species, but it can also act as an impediment to appreciating how these beings are different to us (Taber & Watts, 1996).

If we think that mosquitoes started feeding on humans because they appreciated the protein content of human blood, or that some species of moth decided after due consideration that eating clothes was the means to a better life, then we have an explanation for that phenomenon – but surely not a valid one.

So, I do not claim to know what it is like to be a mosquito, but I am pretty sure it is not quite like being a human. I would suggest that one human's experience is an imperfect guide to how other humans experience the world, and an even more imperfect guide to what it is like to be a chimp; let alone a bat, a dolphin, or an octopus. Certainly, I suspect human experience is a very limited and potentially misleading guide to what it is like to be a mosquito.

Because I have thought about these issues a lot over the years, I was primed to be immediately sceptical of the claims made by Profs Vosshall and Reece. But presumably most of the audience are not professional scientists. I just wonder how many of the listeners accepted these claims at face value, and thought they were learning robust scientific notions?

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¹ Learning a language is like mapping out an archipelago

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"A new born child certainly does not have to learn to make sense of sensory experiences entirely from scratch. The neural connections that develop to allow the processing of visual information, for example, develop in highly complicated ways apparently largely as a result of the unfolding of genetic instructions. We are hard-wired to be able to readily spot edges and movement in the visual field. However, it also seems that our brains are set up to recognise common patterns in sensory information, and to then in effect 'hard wire' themselves to subsequently expect and notice those patterns….

An example of this effect occurs in learning a language. The human vocal apparatus can produce a wide range of sounds, and only a selection of these are used in any particular language. One of the reasons learning a foreign language is sometimes so difficult is because of the need to hear and produce sounds quite unlike those familiar from ones native language. So the sounds used in a particular language are a bit like an archipelago of islands rising above the sea, if the sea is considered to represent the range of sounds that could be used in spoken languages. Different languages offer different patterns of islands.

Now when children are born they do not know in advance which language they will hear and learn – they have no map of the sea to show them where the local islands are. That would not matter if people were precise in speech production and all members of the same language community clearly produced precisely the same sounds. In practice people have different voices and sometimes only approximate the 'right' sounds when they speak. In effect, some of the sounds produced by people are not on the islands at all, but are like swimmers or even boats that are some distance from shore. Incredibly, as the young child hears its local language it comes to recognise similarities in the sounds used, and their brain in effect produces a map of where the islands are – the locations of sounds most commonly used as clumps on the map of the 'sound sea'. Once the map is developed the brain no longer treats each sound heard as being like a map grid reference, but assigns it to the relevant island. Those sounds which occur off-shore (so to speak) are also assigned to the closest island and considered to be located there.

This process means that the person's perception of vocal sounds changes so that they in effect only hear the sounds expected in their language community, even when speech production is not perfect. To shift metaphors, the effect is like having an automatic spell-checker on your email in-box. People might send you mis-spelt messages, and occasionally you may be sent email written in a different language to your own, but (due to the spell-checker) when you open your emails you always find everything is perfectly spelt. Of course, a spell-checker only makes best guesses, so sometimes sentences do not make sense when the wrong spelling is selected automatically, or a word not in the spell-checker's dictionary is replaced, or entire swathes of another language are rendered into a nonsense string of local words.

This effect has been demonstrated using sound synthesisers that can produce fine variations in sound. These can be set up to produce a whole sequence of sounds that gradually shift between two sounds that are used in local spoken language – say a 'p' sound and a 'b' sound. The synthesizer starts with a canonical 'p', say and then shifts slowly to a canonical 'b' in a similar way to software which morphs between different images. However what is perceived is not a gradual morphing. Although an oscilloscope display will show a gradual change in the waveform being produced, the person will hear a string that sounds like p-p-p-p-p-p-p-p-p-p-p-p-b-b-b-b-b-b-b-b-b-b-b-b-b-b. The person's brain first recognises the sounds as being closest to the 'p' island, until a point when it 'decides' they are closer to the 'b' island. Of course this 'decision' is made completely pre-consciously – the person is conscious of repeats of one letter which suddenly shifts to being a different letter (even though there is actually no sudden shift in the sounds, but just a very gradual variation across a spectrum between the two endpoints). We are all familiar with the person with the speech defect or the person with a strong accent who is difficult to understand, but generally our brains present to us speech as if people are producing the same canonical sounds, filtering out much of the variation due to age, gender, and so on. [The figure above] offers a visual analogy of this phenomenon:"

Taber (2014)

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Work cited:

• Nagel, Thomas (1974). "What Is It Like to Be a Bat?". The Philosophical Review. 83 (4): 435-450. doi:10.2307/2183914
• Taber, Keith S. (2014). Student Thinking and Learning in Science: Perspectives on the Nature and Development of Learners' Ideas. New York: Routledge.
• Taber, K. S. and Watts, M. (1996) The secret life of the chemical bond: students' anthropomorphic and animistic references to bonding, International Journal of Science Education, 18 (5), pp.557-568. [Download the article]

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