On human uniqueness and invasive species.

On human uniqueness and invasive species.

We like to see ourselves as special.  “I am a beautiful and unique snowflake,” we’re taught to intone.

Most of the time, this is lovely.  Other than the U.S. Supreme Court, hardly anyone thinks you should be punished for being special.  Of course, the Court’s opinion does matter, since the ignorant claims of five old rich white men have an inordinate sway in determining how U.S. citizens will be allowed to live.  And they, the conservative predecessors of our lockstep quartet (soon to return to a quintet) of hate machines, oft feel that the beautiful snowflakes should melt in prison.  In McCleskey v. Kemp, the court decided that statistical evidence of injustice should not be admissible as evidence; they would only consider documentation of deliberate bias in individual cases.

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Unique when you are on trial, now orange & a number.  Photo by Joel Franusic on Flickr.

Which means, for instance, that if a police force decides to systematically harass black drivers, and winds up stopping hundreds of black drivers and zero white drivers each month, they’re in the clear as long as each black driver stopped was violating some portion of the traffic code.  At that point, each black driver is a unique individual lawbreaker, and the court sees no reason why their experiences should be lumped together as statistical evidence of racial injustice.  Adolph Lyons, after being nearly choked to death by an L.A. police officer, could not convince the courts that the L.A. police should stop choking innocuous black drivers.

Lovely, eh?

So it can hurt if others see us as being too special.  Too distinct for our collective identity to matter.

At other times, we humans might not feel special enough.  That’s when the baseless claims get bandied about.  For instance, K recently received a letter from Stanford’s Graduate School of Education pontificating that “Only humans teach.”  A specious example is given, followed by the reiteration that “Only humans look to see if their pupils are learning.”  Which simply isn’t true.

But people feel such a burning desire to be special – as individuals, as fans of a particular sports team, as people with a particular skin color, or as people who follow a particular set of religious credos – that an ostensibly very-educated someone needed to write this letter.

That’s why the occasional correctives always make me smile.  For instance, research findings showing that other animal species have some of the skills that our sapiens chauvinists oft claim as uniquely human, or other data indicating that humans are not as exceptional as we at times believe.

Consider our brains.  For many years, we thought our brains were anomalously large for the size of our bodies.  The basic rationale for this metric was that more brain power would be needed to control a larger body – this seems tenuous if you compare to robots we’ve created, but so it goes.  Recently, a research group directed by Suzana Herculano-Houzel counted how many actual neurons are in brains of different sizes.  Again comparing to human creations, computer scientists would argue that more neurons allow for more patterns of connections and thus more brainpower, somewhat comparable to the total number of transistors inside a computer.

As it happens, no one knew how many neurons were in different creatures’ brains, because brains are very inhomogeneous.  But they can be homogenized – rather easily, as it happens.  I did this (unfortunately!) with cow brains.  These arrived frozen and bloodied; I’d smash them with a hammer then puree them in a blender till they looked rather like strawberry daiquiri.  For my work I’d then spin the soupy slushy muck so fast that all the cell nuclei pelleted on the bottom of centrifuge tubes, ready to be thrown away.

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After a spin in the blender, all brains look the same. Photo from Wikipedia.

Alternatively, one could take a sample of the soup and simply count.  How many nuclei are here?  Then stain an equivalent sample with antibodies that recognize proteins expressed in neurons but not the other cell types present in a brain: what fraction of the nuclei were neurons?  And, voila, you have your answer!

Gabi et al. did roughly this, publishing their findings with the subtly anti-exceptionalist title “No relative expansion of the number of prefrontal neurons in primate and human evolution.”  We have more neurons than smaller primates, but only as many as you’d expect based on our increased size.

zombie-starfish(Perhaps this leaves you wondering why gorillas rarely best us on human-designed IQ tests – as it happens, the other great apes are outliers, with fewer neurons than you would expect based on the primate trends.  Some of this data was presented in a paper I discussed in my essay about the link between “origin of fire” and “origin of knowledge” myths.  In brief, the idea is that the caloric requirements of human-like brainpower demanded cooked food.  The evolutionary precursors to gorillas instead progressed toward smaller brains – which happens.  The evolutionary precursors to starfish also jettisoned their brains, making themselves rather more like zombies.)

Perhaps all these brain musings are an insufficient corrective.  After all, humans are very smart – I’m trusting that you’re getting more out of this essay than the average hamster would, even if I translated these words into squeaks.

So let’s close with one more piece of humility-inducing (humiliating) research: archaeologists have long studied the migration of early humans, trying to learn when Homo sapiens first reached various areas and what happened after they arrived.  Sadly, “what happened” was often the same: rapid extinction of all other variety of humans, first, then most other species of large animals.

All the Neanderthal disappeared shortly after Homo sapiens forayed into Europe.  There are reasons why someone might quibble with the timeline, but it seems that Homo erectus disappeared from Asia shortly after Homo sapiens arrived.  The arrival of Homo sapiens in Australia brought the extinction of all large animals other than kangaroos.  The arrival of Homo sapiens in South America presaged, again, a huge megafaunal extinction.

On evolutionary timescales, we are a slow-moving meaty wrecking ball.

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Bad as we are, we can always get worse. My country! Picture by DonkeyHotey on Flickr.

And our spread, apparently, resembles that of all other invasive species.  This is slightly less derogatory than the summation given in The Matrix – “[humans] move to an area and … multiply and multiply until every natural resource is consumed and the only way [they] can survive is to spread to another area.  There is another organism on this planet that follows the same pattern.  Do you know what it is?  A virus.  Human beings are a disease, a cancer of this planet.” – but only slightly.

Upon the arrival of Homo sapiens in South America, we quickly filled the entire continent to its carrying capacity, and then, after the invention of sedentary agriculture – which boosts food production sufficiently for an area to support more human farmers than hunter gatherers – resumed exponential population growth.  Although the switch to an agricultural lifestyle may have been rotten for the individual actors – the strength needed to push plows makes human sexual dimorphism more important, which is why the spread of agriculture heralded the oppression of & violence against women throughout human history – it’s certainly a great technology if our goal is to fill the world with as many miserable humans as possible.

We’ll be passing eight billion soon, a population inconceivable without modern farming technologies.  And likely unsustainable even with.

Not, again, that this makes us unique.  Plenty of species are willing to breed themselves into misery & extinction if given half the chance.  Almost any species that follows r-type population growth (this jargon signifies “quantity over quality”) – which oft seems to include Homo sapiens – is likely to do so.  My home town, wolf-less, is currently riddled with starving, sickly deer.