One major reason is that the size of a brain is less relevant for its processing capacities compared with the number of neurons, or nerve cells, it contains. Why 'Bird Brain' Is Actually a Compliment Keating Godfrey, a postdoctoral researcher in the Department of Molecular and Cellular Biology. 'How big or how heavy a brain is does not give you the best measure of an animal's cognitive capabilities,' says the study's lead author, R.

The image covers about one thousandth of a square inch. The cell nuclei of the neurons are stained blue shown in red is the extensive 'wiring' connecting the neurons, some of which are organized into distinct brain centers performing specific tasks. For example, while larger animals, as a general rule, tend to have larger brains than smaller animals, the volume and mass of a given brain alone don't say much about its cognitive capabilities.Ī microscopic image of a section through the brain of Centris pallida, a North American solitary bee with no officially accepted common name. But that approach can be fraught with uncertainties and biases, according to the authors of this study. Instead, brain researchers relied on estimates and extrapolations based on measurements of brain size or mass. Until recently, it was extremely tedious and time-consuming to count or estimate the number of neurons in a brain, even with computer and software-based systems.įor this reason, there were very few reliable neuron numbers available for any animals, including the human brain. To that end, scientists need to know how many neurons make up a given brain. Theories of cognitive capacities of animal brains, including those of fossilized remains of the evolutionary ancestors of humans, are based on such measures. Published in the scientific journal Proceedings of the Royal Society B, the study marks the first time the new cell counting method has been applied to invertebrate animals and provides a robust and reproducible protocol for other research groups studying the brains of invertebrate animals.įor more than a century, scientists have attempted to measure and compare the brains and brain components of vertebrates across species in efforts to draw conclusions about how brains support the animals' behavioral and cognitive abilities and ecological requirements. The work revealed that certain species of bees have a higher density of brain cells than even some species of birds, whereas ants turned out to have fewer brain cells than originally expected. Using a surprisingly simple technique, researchers in the University of Arizona Department of Neuroscience have succeeded in approximating how many brain cells make up the brains of several species of bees, ants and wasps. The common Eastern bumble bee (Bombus impatiens) with superimposed stained brain image to show the relative size and location of its brain.

How many neurons does the brain have