## The Langton’s Ant

###### By Anupum Pant

Think of a cell sized ant sitting on a huge grid of such white cells. The thing to note about this ant is that it follows a certain sets of simple rules. The main rule is that when the ant exits a cell, it inverts the colour of the cell it just left. Besides that:

1. If the ant enters a white square, it turns left.
2. If it enters a black square, it turns right.

Here’s what happens if the ant starts out in the middle and moves to the cell on the right, as a starting step (this can be on any side).

Now as this continues, a seemingly random figure starts taking shape. The black cells are in total chaos, there seems to be no specific order to how they appear on the canvas. (of course the pattern is always the same chaos, considering the ant starts on a blank array of cells).

And yet, after about 10,000 steps are completed by the turing ant, it starts creating a very orderly highway kind of figure on the canvas. It enters an endless loop consisting of 104 steps which keeps repeating for ever and creates a long highway kind of structure.

Suppose, initially you take a configuration of black spots on a canvas (not a blank white canvas). Take an array of cells with randomly arranged black spots, for instance. If given enough time, the ant ultimately always ends up making the looped highway. However, before it starts doing it, it might take a significant amount of steps less, or more, than the ~10,000 steps it took to reach the loop in a blank array of cells.

No exception has ever been found. A computer scientist Chris Langton discovered this in the year 1986.

## Ants and Their Friends

### Background

If you consider the habits, social organization, communities, network of roadways, possession of domestic animals, and counting skills of ants, they are not very different from humans. Yes, ants even domesticate animals. And we’ve talked about their counting skills in the past. Then, I came across a very interesting experiment sir John Lubbock decided to do on ants.

### Experiment

He had in his captivity a number of varieties of ants living in different colonies. One day he saw a group of ants feeding on honey together. He picked twenty five of them and managed to intoxicate them by some method, others were left there, feeding on honey.

Next, he picked twenty five other ants of the same species, from a different colony and intoxicated them too. He then placed all of these 50 intoxicated ants near the honey, in the path which the ants were using to move to and fro from the honey.

He watched them for hours and it was an amazing thing he found. The twenty five ants which belonged to the same colony of ants that were feeding on honey were treated much differently by them, than the other 25 ants of the same species that belonged to a different nest! Somehow they were able to identify the ants of their own nest – differentiate friends from strangers.

Twenty out of the twenty five friend ants (which belonged the same nest) were carried by the honey feeding ants to their home. While about 18 of the other intoxicated stranger ants were picked up and thrown into water.
There were just 5 friend ants which were thrown into water (probably accidentally) and 6 stranger ants which were carried back to home (probably accidentally, again)

Nevertheless, most ants were correctly identified as friends and strangers. Moreover, I think their reaction to drunk friends and drunk strangers was so much like what human beings would do!

### Next Experiments

In an experiment which he did later, the researcher tried separating friend ants (of the same nest) for about 4 months. And when they met after 4 months they were able to clearly identify each other. They caressed each other with their antennae.

In other experiments when he introduced a stranger ants in a nest, the strangers were evicted immediately and sometimes even killed.

There are a couple of other interesting experiments he has mentioned in his article here. Do read it whenever you find time. [link]

## Subtle Differences

###### By Anupum Pant

Who’d have thought that a fun website like 9gag could teach you something useful. This is an artwork that I first saw on 9gag and wanted to find where it originated from (to give the artist its full credit). I believe, I Raff I Ruse is the blog which published it first. I could be wrong, but then the apparent source itself attaches no text that could confirms anything. And then it probably went on NPR, and consequently spread all over the web.

The artwork illustrates subtle physical differences between certain kinds of animals which look very similar to the untrained eye. It’s a very simple thing to know and you should definitely know it. The whole list includes differences between:

• Ape and Monkey