The evolution of the grey wolf

During the Paleocene epoch - about 60 million years ago - a weasel-like animal called 'Miacis' evolved from a group of creatures called 'Creodonts' - the dominant carnivorous mammals of the Tertiary period. The Creodonts were all quadrupeds with large jaws full of sharp teeth; they had clawed feet and small brains and among them were recognisable prototypes of all the great predators of today, such as Sarkastodon - a bear-like creature - and Hyaenodon - a more wolf-like animal. Miacis, their successor, was the latest common ancestor of both the cat (feline) and dog (canid) family.

For about forty million years after the appearance of Miacis, the feline and canid lines gradually diverged until around 20 million years ago, shortly after the start of the Miocene era, the two had completely separated. From this era comes 'Tomarctus' - a very wolf-like animal and an ancestral link between foxes and wolves.

There are a number of theories about which continent wolves, in their present form, originated from. Some favour Asia but the most popular belief is that the wolf had its true, modern origins in America. The periodic presence of the Bering land bridge, connecting Alaska to Siberia during the ice ages, provided a key evolutionary connection in the form of a migratory corridor for wolves to pass back and forth between Asia and America. The effect of this two-way migration was a fresh, periodic genetic influx in both directions and without it, it is quite likely that the two sub-species would have evolved into two physically quite different animals.

(Speaking of land bridges: We also know that in more recent geological times - during the Holocene period (about 18,000 years ago) - the low sea levels accompanying the last ice age allowed other land bridges to form including one which connected the British Isles to Europe. This bridge allowed the migration of wolves into Britain - where they remained until the mid seventeen hundreds).

Around 7 to 8 million years ago there were two early canids hunting the plains of North West America. These were Epicyon and Eucyon. Eucyon is believed to have been the first canid to cross the Bering land bridge back into Asia from America. It moved westward, spreading throughout Asia first, and then on into Europe about four or five million years ago. It was Eucyon which began evolving into the modern grey wolf (canis lupus) approximately two million years ago during the Pleistocene epoch and it reached its present day form about one million years ago. Canis lupus, as it had then become, soon re-crossed the Bering land bridge, back into America and the oldest known remains of modern wolves in the USA date back about 700,000 years. (The fossil record shows the presence of all sorts of other canids in America back as far as 37 million years.).

For almost half a million years, the grey wolf lived alongside canis dirus the now extinct 'Dire wolf'. The Dire wolf is believed to have been a much larger animal than canis lupus, but due to the remoulding of many prey species (faster and fitter) by the heavy selection pressures of the last ice age, it eventually lost out to the grey wolf. The Dire wolf was less agile and also lacking in physical stamina compared to the grey wolf; it was no match for the new swift-footed ungulates and became extinct some 7500 to 8000 years ago. It is also clear that the social organisation and pack psychology of the grey wolf lent it an overall advantage which helped to bring it to its present day position as top canid predator of the modern world.

Danny Winters
Head Wolf Curator
Paradise Wildlife Park