It is a generally known fact that humans are mammals. But are Homo sapiens really mammals or marsupials?
- The group of animals that have womb where the fertilized eggs develop into young ones are called as mammals.
- It is not just the womb that makes the mammals unique, as wombs is present even in the viviparous (baby-laying) snakes and even in fishes like sharks.
- The mammals can produce the food in their mammary glands for the babies to feed on, once they are released out of the womb and come into the planet as a free entity.
- This liquid diet is called as milk and there are specially designed mammary glands called teats which play the role of an outlet to feed the young. This process is called as suckling.
- Because of this habit, the youngsters have to stick with their parents and those who lose their parents at suckling stage would eventually die out or have to be cared by surrogate mothers, in case of animals that live in clans.
- Humans have all the above qualities and by far have the longest parenting proportion in comparison to the lifespan. Parenting is close to 25% of the whole life (15 years before the child becomes independent in a 60-year lifespan).
- This is the longest parenting (if suckling alone is not considered) as compared to any other living animal. Consider this with 10% (2 years out of possible 20 years lifespan) in case of felines and 5% (1 year in case of canines) or even lesser in case of rodents.
Why Not Marsupials?
- Marsupials are one division of mammals, as their babies develop partly in the womb and partly outside.
- The outside growth is taken care of inside the pouches, which are either a bag or pouch in the feminine gender of the species. Remember the last time you saw the kangaroo with the baby joey’s head popping out of her stomach. The joey is actually sitting in the pouch, which is a fold in her abdomen.
- Since the babies are too tiny to leave the mother physically, they get into the pouch and attach themselves permanently to the teat.
- The Joey does not leave for close to 12 months though it stops suckling around 6 or 8 months.
- Human babies are also ensured to cling to their parents for a long period of time even after suckling stops.
- The babies are covered in cloth and other materials which is actually a detached pouch that is not part of mother’s body.
- There are many mothers who tie up their bundle of joy with their backs instead of their stomachs.
- While feeding the mobile baby back pack is moved to the stomach and fed within the pouch, just like the marsupials.
- Even after the Joey weans away, when there is danger it runs back to the mamma for safety and jumps into her pouch. So do children until they are about 8 or 12 years old, depending on the social norms and cultures.
- In many cases, especially in family outings, the male has to carry the pouch, as the mother outsources this to her man, though suckling is always done by the female.
Since humans display both mammalian and marsupialian nature, why not categorize them under Marsupials!