Why are human brains shrinking?
What do we know about immunity to SARS-CoV-2? Why does anything exist at all? Why do plants make caffeine? Why do orcas go through menopause? Why does juice taste weird after brushing your teeth?
This is my twentieth newsletter, so let’s start with a bit of good news.
Antibody immunity to SARS-CoV-2
There’s a research article that published in Nature that indicates that even when antibodies decline, the levels of specific memory B cells against SARS-CoV-2 remain. Memory B cells are immune cells that remain in the body after infection and can rapidly proliferate and generate antibodies.
Between antibodies and memory B cells and T cells, immunity post-symptomatic infection (and likely also after vaccination) is probably in the order of one or more years (not just a few months). The complicating factor might be mutational variants, but some immunity would still be expected.
I think it is likely that once a significant portion of the world is vaccinated or has been infected (hopefully the former) and the pandemic ends, it is possible that SARS-CoV-2 will cause a much milder infection in most people.
Now on to other topics…
Why are human brains shrinking?
The human brain has been shrinking over time from the peak size about 15,000 to 40,000 years ago to now. No one seems to know quite why but there are a couple of theories.
Some scientists think that with the initial advent of agriculture, humans generally had worse nutrition- a trend which has only been reversed recently. Others have pointed to global warming: as temperatures have risen over the last 20,000 years, our bodies and brains shrank together.
The theory that no one wants to hear is that overall, humans are getting stupider. But some are saying it—
As complex societies emerged, the brain became smaller because people did not have to be as smart to stay alive… Individuals who would not have been able to survive by their wits alone could scrape by with the help of others — supported, as it were, by the first social safety nets.
Here’s an article that predicts that language, computers, and other instruments of society are extensions of the human brain and that most of “human memory and cultural information is now stored external to the brain.”
If the human brain is shrinking overall overall over thousands of years, there’s really not much that we can do about. But individual brains also shrink over time due to the effects of age. The brain shrinks 5% per decade after 40, but much more significantly over 70. How can we slow or reverse the effects of an aging brain?
Through physical and mental activity.
Why does anything even exist?
Don’t brush my question off as simply metaphysical musings. I am going somewhere with this.
Stuff is matter. All matter consists of subatomic particles— a cloud of electrons surrounding an atomic nucleus with protons and neutrons. For every matter particle, there should be an antimatter particle with the same mass and amount of charge, but with different spin and charge. We know this mathematically from the brilliant physicist Paul Dirac's beautiful calculations.
Let’s go back to the origin of the universe. At the Big Bang there was energy, but no matter or antimatter. One-billionth of a second after the Big Bang there was an equal amount of matter and antimatter. This is problematic. When matter and antimatter collide there is total annihilation of both with tremendous energy. So why is there any stuff today at all?
It’s possible that most of the matter and all of the antimatter did annihilate each other just after the Big Bang. In that case, the entire universe- everything that exists today- is made of 0.0000001% of matter that persisted after that cataclysm. Figure out why anything exists and you might just win a Nobel Prize in Physics!
Why do plants make caffeine?
I am addicted to caffeine, though I’ve certainly cut back on the number of cups of coffee and tea I drink each day. Much of modern society does not function without a daily dose of this stimulant. But have you stopped to think why certain plants make caffeine at all? What does it benefit these plants?
Caffeine is a methylxanthine alkaloid produced by at least thirty different kinds of plants. It’s non-essential to the plants and is, in fact, toxic so it has to be stored in cellular compartments known as vacuoles.
Caffeine is thought to be a natural herbicide or a pesticide. The theory held for the longest time is that since caffeine is poisonous, plants that produce it have a competitive advantage against their "enemies" in the plant and animal kingdoms. But caffeine gives other animals, including certain insects, a buzz too. This is yet another one of those mysteries that has not yet been solved.
Why does orange juice or lime sherbet taste funny just after brushing your teeth?
I had an aunt who loved me dearly. Whenever I visited, every morning she'd ask if I had brushed my teeth and then offer me a glass of lime sharbat. I would be exasperated because it tasted bitter. We've been there many times with citrus fruits. They don't mix with toothpaste.
This is because there is a kind of surfactant (basically soap) in most toothpastes that help them foam up when we brush. This surfactant, sodium laurel sulfate (SLS), is also found in shampoos and detergents. SLS blocks the normal taste of citrus fruits in two main ways—
1. SLS suppresses the receptors on the taste buds that pick up sweet flavors. So, for a while at least, it's hard to make out any sweet taste, not just the ones from citrus fruits. 2. SLS also breaks up phospholipids which normally block receptors that sense bitterness.
Citrus flavors are a mix of both sweet and bitter. By suppressing the sweetness and enhancing the bitterness, SLS causes that weird orange juice or lime sharbat taste just after brushing.
Why do orcas go through menopause?
This is pretty incredible stuff.
Credit: Pixabay. Creative commons license
Humans are the only primates that go through menopause. Almost no other animals live for decades beyond their reproductive ages. There are two exceptions: killer whales (orcas) and short-finned whale. But why only these animals?
Through the lens of evolution, it makes sense why animals wouldn't survive for much longer than their reproductive capabilities: the primary biological purpose is to propagate, so animals typically do it for as long as they're alive.
So, killer whales and humans are anomalies. Many scientists believe that in humans this can explained by better nutrition, health, farming– we simply live longer. But this doesn't explain why it's so for the killer whales. A little bit about killer whales. Killer whale females live for much longer– I'm talking decades longer than males. They can bear offspring into their forties and fifties and then live past 100 years.
But why do these whales undergo menopause?
Scientists used to think that the reason was cooperation. Now they believe it’s competition. Calves born later in a mother’s life are less likely to survive.
Two years ago, scientists suggested whales do this to focus their attention on the survival of their families rather than on birthing more offspring. But now this same team reports there’s another—and darker—reason: Older females enter menopause because their eldest daughters begin having calves, leading to fights over resources. The findings might also apply to humans, the scientists say.
Good news from science and medicine
Treatment for progeria
The first drug for progeria got approved. Avid watchers of Hindi films will be aware of this condition from the movie Paa. The drug is not a cure, but it does extend lifespan by about 2.5 years.
Children with the disease, known as Hutchinson-Gilford progeria syndrome, or progeria for short, often die of heart failure, heart attack or stroke as teenagers. Most children with the disorder die before they reach age 15. The newly approved drug, called Zokinvy, is the first and only approved treatment for progeria and certain related syndromes, the FDA announced November 20.
Genome editing cures beta thalassemia and sickle cell disease
I'm not sure many people saw this or realize how big of a deal this is but we now have an experimental treatment for beta thalassemia and sickle cell disease which might be permanent. CRISPR is a genome editing technology that won it’s discoverers the Nobel Prize in Chemistry in 2020. Now, in some of the most exciting developments in medicine, it is being used to treat beta thalassemia and sickle cell disease.
"This gives us great confidence that this can be a one-time therapy that can be a cure for life," says Samarth Kulkarni, the CEO of CRISPR Therapeutics.
Gray and the two other sickle cell patients haven't had any complications from their disease since getting the treatment, including any pain attacks or hospitalizations. Gray has also been able to wean off the powerful pain medications she'd needed most of her life.
Prior to the treatment, Gray experienced an average of seven such episodes every year. Similarly, the beta thalassemia patients haven't needed the regular blood transfusions that had been required to keep them alive.
Here’s the link to the Kindle version on Amazon.com.
Here’s the link to the hardcover version on Amazon’s Indian site.
Here’s an excerpt of the book in which I talk about how so many COVID-19 vaccines were developed so quickly (and why they’re not the same).
If you enjoy the book, please do leave me a review on Amazon or on Goodreads.
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