The nature of the human fossil record is less than ideal for the generation of precise correlations between environmental variables and patterns of evolution in specific lineages. Nonetheless, a critical look at what can and cannot be said from individual fossil morphology and the correlation of specific environmental proxies with specific hominin fossils may lead to a greater understanding of the degree of certainty with which we should embrace environmental hypotheses for the evolution ofHomo. Climate shifts have been implicated in both the origin of the genus and its dispersal from Africa. Here, I consider three areas in which a climatic influence has been posited to explain evolutionary shifts in the genusHomo: the origin and dispersal of the genus from Africa; geography, climate and body size in earlyHomo,and the influence of climate-induced sea level rise on morphological isolation inH. erectus. Each of the data sets is far from ideal, and interpretations of each of the data sets are fraught with issues of equifinality. Of the three hypotheses discussed, the clearest link is seen between latitudinal variation (and presumably temperature) and body size inH. erectus. Similarly, climate-induced sea level change seems a reasonable isolating mechanism to explain the pattern of cranial variation in later AsianH. erectus, but the distribution could also reflect incompletely sampled clinal variation. Alternatively, only equivocal support is found for the influence of climate on the differentiation ofH. erectusfromH. habilis(as proxied by body/brain size scaling), and therefore the dispersal of the genusHomocannot be as clearly linked to changes in body size and shape as it has been in the past. These preliminary data suggest that an emphasis on understanding local adaptation before looking at global (and specific) level change is critical to elucidating the importance of climatic factors on the evolution of the genusHomo.