Mammalian Milk: From Humans, Cows to Cockroaches
One way or the other you are existing because you took milk at one point in time. If you didn't, at least one of your ancestors did because we are mammals. We drink milk and we produce milk. Although we drink our own milk in infancy, as we grow older, we depend on the milk of other mammals to give us the nutrient that we want but then, why do we prefer milk from cows and goats rather than other mammals.
Milk is made from modified sweat glands in mammals known as mammary glands, which are meant to give infants the food and nutrients they need before they begin to manufacture their foods themselves. Remember that mammals are animals that produce milk, have hairs, and have 3 middle ear bones. While most people do not continue to drink human milk throughout their lifetime, we have been able to make milk into a dietary staple through genetic mutation for humans of all ages. While we do not drink human milk all throughout our lives, we drink the milk of other animals such as Yak, Reindeer, cows, buffalo, goats, elk, and horses. Although in most countries, dairy milk is limited to sheep, cows, and goats.
With cows, we have been able to genetically create cows that can give about 6 to 7 gallons of milk daily, and for goats, and sheep, we still get about 1 gallon of milk. Cow milk has a fat content of 3.5% and it is close to that of humans which is 4.5% fat and that's why it is good for drinking, compare this with Buffalos that have a fat percentage of 6.9% fat which is good for cheese. While these milk contain fats, that of a hooded seal contains 60% milk while the Black Rhinoceros milk doesn't have much fat at all, just about 0.2% fat and they nurse their young for about 2 years.
Depending on the mammals, each species' milk composition is unique to what their young need. For instance Marine mammals have salty milks as a result of minerals such as sodium in the milk, and this milk contains lots of fat and protein, such as that of Polar bears. Human milk on the other hand contain lots of lactose (Milk sugar) which is needed to nuture the interstinal microbes of the infant and boost the immune system.
Milk is said to contain antimicrobial compounds. Scientist from the University of Sydney has shown that Tasmanian Devil milk contain antimicrobial compound cathelicidins. Humans also have cathelicidins protein but humans have 1 while Tasmanian Devil has 6 proteins which is named Saha-CATH (1-6), where Saha-CATH3,5, and 6 has antimicrobial compounds which worked against bacteria and fungi.
While mammals produce milk, we are not the only ones that do. The pacific beetle cockroach is an insect that produces milk. I mean a milk producing insect. The insect produces a milk-like substance in the brood sac, when their embryos are yet to be born, and they feed them with this milk. Unlike other insect, the pacific beetle cockroach give birth to their young ones alive. The milk contain between 6% to 22% fat, 46% protein, and 25% carbs.
Milk is a vital source of nutrition for all mammals, and as humans, we have a longstanding history of consuming milk from various species. From cows and goats to more surprising sources like the pacific beetle cockroach, milk has played a significant role in the evolution of our diets and dietary habits.