## Categorising languages through network modularity

Today I’ve been learning more about network structure (from Cris Moore) and I’ve applied my poor understanding and overconfidence to find language families from etymology data!

Here’s what I understand so far (see Clauset, Moore, &  Newman, 2008):  The modularity of a network is a measure of how many ‘communities’ it has.  An optimal modularity will split the graph to maximise the average degree within modules or clusters.  You can search all the possible clusterings to find this optimum.  I’m still hazy on how this is actually done, and you can extend this to find hierarchies like phylogenetics, but without some assumptions.  Luckily, there’s a network analysis program called gephi that does this automatically!

## Animal Signalling Theory 101: Handicap, Index… or even a signal? The Case of Fluctuating Asymmetry

The differences between handicaps and indices are usually distinguishable in formal mathematical models or in unambiguous real-world cases. Often though, classifying a trait as a handicap, an index, or even a signal at all, can be quite a difficult task.

For the purposes of illustration I will use Fluctuating Asymmetry (FA for short) as an example.  Fluctuating asymmetry is the term used to refer to deviation from symmetry in paired morphological structures (ranging from birds’ tails to human faces) that should be, all being well, bilaterally symmetric. Deviations from the ideal symmetrical phenotype are caused by inherent genetic perturbations and exposure to environmental disturbances occurring in early development.

Is FA a signal?

In their 2005 book Animal Signals, Maynard-Smith and Harper define a signal as:

‘Any act or structure which alters the behaviour of other organisms, which evolved because of that effect, and which is effective because the receiver’s response has also evolved’

They then argue that FA is unlikely to function as a signal because it is difficult to discern whether receivers respond directly to FA and because there appear to be few examples of displays in which signallers actively advertise their symmetry to receivers.

## Mathematical Modelling 101 – The Price Equation

So in this post I’m going to assume you know absolutely nothing about anything. If you know something about something this probably isn’t what you’re looking for. If you’re looking for something which will go into depth on how the price equation is derived this probably isn’t what you’re looking for either. If you simply want to know what the price equation does and how to use it at face value then welcome! You’ve found the right place.

The price equation is used to calculate how the average value of any variant can change within a population from generation to generation.

Here I will cover everything you need to know to understand the equation and slot in the right values: