Who run the world? Girls

The 'mother's curse' is one is a hypothesis where it is believed that mothers pass on defective genes to their male offspring which are not harmful to their female counterparts. Scientists discovered new evidence suggesting the phenomenon is also present in animals.

This occurs because there are two independent sources of genetic material in eukaryotic cells, the nucleus and the mitochondria. The majority of genetic material in a cell is usually located in the nucleus.

Credit: National Institute of Health

One generally accepted theory is that mitochondria are originally independent bacteria that eventually were swallowed by eukaryotic cells because they lacked some abilities displayed by mitochondria. Genetic material from the mitochondria is only passed down from the mother to its offspring, unlike the genetic material from the nucleus which comes from both the mother and the father.

This results to male offspring being, what Phys.org calls, evolutionary dead ends. Natural selection suppresses the genetic mutations that may potentially harm females but there is no way to do it in males, thus leading to the mother's curse.

Elsewhere in the Animal Kingdom

Recently, a team of researchers from the Vanderbilt University and the Fred Hutchinson Cancer Research Center in Seattle found a mutated mitochondrial DNA in Drosophila melanogaster fruit flies suggesting that the mother's curse is also present in animals. The mutation causes reduced fertility in male fruit flies but does not seem to affect female fruit flies. Their findings were published in the journal eLife.

Evolutionary theory suggests that the mitochondrial and nuclear DNA will always be in competition with each other until one of them is forced to adapt and the other acquires beneficial mutations. This is known as the Red Queen hypothesis. This is based off a quote from the Lewis Carroll character, "...it takes all the running you can do, to keep in the same place."

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