Evolve: Guts

Many evolution buffs, like myself, have been watching the History Channel Series called Evolve, which are airing here in CA at 10pm on Tuesdays. These are well produced pieces that focus each week on a particular trait (eyes last week, guts this week). Both shows have been collections of ~5 narratives, mostly showing how the focal trait works in different animals. The narratives are tied together by asserting that evolution occurred (which I am quite certain it did). As such, these are not really about the historical science of evolution, but rather they are using evolution as an organizing principle to tie together experimental science on how particular traits work in different animal groups, with a preference for charismatic vertebrates. In the end, it all works quite well, and I would recommend the series.


In honor of Guts, I thought I would post a link to some of my favorite gut science. Work by Dirk Haller and (separately) Ruth Ley lies at the interface of ecology, evolution, and medicine. They wonder, how does the composition of bacteria in the gut of humans and mice affect the host - and how does that composition of bacteria get established?

You can think of the bacteria as a community, like a forest or grassland ecosystem, living inside each of us. Communities can have different levels of diversity - they can be comprised of many of just a few species. Those species could be closely or distantly related evolutionarily. And those communities could be established from environmental sources, or established by inheritance.

I saw Dirk and Ruth talk about some of this work at last years GAFOS conference, which is a conference of about 20 Americans and 20 Germans, under the age of 40, who were invited because someone took notice of his or her work. GAFOS is funded by the National Academy of Sciences and the von Humboldt Foundation. I described it in a bit more detail in a previous post, where I linked a symposium this year on the evolution of complex adaptations.

Some of the conclusions that Ruth and her colleagues have made are that certain groups of bacteria are associated with obesity of the host. There exists an experimentally generated line of sterile mice - mice that are born and live in sterile conditions, ie with no bacteria anywhere (amazing!). Some of these sterile and genetically identical mice were seeded with different bacteria, and some combinations were more likely to result in obesity of the mice, given the same amount of food.

Another interesting result is that gut bacteria tend to be passed from mother to offspring, as opposed to being obtained from the environment. This result is based on phylogenetic trees of gut bacteria from different populations. It is heritage, not locality that determines the bulk of gut bacteria.

Dirk's presentation was a really great example of pluralism, which I like to promote. He contrasted the germ theory of disease with the genetic/inherited theory of disease. He hints at a possible link between our currently germ-o-phobic society and the increase of genetic, especially auto-immune diseases like Crohn's disease and asthma. It may be that without the insult of germs, our bodies find it more difficult to distinguish self from non-self. By just having a germ theory of disease, we lose the full picture.

(These are my memories from over a year ago, so I may have some details wrong. Check out Ruth's and Dirk's presentations on this site, to see for yourselves!)


Next week Evolve, Jaws!

Eye evolution: post-dinosaur, pre-Noah's Ark

Back in January or so, I was interviewed by researchers at the History Channel over the phone. They were working on a new series on evolution, and one episode was to be about eyes. I guess they had seen our lab's work last year on cnidarian opsins in the news and decided to talk to me about it. Looks like they might mention this and/or research by Suga and Gehring published in Janurary on cnidarian opsins. Here is the blurb from the History Channel website:



They are one of evolution's most useful and prevalent inventions. Ninety five percent of living species are equipped with eyes and they exist in many different forms. Learn how the ancestors of jellyfish may have been the first to evolve light-sensitive cells. Discover how dinosaur's evolved eyes that helped them become successful hunters. Finally, learn how primates evolved unique adaptations to their eyes that allowed them to better exploit their new habitat, and how the ability to see colors helped them find food.


I remember from the interview that they were really probing for flashy stuff. They wanted to know what they would see if they came to film at UCSB. They didn't seem too interested in filming hydra sitting in a dish (although that's one of the things we are doing in the lab this summer). I can see from the abstract that they settled on dinosaurs and primates - the proverbial charismatic megafauna....


I just looked up the schedule, and the eye evolution program will air just after Dinosaur Fight Club, and just before a documentary about a flood 3,000 years ago that they are dubbing Noah's flood! Should be fun!

The date is Tuesday July 29, eye evolution at 10 pm.

I'll try to give an opinion on the Eye Evolution program here after it airs.