In the previous post, I explained that Otzi descended in large part from early adopters of agriculture in the Middle East or nearby. What I'll explain in further posts is that Otzi was not a genetic anomaly: he was part of a wave of agricultural migrants that washed over Europe thousands of years ago, spreading their genes throughout. Not only that, Otzi represents a halfway point in the evolutionary process that transformed Paleolithic humans into modern humans.
Did Agriculture in Europe Spread by Cultural Transmission or by Population Replacement?
There's a long-standing debate in the anthropology community over how agriculture spread throughout Europe. One camp proposes that agriculture spread by a cultural route, and that European hunter-gatherers simply settled down and began planting grains. The other camp suggests that European hunter-gatherers were replaced (totally or partially) by waves of agriculturalist immigrants from the Middle East that were culturally and genetically better adapted to the agricultural diet and lifestyle. These are two extreme positions, and I think almost everyone would agree at this point that the truth lies somewhere in between: modern Europeans are a mix of genetic lineages, some of which originate from the earliest Middle Eastern agriculturalists who expanded into Europe, and some of which originate from indigenous hunter-gatherer groups including a small contribution from neanderthals. We know that modern-day Europeans are not simply Paleolithic mammoth eaters who reluctantly settled down and began farming.
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Saturday, April 28, 2012
Tuesday, April 24, 2012
Lessons From Ötzi, the Tyrolean Ice Man. Part III
There are two reasons why I chose this time to write about Otzi. The first is that I've been looking for a good excuse to revisit human evolutionary history, particularly that of Europeans, and what it does and doesn't tell us about the "optimal" human diet. The second is that Otzi's full genome was sequenced and described in a recent issue of Nature Communications (1). A "genome" is the full complement of genes an organism carries. So what that means is that researchers have sequenced almost all of his genes.
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Tuesday, April 17, 2012
Lessons From Ötzi, the Tyrolean Ice Man. Part II
Otzi's Diet
Otzi's digestive tract contains the remains of three meals. They were composed of cooked grains (wheat bread and wheat grains), meat, roots, fruit and seeds (1, 2). The meat came from three different animals-- chamois, red deer and ibex. The "wheat" was actually not what we would think of as modern wheat, but an ancestral variety called einkorn.
Isotope analysis indicates that Otzi's habitual diet was primarily centered around plant foods, likely heavily dependent on grains but also incorporating a variety of other plants (3). He died in the spring with a belly full of einkorn wheat. Since wheat is harvested in the fall, this suggests that his culture stored grain and was dependent on it for most if not all of the year. However, he also clearly ate meat and used leather made from his prey. Researchers are still debating the quantity of meat in his diet, but it was probably secondary to grains and other plant foods. It isn't known whether or not he consumed dairy.
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Otzi's digestive tract contains the remains of three meals. They were composed of cooked grains (wheat bread and wheat grains), meat, roots, fruit and seeds (1, 2). The meat came from three different animals-- chamois, red deer and ibex. The "wheat" was actually not what we would think of as modern wheat, but an ancestral variety called einkorn.
Isotope analysis indicates that Otzi's habitual diet was primarily centered around plant foods, likely heavily dependent on grains but also incorporating a variety of other plants (3). He died in the spring with a belly full of einkorn wheat. Since wheat is harvested in the fall, this suggests that his culture stored grain and was dependent on it for most if not all of the year. However, he also clearly ate meat and used leather made from his prey. Researchers are still debating the quantity of meat in his diet, but it was probably secondary to grains and other plant foods. It isn't known whether or not he consumed dairy.
Read more »
Monday, April 16, 2012
Exercise and Food Intake
The New York Times just published an article reviewing some of the recent research on exercise, food intake and food reward, titled "Does Exercise Make You Overeat?". I was planning to write about this at some point, but I don't know when I'd be able to get around to it, and the NYT article is a fair treatment of the subject, so I'll just point you to the article.
Basically, burning calories through exercise causes some people to eat more, but not everyone does, and a few people actually eat less. Alex Hutchinson discussed this point recently on his blog (1). Part of it depends on how much fat you carry-- if you're already lean, the body is more likely to increase hunger because it very much dislikes going too low in body fat. Most overweight/obese people do not totally make up for the calories they burn through exercise by eating more, so they lose fat. There is a lot of individual variability here. The average obese person won't lose a substantial amount of fat through exercise alone. However, everyone knows someone who lost 50+ pounds through exercise alone, and the controlled trials support that it happens in a minority of people. On the other side of the spectrum, I have a friend who gained fat while training for a marathon, and lost it afterward.
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Basically, burning calories through exercise causes some people to eat more, but not everyone does, and a few people actually eat less. Alex Hutchinson discussed this point recently on his blog (1). Part of it depends on how much fat you carry-- if you're already lean, the body is more likely to increase hunger because it very much dislikes going too low in body fat. Most overweight/obese people do not totally make up for the calories they burn through exercise by eating more, so they lose fat. There is a lot of individual variability here. The average obese person won't lose a substantial amount of fat through exercise alone. However, everyone knows someone who lost 50+ pounds through exercise alone, and the controlled trials support that it happens in a minority of people. On the other side of the spectrum, I have a friend who gained fat while training for a marathon, and lost it afterward.
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Sunday, April 15, 2012
Next Primal Chef Event Sunday 5/20
Gil Butler has been working on a television show called Primal Chef, where he invites local chefs to make creative dishes from a list of Paleo ingredients, in a designated amount of time. The format is reminiscent of Iron Chef. The food is judged afterward by figures in the Paleo community. Robb Wolf was a judge on the first episode.
Gil has invited me to be a judge on the next show, along with Sara Fragoso and Dr. Tim Gerstmar. The next day, Sunday April 20th, Gil is organizing a catered Primal Chef event in Seattle, with Paleo dinner, speakers, entertainment, prizes, and a screening of part of Paleo Chef episode 1. You can read the details and sign up here. I won't be speaking because I don't have time to put together another talk right now, but I will be attending the event.
Gil has invited me to be a judge on the next show, along with Sara Fragoso and Dr. Tim Gerstmar. The next day, Sunday April 20th, Gil is organizing a catered Primal Chef event in Seattle, with Paleo dinner, speakers, entertainment, prizes, and a screening of part of Paleo Chef episode 1. You can read the details and sign up here. I won't be speaking because I don't have time to put together another talk right now, but I will be attending the event.
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