By about 125 million years ago, mammals likely increased their vocabulary above a dozen and perhaps for some species at times into the hundreds. This vocabulary, or signaling, was a series of gestures, grunts, and screeches. Today, mammals from this lineage communicate with a range of signals and gestures, not unlike our abstract vocabulary. We see this in their descendants ranging from the opossum, with communication signals of only about a dozen, to wolves, ranging into the hundreds.

Today, wolves use this rich tapestry of communication in the wild: howls to signal location, growls to assert dominance, and a myriad of body postures to convey submission, aggression, or affection. This early foundation of dozens of signals provided the building blocks for the more complex communication systems that would evolve in other branches of the mammalian family tree.

Imagined Image: Eomaia scansoria in their natural environment from about 125 million years ago. These early mammals likely lived in a lush, prehistoric forest setting and had a vocabulary, or signaling, ranging into perhaps a dozen or two of words—well, gestures.