When learning about evolution, every biology student has been taught, since the modern synthesis of natural selection, that mutation of DNA leads to variation that can then be selected on. But how does a random mutation lead to innovation? This process sounds like it might be very slow, even given the ancient age of the earth. How can such small changes create new things? In a great, albeit very dense and intense book, Andreas Wagner (Professor of Evolutionary Biology at the University of Zurich) answers these and many more questions.
 
In “Arrival of the Fittest” Wagner goes to great lengths to take the reader, in a much better way than I can reproduce here, through his ideas about how nature is set up to supercharge evolution. The authors premise is that of a ‘Universal Library’ where every conceivable combination of something can exist. In such a library a single item, be it a DNA code, the sequence of amino acids in a protein or a metabolic pathway, is connected via single changes (in any one of its parts) to other items in the library. Some, in fact probably many of these versions in the library, are useless/defunct in the sense that they would not work in the real world and so any organism that possess them would not survive. However, many of these versions are perfectly viable and so an organism would be able to survive if it had that copy.
 
Using large computer models in these libraries it is possible to move through them by making single changes that do not disrupt the function of the thing you are interested in (be it DNA, protein or metabolism). Following the logic laid down as you go through the book it becomes clear that there are clear pathways through DNA to protein to metabolic pathways. There are even multiple pathways from any one point in the library to any other point (that still gives the same end result) but when the start and end points are compared on their nucleotide/amino acid/enzyme combination level they are completely different. In effect there are many ways to solve the same problem and they are connected in many ways via simple, singular step changes.
 
Not only can the same processes easily be conserved with this logic but new processes are easily made, as these Universal Libraries contain every conceivable combination. Wagner shows that new metabolic pathways can easily be made, allowing for the exploitation of new food stuffs, without loss of function occurring. The amazing thing is that there are huge numbers of these pathways that criss-cross these libraries.
 
These theories show that life processes are robust and that it creates genotype networks which, in Wagner’s words “enable innovation, the very kind that allow life to cope with environmental change, increase its complexity, and so on, in an ascending spiral of ever-increasing innovability.”.
 
I have probably done a very bad job of trying to convey the ideas in this book, but hopefully I have peaked your interest enough to go out an read it, which I definitely recommend (there is a reason that Wagner has been paid to write a book and I haven’t!).
 
This book has genuinely made me look at evolution from a novel perspective, and these revolutionary ideas show how the power of modern computing can be incorporated into evolutionary biology with breath-taking results.

​The common cuckoo is a regular feature of the European spring. Its melancholic call is a harbinger of warmer weather but also a reminder that local birds better beware. Many cuckoo species, but not all, are brood parasites. They lay their eggs in the nests of other bird species to be raised by the unsuspecting host parents. This behaviour is not a trait unique to cuckoos though: ducks, finches and wydahs also trick others into caring for their young.

Cuckoos have multiple adaptation to achieve their nefarious objective, from laying quickly to mimicking the appearance of hawks but their mimicry of their hosts eggs is spellbinding. Females of the common cuckoo typically lay eggs in the nest of only one host species, and so their eggs need to look like the other in the nest or they risk being thrown out of the nest. It appears that cuckoos fall into different ‘races’ and each one specialises in a single host. However, scientists are still unsure exactly how this system works.

One of the prevailing ideas about how cuckoo races work in that egg mimicry is passed down almost exclusively along the female line. This line of thought posits that males can mate indiscriminately and this won’t impact on the ability of females to mimic the eggs of their host species. This is theoretically possible because of the way sex is determined in birds. Unlike mammals, where males are the heterogametic sex (XY), in birds it is the female who possesses two different sex chromosomes (ZW) while males are homogametic (WW). If genes that specify egg patterning are on the Z chromosome then it doesn’t matter who the father is because the female offspring will still inherit the ability to deceive a specific host species.

However, male genes may still play a role in all of this. An alternative idea of how brood parasites maintain their host specificity comes from work carried out on the indigobird, which parasitizes the red-billed firefinch (Payne et al. 2000). In some cool aviary experiments, indigobirds wwere fostered by different host species and then the female offspring were given the choice of which species’ nest to lay in when they matured. Females chose the species that brought them up, so host species that brought them up, so host species is likely to be learned, but interestingly they also chose to mate with males who had been raised by the same host species. The reason for their choice is that males learn their song from their host species, and females exposed to that same song in the nest develop a preference for it. Now this is unlikely to be a direct analogue for how the races of common cuckoo are maintained but it has been shown that males in different habitats, where some host species are more common, have different songs but it remains to be seen if this is just an ecological adaptation or a true signal for female mate choice.
 
Currently we still don’t know exactly how it works, which is great because it mean that there is still a great reason to wonder around places like Wicken Fen and study these amazing birds!

OnOmYesterday I went to the Big Bang Fair at the NEC in Birmingham. This isn't my usual topic for blogging but I thought I'd share some cool science stuff for kids.

The fair is a huge science expo designed to get young people interested in the sciences. There are stands as diverse as the new fastest car in the world attempt, the army engineers, a fully dissected pig and as many robots as a tech head could want. There were thousands of students present, even some exhibiting there own research, and they were loving it. Seeing so many inventive ways to bring science to life was awesome, even if there wasn't much biology. I suppose this is because most of the money in biology is to be made in biomedical fields, something that is really important but I just don't find enthralling.

The thing that blew my mind the most was a 40min show by the Gastronaut. He's a YouTube science communicator and together with his Quantum Mechanical Chocolate Factory they collide fairly high level science with food in an engaging way. Through food the explained crystalline structures, fluid dynamics, diffusion, UV and phosphorescence. Any teacher who wants to bring chemistry alive should check it out.

Gastronaut YouTube channel:
https://m.youtube.com/channel/UC0f5hnnSGWXhNQxDJdxlPsQ

​On this channel you can watch videos about how to extract iron from bran flakes, how to make dry ice and how to make your own chewing gum, all in your own kitchen. These are really cool experiments that can be transferred easily into the class room to make science fun for young kids. But even if you are not a teacher, just someone with small children or nieces and nephews, then these are fun things you can do to get children interested in science.