Study Finds Parents' Natural Tendency to Favour Older Siblings

by Medindia Content Team on  December 20, 2007 at 7:36 PM General Health News
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Study Finds Parents' Natural Tendency to Favour Older Siblings
Nearly every parent denies favouring one kid over the other but a new study has suggested that they instinctively favour the oldest child.

The study, led by Dr Per Smiseth in the University's Faculty of Life Sciences, was conducted on a unique species of beetle, Nicrophorus vespilloides that raises and cares for its young and found that the parents were instinctively partial towards the oldest offspring.

The finding suggests a wholly natural tendency towards older siblings.

"The burying beetle Nicrophorus vespilloides has a similar family structure to that of a human family unit in that there are two parents, a number of offspring and interactions between parents and their young," Smiseth said.

"Of course human families are more complex and parent-child relationships are much more sophisticated. However, studying this beetle can help us understand the basic biological principles of how family relationships work.

"Our study looked at how the parent beetles mediate competition between different aged offspring compared to what happens when the young were left to fend for themselves and indicates that parental decisions are important in determining the outcome of competition between offspring," Smiseth added.

The native to Britain beetles give birth to a batch of about 20 young in the carcass of a dead animal over a period of 30 hours. The parents feed the young grubs on regurgitated flesh from the carcass. The young beetles are able to feed themselves but they grow more quickly and become larger when fed by their parents.

The scientists were able to study the development first with the parents present and then when left to fend for themselves by generating experimental broods comprising two sets of offspring, one set of older grubs and one younger set.

"When both sets of grubs were left to fend for themselves they grew at the same rate and matured to an equal size. However, when we allow the parents to remain with the offspring, there is clear favouritism towards the older siblings, which grow at a faster rate as they take the lion's share of their parents' offerings," said Smiseth.

The research contemplate that there are two explanations for the behaviour: the first is that the parents attach more value to the older offspring as their maturity gives them a better chance of survival than their younger siblings.

The second explanation is that the older grubs, being stronger, are able to dominate their younger rivals and, in doing so, better attract the attention of the parents when begging for food.

"Even if this second theory is true, the parents are still complicit in the bias towards the older siblings. However, the true answer is probably some combination of the two explanations," said Smiseth.

"The research tells us something about the relationships within families. We have this view that families are harmonious and that the overriding concern is to help one another. This is true to an extent but it's not to say that families are not without conflict, especially if the resources cannot be divided equitably," added Smiseth.

The study will appear in Ecology.

Source: ANI

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Yes I agree totally , My parents still are into the same even after we all got married and have kids. When I confronted I was the bad person.


yes i totally agree to the parents favouring the older sibling.... My husband is the older one and his younger one gets treated shit...when i see his situation i can totally compare his with mine as i m the younger one and my parents are totally blind folded.... there was a time when in my teen age i was so bullied by my only sibling 10year elder sister...i tried to commit suicide....i had consumed poison and during the time she got violent and kicked me in the tummy and everywhere....while i was lying on the floor struggling for life.... my mother who was standing beside did do nothing but after 16 years today i still have a lot of grudge against my family for having me go through that shit while i was just 13yrs old...unfortunately today i have an arranged marriage to this man who is just my sister's carbon copy and treats me the same way....u can never fight them back... just forget it...the families are blind folded and never hear matter what they are always right!

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