Also, there is this, again, very important: http://rspb.royalsocietypublishing.org/content/early/2010/11/19/rspb.2010.1890.abstract?sid=bbc3ed30-1fc1-44c4-8d4d

Also, there is this, again, very important: http://rspb.royalsocietypublishing.org/content/early/2010/11/19/rspb.2010.1890.abstract?sid=bbc3ed30-1fc1-44c4-8d4d-41a6fac12c1e http://rspb.royalsocietypublishing.org/content/early/2010/11... "A dramatic rise in obesity has occurred among humans within the last several decades. Little is known about whether similar increases in obesity have occurred in animals inhabiting human-influenced environments. We examined samples collectively consisting of over 20 000 animals from 24 populations (12 divided separately into males and females) of animals representing eight species living with or around humans in industrialized societies. In all populations, the estimated coefficient for the trend of body weight over time was positive (i.e. increasing). The probability of all trends being in the same direction by chance is 1.2 × 10−7. Surprisingly, we find that over the past several decades, average mid-life body weights have risen among primates and rodents living in research colonies, as well as among feral rodents and domestic dogs and cats. The consistency of these findings among animals living in varying environments, suggests the intriguing possibility that the aetiology of increasing body weight may involve several as-of-yet unidentified and/or poorly understood factors (e.g. viral pathogens, epigenetic factors). This finding may eventually enhance the discovery and fuller elucidation of other factors that have contributed to the recent rise in obesity rates." My own guess is that some of the obesity epidemic can be explained by bacteria. This would either be a new strain of bacteria, or (more likely) an old one that has mutated due to the abundant supply of food that humans have been exposed to over the last 150 years. Likely this is a bacteria that has lived in the guts of mammals for a very long time, possibly millions of years. It is interesting to consider that, while a good deal of research has been done into how mammals react to famine, no research that I know of has been done into how the bacteria in our gut responds to our experience of famine. Or prolonged abundance. Of course, there are many novel factors in the environment today. Some chemical that effect our metabolism is also a possible explanation.