Article Critique: Energetics and the Evolution of Human Brain Size and Cooperation and Individuality Among Man-Eating Lions (Article Critique Sample)

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Navarrete A, CP van Schaik, and K Isler. 2011. Energetics and the evolution of human brain size. Nature 480:91-94.
‘Evolutionary trade off’ is a situation where large sized brain is an advantage to the species. Human brain’s size is three time large of closest relative creature and hence more functional than the primates.
The expensive-tissue hypothesis explains that the amount of energy required for digestive system function correlates to the energy required by brain and brain size. Since human brains are large than that of the primates, humans have to utilize more energy than primate. The hypothesis explains that as human evolved through several processes from hominids to modern man, there were several changes that occurred that changed the size of the digestive system such as eating roasted meat that led to contraction of human digestive system.
The authors use fat-free body instead of total body mass to eliminate influences created by variations by the size of adipose depots.
Adipose tissue has a cost in that it has to be carried around a process that can increase predation-induced mortality. However, it is advantageous in assisting animals to endure during food shortages.
The authors state that large brain is a cognitive buffer between starvations. Animals with large brain size also have large fat content storage and hence may not face increased cost of transport for the whole body.
Table 1 shows the variation between fat store and brain size in various body organs between primates and mammals. The information shows the correlation between the relative size of the brain and digestive organs.
Figure 1 shows the relationship between adipose depots, masses of visceral depots and the brain in mammals. The figure shows interpretations and analyzes from more than 100 mammalians species. The figure also shows how the mammals’ control for phylogenetic relationship and body mass.
Figure 2 shows information analyzed from wild-caught female mammals on the relationship between residual brain mass and residual adipose depots mass. The information interprets body function and brain size in relationship to fat-free body.
The authors suggest that improvement in dietary consumption leads to energy levels stabilizing at higher levels hence increasing brain framework. Brain evolution has evolved from small-sized hominids brain capacity to that of modern man that is more complex due to evolution of dietary consumption.
Yeakel JD, BD Patterson, K. Fox-Dobbs, MM Okumura, TE Cerling, JW Moore, PL Koch, and NJ Dominy. 2009. Cooperation and individuality among man-eating lions. Proceedings of the National Academy of Sciences of the United States of America 106:19040-19043.
The authors highlight ecological changes in Tsavo during the late 1800s to form a background of the main reason that carnivores turned to human prey in the region.
The authors used δ13C values and δ15N values in their study to denote carbon value in plants and trophic level to clearly show percentage of prey consumed during an animal’s life. This helps to determine the kind of prey the lions were consuming, that is, whether the prey consumed had higher bone or tooth collagen and hair...