She Has Her Mother’s Laugh [Carl Zimmer]

Start Date: 1 April 2019

Finish Date: 5 April 2019

Goodreads link.

Source: Amazon India Kindle edition


  • I hadn’t realised what a whopper this book was. I started it on a Delhi – Frankfurt flight, and even with a two hour extension caused by Pakistani airspace closure, I hadn’t finished it by the time I landed. I finally got done with it on the next segment of the flight, Frankfurt – Bilbao. That made it a little tough to get through and absorb in one go.
  • A lot of this was familiar, and it seems like Carl Zimmer collected any of his newspaper longform reporting that was related to genetics or heredity, made it even more longform, and then put all the pieces together as a book. Not that there’s anything wrong with that, but it means that I should probably have read it in chunks of two to three chapters to absorb it better.

Specific things which struck me:

The Greek physician Hippocrates argued that men and women both produced semen, and that new life formed when the two were mixed. That blending accounted for how children ended up with a mix of their parents’ characteristics. Aristotle disagreed, believing that only men produced the seeds of life. Their seeds grew on menstrual blood inside women’s bodies, developing into embryos. Aristotle and his followers believed a woman could influence the traits of her children, but only in the way the soil can influence how an acorn grows into an oak tree.

This is similar to how the Mahabharata has Aswatthama being born from semen alone.

  • The story of PKU, which I had last encountered in Class XII, but now I came to appreciate the rich history behind it.
  • The involved way in which Lamarckian heredity is making a sort-of comeback (but an overhyped one)
  • Learning that the reason dwarf wheat is so high yielding is because it doesn’t get flattened by wind as regular wheat does. (Side note: I once went cycling through Germany, and at one point the road went between wheat fields. The variety must have been a traditional one, because I was overshadowed by those giant plants.)

The longest record of height can be found in Europe, where it stretches back thirty thousand years to the Gravettian culture. Gravettian men stood on average six feet tall. When agriculture arrived in Europe some eight thousand years ago, people experienced a tremendous drop in stature. Men lost eight inches of height. The drop was likely the result of Europeans switching to a grain-rich diet much lower in protein.

I cringe a bit every time something that ties into Yuval Noah Harari’s “Agriculture and civilisation are so terrible!” thesis comes up; thought that is less about the fact and more about how Harari takes the facts to absurdity. On the other hand, go protein! Down with rice!

In 2016, an international network of researchers extended this survey to the world. Over the past century, they found, some countries outside of Europe experienced equally impressive gains. South Korean women experienced the biggest gain, growing eight inches in one hundred years. Among men, Iranians grew the most, now standing six and a half inches taller than they did in the early 1900s. Some people barely grew at all: Pakistani men gained just half an inch.

This doesn’t tie in with anything, I just found it interesting.

When German psychiatrists called for the sterilization of even the mildly feebleminded, their proposal was shot down. Many of Hitler’s young Brownshirts would have fallen into that category—not to mention 10 percent of the German army. Friedrich Bartels, the deputy leader of the Reich doctors, rejected intelligence tests because they could condemn decent young German peasants.

Everywhere, even with Nazis, ideology ends up being held back by expedience.

  • The entire chapter on moasicism, chimerism, and other such transgenic creatures (moreover, ones which arise without any human intent) was fascinating. It also made pregnancy sound even more creepy to me. It was bad enough when pregnancy meant that you had another human being inside you, diverting all your food like a tapeworm (thank you for that analogy, House MD), but now it turns out that the fetus might permanently change your genome. Outside of pregnancy, that’s the stuff of horror (or superhero) movies.

But the one-fin flashlight fish has no genes for making light, Haneda and Tsuji discovered. The glowing cells in their light organ do not belong to the fish itself. They are bacteria. They are not just any bacteria, however. If you look in the light organs of any one-fin flashlight fish, the glowing microbes always belong to the same strain, known as Candidatus Photodesmus blepharus. And if you want to find Candidatus Photodesmus blepharus, the one-fin flashlight fish is the only species on Earth where you’ll find it. The same waters around the Banda Islands are also home to a nearly identical species, the two-fin flashlight fish, with its own bacteria-loaded light organ. But the bacteria glowing inside them is different. Each species of flashlight fish inherits its own exquisitely rare microbial partner.

Holy shit.

A number of other studies have come to a similar conclusion: We humans have evolved more tolerance for each other than other species. That gives us more opportunity to learn from one another. And that extra social learning may be crucial for making culture cumulative.

“Alloys are stronger.”

And that one quote by a rabbi about how exchange turns difference from a curse to a blessing. I can’t find it right now though.

The question of consent isn’t new to germ line engineering either. We don’t require that children give their consent in order to get vaccines or antibiotics. That’s what parents are for.

This is the annoyed thought I had while listening to the Flash Forward episode on CRISPR for designer babies.


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