@article {315913,
	title = {Pattern and process in hominin brain size evolution are scale-dependent},
	journal = {Proceedings of the Royal Society B: Biological Sciences},
	volume = {285},
	year = {2018},
	month = {02/2018},
	abstract = {<p>A large brain is a defining feature of modern humans, yet there is no consensus regarding the patterns, rates and processes involved in hominin brain size evolution. We use a reliable proxy for brain size in fossils, endocranial volume (ECV), to better understand how brain size evolved at both clade- and lineage-level scales. For the hominin clade overall, the dominant signal is consistent with a gradual increase in brain size. This gradual trend appears to have been generated primarily by processes operating within hypothesized lineages{\textemdash}64\% or 88\% depending on whether one uses a more or less speciose taxonomy, respectively. These processes were supplemented by the appearance in the fossil record of larger-brained Homo species and the subsequent disappearance of smaller-brained Australopithecus and Paranthropus taxa. When the estimated rate of within-lineage ECV increase is compared to an exponential model that operationalizes generation-scale evolutionary processes, it suggests that the observed data were the result of episodes of directional selection interspersed with periods of stasis and/or drift; all of this occurs on too fine a timescale to be resolved by the current human fossil record, thus producing apparent gradual trends within lineages. Our findings provide a quantitative basis for developing and testing scale-explicit hypotheses about the factors that led brain size to increase during hominin evolution.</p>
},
	doi = {10.1098/rspb.2017.2738},
	url = {http://rspb.royalsocietypublishing.org/content/285/1873/20172738.abstract},
	author = {Du, Andrew and Zipkin, Andrew M. and Hatala, Kevin G. and Renner, Elizabeth and Baker, Jennifer L. and Bianchi, Serena and Bernal, Kallista H. and Wood, Bernard A.}
}
