One of the early calls to celebrate a Mother’s Day in the United States was the “Mother’s Day Proclamation” by Julia Ward Howe. Written in 1870, it was a pacifist reaction to the carnage of the American Civil War and the Franco-Prussian War. The Proclamation was tied to Howe’s feminist belief that women had a responsibility to shape their societies at the political level.
In the years after the Mother’s Day Proclamation, Ann Jarvis founded five Mothers’ Day Work Clubs to improve sanitary and health conditions. In 1907, two years after Ann Jarvis’ death, her daughter Anna Jarvis held a memorial for her mother and began a campaign to make “Mother’s Day” a recognized holiday in the US. Although she was successful in 1914, she was already disappointed with its commericalization by the 1920s. …
Thinking about our first mother:
To say that we get exactly half of our DNA from our father and half from our mother is not quite true.
One tiny piece of our DNA is inherited only down the female line. It is called mitochondrial DNA because it is held as a unique circular strand in small tubular packets known as mitochondria that function rather like batteries within the cell cytoplasm. Some molecular biologists say that, aeons ago, the mitochondrion was a free-living organism with its own DNA, and possessed the secret of generating lots of energy. It invaded single celled nucleated organisms and has stayed on ever since, dividing, like yeast, by binary fission. Males, although they receive and use their mother’s mitochondrial DNA, cannot pass it on to their children. The sperm has its own mitochondria to power the long journey from the vagina to the ovum but, on entry into the ovum, the male mitochondria wither and die. It is as if the man had to leave his guns at the door.
So each of us inherits our mtDNA from our own mother, who inherited her mtDNA intact from her mother, and so on back through the generations – hence mtDNA’s popular name, ‘the Eve gene’. Ultimately, every person alive today has inherited their mitochondrial DNA from one single great-great-great-. . .-grandmother, nearly 200,000 years ago. This mtDNA provides us with a rare point of stability among the shifting sands of DNA inheritance…
When mtDNA is inherited from our mother, occasionally there is a change or mutation in one or more of the ‘letters’ of the mtDNA code – about one mutation every thousand generations. The new letter, called a point mutation, will then be transmitted through all subsequent daughters. Although a new mutation is a rare event within a single family line, the overall probability of mutations is clearly increased by the number of mothers having daughters. So, within one generation, a million mothers could have more than a thousand daughters with a new mutation, each different from the rest. This is why, unless we share a recent maternal ancestor over the past 10,000 years or so, we each have a slightly different code from everyone else around us. …
Over a period of nearly 200,000 years, a number of tiny random mutations have thus steadily accumulated on different human mtDNA molecules being passed down to daughters of Eve all around the world. For each of us this represents between seven and fifteen mutations on our own personal Eve record. Mutations are thus a cumulative dossier of our own maternal prehistory. The main task of DNA is to copy itself to each new generation. We can use these mutations to reconstruct a genetic tree of mtDNA, because each new mtDNA mutation in a prospective mother’s ovum will be transferred in perpetuity to all her descendants down the female line. Each new female line is thus defined by the old mutations as well as the new ones. As a result, by knowing all the different combinations of mutations in living females around the world, we can logically reconstruct a family tree right back to our first mother. …
Not only can we retrace the tree, but by taking into account where the sampled people came from, we can see where certain mutations occurred – for example, whether in Europe, or Asia, or Africa. What’s more, because the changes happen at a statistically consistent (though random) rate, we can approximate the time when they happened. This has made it possible, during the late 1990s and in the new century, for us to do something that anthropologists of the past could only have dreamt of: we can now trace the migrations of modern humans around our planet. It turns out that the oldest changes in our mtDNA took place in Africa 150,000 – 190,000 years ago. Then new mutations start to appear in Asia, about 60,000 – 80,000 years ago. This tells us that modern humans evolved in Africa, and that some of us migrated out of Africa into Asia after 80,000 years ago.
A religious web site claims that mtDNA is actually not strictly inherited maternally after all.
Mammalian mitochondrial DNA (mtDNA) is thought to be strictly maternally inherited…. Very small amounts of paternally inherited mtDNA have been detected by the polymerase chain reaction (PCR) in mice after several generations of interspecific backcrosses…. We report the case of a 28-year-old man with mitochondrial myopathy due to a novel 2-bp mtDNA deletion…. We determined that the mtDNA harboring the mutation was paternal in origin and accounted for 90 percent of the patient’s muscle mtDNA (Schwartz and Vissing, 2002, 347:576, emphasis added).
Does this invalidate the mitochondrial Eve? No, there is still a mitochondrial Eve since there are no fertile men or women have ever been found with paternal mtDNA transmission.
In human mitochondrial genetics, there is debate over whether or not paternal mtDNA transmission is possible. Many studies hold that paternal mtDNA is never transmitted to offspring. This belief is central to mtDNA genealogical DNA testing and to the theory of mitochondrial Eve. The fact that mitochondrial DNA is maternally inherited enables researchers to trace maternal lineage far back in time. (Y chromosomal DNA, paternally inherited, is used in an analogous way to trace the agnate lineage.)
Some sources state that so little paternal mtDNA is transmitted as to be negligible (“At most, one presumes it must be less than 1 in 1000, since there are 100 000 mitochondria in the human egg and only 100 in the sperm (Satoh and Kuroiwa, 1991).”) or that paternal mtDNA is so rarely transmitted as to be negligible (“Nevertheless, studies have established that paternal mtDNA is so rarely transmitted to offspring that mtDNA analyses remain valid…”). One study stated that about 1–2% of a person’s mitochondria can be inherited from the father.
The controversy about human paternal leakage was summed up in the 1996 study Misconceptions about mitochondria and mammalian fertilization: Implications for theories on human evolution. The following quotation comes from the abstract to that peer-reviewed study printed in the Proceedings of the National Academy of Sciences:
“ In vertebrates, inheritance of mitochondria is thought to be predominantly maternal, and mitochondrial DNA analysis has become a standard taxonomic tool. In accordance with the prevailing view of strict maternal inheritance, many sources assert that during fertilization, the sperm tail, with its mitochondria, gets excluded from the embryo. This is incorrect. In the majority of mammals — including humans — the midpiece mitochondria can be identified in the embryo even though their ultimate fate is unknown. The “missing mitochondria” story seems to have survived — and proliferated — unchallenged in a time of contention between hypotheses of human origins, because it supports the “African Eve” model of recent radiation of Homo sapiens out of Africa. ”
The mixing of maternal and paternal mtDNA was thought to have been found in humans and chimpanzees in 1999. However, there has been only a single documented case of human paternal mitochondrial DNA transmission, and it was linked to infertility.