Ah, but what about less cooperative behaviours? Humans grow cattle for meat, for instance, and bred our plants to suit our needs instead of theirs. With altruism, you could argue that both parties are coming out ahead; with farming, one side is getting far more out of the bargain. Are we the only ones clever enough to bend evolution in our favour?
Certainly not! The leaf-cutter ant farms fungus. Worker ants venture out to collect leaves, return to the nest with their haul, chew them into small pieces, and finally feed the fungal matter carefully growing within. They manually keep the crop parasite-free, and make use of anti-mold bacteria specifically targeted against the greatest threat to their harvest, the Escovopsis mold. Surprisingly, the ants have prevented this pest from evolving a resistance to its poison, a trick that we big-brained humans have yet to figure out. Remove the ants from the equation, and the fungus is completely overrun by Escovopsis within days.
Aphids are also farmed by ants. They will be carried out of the nest to a leaf, protected from predators while they feed, then carried back in when the ants retreat for the day. When stroked by the ants they will release a sweet nectar called honeydew. The queens of the yellow meadow ant will even take an aphid egg with them as they jet off to start a new colony. [insert references here]
What pushes this from mutual co-operation to true farming, however, is the harm the ants inflict on the aphids. They secret a chemical on their feet that impairs the ability of the aphids to walk. Their glands produce a chemical that prevents aphids from growing wings, to prevent their “cows” from flying away. If that fails, they simply rip out the wings.
Beavers outright kill their helper. They chew down trees to create dams and lodges, creating deep ponds that are more beaver-friendly.
You might argue these to examples are cheating on my part. Our instances of farming are not instinctual, but instead carefully planned. If you lock a beaver in a bare room, for instance, it’ll start building a phantom dam with invisible wood. That’s a fair point, but it also implies that farming doesn’t take any brains to pull off, which ruins its use for the Intelligence proof.
The used car salesman is an American cliché that comes from a grain of truth. Few people know how to fix cars, let alone have the time, tools, and training to properly inspect an auto. Buyers are forced to trust the salesmen, which gives the latter a big advantage. It is all too easy to repair a car just enough to get it running, and turn a blind eye to the expensive but hidden problems that won’t blow up immediately. By the time trouble hits, the salesman may have skipped town, or swear the buyer must have mistreated the car and wants to blame someone else for their mistakes.
Lying relies on a lot of high-level skills. The liar has to act according to a reality that doesn’t exist; not only does that require a mental model of how the universe works, but that model has to be sophisticated enough to model other mental models. With so many layers of misdirection, it must be a human-only thing.
Except I’ve already mentioned Santino the chimpanzee, who is infamous for pelting unwary visitors with rocks. Back then, I conveniently failed to mention why he’s managed to keep surprising his keepers.
On the day after he played cool, Santino twice repeated his usual pattern: freak out to show dominance when he saw a tour group approach, only to fizzle out in frustration as the group stayed out of throwing range but failed to submit. The third group found Santino calmly resting on a bed of hay, near the edge of his pen, with no rocks in sight. Again, the tour guides declared the coast to be clear and brought the group in for a close look. When they were within throwing range, Santino reached into his bedding, pulled out a few rocks he’d hidden there, and began pelting the hapless group. He kept doing this throughout the year, but sometimes hid the rocks behind a log.
Santino is a master liar. He was able to suppress his desire to show his dominance, and hide the tools he used as enforcement, long enough to trick another species famed for its lying.
[insert section on antelopes faking predator calls for sex]
The male antelopes, observed in southwest Kenya, send a false signal that a predator is nearby only when females in heat are in their territories. When the females react to the signal, they remain in the territory long enough for some males to fit in a quick mating opportunity.
The signal in this case, an alarm snort, is not a warning to other antelopes to beware, but instead tells a predator that it has been seen and lost its element of surprise, the researchers found.
So when the scientists observed the animals misusing the snort in the presence of sexually receptive females, they knew they were witnessing the practice of intentional deception – a trait typically attributed only to humans and a select few other animal species.
So What’s Left?
I’ve racked my brains, and so far I can’t think of anything within them that isn’t partially present in some other species. It’s entirely plausible for our intelligence to be a product of evolution, and so I can invoke Ockham’s Razor.
There’s still one nagging problem. No other animal exploits their intelligence to the degree we do. While I’ve had little difficulty finding bits and pieces of intellect scattered around the place, no-one seems to have mastered them like we have, let alone collect all of them under one brain. Even if the pieces of intelligence existed before we did, isn’t our combination and amplification of them into a cohesive whole a sign of divine nudging?
There are two big flaws in this argument. First, it assumes our species jumped to prominence from humble beginnings alone. In fact, we were competing against at least three other braniacs: Homo Erectus, Homo Neanderthalensis, and Homo Florensiensis. Secondly, it views evolution as a sort of “ladder of life,” where species grow increasingly complex in a linear fashion, conveniently ending with us.
As I point out in the chapter on the Design proof, evolution is nowhere near that tidy. Rewind the clock back 40,000 years ago, and all three of our Homo cousins were competing with us. While all four shared a common ancestor two million years prior, there’s no evidence that they could interbreed at that time. Even though the four of us looked very similar, we were distant cousins like chimpanzees and bonobos currently are. All four of us used tools better than any other species that came before. At least two of us could sail the seas, Florensiensis and Sapiens Sapiens, and there are hints that Erectus might have beaten both to the shipbuilding business. Erectus also earns a medal for being the first to create fire, and were the first of our line to build houses. For a long time, Sapiens Sapiens and Neanderthalensis swapped tools and goods. Neanderthalensis in particular is famed for building decorated houses and burying their dead, perhaps even creating their own animal traps, jewellery, and body paint. Yet the most successful of us all, Erectus, had the intellect of Alex the parrot. The species with the biggest brain was not Sapiens Sapiens, but Neanderthalensis; 1.8 litres worth, for the record, to our 1.4.
We shouldn’t be asking why one species alone has been granted superior intellect, we should be pondering why the most successful wasn’t smart, and the smartest one didn’t win!
One objection is that we’re a young species, and haven’t been given the same chances as Erectus had to prove our longevity. I’m a little dubious at this, given the number of nuclear missiles we have on a hair trigger and our lousy attempts at managing climate changes that we’ve created, but overall I think the point has merit.
The Neanderthalensis skull is a tougher nut. One argument is that they weren’t as smart as their brain size would indicate, since they had difficulty speaking. Robert McCarthy from Florida Atlantic University found some evidence they couldn’t pronounce “E.” That letter serves as an “anchor” for all of our languages, and since language was so important for our success that could be counted as a handicap.
However, that assumes there’s only one way to craft a language; Steven Mithen, for instance, proposes they instead mixed together singing and speech. I’ll also note that whales and prairie dogs have no difficulty communicating through languages completely unlike our own.
Proving that a long-extinct species was able to talk is clearly quite difficult, and can only be approached by piling up heaps of circumstantial evidence. The Neanderthalensis hyoid bone is nearly identical to ours, and this bone is essential to form the wide range of sounds that our verbal languages crave. The nerve that shuttles signals between brain and tongue is also a close match in both species. Their genome may also have contained a human-like FOXP2 gene, an essential part of our language skills.
Recently, David Frayer and his colleagues at the University of Kansas discovered an interesting pattern. Imagine you want to scrape an animal hide clean using simple stone tools. In order to do this properly the hide has to be stretched tight, but suppose there are no other human beings around to help you pull, and no giant stones or frames are around to give you a hand. The easiest solution is to grip one end of the hide in your teeth, pull it tight with one hand, and scrape away with the other. If you have a dominant hand, you’ll likely use that hand for scraping and the other for pulling; otherwise, you’d just pick any old combination. Since accidents happen, you’ll occasionally smack your teeth with the stone tool, creating permanent little nicks in your front teeth. The direction of these scratches will depend on the hand you’re holding the tool in. These marks are small, but still large enough for anthropologists to spot.
I think you can see where I’m going with this. About 93% of all Neanderthalensis individuals had distinctly more down-right nicks on their front-most teeth, which suggests they were right-handed. What might not be obvious is why I’m headed that way.
Many of you may know that about 90% of all Sapiens Sapiens individuals are right-handed. Most of you have also heard that our brains are lopsided; language processing tends to be on the left-hand side of our brain, which corresponds to the right side of the body. The leading theory of handedness claims that having two areas for fine motor control mirrored across the brain is less efficient than cramming it all on one side, because neuron signals have more distance to travel and the two sides could give conflicting orders. Since both hand manipulation and speech require fine motor control, they get shoved to one side. Thanks to the mirroring of the body, this gives an advantage to the opposite side of the body, and most of the time genetics gives the nod to the right side. Fewer of you will know that many other animals also tend to favour one hand, paw, or flipper. About 60% of Chimpanzees, for instance, favour their right hand.
Interestingly, scientists have observed a link between higher brain function and handedness, and have also noted that no other species exhibits the same degree of bias we show. In other words, no other species of animal has 90% of them favouring a single side.
Well, up until David Frayer did some digging. And since handedness is linked to higher brain function and complex tasks, this strongly suggests Neanderthalensis was our intellectual peer, and weakly suggests they were equally adept at language.
So why did they, or for that matter Florensiensis or Erectus, go the way of Raphus Cucullatus?
I suspect the real reason was luck. We traded tools with Neanderthalensis, which gave both our species a crucial leg up on the rest of the family. Both of us also lived in a more bountiful biome that gave ample spare time to refine our tools and practice co-ordinating with one another. This weeded out all but our Neanderthalensis buddies, until climate change rolled in. Their larger bodies required more calories to sustain than ours, and around the time of their extinction an ice age caused the climate to wildly swing around. This would have been devastating to a species that lived in woodlands and hunted by surprising prey, but not so bad to one that liked grassland and chased down their food. Neanderthalensis was starved out of existence, leaving us all alone.
While this line of thought seems plausible, it still has gaping holes. Why didn’t Neanderthals simply move to the more fertile plains and shove the weaker Homos out? They survived multiple ice ages, so why was the last one so fatal for our bigger-brained cousin? There’s also some evidence they subsisted on plants, contradicting earlier claims that Neanderthalensis lived solely on meat, and suggesting they were more adaptable to food changes than we thought.
Science, alas, has not provided us with an answer yet. But it knows enough to suggest our intelligence is not so much a god’s touch as a lucky break.
 I can think of one exception: plunk a human being down in front of a television. Flash them the numbers one through nine, scattered about randomly on the screen, for one second, then replace them with white squares. Ask us to select those white squares in ascending order of the numbers behind them. Almost all of us will fail before we get to our second number, even with training; Tetsuro Matsuzawa handed the same test to chimps, and after training them to settle down in front of the telly, they could repeatedly nail every number.
 There’s some controversy over how to classify Erectus, with a few palaeontologists wanting to break them up into an Asian-only group with H. Ergaster taking over the African/European half. Recent human ancestors are incredibly difficult to classify, since their bones are nearly identical to ours yet too old for genetic tests.
 As usual, there’s controversy over this species too. Some palaeontologists think they were diseased Sapiens Sapiens, though this seems to be a minority view. The bones we’ve found are uniquely fresh and well-preserved, compared to the remains of our other cousins, so genetic testing may solve this dispute.
 Recent genetic tests suggest we may have had a little cross-species action roughly 65,000 years ago, but nothing since. Some archaeologists, however, point to much later skeletons which apparently show a mix of Neanderthalensis and Sapiens Sapiens traits. Both of them could be right; there may have been a hybrid population that went extinct, leaving us relative purebloods to be the last species standing in the Homo line. More recent research has cast doubt on those findings, though, suggesting instead that those shared genes really came from our common ancestor. Separating fact from speculation will take a few decades, unfortunately, and only if the geologic record permits.
 http://www.huji.ac.il/cgi-bin/dovrut/dovrut_search_eng.pl?mesge122510374832688760 [better citation needed: more recent research pins it at 1mya]
 Erectus had survived nearly two million years by then, and spread over much of Africa, Europe, and Asia. In contrast, genetic testing has shown Sapiens Sapiens nearly went extinct within the last 100,000 years; there were roughly 10,000 individuals alive at that point, making our entire species somewhat inbred.
 Right handed Neandertals: Vindija and beyond; David W. Frayer et al, Journal of Anthropological Sciences, volume 88, pp. 113-127
 There are some big problems with this theory; a minority of left-handed people process language equally on both sides of the brain, for instance. Still, the basic pattern holds true for 95% of all right-handers, so this explanation is likely half-true.
 Chimpanzees (Pan troglodytes) Are Predominantly Right-Handed: Replication in Three Populations of Apes; William D. Hopkins et al, Behav Neurosci, 2004 June.
 The Dodo was a very trusting bird that we “Wise Men” decided to club into extinction on a lark.
 On the mainland, anyway. Florensiensis managed to outlive Neanderthalensis by hanging out on tropical islands, which insulated them from climate shifts but limited their food choices. Only they know the true reason for their extinction, unfortunately.
 Energetic Competition Between Neandertals and Anatomically Modern Humans , Andrew W. Froehle and Steven E. Churchill, PaleoAnthropology 2009: 96−116
 Microfossils in calculus demonstrate consumption of cooked foods in Neandertha diets, Amanda G. Henry, Alison S. Brooks, and Dolores R. Piperno, PNAS January 11, 2011 vol. 108 no. 2 486-491