Douglas Goff, PhD, Professor of Food Science at the University of Guelph, stated on his "Dairy Science and Technology Education Series" website (accessed on Mar. 5, 2007):
"Many centuries ago, perhaps as early as 6000-8000 BC, ancient man learned to domesticate species of animals for the provision of milk to be consumed by them. These included cows (genus Bos), buffaloes, sheep, goats, and camels, all of which are still used in various parts of the world for the production of milk for human consumption."
Epicurious, a website about food consumption, stated in the entry for milk in its "Food Dictionary" (accessed Mar. 5, 2007):
"Milk has been used for human consumption for thousands and thousands of years, as proven by cave drawings showing cows being milked. Today, cow's milk is still one of the most popular (especially in the United States) animal milks consumed by humans. Around the world, people drink the milk from many other animals including camels, goats, llamas, reindeer, sheep, and water buffalo."
The Washington Dairy Products Commission lists the different types of milk consumed by humans throughout the world, including information about each type of milk, in the article "Milk From Cows and Other Animals," available at the organization's website (accessed Mar. 5, 2007):
"Cows - Nine out of every ten glasses of milk consumed by people come from cows.
Water Buffalo - Water buffalo produce half of the milk consumed in India. Ghee, a kind of liquid butter, is made from water buffalo milk.
Goat - Some people find goat's milk easier to digest than cow's milk. Fat globules in goat's milk are smaller than in cow's milk.
Reindeer - The fat content of reindeer milk is 22%, six times as much as cow's milk. It is the only source of milk for Laplanders in northern Scandinavia, because no other dairy animal can survive in such a cold, hostile environment. It takes two people to milk a reindeer - one to do the milking and the other to hold the reindeer's horns.
Horse - Over 700 years ago, Mongolian warriors made a dried-out concentrated paste from horse milk. When they were on the march, they added it to water and drank it. In southeastern Russia, people use horse milk to make a slightly alcoholic drink called kumiss.
Sheep - Milk from sheep has twice the fat content of cow's milk. Sheep milk is used to make French Roquefort and chevre cheeses.
Camel - In the hot desert, camel milk lasts longer than other types of milk. It can last for seven days at 86 degrees Fahrenheit (30 degrees Celsius), and will last for three months when properly refrigerated.
Yak - In the cold mountains of Tibet, people make yak butter tea. It tastes like a salty, creamy soup that has been whipped to a froth."