Monotremes, Marsupials, Eutharians, And Vegetarian

One of the most defining features of mammals is the ability to give nutrition to young via a lactation system instead of egg-yolk that is observed in other lineages. Lactation evolved during the Triassic period—specifically the Cynodant lineage—along with other Mammalian characteristics such as fur. Certain milk proteins, and quite many other parts of the lactation system, have been conserved through evolution and time. It is hypothesized that lactation arose amongst mammals that showed maternal care. Many of the mammalian species on Earth have different reproductive strategies. This has an affect on the form of lactation cycle, which results in differences in lactation. Milk composition is also another factor that is another source of differences …show more content…
Monotremes have small hatchlings that rely on lactation milk as a nutritional source. Eutherians, the mammalian line that evolved placenta resulting in intrauterine development, have young that heavily rely on milk. The milk in Eutherians does not change through a young’s development and its composition is constant. Marsupials, in comparison to Monotremes and Eutharians, have one of the most complicated and specific lactation systems. Their milk is constantly changing in order to better cater to the needs of the young through its different developmental stages. One of the earliest forms of the lactation system is observed in the egg-laying Monotremes: the platypus and echidna. This is because Monotremes don’t have teats, and in fact, the milk is secreted from duct openings onto a skin patch on the …show more content…
Through out the evolution of lactation, many different changes have been made on the basis of biochemistry, anatomy, and physiology. In terms of biochemistry, the components of the milk itself have evolved. Anatomically, through out evolution, the gland structure and lactation in females and the teeth and cheek anatomy of the young has also significantly changed. Physiologically, hormonal control of lactation has evolved as well. While the energy and efforts of the mother are worth it in the long run, they still have to be mindful of different climate and environmental changes and it’s effects on lactation and care for the young. The timing of birthing young and providing them with nutritional milk has to coincide with the mother being situated in an environment where there are enough resources available and the reproductive success is