A Natural History of Parenting by Allport Susan;

Author:Allport, Susan; [Allport Susan]
Language: eng
Format: epub
Publisher: Open Road Integrated Media, Inc.
Published: 2016-05-17T00:00:00+00:00

Recognition, then, is the key that turns the lock of parental care in bats, as it has long been known to be the key to care in sheep and goats. Even during the years when the theory of group selectionism held sway, there were those who knew how difficult it is for a lamb or a young goat other than a parent’s own to enter the exclusive club of parental affection. Shepherds and goatherds with an orphan lamb or kid on their hands had used every trick they could think of to fool another mother into believing the orphan was her own. Skinning the mother’s own dead lamb and draping the skin over the orphan is the one that is best known, but squirting the orphan with kerosene or the mother’s milk is said to work better.

Scientists can hardly be blamed, though, for taking so long to realize that the exclusivity of sheep and goats applies to all animals. For a while there appeared to be so many exceptions to the rule that parents care for their own young that recognition and exclusivity did not seem to be rules at all. There were the murres and the free-tailed bats, of course, as well as reports of adoption among many animals. Then there was the fact that the young of many species can be transferred from one nest into another with total acceptance by the parents. If the nestlings of altricial birds are moved into the nest of unrelated adults, the new adults will feed them as if they were their own chicks. Kittens can be moved into the litters of strange cats and puppies into the litters of strange dogs. Joeys, the young of marsupials, can be moved from one pouch to another with absolutely no question of being rejected.

And not only can these transfers be made within species but cats have been made to mother rats; dogs have mothered cats; rats have mothered mice. Researchers have swapped red kangaroo joeys with gray kangaroo joeys and kangaroo joeys with wallabies. No wonder researchers were slow to catch on.

But as biologists made more and more transfers, a telling trend began to emerge. The chicks of altricial birds can only be moved from nest to nest when they are very young. When they are close to fledging and have begun to give their own unique signature calls, foster parents will refuse to feed them. Similarly, kittens and puppies can only be swapped before they have begun to move about on their own. Kangaroo joeys will only be accepted by foster mothers if they are young enough to be permanent residents of the pouch. As soon as they start to venture from the pouch (at 190 days of age for the red kangaroo, for instance), the mother allows only her joey to reenter her portable nest.

And, of course, this makes beautiful sense. Parental care is exclusive, but parents only recognize their own young and reject strange young when there is a chance that a mix-up might occur and their valuable parental care might be misdirected.

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