Many attempts have been made to correlate degrees of both animal and human intelligence
with brain properties. With respect to mammals, a much-discussed trait concerns absolute …

Understanding the mechanisms of evolution of brain pathways for complex behaviours is
still in its infancy. Making further advances requires a deeper understanding of brain …

Some birds achieve primate-like levels of cognition, even though their brains tend to be
much smaller in absolute size. This poses a fundamental problem in comparative and …

Many evolutionary biologists are concerned with the tremendous amount of diversity of
species, and their phenotypes, that we can currently observe in nature, and one of the most …

Comparative studies suggest that at least some bird species have evolved mental skills
similar to those found in humans and apes. This is indicated by feats such as tool use …

Relative brain sizes in birds can rival those of primates, but large-scale patterns and drivers
of avian brain evolution remain elusive. Here, we explore the evolution of the fundamental …

Vocal learning is a critical behavioral substrate for spoken human language. It is a rare trait
found in three distantly related groups of birds-songbirds, hummingbirds, and parrots. These …

Environmental variability has long been postulated as a major selective force in the
evolution of large brains. However, assembling evidence for this hypothesis has proved …

Allometric relationships among morphological traits underlie important patterns in ecology.
These relationships are often phylogenetically shared; thus quantifying allometric …

The question of when modern birds (Neornithes) first diversified has generated much debate
among avian systematists. Fossil evidence generally supports a Tertiary diversification …