The latest issue of "Nature" magazine has a commentary on the recent "Science" article that gave insight into the differences between chimp and human diets. Citation: Nature 427, 208 (15 January 2004); doi:10.1038/427208a Evolutionary biology: Our relative genetics DAVID PENNY Abstract: Data on the chimpanzee genome help in detecting differential selection on individual genes, and in judging whether normal microevolutionary processes are sufficient to account for human origins. A quote from the article: "One of Clark and colleagues' findings is that human enzymes for amino-acid breakdown (catabolism) have been under positive selection. This is concordant with the generally high proportion of meat (and thus protein) in the human diet, at least in comparison with the more herbivorous chimpanzee and gorilla. The increased capacity to break down amino acids is not surprising in another respect. For example, failure to catabolize phenylalanine has several adverse effects, including brain damage. Overall, the finding lends support to theories4 that an increased proportion of meat in the diet of early humans was important for an increase in brain size. Regardless of that, there could also be ethical implications. If early humans ate meat 'naturally', then for example being vegetarian could be considered a personal choice rather than a universal ethical decision. But all that can be claimed here is that scientific knowledge will be necessary, even if not sufficient, for solving such ethical questions." Tom Billings