Week 8: A million neurons is plenty

The brain-size puzzle, and why counting the right thing makes most of it disappear.

Part III — The control group12 April 2027Open the slidesWeek 8 seminarSchedule

Olkowicz and colleagues (2016) measured neuron numbers across 28 bird species: parrot and songbird brains carry around twice the neurons of equal-mass primate brains, concentrated in the forebrain. Corvids and parrots were never small in the currency that matters. Herculano-Houzel’s parallel argument is that our own brain is an ordinary primate brain scaled up.

Then the ant. Wittlinger, Wehner and Wolf (2006) put Cataglyphis on stilts and on stumps and showed distance is measured by stride integration. What the animal stores is a vector rather than a route, so it cannot audit its own error, and a lost ant is behaviourally identical to one that is not.

That sentence is the one I want you carrying into week 12.