zondag 23 februari 2014

What if Columbus was a lazy arse?

A reflection on human history

First of all, my excuses for the word "arse". I just could not resist after seeing some episodes from the BBC sitcom "Mrs. Brown's Boys" where the word is used often. You can check out the first episode of the show here.

But let's get started now: Why was I thinking about the consequences of Christopher Columbus being a lazy arse (sorry again)? It has to do with a recent paper in Science (on Valentine's Day by the way, which is actually totally irrelevant here). In this paper Garrett Hellenthal and his colleagues used modern genetic data to look for ancient admixture events between human populations. They managed to identify the genetic impact of many important historical events, such as Arab slave trade and European colonialism.

This research shows the urge of humans to explore the world. As a matter of fact, my sister is on a world trip with her boyfriend at the moment (but again irrelevant here). But what if explorers, like Columbus of Marco Polo, did not set out to discover the world? What would be the impact on human genetics?

Admixture events between human populations would be rare. And if you look at the route our species followed (out of Africa, over the Bering Sea and down to the most Southern Point of South America), it looks a bit like an incomplete circle (see picture, taken from the book "Guns, Germs and Steel" by Jared Diamond).

So, could humans have become a so-called ring species? A ring species, is a connected series of neighbouring populations, each of which can interbreed with closely related populations. But the two ends of the ring (in this case Africa and South America) are to distantly related to interbreed. Examples are gulls (genus Larus) around the polar circle, and the Greenish Warbler (Phylloscopus trochiloides) around the Himalayas.

But because of our historical curiosity to explore and discover the world, we shall never find out. Although a mariage between an African and a South American is quite rare. If you do know such a couple, give me a ring!

dinsdag 18 februari 2014

There is more to life than Chimps!

A reflection on different "centrisms"
I get the heebeegeebees (which actually a pop group from the 80s) when I see people attribute human characteristics to animals. This behaviour is known as anthropomorphism. A closely related phenomenon is anthropocentrism, the belief that humans are the central and most significant species on the planet. But we are of course just a small twig on the tree of life.
You could argue for each species on this planet that it is the most important one. Bacteriocentrism would entail that Bacteria are the most important and influential organisms. And because you can find them everywhere (they are watching you right now!), you can defend bacteriocentrism.
Recently, I came across the term chimpocentrism. This might seem as regarding the chimp as the most important species on this planet. But actually it is just a special case of anthropocentrism. Scientists use the chimp, which is our closest relative, to study the evolution of humans. This chimpocentrism can be dangerous to draw big conclusions. Krist Vaesen from Eindhoven University draws attention to this issue in a recent article. By ignoring the rest of the animal kingdom, we might miss important clues about what makes us humans.

woensdag 5 februari 2014

Miraculous Mutations

A reflection on mutation rate after Noah's Ark.
I watched the debate between Bill Nye (the Science Guy) and Ken Ham (the director of the Creation Museum). It was painful to see how Ken Ham sticks to the literal interpretation of the Bible. This obviously includes the Flood and the building of the Ark by Noah. In order to explain how all animals fitted on the Ark, creationists refer to Biblical "kinds". A special discipline called Baraminology (see a previous post) studies these kinds. Creation "scientists" believe that the kinds present on the Ark evolved into different species by micro-evolution. They even use hybridization to determine which species can be traced back to a certain kind. And my PhD focuses on hybridization in geese...
Two goose species that extensively interbreed are Greylag Goose (Anser anser) and Canada Goose (Branta canadensis). I calculated the genetic distance between them based on the cytb-sequence: they differ about 9%. The current molecular clock for mitochondrial DNA is 2% per million year. That means that these 2 species diverged approximately 4-5 million years ago (which has been confirmed by fossil evidence).

If, however, we assume that these species evolved from the "Biblical Goose-kind" about 4000 years ago, the mutation rate would be about 1125 times faster. With such a mutation rate, the possibilities seem endless! Maybe even a goose that lays golden eggs... Which could actually be possible in the fantasy world of Ken Ham.  

zondag 2 februari 2014

Difficult Dilemma

A reflection on the famous Prisoner's Dilemma.

I came across this video on Facebook last week (first watch it, to avoid spoilers further in the text):

It is based on the famous Prisoner's Dilemma, which the host of the show explains nicely. Richard Dawkins also devoted some pages on this in his breakthrough-book The Selfish Gene. It turns out there are always cheaters (like this women) who can take advantage of cooperators (like the poor guy). And it is not just restricted to humans. I recently wrote two articles for a Dutch popular science website, one on bacteria and one on fruitflies. In both cases there was cheating involved.   
So, the bottom line is...don't trust anyone!