Jump to content

Equus: The Genus that Includes Horses and Donkeys


Recommended Posts

A little primer for those who care:

Both Horses and Donkeys are in the same Taxonomic Family (Equidae) and Genus (Equus)

Donkeys have a Sub-Genus (Asinus) which horses do not have, and that is where they split off. A Sub-Genus is between a Genus and a Species, and to be honest with you, I really don't know what it is - I guess it's something they discovered after they had the nomenclature in place, and needed to "wedge" another level in.

Anyway, that's all pretty drab stuff (not that what you're about to read will make you do somersaults):

The cutoff for being an "adult" is often three-years-old, but some disciplines consider it four-years-old. This applies to all of the following:


A male adult horse (which has not been gelded) is called a Stallion.
A male non-adult horse is called a Colt.
A female adult horse is called a Mare.
A female non-adult horse is called a Filly.
A horse 1-2 years old is called a Yearling
A horse less than 1-year-old is called a Foal (rhymes with "Goal").
A small horse is a Pony (a Pony is not necessarily a baby horse).


A male adult donkey (which has not been gelded) is called a "Jack" (hence the term "Jackass").
A female adult donkey is called a "Jenny." 
A small donkey is a Burro - more precisely, a Burro is a small donkey (not all small donkeys are Burros).

A castrated male horse or donkey, of any age, is called a Gelding.
All of that, leads to this:


A Jack mating with a Mare produces a Mule.
A Stallion mating with a Jenny produces a Hinny (you can remember this because "Jenny" sounds like "Hinny").
Both Mules and Hinnies are sterile - they cannot breed.
The reason for this is due to the number of chromosomes they inherit.
A Horse has 64 chromosomes; a Donkey has 62 chromosomes.
Both Mules and Hinnies have 63 chromosomes, which causes reproductive problems.
A Mule gets 32 Horse chromosomes, and 31 Donkey chromosomes.
A Hinny gets 32 Donkey chromosomes, and 31 Horse chromosomes.

If you're interested in more in-depth information this is a good webpage:
Jun 20, 2007 - "Chimeras, Mosaics, and Other Fun Stuff" on genetics.thetech.org

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Create New...