I liked the straightforward information about the different pathways to domestication in Zeder’s article. Her diagrams about reduction in brain size were really interesting to see laid out side by side, however I’m taking them with a grain of salt because I’m not quite certain how reliable such comparisons are. How was the data obtained to determine the relative brain size in ancestral species? For example, the dog’s “ancestral species” is now extinct; we don’t even have enough genetic data to figure out what it looked like, let alone how big it’s brain size is. And how far back is considered “ancestral”? There are certain ancient species that stand out to us when looking at the evolution of, say, the horse; but which of these are we considering it’s ancestor? Perhaps these are a bit too in-depth and specific for the point Zeder was trying to make, but I think they are valid points to consider none-the-less. I wonder what the graph would look like if she included the brain size of the wild (not just feral) “counterparts” of modern domesticates- wolves, wild pigs, wild ferrets, etc- to their common ancestor. Have their brain sizes decreased as well (though not to the same extent)? Or have they stayed the same- or even increased (as unlikely as that is)?
Overall though, I really enjoyed the article. It helped me make sense of a lot of the thoughts swirling around in my head about how different animals came to be domesticated in different ways.
On to Dunn: My inner skeptic definitely came more into play while reading The Wild Life of Our Bodies this week, especially in chapter seven. I may just be too stubborn, but there is still a part of me that finds it very difficult to believe Binford’s theory, with all its “perhaps'” and “maybes” and “could have beens.” I don’t think the discovery of the milk-digesting gene supports the theory as much as Dunn seems to, and I don’t quite understand why Binford’s theory depends so much on crops that the majority of early people could not have processed. Why would they have farmed such crops in the first place? Maybe I missed something, but I find it a little hard to swallow (haha).
Our history of milk-drinking is equally as astonishing to me, however I’m not as dubious of Tishkoff’s conclusions. What amazes me the most is that milk drinking even became an option for early people. Aside from wishing I could meet the first person who had the crazy idea to go tug on another animal’s teat and drink the stuff that came out (although I think our conversation would be pretty limited), I’d like to know why they kept doing it, even after the milk make pretty much everybody sick except those few mutant people we can attribute our ability to produce lactase.
Dunn’s discussion of the genetics behind digestive enzymes like lactase and amylase led me to another thought: will gene therapy become an common option for dieting and weight loss? It currently exists, but not in a widely accessible form. But with the rising obesity problems and huge market for a lazy way to lose weight, once the cost is brought down it could become as common as craze diets.
March 3, 2014 @ 9:56 pm
As fascinating as gene therapy for weight loss is, I hope we can take up the issue Megan raises in her comment about milk. Corinne highlights the obvious when she considers what prompted humans to start drinking the milk of other animals (awkward!), and the article Megan cites offers good insight about the importance of fermentation and dairying to making milk palatable and digestible for humans. Fermented mare’s milk helped sustain the armies of Ghengis Khan and is (still) an important food in central Asia. (https://blogs.lt.vt.edu/freerangedomesticate/2013/02/12/drink-your-kumis-or-fermentation-as-humanitys-best-friend/)
March 3, 2014 @ 4:07 pm
In response to your musings on milk specifically, I too have often wondered what prompted someone to drink milk in the first place, maybe they figured if it’s good for babies, why not get it somewhere else for adults. This theory clearly has no backing, but it’s difficult to find many possibilities, like you stated. I wonder then, after milk was first introduced, how we had so much of it that we eventually evolved the enzyme necessary to digest it, especially given that apparently we could not even properly digest it. Why did we continue to consume it? Did our bodies become dependent on it? Is this what “made us fat?”
I found this article on the history of milk:
http://www.nature.com/news/archaeology-the-milk-revolution-1.13471
“During the most recent ice age, milk was essentially a toxin to adults because — unlike children — they could not produce the lactase enzyme required to break down lactose, the main sugar in milk. But as farming started to replace hunting and gathering in the Middle East around 11,000 years ago, cattle herders learned how to reduce lactose in dairy products to tolerable levels by fermenting milk to make cheese or yogurt. Several thousand years later, a genetic mutation spread through Europe that gave people the ability to produce lactase — and drink milk — throughout their lives. That adaptation opened up a rich new source of nutrition that could have sustained communities when harvests failed.”
This excerpt at least explains how we began to develop the ability to digest it, and according to this article, our bodies did not necessarily make the whole change; rather, the way we began processing milk made it easier to digest. It also gives brief insight into why milk became a prominent nutrient source
March 3, 2014 @ 1:16 pm
I’m not sure whether I agree with gene therapy for weight loss, but I don’t think it should be necessary. It’s pretty easy to see why we have a weight problem in this country. Our economic system has produced a ridiculous number of sources of food that difficult to resist (e.g., sugar, fat, salt) and very easy to obtain. I was reminded of this when I traveled to Orlando this week. I haven’t traveled outside the Virginia-Maryland-North Carolina region in a while, and the number of restaurants and food stores in northeast Orlando is astonishing in comparison to most places around here. Gene therapy would just be a means to circumnavigate the obvious problem of food availability and consumption created by our economic system.
March 3, 2014 @ 11:48 am
I like your skeptical approach towards the theories presented. Your musings or objections are presented thoughtfully and clearly without being aggressive or overbearing (like mine often come off). Also, very punny…
The idea of gene therapy for weight loss is intriguing, and not solely for the massive market for such a product or therapy. You mention market for “lazy” ways to lose weight, which suggests such methods may be inherently bad or at least frowned upon. However, look at it from another angle: if we can use gene therapy to regulate obesity, we can use it to regulate all sorts of things, including previously untreatable genetic diseases. Now, because the market for a fat reducing gene therapy is so huge, it gives a huge financial incentive for such therapies to be researched and tested. If the only way to get gene therapy for cystic fibrosis is as an offshoot of the funding for lazy weight loss cures, I’ll take it!
March 2, 2014 @ 3:48 pm
Since I have little background in any of this information I often too easily believe the theories we read about. It is nice to see someone who can critically examine the readings and make me realize that maybe I shouldn’t ingest it all too quickly. I like the idea of gene therapy as a weight loss program because of the high need for it today. We have become a very overweight population and people want an option to easily fix it.