Amazing ant antics
Have you ever taken part in a game where a group of you get taken to a mystery location (without being able to see your surroundings on the way), are dropped off, then challenged to find your way back? The first team back wins.
Now convert that to the real-life matter of how animals find their way back to their birthplace in order to mate and reproduce. For instance, think of pacific salmon,1 monarch butterflies,2 and migratory warblers.3 And what about creatures returning home after foraging for food? It’s no game but can be a matter of life and death. Social insects like ants live in structured colonies within nests. When they leave these to forage for food, they, too, are amazingly skilled at finding their way back home.
Scientific studies of navigation skills and other instincts in animals continue to amaze scientists and laypeople alike. Researchers from universities in the UK and Australia wanted to better understand the remarkable homing abilities that ants possess. They reported their findings in a 2022 paper.4
The scientists studied a colony of ants routing between home (their nest) and their source of food, a tree they commonly went to in search of nutrients.
Anticipating the route home
Think about a trip to the grocery shop, buying food to feed the family. Irrespective of whether you always go to the same supermarket or try a different one every time, the idea is that you get home quickly in order to place the purchased items in the pantry and fridge/freezer. The route may involve many twists and turns, but there is an imaginary straight-line path between the supermarket and your home—this is called the ‘home vector’. From the supermarket, this home vector has a direction and a distance.
Of course, with buildings in the way, you can rarely take this shortest route home. But what about small creatures that have foraged and strayed a long way from home? How do they avoid getting lost? Ants are able to compute the distance and direction from home automatically, by a process known as path integration. It is programmed, instinctive behaviour. The animal keeps track of compass heading and distance travelled so it can compute a direct path home.5 Navigation systems expert Eric Cassell describes the remarkable multiple techniques desert ants employ:
… visual landmarks, vector memories of route segments, and path integration. In addition, they use chemotaxis in close vicinity of a food source by the detection of odors. They also use a combination of sensor information sources for path integration, including a sun compass, biological clock, and two forms of odometers.6
The experiment
The scientists captured ants of the species Myrmecia croslandi at their foraging tree, 11 m (36 ft) away from their nest.7 This site was called ‘full vector’ (indicated by🌳in the Table). They then used a technique called ‘chill-coma anesthesia’ (which sounds worse than it is) to induce memory loss in the ants, by cooling them (❄in the Table) to 0°C (32°F) for 30 minutes. After they recovered and could walk again, the ants were given some sugar as food and then released at an unfamiliar location. This was so that they could not use visual clues to return to their nest. The researchers compared their behaviour to that of non-chilled, full vector🌳ants that were released at an unfamiliar location. Still other ants were captured at their nest (referred to as ‘zero vector’, indicated by🏠in the Table) and treated in the same way—some of these zero vector🏠ants were cooled whereas others were not—before being released at an unfamiliar location.
Table summarising the four categories of ant-treatment:
| Temperature | Captured at the home nest (zero vector) | Captured at the foraging tree, 11 m from home (full vector) |
|---|---|---|
| Chilled (to induce anesthesia) | ❄🏠 | ❄🌳 |
| Normal | 🏠 | 🌳 |
Chilled ants have vacant minds
The scientists discovered that “anesthetizing ants by cooling causes memory loss of the distance, but not the direction, to their nest”.4 The chilled full vector ants❄🌳initially ambled around near their release point, before heading in the right direction, but stopping short of where their nest (in their minds) would be. In contrast, normal full vector ants🌳covered the proper distance in the expected direction.
Zero vector ants🏠wandered around in confusion, thinking they were at/near home, but they could not find their nest.
The research shows that even with impaired memory, ants can often set off in the direction of home, but are not able to remember the distance they need to walk. Or, if the ants were captured at their nest, both groups (chilled and normal temperature) were looking for their nest at the place where they were released. Although they were in a location some distance from the nest, they did not have a home vector, because they expected to be home.
Eric Cassell has this to say about desert ants:
It has also been determined that despite the fact that path integration navigation theoretically degrades linearly with distance, as occurs in human-made inertial systems, path integration affords the ants surprisingly accurate information about the nest position even after wide-ranging foraging runs. This is a further indication of the advanced engineering of their navigation system. And keep in mind, this is all managed in a brain that is only about one-fourth the size of a honey-bee brain, and the skills are largely innate, not learned or taught.8
Interestingly, all ants, whether chilled or not, and whether captured at the foraging tree or the nest, when released near their foraging tree (a location familiar to all of them), immediately knew their way home to the nest. The ants with amnesia (❄) must have been using visual signposts rather than path integration to get home.
An elegant design
Despite its small size (roughly the size of a pinhead) the brain of the humble ant is a powerful computing device. Ants can use real-time visual data to identify their surroundings and thus location, but have backup mechanisms in case the images received through their eyes cannot be readily identified.
Presumably, ants did not need to have such a robust backup plan simply to ensure the survival of their kind. This is one more example of ‘over-engineering’ in nature. So why did God create such ‘over-engineering’ as one sometimes sees in nature?9 Perhaps He did so to leave an ‘information trail’ that might make these scientists, or at least some of their readers, wonder about an omniscient Creator who cares about ants, and much more so about people.
References and notes
- Dreves, D., Pacific salmon: the ocean’s high achievers, Creation 18(3):26–28, 1996. Return to text.
- Poirier, J., The magnificent migrating monarch, Creation 20(1):28–31, 1997. Return to text.
- Sarfati, J., Migratory birds use magnetic GPS, Creation 44(2):16–17, 2022. Return to text.
- Pisokas, I. et al., Anesthesia disrupts distance, but not direction, of path integration memory, Current Biology 32:445–452, 2022. Return to text.
- Bell, P., Animal behaviour intelligently designed! (book review) J. Creation 36(1):35–40, 2022. Return to text.
- Cassell, E., Animal algorithms, Discovery Institute Press, Seattle, p. 63, 2021. Return to text.
- Myrmecia ants have an average length of 24 mm, cf. the average human being at 1.65 m. So 11 m equates to ≈ ¾ km (≈ ½ mile). Consider too the relative proportions of objects en route. Return to text.
- Ref. 6, p. 65. Return to text.
- Catchpoole, D., Over-engineering in nature: an evolutionary conundrum, 23 Nov 2021. Return to text.
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