HENRY the Human Evolution News Relay

Simon Greenhill
April 25th, 2008 - 11:08

Thanks for the comment! I mentioned that paper when it came out, and thoroughly enjoyed it.

It seems to me that phylogenetics is often taught in two ways – either “learn all this jargon”, or “learn what clade came before Carnivora”. Both of which are dull and kind of useless. So, people learn that trees describe evolution, and have lots of weird latinate words attached to them.

What I try to do is to show that trees are boring. What is interesting is how we can use them to test hypotheses about evolution.

My favorite example is the cute April Fools paper by Shykoff and Widmer which attempts to solve the vexed question of whether the chicken came before the egg:

It has come to our attention that the well known question ‘Which came first, the chicken or the egg?’ remains unanswered despite recent developments in comparative biology that provide the methodology for solving this problem. One approach taken in modern comparative biology involves examining trait distributions across groups of similar taxonomic level to determine, among other things, if a trait arose de novo in a particular group or was already present in that group’s ancestors (see Ref. [1] for a thorough discussion of the comparative method and its applications). This method, then, is ideally suited for investigating whether eggs or chickens came first.

To employ the comparative method a trustworthy phylogeny for the groups of interest is necessary. It has been accepted at least since the 1960s that birds and other reptiles form a monophyletic group, with birds and crocodilians representing the most recently derived clade within that group[2]. Oviparity is the most common and broadly distributed reproductive mode found in the reptiles and birds, and must therefore be considered the ancestral character state for the entire group (see Fig. 1). Eggs, therefore, clearly came before chickens.

I think you have to show why we care about trees first, before anything else.

–Simon