Extinct megafaunal mammals in the Americas are often linked to seed-dispersal mutualisms with large-fruiting tree species, but large-fruiting species in Europe and Asia have received far less attention. Several species of arboreal Maloideae (apples and pears) and Prunoideae (plums and peaches) evolved large fruits starting around nine million years ago, primarily in Eurasia. As evolutionary adaptations for seed dispersal by animals, the size, high sugar content, and bright colorful visual displays of ripeness suggest that mutualism with megafaunal mammals facilitated the (...) evolutionary change. There has been little discussion as to which animals were likely candidate(s) on the late Miocene landscape of Eurasia. We argue that several possible dispersers could have consumed the large fruits, with endozoochoric dispersal usually relying on guilds of species. During the Pleistocene and Holocene, the dispersal guild likely included ursids, equids, and elephantids. During the late Miocene, large primates were likely also among the members of this guild, and the potential of a long-held mutualism between the ape and apple clades merits further discussion. If primates were a driving factor in the evolution of this large-fruit seed-dispersal system, it would represent an example of seed-dispersal-based mutualism with hominids millions of years prior to crop domestication or the development of cultural practices, such as farming. (shrink)

The field theoretic approach of the target article is simplified by setting the parameters of the dynamical field equation so that the system is near the critical point between cooperative and non-cooperative dynamics. However, embodiment of cognitive development would require a closer connection between the dynamical field interactions and the physiology of the cerebral cortex.

Random-excitation granule cells are likely to overwhelm spatiotemporal sequences described as in Braitenberg et al.'s target article. A mechanism is proposed involving the Golgi cells to reinforce tidal waves against noise. The recurrent inhibition by the Golgi calls can recruit random excitations of granule cells in phase with sequences of mossy fiber input.