A crude plot of average hominid brain sizes over time.

<p>Although after an initial flatlining this plot appears to show consistent enlargement of hominid brains over the last 2 million years, it is essential to note that these brain volumes are averaged across a number of independent lineages within the genus <i>Homo</i> and likely represent the preferential success of larger-brained species. From <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.1001934#pbio.1001934-Tattersall1" target="_blank">[20]</a>. <i>Image credit: Gisselle Garcia, artist (brain images)</i>.