16. Jun, 2016

Birds are smart because they have compact brains

A bigger brain does not always mean a smarter brain.  For example, elephants have much larger brains than humans, but much of  their brain space is needed to control their colossal  body, and not their information processing capacities. When comparing brains of different species behavioral biologists often use relative brain size:  this is brain size corrected for body mass. On the relative scale humans, dolphins and great apes score higher than the elephant.

How about birds?  Birds  have large wings but a light body and walnut (or peanut) sized brains. However, they do have the reputation of being  pretty smart. This holds not only for singing birds that produce amazingly complex songs, but also corvids (members of  the crow family) and parrots. Corvids are clever in using  instruments like little hooks to obtain food.  Magpies successfully  pass the mirror test, a test of self recognition used  in  research of cognition in babies and higher mammals. The African grey  parrot is very clever in understanding numbers and concepts: the legendary grey parrot Alex (see picture) trained by Irene Pepperberg, a lecturer at Harvard University  is a good example.

These avian capacities must have resulted from the unique adaptation of their brains to the environment during evolution, resulting not in brains that are larger (and also heavier) but lighter and with a more efficient architecture*.  Now how can a  tiny brain be so smart? A recent study published  by  the research team  of Pavell Nemec** from Prague sheds some new light on this interesting problem. They compared the brains of different mammals and birds with the same brain size.  They  found that bird brains have more  neurons (nerve cells)  than mammalian brains and even primate brains of similar mass.  So  it’s not de brain size per se that determines  smart or intelligent behavior, but the density or the number  of nerve cells packed in certain areas of the brain. Avian brains seem to consist of small, tightly packed neurons and, importantly, many of these neurons are located in the forebrain, the area  that is connected  with cognition in humans. They also  found that parrots and corvids have forebrain neuron counts equal to or greater than primates with much larger brains.

  Sources:

  *Emery NJ (2006) Cognitive ornithology: The evolution of avian intelligence. Philos Trans R Soc Lond B Biol Sci 361(1465):23–43.

**Olkowicz S.  et al.  (2016). Birds have primate-like numbers of neurons in the forebrain PNAS Early edition  www.pnas.org/cgi/doi/10.1073/pnas.1517131113