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Reduction of Brain and Sense Organs in the Fossil Insular
Bovid Myotragus Meike Köhler, Salvador Moyà-Solà

Institut de Paleontologia M.C., Sabadell, Spain

Brain, Behavior and Evolution 2004

Our study of the fossil rupicaprine bovid Myotragus [Bate,
1909] from the Mediterranean island Majorca (Spain) provides
evidence that this animal underwent significant changes
(reduction) in the relative size of brain and sense organs
after geographic isolation at the end of the Messinian
Salinity Crisis (Miocene-Pliocene boundary, 5.2 Mya). The
changes in the central nervous system of Myotragus parallel
the pattern reported for domesticated animals, in which
decrease in relative brain size is accompanied by a decrease
in the relative size of their sense organs. We interpret the
important size reduction of brain and sense organs in
Myotragus as an adaptive strategy for more efficient energy
use under the special environmental conditions of the insular
ecosystem, characterized by absence of predation and
limitation of trophic resources.


In a nutshell:
A study by Bovid Myotragus Meike Köhler and Salvador Moyà-Solà
shows that a sheep-like animal named Myotragus balearicus, which lived
on the islands of Majorca and Minorca since about 5,2 million years ago until
it's extinction about 5000 years ago, underwent a reduction in size
of brain and sensory organs through evolution. The reason for this is
insular dwarfing: a process caused by the lack of natural predators and
a limited amount of food, which causes natural selection to favor small
animals over larger ones.
The same effect has been reported in domesticated animals.