Mystery 5 is only a real mystery if indeed animals under controlled conditions are getting fatter over time. The author presents two sources for this claim.
Even if it’s true it might however be genetic. Mice that live in a controlled environment where they are protected likely want to put on more fat in preparation for getting pregnant and have less need to spend energy on running around and a lot of other activities in which wild mice burn calories. The effect might be downstream from breeding the same way how the mice were bred to be more susceptible to cancer.
Again, we compared the meta-analytically derived estimates for each of these groups, and find that the laboratory animals show a greater increase in per cent weight gain and odds of obesity than non-laboratory animals
I created https://skeptics.stackexchange.com/q/52923/196 to fact-check that claim.
Even if it’s true it might however be genetic. Mice that live in a controlled environment where they are protected likely want to put on more fat in preparation for getting pregnant and have less need to spend energy on running around and a lot of other activities in which wild mice burn calories. The effect might be downstream from breeding the same way how the mice were bred to be more susceptible to cancer.
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