The Best Australian Science Writing 2014 Page 19
True, it is possible that these shared pet addictions, although practically universal, were culturally driven. But how then to explain Geronimo’s pet cat? The elderly Apache warrior adopted and doted on a tabby while imprisoned by the US government at Fort Sill. Yet Geronimo was born into a culture famous for encouraging its children to torture animals. What could have softened the grizzled old fighter’s heart if not an instinctual human propensity to love pets, released when those cultural constraints were lifted?
If there is a universal human instinct to love pets, however, it must have arisen early in our evolution, certainly before our dispersal from Africa. What evidence is there that it did? DNA analysis using molecular clocks is not much help, giving dates that vary from 100 000 to 24 000 years before the present. The archaeological record, too, is unfortunately of little help.
I’m going out on a limb here, however, to say that I think there were such pets. Here’s why.
The intuition first hit me while trudging up a small sand dune in the broiling heat of the Pilbara desert. I’d been walking all day with a Mardu elder man, Djalego, looking for Aboriginal archaeology. We came across a dingo mother’s den instead, dug into the sand in a tangle of mulga roots.
‘Tingku [dingo] bitch move ’em pups last night time,’ Djalego announced, surveying the tracks at the den mouth. He flashed me a wide grin. ‘Lucky for her – I take ’em back for kids if I find ’em.’ He would, I knew, have been as good as his word. Djalego’s community at Jigalong is thronged with mobs of halfloved, half-feral mutts ranging from chihuahua to dingo and anything in between. Tribal peoples everywhere have always had such encounters – British explorer Samuel Hearne, for example, reported in the 18th century that Inuit hunters would often dig into wolf burrows simply to play with the cubs, sometimes even painting their faces with ochre and vermillion, before either returning them or taking them back to camp.
That’s when it struck me – possibly because the Australian desert is so reminiscent of African savannah, with its tawny spinifex standing in for grasses and gnarled mulga for acacia scrub – that this scene must have played out tens of thousands of times in our ancestors’ two million or so years on the African savannah. We know Homo ergaster and erectus ranged roughly as far as modern hunter-gatherers, and that their similar growth trajectories mean they would have had ‘kids at home’ too. Why, then, wouldn’t they have raided the occasional Lycaon sekowei den (the Pleistocene ancestor of the African Painted Wild Dog) and taken a cute and cuddly little piebald bundle back home for their own erectus tots? To say nothing of warthog piglets, sabretooth kittens, impala kids, or any of the multitude of potential pets out there on the African savannah.
One thing bothered me, however. Although Djalego had said the pups would be pets, were they perhaps really slated for another role – hunting? Dingoes are commonly assumed to be great aids to Aboriginal hunters; many proponents of the ‘animal connection’ hypothesis believe wolves co-evolved with early hominins in the same role. Might Djalego have been actually intending to use the dingo pups for tracking prey with his kids’ fun being just a side benefit? He quickly disabused me of the notion. ‘Tingku bark too much, scare off that malu [kangaroo],’ he said, miming a hunter missing his rifle shot.
Anthropologists’ accounts show his experience is universal. Hunts using dingos invariably end in farce, the dog tearing disobediently off out of sight to the tune of shouted curses from the hunters, only to emerge from the scrub hours later with a bloody muzzle to show it has hunted and eaten well, even if its owner hasn’t. Even the lovable, lolling half-breeds of Jigalong and other communities are useless: the only dogs Aboriginal people have ever successfully hunted with were purpose-bred domestic breeds, like the famous ‘kangaroo dogs’, bred from British deerhounds and greyhounds, used in colonial-era Tasmania.
This is also, incidentally, why the co-evolution hypothesis of wolf/human hunting collaboration is almost certainly wrong. For wolves are even wilder than the dingo. Given that no hunter-gatherer group in history has ever been found to use wolves or any other wild canid for hunting, it seems unlikely that Homo habilis, ergaster or erectus did either – even for the scavenging that may have been their main subsistence.
If they did pick up kits, pups, piglets or other assorted adorables, out there on the savannah, they did it for the same reason Djalego did: love.
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The love of pets might indeed, to paraphrase Anatole France, have awakened the Homo erectus soul, but how, again, could we know it was there if it doesn’t show up in the archaeological record?
There is one way: by looking for analogues in animals close to our ancestors. We may be the pet-keeping species but there are intriguing hints that chimps and bonobos would join us in the cross-species affection club if they could. Two Swiss researchers in Tai National Park, Ivory Coast, saw four young chimps playing with an intensely alarmed young duiker, trying to give it piggyback rides – just like an infant chimp. And primatologists in the central region of the Democratic Republic of the Congo saw even more elaborate behaviour.
In one four-week period, they saw two male bonobos in three separate incidents playing with infant monkeys of two unrelated species – the Angolan colobus and the red-tailed monkey. Again, the apes tried to piggyback their unwilling playmates, just like young bonobos, and when they didn’t cooperate, they groomed them. In other words they petted them.
Unfortunately, chimps and bonobos are far too wild and violent for this cross-species pet play to ever succeed: most of these proto-pets died from their ‘games’ within the hour. Yet the apes clearly find their unfortunate playmates ‘cute’ in just the same way we do our pets. Their behaviour is also obviously, in intent at least, a primitive attempt at pet-keeping. It is affectionate, playful, and aimed at keeping the ‘pet’ with its ape ‘owner’. But what motivates it? The clue lies in the chimps’ pseudo-parenting behaviours. They groomed their animal charges as if they were real ape babies, played with them like babies, and even tried to make them piggyback ride like real baby chimps and bonobos.
The cuteness that makes a chimp or bonobo pick up and cherish (or attempt to, despite their klutzy violence) a non-related animal pet is apparently that pet’s ability to trigger parenting behaviours in its ape ‘owner’. This is clearly unwelcome and no evolutionary advantage at all to an Angolan colobus or duiker infant. It will, in fact, probably eliminate it from the gene pool in minutes. But what if a pet animal was able to make an owner pick it up who could carry it gently away, who would feed it titbits, and who would keep it warm (when it invented fire), and dress its fur with custom kitty-comb grooming gloves in front of the TV (when it invented those) too?
The fact that our pets make us love them by hijacking our parent/infant bond will be no shock to most proud fur-baby owners. It is to any self-respecting Darwinian theorist, however. Why hasn’t natural selection weeded out this surprising, anti-evolutionary vulnerability?
There is one possible answer from zoology. Konrad Lorenz wrote extensively about fixed action patterns (FAPs), instinctive behaviours in animal parents automatically triggered by actions of their young that Lorenz called releasers. Adult African painted dogs, for example, involuntarily regurgitate food (the FAP) when their pups lick their muzzles (the releaser). A newborn kitten’s first poop, similarly, prompts its mother to eat it (the faeces, that is, not the kitten). Some FAP releasers, however, are shared across species. One of the most important, according to Lorenz, is the suite of physical characteristics common to most mammal infants – large eyes, broad and vertically squashed faces, and reduced nose and jaw size. Lorenz called this set of releasers the baby schema. One glance from those impossibly big-eyed cuties, he said, was enough to ignite hormonally driven parenting FAPs in mammals as diverse as marmots and musk oxen.
Not to mention Homo domestica bestia alitura, the pet-keeping species.
The baby schema evolved because in normal circumstances it works. Any big-eyed, short-faced fluf
f-ball a mammal parent runs into usually is indeed its offspring. If it’s not, other FAPs based on scent or behaviour commonly weed the impostor out. Yet as those Congolese bonobos show, every now and then, when species collide, the baby schema can make things get weird. It seems, for example, to trigger the parenting FAP in chimps and bonobos, at least occasionally, no matter what species it’s on. And intriguingly, although apes can identify which young are not their own through smell (as can we), even that doesn’t seem to stop them. They not only play with these cross-species pets, but also frequently adopt non-related chimp or bonobo infants, so strong is their baby schema FAP response.
However cute some FAPs are, though, they also have a sinister side. Because they’re fixed and instinctual (meaning the animal can’t stop doing them, even if they’re compromised), FAPs are a prime target for parasites. Parenting FAPs, for example, are often exploited by brood parasites, who trick the host into raising the parasite’s young by hacking that host’s FAP’s releaser code. The classic examples are the cuckoos, who exploit the ‘worm-dropping’ FAP of their reed warbler and cowbird hosts – their compulsion to drop food into the nearest gullet when they see it gape and hear its owner cheep. When a cuckoo smuggles its egg into the host’s nest, of course, the cuckoo chick’s superb mimicry of the ‘gaping, cheeping’ releaser allows it to divert a portion of those worms to itself.
We humans turn out to be every bit as prone to FAPs provoked by infant releasers (in our case, the baby schema) as other animals. Just glancing at a human baby’s cute, big-eyed little face, for example, provokes immediate, involuntary activity in our zygomaticus major – our smiling muscle. The activity also gets more intense, not less, the longer we look. Baby faces similarly provoke an involuntary change in our voices. We start talking in high-pitched, phonically exaggerated ‘baby talk’. Infant faces have also been shown to completely bypass our normal visual processing system and instead directly access the most basal reward regions of the brain: the cingulate cortex, basal ganglia and thalamus.
To top it all off we’re also just as easily fooled by brood parasite impostors as those befuddled reed warblers. Studies show, for example, that exposure to the cute faces of our pets triggers parental FAP reactions in us indistinguishable from the authentic thing. (If anything, we’re even less discriminating since our cuteness sensor can even be stimulated by inanimate, baby-faced objects like car fronts.) We’re not faking it, either: urinary tests show we get the same surge of bonding hormones, predominantly oxytocin, from patting pets that we do from touching human babies. That’s probably why around 83 per cent of us, in one recent survey, confessed that we do secretly view our pets as actual children.
This is a remarkable feat of brood parasitism. How have our pets pulled it off? Their secret seems to lie in the ‘supernormal’ releasers they have evolved – FAP triggers so powerful they make a host prefer its brood parasite’s young to its own – to keep us in thrall. Dogs’ and cats’ faces, for example, do not grow out of the baby schema the way ours do; even old cats and dogs still look a little baby-like. They are, what’s more, becoming more so the longer they live with us. Dogs’ snouts, for example, have been getting shorter, their skulls broader, and their eyes proportionally larger and more forward facing over the last 30 000 years – even before we created faux-baby breeds like chihuahuas. Behaviourally, too, dogs out-baby real babies. They’re hyper-responsive to human gestures and expressions. Experiments show, for example, that they study human faces intently for problem-solving hints, and understand pointing gestures better even than chimps. Crucially, they never stop doing so, while all human parents eventually face the trauma of becoming invisible to their kids. Exposed to supernormal stimuli like these, is it any wonder many of us report feeling more empathy for pets than for children, and that many married pet owners admit to secretly loving their pet more than their spouse?
So has human history since the Pleistocene possibly been nothing but a succession of pats along the road to our animal companions’ rise to the status of parasitic master race? Were we done for the moment that first Homo habiline or erectine stooped down to pluck that first cuddly fur ball from its nest, den or burrow? I say yes. For a while, a million and a half years or so, we were protected by our sparse population. We were still too few to form a real niche in which our proto-pets could diverge genetically from their wild relatives and evolve into obligate human parasites (species that can’t live without us). Instead they almost certainly did what captured full-blood dingoes do today: spent their youth in camp before melting back into the wild as adults. Our real, headlong plunge came when we started living in semi-permanent settlements around 20 000 years ago. It was only then that the wolves and wildcats, which would become our dogs and cats, could settle down for their whole lives too and begin their evolution into the most successful love parasites the world has ever seen. And once they’d done that the rest, like us, was history.
This is Peter McAllister, last survivor of the planet of the pets, signing off.
The carnivorous platypus
Uniquely human
Penis size may be driven by women (Oh, and it matters …)
Rob Brooks
How important is penis size? Authors from the Australian National University, Monash and La Trobe recently provided the most complete answer yet: the size of a flaccid penis can significantly affect how attractive a man’s body is to women.
Writing in the Proceedings of the National Academy of Sciences (a journal commonly known by its initials as ‘PNAS’), Brian Mautz, Bob Wong, Richard Peters and Michael Jennions use a clever experimental manipulation of computer-generated imagery (CGI) to test the effects of variation in penis size relative to height and torso shape (shoulder width relative to waist width) on the attractiveness of male bodies to women. While they found that torso shape was by far the most important determinant of attractiveness, penis size has about as much influence on attractiveness as height.
It’s the kind of science made for easy-reading hundred-word news-porn in the tabloid press (‘Size really does matter’). Or for wowser columnists to work up a morning’s indignation that a scientist somewhere did something interesting when everybody knows the rules: scientists should be finding new ways to extract coal-seam gas or cure the cancers that tend to afflict late-middleage columnists (as in the controversy in March 2013 when Fox News attacked Patricia Brennan’s research on duck penises). If Tom Waterhouse wasn’t so busy swotting for Friday night football, he’d have already installed Mautz as hot favourite for the next igNobel Prize (for science that makes you laugh and then makes you think).
And yet for such a tabloid-ready topic, the paper itself is a study in how science should proceed in sober and restrained steps.
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Genitalia tend to vary more dramatically than almost any other physical trait. And evolutionary biology has made stunning progress in resolving why.
For the most part, studies of animal penis size and shape have focused on the effectiveness of various structures in delivering sperm to where it needs to be, in removing sperm that a female had received from previous mates, in stimulating the female to use that male’s sperm, or even inflicting damage on the female so she would not mate again.
One of the more striking features of the human penis, when compared with other primates, is its length. Relative to body size, the human penis dwarfs that of bonobos, common chimpanzees, gorillas and orangutans. And our erect stance and face-to-face social interactions make the penis a highly conspicuous feature.
That conspicuousness has led anthropologists and popscientists alike to speculate on the potential for penises to act as a sexual signal. Some have even suggested that a large penis may be a signal of more general health and vigour, and that the evolutionary loss of the human baculum (penis bone) may make the penis an honest signal because size and arousal can’t be faked.
The function any preferences for penis size serve remains, for now, largely in the province of hypo
thetical speculation. Because much murkiness surrounds whether such preferences exist and, if so, just how important those preferences are.
* * * * *
Titillating news stories, fictional references and even song lyrics speak to a persistent fascination with properties of the penis. That fascination hints at a deeper, largely unspoken obsession with the links between size, virility, masculinity and attractiveness. Some might say that penis size presents an exclusively male obsession, pointing to the importance of embellishments such as Renaissance codpieces and New Guinea phallocarps in male– male interactions. Are not men at least as obsessed about questions of size as women?
Unfortunately for this line of argument, men are expected to obsess about precisely the traits that women – overtly or subtly – use to discriminate among their mates. And a strong whiff of male insecurity about how women are likely to judge their equipment inheres to most public discourse about penis size.
Consider what I call the Goldilocks cop-out. Most media stories on the topic of penis size conclude that as long as the penis in question isn’t way too big or way too small, it’s likely to be ‘just right’. Within the large zone of ‘just-rightness’, few commentators are willing to claim that size really matters. The Goldilocks cop-out mollifies male insecurity.
If evolutionary psychologists are right – and I believe they are – then men’s obsession with paternity presents a tectonic force shaping behaviour and societies. It doesn’t take much imagination to see that part of that insecurity can be bound up in fears about penile inadequacy.
Makers of penis enlargers promising ‘extra inches’ and purveyors of nasal snake-oil guaranteeing ‘longer-lasting sex’ exploit those fears. Fears that they will never attract a mate. And fears in those who already have a mate that they might inadvertently be raising another man’s progeny.