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Genetic Linkage

17 Timepoints When a Human Life Might Begin, 2022 Version

I originally published When Does a Human Life Begin? 17 Timepoints here at DNA Science in 2013. My intent was to inform those who confuse embryo with fetus with baby by presenting how biologists describe human prenatal development – beginning at fertilization. Human gestation is on average 38 weeks, not 40, according to biology.


I rerun "17 Timepoints" periodically to counter assaults on woman's reproductive rights – which unfortunately happens with disturbing regularity.


In 2017, I reposted when The Federalist published "Life Begins at Conception, Says Department of Health and Human Services."


Then in September 2021, Genetic Literacy Project reran "17 Timepoints" with the updated headline (which I didn't write) Viewpoint: 'The fetus is 1/25th of an inch' — Texas abortion ban bungles the science on when human life begins, contends biologist and professor.'


And along the way, various right-to-lifers have responded to my post with insults to my expertise, but no sign of actually understanding the biology. So it goes …


Now the rerun of "17 Timepoints" is in response to the leaked Supreme Court document threatening Roe v Wade, published in Politico and written by Josh Gerstein and Alexander Ward. To paraphrase Ronald Reagan, here we go again.


To continue reading, go to my DNA Science blog at Public Library of Science, where this post first appeared. 

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The Utter Oddness of COVID Anosmia

The sudden inability to smell and taste that comes with COVID is startling and difficult to describe. I was lucky to experience it only for a few days.


Anosmia is the partial or total loss of the ability to smell, which vanquishes most of the sense of taste, too. The COVID version is more profound than the familiar dulling of the sense from the mucus of a common cold. And it has a different origin.


The odd part of COVID anosmia is that the virus alters gene expression in nerve cells in the nose – even though the virus can't actually enter nerve cells (neurons). Then the temporarily crippled cells can't signal the brain that the person is inhaling near the seashore or passing a garbage dump. Understanding the basis of the secondhand assault may clarify other puzzling effects of the changeling coronavirus – perhaps even long COVID.


Clever experiments recently revealed how COVID anosmia happens. Benjamin R. tenOever and colleagues from the NYU Grossman School of Medicine and Columbia University report their work using golden hamsters and the noses of human corpses in Cell.


First, a closer look at how the sense of smell works.


To continue reading, go to my DNA Science blog at Public Library of Science, where this post first appeared. 

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