An Adaptive Threshold in Mammalian Neocortical Evolution
Figure 6
Mouse and marmoset, both low-GI species, may generate 109 neurons more efficiently by adopting the human neurogenic program than by extending neurogenic period or expanding neuroepithelial founder pool size.
(A) Using its observed neurogenic program (yellow dashed line), the mouse may achieve 109 neurons by extending its observed neurogenic period 14-fold (blue dashed line) or, by using the human neurogenic program (red dashed line), 4-fold. Similarly, the marmoset (green solid line) may achieve 109 neurons using the human neurogenic program (solid red line) in 50% of the time it would take using its observed neurogenic program (solid blue line). (B) The barplot shows the amount by which both species' neuroepithelial founder pools would have to increase to achieve 109 neurons using either their observed (blue) or the human (red) neurogenic program. In (A) and (B), yellow and green line endpoints (A) and bar heights (B) represent observed values for mouse and marmoset, respectively. See Table S4 for primary data and estimates.