Why do giraffes have long necks?
Plus new information on when the first humans might have arrived in India, the boy who felt no pain, the laughter epidemic, and Alzheimer's and dementia risk from Long COVID.
Hello! How have you been?
First some boring stuff. It’s been nearly a year!
I started this newsletter to share critical information about COVID-19 with friends. Over the course of 37 newsletters, I’ve diversified into many areas of science and have shared what I’ve found fascinating. I’m grateful to the 1000 or so people who open this newsletter every week.
Overall, anywhere from one-third to half of those who’ve signed up open any particular newsletter each week. That said, I don’t get much feedback on my newsletters, so I’m not sure how many people actually read them. If you do, please feel free to drop me a note or hit the “like” on the newsletter. I’d really love to hear from you!
After a year of newsletters, two dozen or so popular science articles for media (you read the eighteen I’ve written for Hindustan Times here), and a book on COVID-19, you will understand why I will slow down or take a break. Everything that I do takes away time from something else. But again, that’s why I want to hear from you. ;-)
Now, on to the interesting bits.
The boy who felt no pain
What if you could never feel pain? Would you take it?
You don’t have to wonder. My column this week in Hindustan Times is on rare genetic variations in people that cause them to not feel any pain.
A University of Cambridge geneticist had heard stories about a child in a Pakistani marketplace who was hurting himself to entertain tourists. This boy stuck knives through his arms and walked over burning coals. He felt nothing.
The Cambridge geneticist reached out to a London neuroscientist who studied how humans feel pain. Together they decided to meet and study the boy. But by that time, tragedy had occurred. As he turned 14, the boy died from head injuries after jumping from the roof of a building. The Cambridge geneticist did not give up. With Pakistani colleagues, he found three members of the Quereshi biradari who didn't feel pain. Scanning the genomes of these pain-resistant people, they were able to identify a rare mutation. The discovery was published in a landmark paper in Nature.
Since then others have also been found with this rare mutation. They fracture bones. Infants chew through their tongue and lips. Women give birth without feeling pain. They're of normal intelligence. But oddly enough, they also go through life without the sense of smell. You can read the rest of the fascinating search for painkillers here (Click “skip” or register at the prompt to get past the registration wall).
Why do giraffes have long necks?
There's the answer you might remember from school and the answer your child has to write to pass an exam— "To eat leaves from the tops of trees."
And then there's the accurate answer— "No one knows for sure."
Lamarck thought giraffes stretched their necks to reach the top. Darwin thought there were long-necked and short necked giraffes and the longer ones got selected progressively over generations. Darwin was right on the how. Both assumed as have many others they knew the why.
This is a foundational story on evolution that every educated person knows. But it's also a classic case of correlation not equalling causation. Since the Nineties there has been a lot of debate among professional biologists on why giraffes have long necks.
Giraffes might have long necks to reach the tops of trees. They might have long necks because it helps them to get mates. Males use their necks to fight with one another. Giraffes might have long necks to see more of trees and predators. It could also be more than one reason.
"Diabetics faced a cruel choice: death by diabetes or death by starvation."
In 1930, Elizabeth Evan Hughes made a spectacular recovery (from certain death) after receiving one of the first doses of insulin. She died 60 years later after over 40,000 injections of insulin.
U.S. vaccines update for kids:
The Pfizer and Moderna trials for small children (6 months to 5 and 5-11) started in March.
The Pfizer Emergency Use Authorization request for children between 5-11 is expected this month and Moderna’s later in Fall.
Human migrations to India
Yesterday, one of the most significant studies on the dispersal of humans to the Arabian Peninsula and potentially eastward to India and Southeast Asia was published in Nature. This lays the foundations for work on early human migrations in Asia and Australia.
The emerging picture from Arabia supports the suggestion that the initial development of the stone tools characteristic of the Middle Palaeolithic period in India between 172,000 and 385,000 years ago might have resulted from immigration by Homo sapiens or one of its hominin relatives.
It is likely that humans were in India 74,000 years ago before the mega-eruption of the Toba volcano in Indonesia. We knew this before today. Now, it is possible that they were in India much before that, even though remains have not been found.
If there were migrations of humans out of Africa into Arabia ~400,000 years ago during periods of greater rainfall as we just learned, there is very high likelihood that some of these groups continued east to India, though their remains have yet to be discovered.
An epidemic of laughter
In 1962, three schoolgirls started laughing uncontrollably. Laughter spread quickly affecting 1,000 people over several months. It caused 14 schools to close. To this date no one knows why.
The Tanganyika laughter epidemic is one of the weirdest episodes of modern medicine
A report of this epidemic can be found in an article in the Central African Journal of Medicine dated May, 1963.
Here’s what else I’ve read this week:
Here’s how a flower extract keeps off mosquitoes.
One in three trees face extinction in wild, says new report.
A study in mice shows that high-fructose corn syrup promotes obesity by boosting the ability of the intestine to absorb nutrients.
Doctors are worried about the chance of Alzheimer’s and dementia in those who have Long COVID. I will be reading up more of the scientific literature on this and will write something myself if there’s interest.
Loved this!
I so look forward to your posts. Keep writing!