August 25, 2012 | David F. Coppedge

Ingenious Ants Can't Prevent Stupid Evolution Quotes

After praising the wisdom of the ant, a science writer reveals little of his own.

The date is August 21.  The place is Current Biology.  The perpetrator is Michael Gross, a science writer at Oxford.  For 30 paragraphs, he dazzles readers with the wonders of the ant brain.  In “How Ants Find Their Way” (Current Biology, Volume 22, Issue 16, R615-R618, 21 August 2012, doi:10.1016/j.cub.2012.08.004), he waxes eloquent about how smart the ants are and how little we humans know about how they navigate. Then, in the only mention of evolution in the article, Gross commits a serious logical faux pas – best appreciated after a look at the amazing ant.

Surely each of us, pestered as we might be about ants in the kitchen, has marveled at how they so quickly establish their trails – communication networks that may traverse many meters (a long hike for an ant).  Disrupt the trail and, before long, they have found a new way.  How do they do it?  “Insects use a wide range of tools for orientation, including visual memory, smell, and counting steps,” the summary states.  “The tricky question is how they combine and compute different kinds of inputs, and whether their methods can help us understand more complex brains or create artificial ones.”  Right off the bat we learn that ants compute.  How did a computer get into a brain smaller than a pinhead?  Let’s review seven of the applications (in modern parlance, apps) available in their tiny navigation computers.

(1) The first technique an ant uses to find its way is to count its steps.  “Essentially, when the ant leaves its nest to go foraging, it counts the steps and keeps a record of how many steps it is away from home at any given time, like a pedometer,” Gross writes (see 6/29/2006). “In addition, it also records changes in direction.”  There’s an app for that – right in the ant’s brain: the “path integrator“.  It’s an “unflappable” tool that works even when mischievous experimenters try to get the ant off track.

(2) Another app an ant uses is the sun compass.  Even at night, some ants can detect polarized skylight to orient themselves.

(3) A third app an ant uses is “the vibe” – vibration signals the ant can generate as a call for help, or vibrations from the nest the ant can memorize to find the way home.

(4) A fourth app in the ant’s orientation toolkit is carbon dioxide sensing, used to locate its nest.  Since all nests create CO2 plumes, the ant has smarts to trust the path integrator app in conjunction with the CO2 sensor.  “The research suggests that ants can use any of a wide range of sensory signatures associated with a place of interest to complement their path integration information,” Gross says.

(5) A fifth app is the magnetic compass– an ability to orient to the earth’s magnetic field.  Monarch butterflies and some birds also have this ability.  In ants and in birds, proteins called cryptochromes are thought to be the seat of magnetosensation, but the theory needs more study.

(6) A sixth app is the sense of smell, obviously.  For this, ants are well equipped.  We shouldn’t take this sense for granted; “tracking an odour plume is a complex computational task, as the distribution of the relevant substance in the fluid may be irregular and will depend on flow dynamics,” Gross explains.  Scientists are only beginning to understand this highly complex sense in insects (for mind-boggling introduction, see the 6/27/2005 entry).  If ants are equipped like fruit flies are, they “can perceive substance gradients in an odour plume ‘in stereo’, enabling them to navigate towards a source of food odours, for example.”  Your picnic lunch isn’t safe.

(7) A seventh app is vision.  Ants do look around with their compound eyes; they are known to identify landmarks to hone in on sites the path integration app has brought them near.  Gross quotes entomologist Jochen Zeil (Australian National University, Canberra) who states we are only beginning to understand how ants use vision in orienteering: “Quite generally, we are just starting to acquire, develop and apply tools that allow us to reconstruct the navigational information available to animals under natural conditions,” he said.  “We know that both localization of goals and direction of heading along routes can be achieved without segmentation of the visual scene into discrete objects, which is considered to be computationally demanding — but who knows?”  as if to hint they might perform that computation in their little computers.  Gross adds to the wonder by stating, “The biggest challenge is to find out how the insects store complex geographical information in their very small brains.”  Researchers have witnessed inklings of this: “certain parts of the brain of insects reconfigure themselves when exposed to information related to navigation,” but mapping the external geographical information to the neuronal response scientifically is a long way off.

(8) Gross didn’t mention the chemical cues ants share with fellow hikers on the trail when they touch their antennae together.  To this we can consider the roles of scout ants that sally forth alone in complex paths they must remember all the way home, so that their brethren can find the best path to the food source.  In the 11/15/2000 entry, we described how ants quickly solve the complex “traveling salesman” or “Chinese postman” algorithm,  a challenge even for supercomputers (10/26/2010).

Putting it all together:  After examining the apps separately, the challenge is to know how the ant integrates them.  What if, for instance, one app says go east, but another says go west?  We’ve each experienced conflicts about directions by passengers in a car (at least before Garmin Nuvis).  “We may have more or less rational ways of evaluating and combining information from different sources, but how do ants manage that?” Gross asks.  Good question.  Once again, scientists are only beginning to answer it.  More mischievous acts by scientists trying to confuse the ants have revealed that sometimes they will compromise between conflicting signals, or superpose the inputs to determine a resultant vector – pretty good math for a brain as small as an ant’s.

Now, the explanation:  Evolution is only mentioned twice in Michael Gross’s article, at the very end – but the context (above and below) is what guarantees it the Stupid Evolution Quote of the Week award.  Here are the final two paragraphs containing the E-word:

Insect navigation is important for a whole range of reasons. For neuroscience, it offers the chance to observe information processing in manageable systems under conditions that are close to nature and thus relevant to evolutionary considerations. The crucial importance of navigation and homing behaviours is evident from the observation that most animals need these abilities to some extent — even sessile animals often have navigating larval stages.

Therefore it is no big surprise that evolution has driven natural navigation systems to a degree of perfection that human engineers can only dream of. “I think that every animal we look at is a more competent, more robust, more flexible, more miniaturized and a more energy-, material-, sensor- and computation-efficient agent than anything we have ever built,” concludes Zeil. “So would anyone need more justification for how fundamentally important, intellectually challenging and promising it is to conduct research into the navigational abilities of insects?”

In short, he says, if you want to find perfection, look to unguided, mindless, purposeless processes of Darwinism.

“No big surprise.”  Sigh.  How does one respond to a statement like that?  Without LOL, that is.  Go to the ant, thou sluggardly of mind.

Save this SEQOTW for the Stupid Evolution Quote of the Year contest.  (Note: we award this only to Michael Gross, not to Jochen Zeil, who actually said something praiseworthy; re-read that part and be amazed.)

Meanwhile, the rest of us can enjoy and give thanks for the wisdom our Creator has exhibited in the lowly ant, with its tiny brain able to put our best-designed systems to shame.  Take a moment to admire an ant before stepping on it or spraying it.  And when you see them enjoying their natural habitat outdoors, pay them respect and leave them be.

For more on amazing ants, and why you should buy your kids an ant farm, see the 3/16/2006 and 6/29/2006 entries.





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